Site-specific design strategies in coastal defense structures: Consolidation of ecosystem resilience for fisheries and mitigation measures against coastal hazard

Haruka Yoshimura, Ph.D.

Fig. 1 Recreational Shellfish Harvesting during Spring Low Tide (Tokyo: 35°41′ N, 139°47′ E) from the series Cultures and Customs of Edo throughout Four Seasons, Tchikanobu Yosyu (揚州周延, 1838–1912), originally published 1890 (Image courtesy of the National Diet Library, Japan). Historically, Japan developed unique mitigation measures to protect coastal areas from risk of coastal hazards such as tropical cyclone (typhoon) and tsunami integrated with marine resources management. Along the coastal landscapes elaborately shaped by humans, marine resources were abundant and varied, which in turn provided venues for numerous pleasurable activities for people. This multi-colored print in the Meiji era (1868–1912) depicts people enjoying shellfish harvesting nearby the central part of the city of Edo, sea-breeze blowing softly onto a young mother and two boys with a basket full of clams (蛤, Orient clam, Meretrix lusoria, the most valued clam among variety of calms). As depicted in the middle distance, expensive large fishes such as red seabream (tai, 鯛, Pagrus major, up to 1 m/3.3 ft) and flounder (hirame, 鮃, Paralichthys olivaceus, up to 85 cm/3 ft), which highly praised for Japanese cuisine sashimi (sliced fresh fish served raw with garnished herbs) and/or Edo-style sushi (sliced raw/cooked fish/shellfish on an oval-shaped ball of vinegared rice), were able to be caught by hands. While specifically designed for Edo, the comprehensive approach of ‘landscape architecture between the sea water and the sea-strands’ is appliable to many coastal cities around the world as mitigation measures suitable for the era in the face of climate change.

1.     Introduction

 

1.1 Unique land governance in coastal megacity of Edo: Strategies of fisheries management integrated with coastal protection

 

Edo (lit., bay-entrance or estuary), the former name of the Japanese capital Tokyo (35°41′N, 139°45′E; Fig. 6-A), lies on the shores of Edo (Tokyo) Bay. In 1590, Ieyasu Tokugawa (徳川家康1542–1616) settled in Edo and established his Shogunate (military governing dynasty) in 1603. Edo began to increase in extent and population, and had estimated population of over 1,000,000 as early as the middle of the eighteenth century, making it the largest metropolis in the worlds (Sansom 1963; Uspensky 2003).  

Edo depended upon resources such as grain (rice, barley, and so on), building materials and other material goods from distant parts of Japan (Sansom 1963). On the other hand, fisheries resources were abundant and varied, and were adapted to almost all the requirements of the people so it should not be necessary to depend on any other parts of Japan for the supplies. Edo had a strong cultural relationship with the natural environment of coastal zones. The ties with the coastal sea were felt even nearby the central part of the city. Recreation of edible shellfish gathering at spring low-tide (Fig. 1) represents essence of the effective policy and management strategies.

Although humans depend upon marine ecosystems for diverse resources and services, productivity and functions of the ecosystems are deteriorating (Worm et al. 2006; Halpern et al. 2008; Diaz and Rosenberg 2008). Consequently, global fisheries landings have been declining since the late 1980s (Pauly et al. 2003; Pauly and Zeller 2016). Seafood supply to meeting the protein requirements of human populations is important for human health (Golden et al. 2016), food security (Garsia and Rosenberg 2010), and for social resilience (Adger et al. 2005; Goes et al. 2020). In Edo, the food security supported by fisheries productivity was reflected in the policy of land governance. Japanese land governance in coastal zones was unique.

Hiroshige Utagawa (歌川広重1797–1858) illustrated many coastal landscapes in urban and peri-urban areas of Edo, showcasing landscapes of diverse site-specific design strategies by unique engineering techniques to protect coastal areas from risk of coastal hazards, to control erosion, and to maintain productive fisheries. Notably, Japanese coastal protections were designed to preserve/restore submerged vegetation and beaches which occur in front of the structures and adjoining unprotected beaches. Owing to his samurai background, Hiroshige had knowledge of the conceptual framework for design and land-use planning in Eastern philosophy. Hiroshige depicts the integrated coastal management strategies of the megacity in the context of a great conurbation.

Cities are supported by appropriate ecosystem services in urban areas and from around the world (Folke et al. 1997; Kaye et al. 2006; Grimm et al. 2008). However, capacity of the planet to sustain cities with ecological services is increasingly eroded (Hooke et al. 2012). Therefore, there is pressing need to take into account appropriate ecosystem services in urban governance to sustain cities (Seitzinger et al. 2012).

Management of coastal ecosystems is connected with important policy issues: coastal hazard mitigation, management of fisheries resources for food security, erosion control, natural sinks on land and the ocean removing atmospheric CO₂ via photosynthesis (Canadell et al. 2007), and CO₂ sequestration in a vast area of ocean (known as ‘blue carbon’). A strategic approach for restoration of resilience of coastal ecosystems should be reflected in policy decisions.

 

1.2 Increasing risks of coastal hazards in population in coastal area

 

Rapid population growth and urban land expansion in coastal area

Historically, populations have preferred live in estuarine and coasts. Although low-elevation coastal zones below 10 m (33 ft) elevation covers only 2% of the world’s land area (McGranahan et al. 2007), an estimated population between 750 million and nearly 1.1 billion lives in these zones in 2015 (MacManus et al. 2021). The global population reached 8.0 billion in 2022 (UN 2023). The population growth in the low-elevation coastal zone is assumed to continue to increase (Neumann et al. 2015).

The low-elevation coastal areas are among the most rapidly urbanizing around the world. About 34% of the area of urban land use, impervious surfaces and the built environment, occupies within 10 m of low elevation coastal zones. Urban land expansion rates in the coastal zone were significantly higher than in the non-coastal hinterland from 1970 to 2000 (Seto et al. 2011). The coastal urbanization can be expected to continue into the future or to even increase (MacManus et al. 2021).

 

Increasing risks of coastal hazards in population in low-elevation coastal zone

Coastal populations in coastal lowlands of less than 10 m elevation are especially vulnerable to risks of sea-level rise resulting from climate change (Nicholls and Cazenave 2010), storm-surge flooding by stronger tropical storms (Emanuel 2005; Rahmstorf 2017; Garner et al. 2017), and tsunamis (Kron 2013; Esteban et al. 2013; Maramai et al. 2014).

Currently, ecosystem structure and function in estuarine and coastal seas have been lost as a result of human activity (Lotze et al. 2006). Coastal habitats provide buffers in protecting coastlines (Shepard et al. 2011; Narayan et al. 2016), and comprise the basis for fishery productivity (e.g., Chesney et al. 2000). Therefore, the degradation of coastal wetlands, salt marshes and mangroves, can result in an increased vulnerability of populated coastal zones and depleted fishery resources.

 

2.     Need for land governance in land-sea interface

 

2.1  Unforeseen negative impacts of hard engineering coastal defense system: Negative impacts on climate; Accelerated erosion; Loss of nursery and foraging grounds

 

2.1.1       Negative impacts of hard coastal structures on climate

To date, risk management policy on coastal protection has relied heavily on hard measures such as seawalls and bulkheads (Airoldi and Beck 2007; Rosenzweig et al. 2011; Suppasri et al. 2016). In Europe alone, 22,000 km² of the coastline are artificially covered with concrete or asphalt, and artificial surfaces increased by almost 1,900 km² between 1990 and 2000 alone (Airoldi and Beck 2007). Gittman et al. (2015) estimated that 22,842 km of continental US shoreline – approximately 14% of the total US coastline – has been hardened and armored.

Photosynthesis in coastal zone influences global climate, via natural sinks on land and the ocean removing atmospheric CO₂ through photosynthesis (Canadell et al. 2007), via CO₂ sequestration in the deep sea (phytoplankton: Field et al. 1998, Falkowski et al. 1998; coastal vegetation: Duarte et al. 2005, Duarte 2017), and via solar radiation valance. The hard engineering coastal defense systems destroy the most productive estuarine and coastal ecosystems, which in turn leads to unforeseen negative impacts on global climate: weakening CO₂ sequestration capability; rising sea surface temperatures and increase in evaporation from oceans. Declining marine photosynthesis (coastal vegetation and phytoplankton) weakens the capacity of natural sinks removing atmospheric CO₂ and CO₂ sequestration in the deep sea, which sequentially accelerates global warming. Decline of marine photosynthesis results in decrease of absorbed solar radiation energy by photosynthetic plant pigments. The fraction that previously absorbed for photosynthesis is absorbed by sea water, which in turn increases in sea surface temperatures. Evaporation from the oceans can increase, as the fraction of solar radiation energy that was previously absorbed by photosynthetic pigments is allocated to latent heat flux (solar radiation energy used to evaporate water from the ocean surface). Intensified supply of moisture source of precipitation by the warmer wetter marine air leads to changes in precipitation pattern, and increase the frequency and severity of tropical cyclones (http://harukanoor4.blogspot.com/2022/).

 

2.1.2 Accelerated coastal erosion   

 

Sandy beaches, which occupy more than third of global coastline, are already eroding. Furthermore, sandy shorelines worldwide are under threat of erosion due to the rising sea levels and more intense storms by climate change (Vousdoukas et al. 2020).    

The hard engineering coastal defense structures such as seawalls, which grow rapidly in the second half of the twentieth century, accelerate erosion, causing beach loss. The reflected wave energy by the seawall leads to scour at the base of seawalls, accelerating beach loss in front of them. And eventually, larger and stronger seawalls are needed over time (e.g., Loucks et al. 2005). Furthermore, hardening shoreline promotes erosion an adjacent beach. Increasing development and seawall construction result in expanding erosion and beach loss due to flanking: erosion triggered and accelerated by nearby hardening shoreline (Summers et al. 2018).

Recent studies using satellite images to track the shoreline change reveal that coastal shorelines worldwide are rapidly eroding (Luijendijk et al. 2018; Mentaschi et al. 2018). The ongoing coastal erosion degrades coastal resilience and increases vulnerability against coastal hazard caused by sea level rise and increased extreme weather expected with climate change.

The natural coastal replenishment dynamics have already altered, because sediment supply to coastal regions decreased, due to installation of dams (e.g., Mentaschi et al. 2018). Therefore, design for shoreline stabilization and implementation of effective adaptive measures are required more than ever before.

 

2.1.2       Failure to protect coastal communities

 

Failure of hard measures on the 2011 Tohoku tsunami

Although coastal protection has relied heavily on hard engineering measures in risk management policy, it is becoming increasingly clear that hard structures can fail.

‘Tsunami,’ most commonly generated by earthquakes in marine and coastal regions, is a Japanese word, represented by two characters tsu (津, meaning ‘harbour’) and nami (波, meaning ‘wave’). Major tsunamis, produced by large and shallow focus earthquakes associated with the movement of oceanic and continental tectonic plates, frequently occur in the Pacific, where oceanic plates slide under the continental plates (Bernard et al. 2006).

On 11 March 2011, a 9.0 magnitude earthquake occurred 130 km (81 miles) off Japan’s Pacific coast. This earthquake (epicenter: 38°06.2′ N, 142°51.6′ E; depth: 24 km/ 15 miles) triggered a massive tsunami, causing extensive damage mostly along 600 km (373 miles) of the Sanriku Coast, killed 15,883 people, with an additional 2,656 missing (Mori et al. 2011; Tsuji et al. 2014).

 While there is no other nation that engineering measures such as concrete seawalls and flood dykes have been developed to protect populated coastal areas from tsunami, the coastal hard countermeasures were significantly damaged by the tsunami.

At Taro in Miyako city (39°44′ N, 141°59′ E), the huge wave poured over the seawalls (with a height of 10 m/33 ft and a total length of over 2.4 km/1.5 miles), consequently swept away almost all houses and fishing facilities (Tsuji et al. 2014). The tsunami waves, topped around 20 m/66 ft, battered other coastal sites. The tsunami waves penetrated inland and traveled up rivers, overflowing river banks. In the 2011 Tohoku tsunami, the maximum run-up height was 39.7 m (130 ft) at Miyako (Mori et al. 2011).

Tsunami wave amplifies in funnel-shaped bays such as submergent coastline: drowned river valleys or rias (Mori et al. 2011; Suppasri et al. 2013), and drowned glaciated valleys or fjords (Maramai et al. 2014). The height of inundation and run-up at the mouth of a bay increases much higher inside the bay, as the wave reflections and refractions within the bay. Due to the local geography of submergent coastline of rias, the Sanriku Coast has a long history of devastating tsunamis with the amplified waves. As a countermeasure, large-scale tsunami breakwaters were constructed at the entrance of the bay notably in Kamaishi and Ofunato.  In Kamaishi (39°16′ N, 141°53′ E), the world largest concrete caisson seawall erected to protect harbor in the entrance of the Kamaishi bay at a depth of 63 m/207 ft, a length of 2 km/1.24 miles and a cost of JPY 120 billion ($1.5 billion), in addition, populated coastal areas were completely surrounded by concrete tsunami walls up to 6.1 m/3.3 ft. Although the concrete caisson seawall helped to reduce the impact of the tsunami and to delay the arrival time, both of the engineering structures, the caisson seawall at bay entrance and concrete tsunami walls, were collapsed by the waves and they did not prevent major destruction and loss of life (Suppasri et al. 2013).

 

2.1.4 Ecosystem-based coastal protection

 

Coastal vegetation has provided coastal protection from waves and storm surges, for millennia. Salt marches reduce the height and velocity of incoming waves by buffering of vegetation structures and stabilizing sediment, rising the marsh land height (Morgen et al. 2009; Barbier et al. 2011). In addition, marshes are effective in wave dissipation of storm surge and remain resilient even at extreme events (Möller et al. 2014).

Similarly, seagrass meadows stabilize sediment by the roots and rhizomes, preventing erosion, which in turn provide shoreline protection (Duarte 2002). Kelp forests reduce the longshore current and wave energy, promoting sedimentation. Notably, ecosystem-based coastal protection has the benefit that coastal plant habitats can adapt to changes in climate, and self-repair after major storm events (Morris et al. 2020).

Therefore, coastal defense using natural or restored vegetated coastal habitat systems plays a critical role in reducing the vulnerability of coastal communities that faced with a changing climate (Temmerman et al. 2013; Spalding et al. 2014).

 

2.2 Loss of nursery and foraging grounds leads to decline of global fisheries

 

1.2.1       The nursery role of underwater seagrass meadows.

 

Most marine species of commercial value require more than a single habitat to live and spawn. The fish species of major industrial offshore fisheries, such as Alaska (walleye) pollock (介宗鱈, Theragra chalcogramma, the most landed species on the planet), Atlantic cod (Gadus morhua), Pacific cod (真鱈, Gadus macrocephalus), Atlantic herring (Clupea harengus), and Pacific herring (nishin, 鰊, Clupea pallasii), spend their adult life shoaling in deep offshore waters where they live, feed, and spawn. However, juveniles require seagrass meadows as nursery grounds where young growth stages can take advantage of the protection and abundant food. Although the important link between seagrass meadows and offshore fisheries may not always been appreciated, loss of seagrass meadows (nursery and foraging grounds) leads to decline of productivity of global fisheries (Unsworth et al. 2018).

 

1.2.2       The nursery role of salt marshes.

 

The coastal vegetation provides essential nurseries for commercially important fish/shellfish species: salt marshes, mangrove forests (Moyle and Cech 2004), and kelp forests (Dayton 1985). Intertidal salt marshes in temperate and high-latitudes serve as nurseries for commercially important fisheries species, such as shrimp, oysters, clams, and fishes (Boesch and Turner 1984; Moyle and Cech 2004; MacKenzie and Dionne 2008). In spite that several kinds of shrimp live and spawn as adults offshore, they require salt marshes during critical life history stages as nursery grounds. Salt marsh ecosystems provide refuge habitat that is mostly inaccessible to large fishes by their complex and tightly packed plant structure, along with abundant food. Shrimp is important in the diet of almost all commercially important fish species of coastal fisheries at one history or another. Salt marshes associated fisheries productivity arises directly the provision of nursery and forage grounds for various fish and invertebrates. Thus, salt marsh ecosystems enhance quantity and quality of fisheries resources (Boesch and Turner 1984; Barbier et al. 2011).

Salt marshes play a significant role in supporting fisheries productivity. However, the connection between salt marshes and offshore fisheries have not been fully appreciated as a result of perceived spatial disconnect (most fishing activity take place offshore) (Odum 1971).  Loss of salt marshes (nursery and foraging grounds) leads to decline of productivity of local and global fisheries.

 

2.2.3 The nursery role of kelp forests.

 

Nursery role of kelp forests

Kelp forests serve to maintain fisheries as nursery and foraging grounds (Moyle and Cech 2004). Shaffer et al. (2020) provide intriguing insights into nurseries of kelp forests, which are densely inhabited by juvenile salmonoids and forage fishes, in a case in the northeast Pacific nearshore. Due to the structural complexity, the kelp forests provide refuge from predators. Global fisheries production is maintained by marine food webs—the flow of energy from phytoplankton (primary producers) through intermediate consumers to predators. In the kelp forests, phytoplankton are consumed by zooplankton (small crustaceans such as copepods and decapods). (Decapods are an order of crustaceans, including many commercially important fishery species, such as crabs, lobsters, shrimp, and prawns.) Sequentially, these smaller zooplankton are consumed by forage fishes: small, schooling, filter-feeding fish such as Pacific herring (Clupea pallasii), surf smelt (Hypomesus pretiosus), and Pacific sand lance (Ammodytes hexapterus). The forage fishes are then consumed by commercially important salmonoids, including Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), steelhead trout (O. mykiss), and cutthroat trout (O. clarkia). Furthermore, kelp zones are important for Pacific herring, as extensively used for spawning (Shaffer et al. 2020).

 

Loss of kelp forests leads to decline of herring and salmonoids

Kelp forests are typically found in temperate waters between 6 and 30 m (17 and 98 ft) (Moyle and Cech 2004). Kelp forests dominate along approximately one-quarter of the world’s coastlines (Filbee-Dexter and Wernberg 2018), because brown algae have evolved to extend their distribution deeper seawaters than seagrasses.  

Kelp forests are declining across the globe (Lotze et al. 2006; Krumhansl et al. 2016; Filbee-Dexter and Wernberg 2018; Coleman et al. 2022). Because of the important link between nursery habitat and fisheries productivity (Unsworth et al. 2018), loss of kelp forests (nursery and foraging grounds) leads to decline of productivity of herring, salmonoids, and valuable commercial crustaceans.

Herrings distribute throughout the northern coastal marine areas of the Atlantic and Pacific oceans and parts of the Arctic Ocean. In the 20th century many herring stocks around the world have collapsed (Hay et al. 2001). High abundance of forage fishes such as Atlantic herring (Clupea harengus) and Pacific herring (鰊, Clupea pallasii) plays a vital role in global fisheries production and global food security (Smith et al. 2011). Therefore, the population collapse of herring (Clupea spp.) is a challenge to sustainable fisheries management (Trochta et al. 2020).

Since the 1850s, the Pacific salmon, including Chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), steelhead trout (O. mykiss), and cutthroat trout (O. clarkia), have been declining, while many stocks have been completely extirpated (Nehlsen et al. 1991). Pacific salmon have a broad range throughout north portions of the Pacific Ocean and have a complex life history: most forms are anadromous with a juvenile phase in fresh water, followed by a long migration to the ocean for feeding/growth, and generally return to their natal streams for spawning.

In the temperate and subarctic regions of North Atlantic Ocean, the abundance of adult Atlantic salmon (Salmo salar) returns among many wild and hatchery stocks has declined since 1985. Despite of the implementation of recovery program such as closure of commercial fisheries, restriction/prohibition of angling, and removal of dams, the collapse of some stocks has occurred (Dadswell et al. 2022).

 

Loss of kelp forests may lead to decline of commercially important crustaceans such as lobster, red king crab, and snow crab

Shaffer et al. (2020) indicate abundant decapods (an order of crustaceans, including lobsters and crabs) in the kelp forests in a case in the northeast Pacific nearshore, which suggests that many valuable commercial crustaceans such as crabs and lobsters use kelp forests as a nursery and feeding grounds. Despite of the increasing economic importance of crustaceans to humans (Susanto 2021), commercially important crustaceans are declining in the seas around the world.

Norway’s coastal lobster fishery has a long history. Export of live lobster to central Europe started around 1650. The official landing of 1.3 million (515 tons) of the European lobster (Homarus gammarus) in 1928 is declined to 41 tons in 2019 (Kleiven et al. 2022).

In Kamchatka in far eastern Russia, large-scale fisheries of the red king crab (タラバガニ, Paralithodes camtschaticus, a highly valued delicacy on the international market), started in 1925, and by 1927 annual landings were as high as 30 million crabs. Despite repeated fishery closures, the abundance of P. camtschaticus decreased. Landings of the reopened fisheries in 2013 was 6,785 tons, which was less than one tenth of the landing in 1927. Red king crabs were historically fished in spring in coastal waters at the approximate depth of 10–30 m (33–98 ft) where red king crabs gather for mating (Dvoretsky and Dvoretsky 2018). Which suggests that red king crabs use kelp forests for spawning, as kelp forests are typically formed in the depth of coastal waters. During summer and autumn, fishing follows red king crab migration to depths greater than 35 m (115 ft) and then down to 100 m (328 ft) (Dvoretsky and Dvoretsky 2018).

The commercial fishery of red king crabs (P. camtschaticus) in Peter the Great Bay, Sea of Japan, commenced in 1874, was contributed to industry of canned king crabs with the high export value. Associated with improved fishing methods, landing of P. camtschaticus increased and reached to 11,500 tons in 1943. However, these overfishing led to depletion of red king crab abundance. Despite repetitive fishery closure, the commercial stock of this region was only 830 tons in 2000 (Dvoretsky and Dvoretsky 2018).

The second largest population of red king crab resides in the Bristol Bay, Alaska, in the southeastern Bering Sea. During 1959 to 1979, trawling and tangle-net fishing were prohibited in a 67,000 km² area of Bristol Bay (shaped a broad and unbroken coastal zone) known as the Pot Sanctuary, which was once a successful reproductive strategy for red king crab, the most valuable single-species fishery in Alaska. In 1980, bottom trawling was begun within the Pot Sanctuary. Landing of male red king crab in 1980 recorded 59,000 tons, but by 1983 the catch had dropped to zero (Dew and McConnaughey 2005).    　

Socio-economic resilience of the Northwest Atlantic coastal zones of Newfoundland and Labrador, Canada, depends upon fisheries resources. The early 1990s’ fishery closures of Atlantic cod (Gadus morhua) and other important fish stocks such as American plaice (Hippoglossoides platessoides) increased in importance of fishery of snow crab (ズワイガニ, Chionoecetes opilio). The snow crab resource is in decline, after peaks in the late 1990s and between 2008 and 2010.  Landings have been maintained at 50,000–60,000 tons since 1999. In spite of world’s largest snow crab fishery since the mid-1990s, recruitment prospects are diminishing: reduced abundance of all sizes; a marked decrease in the abundance of mature females (Mullowney et al. 2014).

Fisheries productivity is supported by nursery grounds: salt marshes, seagrass meadows, and kelp forests. To restore productive fisheries productivity, there is an urgent need to preserve/restore salt marshes, seagrass meadows, and kelp forests as nursery grounds. Acknowledged that fisheries productivity plays a vital role in food security, a strategic approach for restoration of large-scale coastal ecosystems should be reflected in the policy decisions.

 

3.     Unique approaches to coastal hazard mitigation in Eastern philosophy

 

3.1 Effectiveness of natural landforms (geographical features) on tsunami mitigation

 

3.1.1 Evidence-based approach in effectiveness of tsunami mitigation: coastal topography and vegetation cover

 

Since the Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005, the need for an integrated approach to resilience of coastal ecosystems that support local societies and economies, and coastal hazard mitigation has been recognized (e.g., Adger et al. 2005). There is mounting evidence that natural landform provides buffering from tsunamis. In the Indian Ocean tsunami on 26 December 2004 generated by an earthquake of magnitude 9.0 off the west coast of northern Sumatra (Indonesia), villages situated behind the elevated places with steep topography and/or dunes were protected against the huge tsunami waves in India (Kathiresan and Rajendran 2005; Chadha et al. 2005) and Sri Lanka (Liu et al. 2005). In Chile, dune provided buffering from tsunami waves in the Chile tsunami on February 27 2010 generated by a large earthquake of M 8.8 (Esteban et al. 2013). Presence of coastal vegetation has been recognized as effective in reducing the deaths and damages caused by the 2004 Indian Ocean tsunami in India (Danielsen et al. 2005; Chadha et al. 2005), in Sri Lanka and Thailand (Tanaka et al. 2007) and in Indonesia (Laso Bayas et al. 2011). The natural coastal elevated landforms (topography) along with presence of vegetation such as dense mangrove forests increase tsunami mitigation effectiveness, in the 2004 Indian Ocean tsunami in India (Kathiresan and Rajendran 2005).

 

3.1.2 Legend in tsunami mitigation in Japan

 

3.1.2.1 Ancient legends of tsunami mitigation in Japan.

 

As the Japanese archipelago is prone to tropical cyclone and tsunami, once Japanese architects were aware that local geographical features such as island, coastal hill and/or cape contribute to coastal protection by reducing wave energy.

The scientific definition of a tsunami is a series of sea waves generated by earthquake, landslide or other disturbance under the ocean. However, a Japanese word ‘tsunami’ included exceptional storm surge (an episodic increase in sea level driven by shoreward wind-driven water circulation and low atmospheric pressure) caused by tropical cyclones (typhoon) until around the Meiji era (1868–1912). Numerous local chronicles indicate that coastal topography such as island, coastal hill and/or cape together with vegetation cover provides natural barrier against coastal hazard such as tsunami and storm surge.

 

3.1.2.2 Tsunami mitigation Hachiman.

 

A legend of tsunami mitigation during the Kamakura period (1185–1333) influenced urban design of Edo. In Edo, Japanese architects evolved diverse tsunami mitigation structures. The Kamakura Shogunate was established in 1185 by Yoritomo Minamoto (源頼朝) in Kamakura (鎌倉: 35° 19′ N, 139° 33′ E; Fig. 6-C). Based on the Japanese traditional land planning, the government built numerous Shrines/Temples to maintain appropriate ecosystem areas of strategic importance integrated with military strategic points. As Hachiman (八幡, the Japanese Shinto god of war, originally an agricultural deity in local area in Kyusyu) became the guardian of the Minamoto clan,  huge number of Hachiman Shrines/Temples were constructed.

In 1311, devastating tsunami (probably a storm surge at local scale) hit in Yokohama, near the entrance of Edo (Tokyo) Bay. The tsunami destroyed a village, but the neighboring village was less impacted, safe and sound. Tomioka Hachiman (富岡八幡: 35°22′ N, 139°38′ E; Fig. 6-D) on coastal mountains (around 40 m/131 ft) covered with dense forests acted as a buffer and protected the village behind it. For which, people adored it, called as Namiyoke Hachiman (波除八幡, tsunami mitigation Hachiman). It was particularly popular among merchants associated with shipping and fishermen seeking to give sail without trouble.

 

3.1.2.3 Ancient legend: Effectiveness of multiple-buffering in tsunami mitigation

 

Tsunami mitigation legend of Matsushima

Although the origin of the legend is unknown, the tsunami mitigation of Matsushima (松島, 38°38′ N, 141°07′ E) in effectiveness of multiple-buffering was recognized among the ancient Japanese architects and decision makers in ancient times. Hence, decisions were made to provide adequate tsunami mitigation effectiveness, by adopting the multiple-buffering in coastal design and land-use planning.

In Fig. 2, Hiroshige depicts a bird’s-eye perspective of the Matsushima Bay from Tomi-yama (116.8 m/383.2 ft asl), a coastal mountain, viewing dotted 200 islands, seen in the far background Miyato-jima Island and Shichigahama Peninsula lying at the bay entrance. This print is depicted natural structure of multiple-buffering ranged 6.7 km (4.2 miles) long from the bay entrance to inside coast, which provided effective buffering against the destructive tsunami waves.

 

Effectiveness of the multiple-buffering in the 2011 Tohoku tsunami

Matsushima, famed for its beautiful scenery, is close to the epicenter of the earthquake that generated the 2011 Tohoku tsunami. In the Matsushima Bay, protruding Shichigahama Peninsula and Miyato-jima Island lying in the mouth of the bay provide a sheltered harbor. The semicircular-shaped bay, 1.7 km (1miles) wide at the entrance, is dotted by over 200 small islands covered by trees of Japanese black pine (Pinus thunbergii).

On 11 March 2011, the tsunami destroyed nearby coastal communities. For instance, Minami-Sanriku (a town near the bay entrance, 38°41′ N, 141°28′ E), where tsunami inundation height measured around 15 m (50 ft), was destroyed and about 1000 people died or missing in this town of 17,700. The tsunami waves hit the island lying in the mouth of the bay, inundation height ranged 8 and 9 m (26 and 30 ft), caused considerable casualties. Whereas, inside lowlands of the Matsushima Bay suffered relatively little damage. The tsunami inundation height around 3 m/1 ft and there were 2 losses of lives. In some sites, the elevation of watermarks on buildings indicated much lower inundation heights of 1.2 m (3.9 ft) or 0.5 m (1.6 ft) (Hasegawa et al. 2011).

Huge tsunami waves at the mouth of the bay had reduced to around 3 m (9.8 ft) or less by the time they reached the inside town, as Shichigahama Peninsula and Miyato-jima Island lying at the bay entrance behaved as a large-scale tsunami breakwater caisson, and dotted islands acted as a buffer.

Fig. 2 View of Matsushima with a Distant Prospect from Tomi-yama Mountain (Matsushima, Miyagi prefecture: 38°38′ N, 141°07′ E) from the series Pictures of Legendary Landscapes in the Sixty Provinces, Hiroshige, originally published 1856–1858 (Image courtesy of the Waseda University Library, the ukiyo-e.org https://johnresig.com/projects/ukiyoe/ by Resig J). Hiroshige depicts a bird’s-eye perspective of the dotted some 200 islands in the Matsushima Bay from a coastal mountain (116.8 m/383.2 ft asl), seen in the far background Miyato-jima Island and Shichigahama Peninsula lying at the bay entrance. The Tohoku tsunami on 11 March 2011 destroyed nearby towns, but damage of inside lowlands of the Matsushima Bay was relatively minor. Because the island and peninsula lying at the bay entrance behaved as a large-scale tsunami breakwater caisson, and dotted some 200 islands acted as a buffer. This Hiroshige’s print represents how vegetated multiple-buffering structure should be shaped to provide adequate tsunami mitigation effectiveness.

3.2 Unique multiple-buffering system to protect coastal areas and to preserve/restore submerged aquatic vegetation

 

3.2.1       Placement of multiple-buffering to protect low-lying coastal areas and to stabilize beaches

 

To sustain the megacity of Edo that rapidly increased in extent and population, the coastal zones of Edo Bay had been dramatically transformed by humans. The coastal architecture to protect low-lying coastal areas was unique in translating learning-based knowledge into effective policy and management strategies. Ancient Japanese architects and decision-makers developed site-specific civil engineering design in coastal protection: construction of multiple-buffering structure and strategic placement of coastal ecosystems which provide nursery and foraging grounds for fisheries productivity.

In traditional Eastern philosophy, management of fisheries resources was considered as a core issue of governance for food security. Therefore, the primary functions of the sea dyke system were to protect low lying coastal areas from inundation by the sea and also to enhance resilience of coastal ecosystems as the nursery and foraging grounds for fisheries productivity. Japanese dyke system was intended to shape complex habitats: coastal forests, salt marshes, underwater seagrass meadows, and deep-water kelp forests.   

For instance, an ancient marsh reclamation work at the ancient sea shore of Edo Bay (Fig. 3; Fig. 6-E) represents the Japanese multiple-buffering coastal protection structure.

Fig. 3-1 Azuma-no Mori Shrine and the Entwined Camphor (Tokyo: 35°42′ N, 139°49′ E; Fig. 6-E) from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the ukiyo-e.org https://johnresig.com/projects/ukiyoe/ by Resig J, the Artelino). According legend, during his campaign against the tribes in eastern Japan, Prince Yamato-takeru was caught by a storm in boats in Edo Bay. He survived through the self-sacrifice of his wife Princess Ototachibana. When he reached a small islet among marshes, he built an earthen mound and buried her robe that was deposited on shore by the waves. This legendary coastal area had been reclaimed in ancient times, until around the Kamakura period (1185–1333). Hiroshige depicts the ancient sea dyke system in the foreground, and the Azuma-no Mori Shrine at the upper left of the picture.

Fig. 3-2 Schematic structure of coastal multiple-buffering system in a case of the Azuma-no Mori Shrine. In reclamation work of Eastern philosophy, earthen dykes, elevated mounds/mountains and artificial islands combined with intertidal wetlands were placed to protect low-lying coastal areas. The earthen dykes were intended to stabilize beaches. To close biogeochemical cycles in land-sea connectivity, continuous (non-fragmented) vegetation, deep sacred forests, trees planted on the dykes, and salt marshes, was elaborately shaped. Marine photosynthesis requires huge amounts of essential nutrients such as Fe and Si compounds in the forms of humus, leaf litter and detritus. The shaped continuous vegetation works as a pathway of essential nutrient from land to sea. Thereby, submerged aquatic vegetation, underwater seagrass meadows and deep-water kelp forests, flourishes. The flourishing underwater vegetation, in turn, contributes to stabilize beaches. Multiple-buffering system, which consists of diverse habitats, supports land-sea linkage in biogeochemical cycle as basis of fishery productivity. 

3.2.2 An example of ancient multiple-buffering coastal protection structure

 

The history of reclamation in Japan dates back to the Nara period (A.D.710–794), around 1,300 years ago. Hiroshige depicts a well-preserved landscape of the ancient march reclamation work at the ancient sea shore of Edo Bay in Fig. 3-1.

Azuma-no Mori Shrine was devoted to the worship of the deity of Princess Ototachibana. This shrine is surrounded by myth and legend. During the campaign against the tribes in eastern Japan, the legendary Prince Yamato-takeru, his wife and entourages, were caught by a great storm in boats crossing in Edo Bay. In order to appease the anger of Ryujinn (龍神, the Japanese mythological god of the sea, typically portrayed as dragon), his wife, Princess Ototachibana leapt into the seething waves.  Prince Yamato-takeru survived through the self-sacrifice of his wife and reached a small islet shore among marshes safely. A few days after the Princess’s death, the waves deposited her robe on shore. Prince Yamato-takeru built an earthen mound and buried it beneath the mound.     

This legendary coastal zone had been reclaimed in ancient times. In 1199, Yasutoki Hojo (北条泰時, 1124–1242), the head of the Kamakura shogunate, ordered construction of the shrine building (Fig. 6, E).

Ieyasu settled in Edo Castle (Fig. 6-A) in 1590 and began to organize the new capital. The tidal marshes in the eastern part of the Sumida-gawa River (Fig. 6-B) had been reclaimed for urban development from around 1596 (Endoh 2004). Kita-jyukken-gawa River, seen in foreground in Fig. 3-1, was a canal, dug out in 1663 to link Sumida-gawa River (which was separated from the Tone-gawa River to reduce flood risks in city of Edo in 1629) and Naka-gawa River (Fig. 6-F, an arm of the Tone-gawa River that flowed into Edo Bay), probably along ancient earthen sea dyke.  

Hiroshige depicts the ancient reclaimed marsh land with the Azuma-no Mori Shrine in the center of the picture, viewing from the direction of the Edo period’s reclaimed land. In Fig. 3-1, the ancient reclaimed marsh land is protected by irregularly bending earthen sea dyke on which pines and cherry trees are grown. The entrance approach to the shrine is marked by a torii gate. Along the gateway, on one side there are rice paddies. On the other side of the gateway, an extensive area of salt marsh pool (in ancient time) is connecting irregular-shaped moat system enclosed the precinct of the shrine.

The multiple-buffering coastal protection system consists of earthen sea dyke, salt marsh pool, elevated mound covered with a sacred forest like an old-growth forest consists of diverse native tree species, saltwater-filled moat, and dyke of moat (Fig. 3-2). Ancient Japanese architects innovated diverse design of multiple-buffering coastal structure appropriate for local and regional geography, and social requirement.  

 

1.2  Strategic placement of continuous (non-fragmented) vegetation over land and sea to close biogeochemical cycles

 

3.3.1 Architecture of pathway to close biogeochemical cycles

 

Pathway of essential nutrients supply from land to sea

In Eastern philosophy, one of the important concepts in land-use planning/management was to close biogeochemical cycles, known as rinne 輪廻: ‘cycle of life.’ For architecture of underwater seagrasses meadows and deep-water kelp forests, ancient Japanese civil engineers had taken a unique approach to close biogeochemical cycles. In the reclaimed marshlands, earthen sea dyke was constructed to create calm shallow sea waters for rapid restoration of submerged aquatic vegetation. Strategic placement of continuous (non-fragmented) vegetation over land and intertidal zone (for instance, in Fig. 3-2, a series of sacred forest and salt marsh) was intended to restore submerged aquatic vegetation over coastal sea. Continuous (non-fragmented) vegetation over land and intertidal zone facilitates flow of essential nutrients from land toward coastal seas. The dynamic flow of essential nutrients in land-sea connectivity, in turn, leads to resilience of underwater vegetation as nursery grounds—basis of fisheries productivity.  

Note that supply of essential nutrients for marine photosynthesis (blooms of diatoms-dominated phytoplankton and marine vegetation) is not equivalent to nutrient loading, because nutrient loading (nutrient pollution) from synthetic fertilizers in agriculture and from treated/untreated sewage effluent induced by rapid urbanization causes harmful algal blooms, which are increasing frequency and intensity on a global scale (e.g., Parsons and Dortch 2002; Anderson et al. 2008; Heisler et al. 2008; Paerl and Huisman 2008). Terrestrial and marine ecosystems shape consolidated closing biogeochemical cycle, constituting a complex and dynamic system. Marine photosynthesis requires huge amounts of essential nutrients such as Fe and Si compounds in the form of humus, leaf litter and detritus from terrestrial vegetation. Decay of the blooms of diatoms-dominated phytoplankton and coastal vegetation release nutrients. The released nutrients in turn enrich nearby coastal seas.  

 

Submerged aquatic vegetation requires supply of essential nutrients from land

Submerged aquatic vegetation, seagrass meadows and kelp forests, requires supply of essential nutrients from land.

Primary production of marine phytoplankton (single-celled algae with invisible size) is enormous. Marine phytoplankton produce nearly half of global net production each year (Field et al. 1998). Diatoms (single-celled algae armored with silica cell walls) dominated phytoplankton blooms play a dominant role in shaping our productive fisheries (Armbrust 2009; Goes et al. 2020).                      

The diatoms-dominated marine phytoplankton, the basis of abundant fisheries resources, require supply of essential nutrients from terrestrial vegetation, such as iron ‘Fe’ (Martin and Fitzwater 1988; Kuma and Matsunaga 1995) and silica ‘Si’ compounds (in light of ‘evolution of modern eukaryotic phytoplankton’: Falkowski et al. 2004). Therefore, large quantities of essential nutrients equivalent to approximately half of global net primary production must be supplied from terrestrial vegetation.

Likewise, supply of essential nutrients from terrestrial vegetation plays a significant role to sustain the nursery and foraging grounds. The availability of soluble Fe, which derives from organic compounds via the leaf litter decomposition of forests, is required for growth of kelp forests (Matsunaga et al. 1999)

All living things are made of one or more cells, and all the cells are mostly composed the same substances that carry out similar biological functions. When the living cells complete their life cycle, all the essential nutrients of cells tend to circulate in the biosphere, known as biogeochemical cycle. Cytochromes, for instance, a group of hemoprotein cell components with a central Fe atom at its core, serve a vital function in both photosynthesis and cellular respiration. As cytochromes are found all animals and plants, and many microorganisms, humus and organic compounds from terrestrial vegetation (e.g., leaf litter, wood, and other plant parts) that exported to seas/oceans are source of Fe compounds. Hence, soluble Fe compounds and/or cytochromes derived from an enormous amount of organic matter from terrestrial primary productivity may contribute marine primary production such as phytoplankton and macroalgae that form underwater kelp forests.

 

Architecture of biogeochemical pathway in land-sea connectivity

Resilience of seagrass meadows, the important nursery and foraging grounds, requires habitat connectivity. Seagrass meadows are connected adjacent salt marshes, oyster reefs, and sandy shores in temperate regions; and the seagrass meadows are associated with mangroves and coral reefs in the tropics (Unsworth et al. 2015). Furthermore, a considerable portion of net production of seagrasses exports to adjust ecosystems both to the land and seaward (Duarte 2002), suggesting interdependent trophic links between terrestrial and submerged aquatic vegetation. The linkages between intertidal wetland vegetation and seagrass ecosystems facilitate transfer of large amounts of essential nutrients associated with leaf litter and detritus in sustaining productivity of the nursery grounds.

In Eastern philosophy, the basic concept underlying the design of multiple-buffering was to close biogeochemical cycles. Placement of contiguous ecosystems: deep sacred forest, salt marsh pool, and earthen sea dyke, was designed to serve a pathway of biogeochemical cycles. Ecological connectivity between land and sea plays a significant role, as abundant essential nutrients produced by terrestrial vegetation transport to underwater seagrass meadows and deep-water kelp forests.

 

3.3.2 Unique design of sea dykes to preserve beaches and for efficient restoration of submerged aquatic vegetation   

 

Unique design of coastal engineering to shape calm shallow seawater

Aware that submerged aquatic vegetation plays an essential role in fishery productivity, unique design of coastal engineering had been developed in Eastern philosophy.

Seagrasses grow in soft mud/sand in calm shallow seawater. The irregularly bending earthen sea dykes were intended to stabilize beaches in front of the structure and to restore intertidal vegetation such as common reed (Phragmites australis) and submerged aquatic vegetation over coastal sea (Fig. 3-1, 3-2). Numerous irregular-shaped earthen groynes (groins), man-made sandbars that extended into sea from earthen sea dyke, were constructed. These man-made sandbars were shaped by closely spaced wooden piles driven into the seabed. In addition, ‘loosely spaced wooden piles’ driven into the seabed served as a sort of breakwater, preventing the dyke being washed away. These coastal dyke engineering structures create a condition of calm shallow seawater, facilitating resilience of underwater meadows of seagrasses. The resilience of seagrass meadows in front of the dyke structure in turn shapes a variety of habitats: sallow slow-moving seawater and still deep seawater wetlands, making nursery habitats where young growth stages of fish and crustaceans can take advantage of feeding and protection from predation (Fig. 3-1, Fig. 7-1, 7-2, Fig. 8-1, 8-6, Fig. 9-3, Fig. 10-1, 10-2, 10-3, Fig. 12-1, Fig. 13-2).

The roots and rhizomes of seagrasses stabilize the seabed, preventing erosion, which in turn contributes to reduction of sedimentation type pollution keeping clear waters (Duarte 2002). Underwater meadows of seagrasses perform a function as pathway of essential nutrients supply from land to the deep-water kelp forests. Human-created conditions: soil stabilization, wave attenuation, and adequate supply of essential nutrients, facilitate colonization of the deep-water kelp forests.

 

Ecological function: Pores of earthen sea dyke

Salt marshes maintain fisheries by serving nurseries for many fishes and crustaceans (Boesch and Turner 1984). Accordingly, loss of coastal wetlands leads to depleted and collapsed fishery stocks, in a case of US (Chesney et al. 2000).

Abundant fisheries resources are maintained trophic transfer in marine food webs. In particular, shrimp is important in the excellent diet of almost all commercially important species of coastal fisheries at one life history or another.

Several kinds of shrimp live and spawn as adults offshore, and the eggs and planktonic forms of young larva move shoreward into intertidal salt marshes and associated networks of tidal creeks, embayment, and salt marsh pools. The small eggs and planktonic forms of young larval stages pass through barrier such as natural shaped earthen embankment, and take advantage of refuge from predators and abundant food for rapid growth. The maturing shrimp then move back to ocean for spawn (e.g., Odum 1971).

Shrimp productivity depends on area of vegetated wetlands. In a case of in the northern Gulf of Mexico, the mean annual yield of shrimp caught inshore is highly correlated with the area of vegetated wetlands (Boesch and Turner 1984). Due to the important link between nursery grounds and fisheries productivity (Unsworth et al. 2018), loss of salt marshes leads to decline of fisheries.

  

Placement of vegetated wetlands in Edo

Ancient Japanese architects were aware of a significant role of shrimp in marine food webs in fisheries resource management. Therefore, vegetated wetlands were strategically placed.

 In Edo, fairly small shrimp, shiba-ebi (芝海老, Metapenaeus joyneri, 10-15 cm/4-6 inches) serve to maintain fisheries by enhancing quantity and quality of commercially important fisheries species.

In light of nurseries of shrimp, ancient Japanese architects were aware of ecological function of earthen dykes’ pores that shrimp eggs and planktonic forms young larval stages pass through. Invisible phytoplankton and zooplankton (small crustaceans such as copepods and krill; larva of fish, squid, lobsters and crabs) also pass through the pores of the dykes. Thereby, the invisible phytoplankton and zooplankton via pores of dykes were constantly supplied as food for shrimp growth. Although these earthen sea dykes were often retained by dry-stone wall, the pores of the dykes do not undermine the ecological function due to spaces between the rocks (Fig. 4). The earthen sea dykes were equipped with water gates, by which mature shrimps move back sea. Abundant released shrimps via the water gates from man-made ‘vegetated coastal wetlands’ boosted quality/quantity of fisheries resources.  

Owing to the land-sea interactions, coastal wetlands and the sea are highly productive ecosystems maintaining commercially important fisheries species.  Earthen sea dykes’ pores play a significant role in linkage between coastal wetlands and the sea, which is critical for habitats of shrimp that enhance quality/quantity of fisheries resources.

 

3.3.3 Coastal architecture for self-sustainability

 

In Eastern philosophy, land-use planning/management associated with high primary productivity of vegetation such as forests over the whole country was regarded as first principle in the critical infrastructure for food-security via abundant fisheries resources management. Furthermore, unique design of river engineering in preserving natural corridors of land-sea linkage was developed: Floods were allowed in desolate areas to decrease peak discharge, volume, frequency of floods in inhabited areas. Extensive flood-water retarding zones that served as a sort of ‘dam’ were strategically allocated over large geographic areas. Discontinuous levees that directed waterflow were constructed, for guiding flood-waters into the flood-water retarding zones. Besides, in estuarine and coastal zones, coastal protection integrated with a variety of habitats for resilient fisheries was designed to close the biogeochemical cycle between land and sea (http://harukanoor4.blogspot.com/2022/).

Strategy of coastal hazard mitigation in Eastern philosophy was unique in taking into account maintaining the dynamic equilibrium in land-sea connectivity. Unique design of coastal engineering was invented to prevent erosion and accelerate soil sedimentation.

Whereas, coastal engineering structures were intended to preserve and to restore submerged aquatic vegetation that serves as important nursery grounds for fisheries. Management of high primary productivity of vegetation such as forests over the whole country is an underlying requirement, as the resilience of submerged aquatic vegetation, underwater meadows of seagrasses and deep-water kelp forests, necessitates abundant supply of essential nutrients from land via the pathways of biogeochemical cycles.  

The coastal architecture that takes into account of a naturally dynamic coastal system is a constructive method, because the landscapes constructed by the coastal engineering intended to preserve beaches integrated with strategic placement of ecosystems, once established, becomes more and more effective each year as it grows as a measure of coast-line stabilization and for prolific marine ecosystems.

Fig. 4 Durable coastal structure of dry-stone wall, preserving land-sea connectivity. Wooden pile foundation after Ohno (1992). Shrimp play a significant role in marine food webs, and shrimp productivity depends on area of vegetated wetlands (Boesch and Turner 1984). To enhance quality/quantity of coastal fisheries, vegetated wetlands (nurseries of shrimp) with site-specific design were strategically placed: seawater filled canal (Fig. 8-1, 8-2, 8-5; Fig. 9-1), and seawater filled ponds in lavished gardens (Fig. 8-3, 8-4; Fig. 9-2). Adult shrimp spawn offshore and young larval stages pass through barrier such as earthen dyke via pores to use the nursery grounds of vegetated wetlands. Japanese traditional dry-stone walls preserve the ecological function of earthen dyke’s pores that pass through invisible phytoplankton and zooplankton through the spaces between the rocks. In addition, Japanese traditional dry-stone walls are effective as measures of erosion mitigation, as the spaces between the rocks act to dissipate wave energy and minimize reflective waves. Traditionally, seawalls were constructed using dry-stone walls in sites, where durability and dignity were important (e.g., Fig. 7-1, 9-1). Owing to the excellence in erosion mitigation, prolific fishery grounds are shaped in front of the structure (Fig. 7-1).     

3.4 Unique civil engineering technology in coastal hard structure: Magnificent durable coastal structure of dry-stone wall

 

3.4.1 durable coastal structure of dry-stone wall

 

Japan had unique civil engineering techniques in construction of man-made island and/or sand bar.

A few years before Hiroshige created his series of “One Hundred Views of Edo,” Japan’s 250-year-old of self-imposed isolationist foreign policy was on the transformative change.

On 8 July 1853, Commodore of the United States Navy Matthew C. Perry entered Uraga harbor at the entrance to Edo Bay with his squadron of four steam frigates. He brought a message from President of the United States Millard Fillmore demanding to open Japanese ports to American trade. After several days stay in Japan, Perry departed for Hong Kong, promising to return the following year for the Japanese reply.   

The arrival of the squadron forced the Japanese government to think of coastal defenses. A series of eleven island-forts (daiba, 台場: Fig. 5; Fig. 6-G) equipped artillery between Shinagawa (品川, Fig. 6-H) and Fukagawa Susaki (深川洲崎, Fig. 6-I, the eastern estuary of Sumida-gawa River) in Edo Bay was planned. Construction work began immediately after Perry’s departure and six forts were complete within nine to ten months, another two half-finished. Japan had construction logistics to carry out the intensive construction work of the island-forts: square and/or pentagon-shaped island-forts influenced by Western citadel architecture, with the sides 122 to 177 m (367 to 581 ft) long, covered an area of around 33,000 m² (about 8 acres) respectively, all sides of the shoreline retained with dry-stone walls of around 7.76 m/25.5 ft height (Ohno 1992). The earth for the forts (over 480,000 m³) was taken from the coastal hills of Shinagawa (Goten-yama Hill, Fig. 5; Fig. 6-J) and Takanawa.

Perry returned on 13 February 1854 after only half a year. Offshore of Shibaura (芝浦, Fig. 6-K) a deep and wide channel provided only one route from the entrance of Edo Bay to the ports of Edo Castle for large freighters and fishing vessels. Due to the emergence of the man-made six island-forts, Perry and his squadron relinquished their plan of entering deep inside of Edo Bay. They landed Yokohama (横浜, Fig. 6-L) and Japan was forced to open up to Western trade. Eventually, the island-forts project was suspended.

Fig. 5 Shinagawa: View of the station from Goten-yama Hill (Tokyo: 35°37′ N, 139°44′ E; Fig. 6-J) from the series Fifty-three stations of the Tokaido Highway, Hiroshige, originally published 1855.  In 1853 the arrival of US Commodore Perry and his squadron of four steam frigates prompted the Japanese government to take emergency measures on coastal defenses. Due to strategic importance of offshore of Shibaura: only one route to the ports of Edo Castle for large vessels, construction of eleven island-forts (daiba, 台場) was planned. Within nine to ten months six forts were complete. The earth for the forts was excavated from Goten-yama Hill. Accordingly, the appearance of Goten-yama Hill changed radically, despite once one of the most popular places to admire the cherry blossom. Hiroshige depicts the traces of the earth excavated work of Goten-yama Hill in the foreground, and four recently constructed man-made island-forts, all sides of the shoreline retained with dry-stone walls, in the near distance.

3.4.2 Effectiveness of dry-stone walls in erosion control

 

The dry-stone walls submerged by seawater were constructed upon wooden pilings made of pine trees not to sink into the soft ground (Fig. 4). Conceptual basis of this method is similar to the technology in Venice in Italy.

Venice, formed on a lagoon, was built on wooden piles (diameter: varying from 10 cm/3.94 inches to 25 cm/ 9.84 inches; length: a maximum of 350 cm/137.8 inches to less than 100 cm/39.4 inches) made of variable tree trunks, alder (Alnus spp.), larch (Larix decidua), oak (Quercus spp.), and Scots pine (Pinus sylvestris), to provide foundations for buildings on the soft ground. Above the pile head, planking (two or more layers of timber) positioned horizontally. For planking, woods made of variable tree species, larch (Larix decidua), oak (Quercus spp.), and Norway spruce (Picea abies), were used (Macchioni et al. 2016). These woods do not rot in wet and oxygen-poor conditions and become as hard as stone when left in immersed in water.

In Edo, the dry-stone walls submerged by water were constructed on wooden pile foundations made of pine trunks driven deep into the ground. Pine round wood logs submerged in water do not decay in wet and oxygen-poor conditions. To ensure the long-term stability, piling foundations were elaborately designed (as for specific details, see Fig. 4).

Japanese traditional dry-stone walls are effective as measures of erosion mitigation, eventually resulting in a stable coastline. The structure of the walls is designed as a basis for self-organized ecosystems.

Steep slope stabilization of dry-stone wall achieved by root systems of trees and vegetation binding stones together (Yano et al. 1983). For the stabilization of banks, a perennial grass (Imperata cylindrica), effective in erosion control of exposed soil owing to the quick growth, and Japanese black pine (Pinus thunbergii, up to over 40 m) were planted. The perennial grass (Imperata cylindrica) spreads rapidly and binds stones together by the tough rhizome network. The Japanese black pine (Pinus thunbergii), tolerant to salt spray, has ability to endure unfavorable site conditions that other tree species do not thrive.

At the base and in front of the vertical masonry, rocks and wood piles accumulate oysters that grow together, forming rock-like reefs. Which in turn reduced wave energy preventing erosion. In Japanese traditional dry-stone walls, the spaces between the rocks play important role in erosion mitigation. When waves hit stone walls, the spaces between the rocks act to dissipate wave energy and minimize reflective waves. The oyster reefs at the base and in front of the vertical structure of masonry prevent erosion and provide productive coastal habitats. The use of self-organizing ecosystems for the erosion control is a constructive method, because the ecosystems, once established, becomes more and more effective each year as it grows as a means of controlling erosion.

 

3.4.3 Wooden pile foundation design of Japanese traditional dry-stone wall structure

 

An example of Japanese traditional dry-stone wall structure along with wooden pile foundation

Ohno (1992) deals with wood foundations of Japanese traditional dry-stone wall structure in a case of the Shinagawa-daiba (Fig. 4).

To ensure long term stability, piling foundations were elaborately designed. Prior pilings, the soils underneath the masonry were consolidated. Crushed stones were thrown in the ground to place the masonry with width 550 cm (18 ft) long and depth 121 cm (4 ft) from the level of low tide. Piles (diameter: around 15 cm/6 inches), made of roundwood of pine (Pinus densiflora; Pinus thunbergii), were driven into the ground around 91 cm (36 inches) of pitch to form a long row along the masonry surface. Pile length ranged from 637 cm (21 ft) in the outside row, 550 cm (18 ft) second row, and to 455 cm (15 ft) in the inside row. Above the pile heads, wooden ladder-shaped frames were placed, as horizontal elements to spread the vertical forces. The ladder-shaped frames mainly made of pine round woods (diameter: around 21 and 24 cm/8.3 and 9.5 inches; length: 303 cm/99 ft) were set along the surface of masonry laying perpendicular to the driven piles, and large iron stables were driven into both the piles and wood frames to hold them together. On the ladder-shaped frames, pine timber planking (thickness: 21cm/8.3 inches; width: 36 cm/12.5 inches; length: around 424 cm /14 ft) were positioned and stabilized using large iron stables.

At the base of the vertical structure of walls, closely spaced pine wood piles, diameter: around 12 and 15 cm (4.8 and 5.9 inches); length: 455 cm/15 ft, were driven deep into the ground to reduce scoring of wave reflection (Ohno 1992).

In front of the vertical walls where prone to erosion by reflective wave energy actions, horizontal masonries (width: 546 cm/18 ft or 728 cm/24 ft) were constructed on wooden pile foundations. Pine round wood piles were driven into ground as closely together forming 3 or 4 rows along the coast at intervals of around 182 cm/6 ft. To make the wooden foundation rigid, horizontal elements of pine wood were placed and stabilized using large iron stables.

Fig. 6 Locations that Hiroshige depicts: (a) location of Edo and the peri urban areas; (b) Japanese map of Edo in 1849 (Image courtesy of the Geographicus Rare Antique Maps via Wikimedia commons); (c) Coastal area of Tokyo in 1959 (the Geographical Survey Institute, Japan). A: Edo Castle (Imperial Palace); B: Sumida-gawa River 隅田川; C: Kamakura (鎌倉, center of the Kamakura Shogunate, 1185–1333): D: Tomioka Hachiman (富岡八幡, legend of tsunami mitigation by a forested coastal hill); E: Azuma-no Mori Shrine (吾嬬の森, remnants of the multi-buffering coastal protection by ancient marsh reclamation); F: Naka-gawa River (中川, an arm of the Tone-gawa River); G: constructed island-forts (daiba, 台場, six island-forts were complete within nine months in 1854); H: Shinagawa (品川, a man-made long sandbar extruded out into the sea at the river mouth to protect the amusement quarters); I: Fukagawa Susaki (深川洲崎, sea dyke: a long earthen sandbar ran far out into the sea to protect the low-lying gavage filled-up land); J: Gotenn-yama Hill (御殿山, for the island-forts construction, the earth was excavated); K: Shibaura (芝浦, elaborately shaped coastal defense integrated with fisheries resources management in front of Edo Castle); L: Yokohama (横浜, a fishing village protected by two characteristic man-made island at entrance of embayment); M: Tsukuda-jima Island (佃島, artificial island at the mouth of Sumida-gawa River, serving as a sort of caisson breakwater); N: Fukagawa Hachiman (深川八幡, exquisite garden as part of multi-buffering coastal protection deserve to the Eastern Capital on the low-lying gavage filled-up land); O: Kiba (木場, lumber-yard, part of  the multi-buffering coastal protection: seawater-filled ponds that the logs were stored and gardens of wealthy merchants); P: Fukagawa Susaki Jumantsubo (深川洲崎十万坪, vacant open space as a flood mitigation measure); Q: Hama-goten (浜御殿, sea shore palace, villa of the shogun family, a sort of outpost at the sea opening of the moat system of Edo Castle); R: Zojo-ji monastery (増上寺, The influential Buddhist center occupied an enormous area of 833,250 m²/206 acres covered with deep sacred forests, effective in urban summer cooling strategies); S: Suitengu shrine in Akabane (an example of protected urban forests: main residence of the Arima family from the north of Kyushu island); T: Furu-kawa River at Hiroo (広尾, placement of tall dense man-made forests surrounding farmhouses; small river engineering for prolific inland fisheries); U: Fudo temple in Meguro (目黒不動, man-made sacred forests to stabilize the fragile bluff of Musashino plateau and to enhance quantity/quality of groundwater); V: Haneda Benzaiten (man-made island covered with deep sacred forests at the estuarine of Tama-gawa River; currently occupied by the Haneda Airport/Tokyo International Airport); W: Futoko-tamagawa (二子玉川, popular place for anglers to enjoy ayu fishing along with the beautiful scenery of riffle-pool sequence river engineering); X: sea off the Miura Peninsula (placement of rocky reefs and man-made islands as consolidated structure of cliff erosion mitigation and productive coastal habitats); Y: coast of Tenjin-yama (placement of rocky reefs as consolidated structure of cliff /sandy coast erosion mitigation and productive coastal habitats) 

4.     Examples of site-specific design in the metropolis

 

4.1 An artificial island at river mouth, served as a sort of caisson breakwater

 

At his age 39 during the ‘Warring States period’ (a period of near-constant civil war and social turmoil), Ieyasu was at the verge of the abyss. Mitsuhide Akechi (1528 ?–1582), an officer under the powerful warlord Nobunaga Oda (1534–1582), raised rebellion against his lord in 1582. Akechi’s forces surrounded Nobunaga, who was resting in a temple in Kyoto. The temple was set on fire, and Nobunaga perished inside.

When Ieyasu was learned about Nobunaga’s death, he was in Sakai (Osaka Prefecture) where was Akechi’s territory far from Ieyasu’s home Okazaki (Aichi prefecture), with his several entourages without armament. As main highways and sea routes were seized and taken control, Ieyasu decided to make across mountainous area of Iga by foot over 100 km (62 miles), in spite of high risks of raids by armed civilians. However, the retreat was obstructed by a huge flow of an arm of Yodo-gawa River from the start.

At the difficult time of Ieyasu, fishermen in a Village Tsukuda (佃) in Settsu (in Osaka Prefecture) provided a fisher boat and navigated to a safer place. For which, Ieyasu issued a special decree granting the privilege of shirauo (シラウオ, Salangichthys microdon) fishing in Edo area for the fishermen. In addition, Ieyasu allowed to reclaim a marsh land at the mouth of Sumida-gawa River.

Ancient Japanese architects and decision-makers were aware that placement of man-made island at the river mouth and/or entrance of bay dissipates wave energy, serving as a sort of caisson breakwater (http://harukanoor4.blogspot.com/2022/). Furthermore, the mouth of Sumida-gawa River was an important military strategic point. It took 15 years to complete the construction of the artificial island in 1644 by the villagers, a rectangle with sides around 180 m (591 ft). They named it Tsukuda-jima (佃島, Fig. 6-M) and brought the Japanese Shinto deity of Sumiyoshi (住吉), the protector of seafarers, from their homeland to the newly constructed the shrine building in 1646.

In Hiroshige’s time, Tsukuda-jima, having a fine view out to sea, was a place for the inhabitants of Edo to enjoy a day trip via a cross-channel ferry. In Fig. 7-1, Hiroshige depicts the artificial island (佃島) in the background of the left of the picture. The shoreline is retained with dry-stone walls. Notably, dry-stone wall stabilizes the shoreline, forming prolific fishery grounds of calm shallow sea waters in front of the structure. The coastal water is too shallow for large vessels to get closer to shore. Vessels drop anchor a short distance away and use small boats to shuttle passengers. The visiting anglers amuse themselves. The fishermen at work, a fisherman casting net and another fisherman drawing fishing net, implying abundance of fisheries resources.  

A stone torii gate marks the entrance to an extensive sacred grove of Sumiyoshi. One side of the artificial island is fringed with irregular-shaped man-made sandbanks created by wooden piles driven into seabed, forming tidal marshes (Fig. 7-1, 7-2). Non-fragmented vegetation, dense sacred forest and lush tidal marshes, facilitates habitat connectivity between land and sea, leading to the resilience of seagrass meadows and kelp forests. The contiguous vegetation in land-sea connectivity, in turn, enhances estuarine and coastal fisheries productivity.      

The unique culture of the shirauo fishermen’s village (Fig. 7-2) was flourished on habitats of linkage between river and sea, as shirauo (a small transparent fish which turns milky white when cooked, typically around 8 cm/3.1 inches long, highly valued for Japanese cuisines) is anadromous fish (migrate from the sea up into fresh water to spawn).  

Fig. 7-1 Tsukuda-jima Island Viewing Sumiyoshi Shrine (Tokyo: 35°40′ N, 139°47′ E; Fig. 6-M) from the series Famous Places in the Eastern Capital, Hiroshige, originally published Mid-1840’s (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). Ancient Japanese architects and decision-makers were aware that placement of man-made island at the river mouth and/or entrance of bay dissipates wave energy, serving as a sort of caisson breakwater (http://harukanoor4.blogspot.com/2022/). The mouth of Sumida-gawa River was an important military strategic point. For the indebted Tsukuda (佃) villagers, Ieyasu gave permission to reclaim a marsh land at the mouth of Sumida-gawa River. It took 15 years to complete the construction of the artificial island in 1644 by the villagers, a rectangle with sides around 180 m (591 ft). A shrine building was newly built and the villagers brought the Japanese Shinto deity of Sumiyoshi (住吉), the protector of seafarers, from their homeland (in Osaka Prefecture) in 1646. Hiroshige depicts the artificial island (佃島) in the background of the left of this print. The shoreline is retained with dry-stone walls. Notably, dry-stone wall stabilizes the shoreline, forming prolific fishery grounds. Placement of non-fragmented vegetation, the sacred forest marked by a stone torii gate and tidal marshes on irregular-shaped man-made sandbanks, serves a pathway of biogeochemical cycles for resilience of underwater seagrass meadows and deep-water kelp forests. The vegetation connectivity between land and sea in turn enhances quality/quantity of coastal fisheries.

Fig. 7-2 The Sumiyoshi Shrine Festival from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the Library of Congress via Wikipedia). The shrine’s fame is a festival that is held once every three years. Several sacred palanquins are solemnly paraded and dipped in the sea, symbolizing union with the protector of sea and people who harvest from sea and sail sea. Hiroshige depicts a sacred palanquin is being carried in procession to sea behind the festive banner. The magnificent palanquin with golden phoenix on the roof is water-proofing by lacquer (produced from sap tapped from the trunk of vanish tree, Toxicodendron vernicifluum) and gold. This print implies prolific coastal marine ecosystems underpin resilience of coastal communities. 

4.2 Unique multi-buffering coastal protection in the land beneath the sea

 

The governance of land-use in the hazard-prone areas

In Edo, large tracts of salt marshes and mud flats that spread in the eastern parts of Sumida-gawa River were reclaimed from around 1596. Reclamation works gradually outspread the area lay beneath the sea. From around 1655, urban waste was used to fill up the area lay beneath the sea. The district, reclaimed estuary of Sumida-gawa River, was called Fukagawa (深川, Fig. 6-I, N, O, P) (Endoh 2004). The Fukagawa district was protected by unique shape of earthen sea dyke called Susaki (深川洲崎, Fig. 6-I; Fig. 8-1, 8-2; Fig. 8-7-I).

The reclaimed lands of Fukagawa were assigned to mainly feudal lords, 大名 daimyo—‘the governors of provinces,’ for residential areas. All the mansions of feudal lords had gardens.

The gavage filled-up lands were intended to protect the important political/commercial center of Edo and low-lying areas from coastal hazards, and to boost quality/quantity of fisheries resources. Land-use planning and management in Fukagawa were unique, adopting the multi-buffering in coastal hazard mitigation. To mitigate wave energy, the gardens had artificial islands/mountains covered with trees/forests. The vegetated artificial islands/mountains in gardens are intended to absorb wave energy and reduce wave reflection like the dotted islands in the legendary Matsushima Bay. To store floodwaters, saltwater filled ponds were constructed. These seawater-filled ponds, in turn, served as nurseries for many species of fishes and crustaceans, including shrimp shiba-ebi (芝海老, Metapenaeus joyneri), the excellent diet of commercially important species of fisheries. Hiroshige depicts the typical landscaping garden of the gavage filled-up lands in Fig. 8-3 and 8-4 (Fig. 6-N, Fig. 8-7-N).

In Hiroshige’s time, lumber yards lay in Fukagawa (Fukagawa Kiba, 木場, Fig. 8-5, Fig. 6-O, Fig. 8-7-O). The timber was necessary to build and rebuild after the constant fires and upheaval as the result of repeated earthquakes. The logs were mainly stored in saltwater-filled man-made ponds. Kiba was a popular place for wealthy merchants to build villas with lavished gardens similar to the feudal lords’ gardens. In Kiba, the forests/trees in gardens and man-made ponds connected by canals shaped attractive landscapes (Fig. 8-5).       

In Fig. 8-6 (Fig. 6-P, Fig. 8-7-P, Fukagawa Susaki Jumantsubo深川洲崎十万坪), the vacant open space appeared late in the eighteenth century, following the storm surge caused by a typhoon that seriously affected the Fukagawa district in 1791. Following the catastrophic storm damage, the Tokugawa shogunate government bought out the waterfront area of Fukagawa, previously occupied villas of feudal lords and built-up areas. As a coastal hazard mitigation strategy, construction of any buildings was prohibited, leaving wilderness (Tokyo City government 1915).

Hiroshige depicts landscapes of the gavage filled-up lands that land-use planning connected to some of important policy issues: disaster mitigation, management of prolific fisheries resources, and opportunities of recreation for people.

 

Reclamation works integrated with waste assimilation

Ieyasu ordered reclamation work to meet rapidly increased needs for residential areas immediately after he settled in Edo in 1590. Large tracts of salt marshes and mud flats that spread in the eastern parts of Sumida-gawa River were reclaimed from around 1596 and a considerable area of the low-lying reclaimed land was assigned to feudal lords, 大名 daimyo, as residential areas.

The reclamation works gradually outspread the area lay beneath the sea. In 1624, a Shingon monk, Chosei (長盛) founded Eitai-ji Temple on the artificial island called Eitai-jima Island, reclaimed shoal at the estuary of Sumida-gawa River. As the area lay beneath the sea, the reclamation work was difficult and tough. Strong waves so many times breached the sea dykes. Hence, he brought and placed the Tomioka Hachiman (Namiyoke Hachiman, tsunami mitigation Hachiman) from Tomioka (in Yokohama, Fig. 6-D) within the precinct.

Meanwhile, disposal of any kind of waste to urban areas and to water bodies (rivers/streams and seas) was strictly prohibited in 1655. Urban waste in Edo was mostly organic matter such as food scraps, paper, and wood; not included synthetic organic polymers—or plastics, which cannot be easily removed (Worm et al. 2017). Household waste was collected and shipped to the artificial island, Eitai-jima Island, and used to fill up the area lay beneath the sea. Twenty-six years later, other areas lay beneath the sea were assigned as garbage fill-up place in 1681 (Endoh 2004). From around 1655, reclamation works of Edo Bay lay beneath the sea were integrated with urban waste management.

Waste assimilation is one of important ecosystem services (e.g., Cosanza et al. 1997). Through the learning-based approach, ancient Japanese architects and decision-makers were aware that vegetation of high primary productivity such as tall dense forests and salt marshes efficiently assimilates organic matter—the sugars, amino acids and other biological molecules. In Fig. 8, Hiroshige depicts landscape architecture of the garbage filled-up land, showing strategic placement of coastal forests and vegetated wetlands for efficient waste assimilation. Landscape architecture of the waste filled-up land was unique in an integrated approach combined coastal hazard protection and marine resources management.

 

Sea dykes as part of the multi-buffering coastal protection to shape diverse productive habitats

Sea dykes along with intertidal wetlands were one of effective multi-buffering to mitigate coastal hazards. Man-made sandbar was called susaki (洲崎). Ancient Japanese architects were aware the connectivity of seas and intertidal wetlands plays an essential role in shrimp productivity, which contributes to enhance quality/quantity of coastal fisheries resources via trophic transfer in marine food webs. Therefore, sea dyke was often designed in such a way as to create a long earthen sandbar that protrudes into sea, like a spit/promontory (Fig. 8-1, 8-2; 10-1).  These sea dykes, also called susaki, were coupled with productive intertidal wetlands in their structure.

Hiroshige depicts the earthen dyke, ‘susaki,’ constructed in the garbage filled-up land at the estuary of Sumida-gawa River from the direction of Edo Bay in winter (Fig. 8-1), and from a bridge over a tidal channel in spring (Fig. 8-2) (Fig. 6-I, 8-7-I). On the headland covered with a dense sacred forest, a shrine dedicated to Benzaiten (弁才天, 弁財天) stands behind a torii gate. Such shrines dedicated to Benzaiten or Benten (Japanese goddess of everything that flows: water, time, words, and music; derived from the Hindu goddess Saraswati) were often placed these man-made spits/promontories, which ran far out into the sea or estuary.

Any fishing and shellfish gathering were forbidden in a broad and unbroken coastal sea along the precinct of the Benzaiten shrine, creating a sanctuary of nursery/feeding habitats for prolific fisheries resources including commercially important shellfish such as Manila clam (asari, 浅蜊, Lajonkairia lajonkairii) and Asian hard clam (hamaguri, 蛤, Meretrix lusoria).

    

Sea dykes intended to stabilize beaches and to protect low-lying areas from coastal hazards

The irregularly bending earthen sea dykes were intended to stabilize beaches in front of the structure and to restore intertidal vegetation such as common reed (Phragmites australis) and submerged aquatic vegetation over coastal sea, as well as protection of low-lying coastal areas. Numerous irregular-shaped earthen groynes (groins)—man-made sandbars—that extended into sea from the earthen sea dyke were constructed. These man-made sandbars were constructed by closely spaced wooden piles driven into the seabed. In addition, ‘loosely spaced wooden piles’ are driven into the seabed served as a sort of breakwater, preventing the dyke being washed away (Fig. 8-1, 8-2). These coastal dyke engineering structures created calm shallow sea waters, making favorable condition for growth of underwater seagrass meadows. Seagrasses attenuate waves, which in turn accelerates sedimentation, contributing shoreline protection.

 

Venues for numerous pleasurable activities for people

In landscape architecture, design of places of relaxation for the population was considered as one of the duties that the ruling class was obliged. Therefore, the landscapes were designed to serve the population as venues for numerous pleasurable activities.

The extensive tidal flats in front of the sea dyke formed a prolific marine ecosystem. During the spring low tide, the intertidal zone was open to the public for recreational shellfish harvesting (Fig.1, Fig. 8-2). People also enjoy to catch by hands the valuable large fishes such as red seabream (tai, 鯛, Pagrus major) and flounder (Hirame, 鮃, Paralichthys olivaceus) that are trapped in tidal pools (Fig.1). The event was a truly popular. The occasion was attended by enormous numbers of people. The function of coastal nursery/feeding habitats for prolific marine resources was maintained as forbidden seawaters. Even in the popular event, people did not enter the broad and unbroken sacred coastal zone in front of the Benzaiten shrine (Fig. 8-2), being respectful for the forbidden seawaters.

In Fig. 8-2, Hiroshige depicts that the place is popular for the inhabitants of Edo to stroll and to picnic. The gate of the Benten Shrine was surrounded by shops and restaurants. Behind the umbrella-wearing women in the foreground, an elaborately shaped landscape is spreading: the Benten Shrine at the headland of susaki embankment, exposed mudflats in front of the dyke at the spring low tide, and vegetated wetland behind of the dyke. In light of the susaki embankment, Hiroshige’s notations are completely precise records of the structure: The channel keeps adequate water depth for the vessels at extreme low tide; The meadow of the floodplain of the channel is designed a considerable area for picnic and/or outdoor feast.  

 

Gardens as part of the multi-buffering coastal protection structure

The gardens in low-lying areas were part of sophisticated multi-buffering in coastal hazard mitigation. The temple/shrine complex, Eitai-ji/Hachiman in Fukagawa was built on the artificial island, Eitai-jima, in the gavage filled-up land. Estuary of Sumida-gawa River was a pivotal strategic point from attacks by sea, and coastal hazard protection of a vast area of low-lying reclaimed land. This temple/shrine complex, occupied an enormous area of 200,026 m² (50 acres), received cordial protection by the Tokugawa shogunate. It was called Fukagawa Hachiman, which was famed for its beautiful garden. Each year in early summer, the garden was open to the public (Fig. 8-3, 8-4).

In the eastern parts of Sumida-gawa River, a considerable area of the low-lying reclaimed marsh lands from around 1596 was assigned to feudal lords as residential areas. The governors of provinces numbered some 300, had several mansions in Edo: main office and residence of lord’s family near Edo Castle; residence of lord’s entourages; and villa equipped with warehouse. The gardens of the feudal lords’ mansions numbered some 1,000. 

Extensive area of the gavage filled-up land in the area lay beneath the sea from around 1655 was also assigned to feudal lords for residential areas (Endho 2004). Aware of coastal hazard vulnerability of the reclaimed land beneath the sea, the suburban residences in the low-lying areas were used as villa.

The gardens in the gavage filled-up land were intended to protect the important political/commercial center of Edo and low-lying areas from coastal hazards, and to boost quality/quantity of fisheries resources.

Hiroshige depicts a typical garden in the gavage filled-up land in Fig. 8-3 and 8-4 (Fig. 6-N, 8-7-N). To attenuate waves and mitigate storm damages, elevated mounds and trees/forests are elaborately placed. The artificial mountain in Fukagawa Hachiman is highly raised, constructed with a zigzag path leading to the summit, where is provided a pleasant place to spend time admiring views out to sea (Fig. 8-3, 8-4).

Ponds were dug to fill with saltwater even at spring low tide, and the excavated soil was used to construct artificial islands/mountains. Irregular-shaped ponds were connected to sea via canals (Fig. 8-7-N).

 

Timber yards in Kiba designed as part of the multi-buffering coastal protection

The supply of timber necessary to build and rebuild after the constant fires and upheaval as the result of repeated earthquakes depended upon sources in distant parts of Japan. In early Edo period the timber yards were constructed in the very center of the city. The yards were moved several times, before it settled in 1701 in the gavage filled-up land of Fukagawa, called Kiba (木場, Fig. 6-O, 8-7-O). The logs were mainly stored in saltwater filled man-made ponds (Fig. 8-5). In Kiba, numerous wealthy merchants constructed villas with lavished gardens with artificial islands/mountains covered with trees/forests and saltwater filled ponds, similar to the feudal lords’ gardens. These man-made seawater-filled ponds were connected to sea through the seawater-filled canals (Fig. 8-7-O). The timber yard, occupied an enormous area of 297,000 m² (74 acres), served as nurseries supporting prolific coastal fisheries. Urban planning of Edo was unique in establishing coastal protected areas.

 

Vacant open space as a flood mitigation strategy

The proactive acquisition of vacant open spaces in flood-prone areas is expected to play an increasing role as a flood mitigation strategy (e.g., Atoba et al. 2021). Edo had an innovative approach in purchasing damaged properties and restoring them to open spaces integrated with fisheries resources management.

In 1791, a devastating storm surge caused by a typhoon hit Edo. The worst affected area was the waterfront district of the low-lying gavage filled-up land of Fukagawa, known as Jumantsubo (十万坪)—‘One hundred thousand tsubo’ (a tsubo was 3.33 m² or roughly four square yards). The gavage filled-up land early in the eighteenth century occupied feudal lords’ mansions and built-up areas. Following the storm surge damage that over three hundred buildings were destroyed and dozens of people were killed, the Tokugawa shogunate government bought out the waterfront area of Jumantsubo of 333,333 m² (82 acres) and prohibited to construct any buildings, leaving the vast emptiness as wilderness (Tokyo City government 1915). In Fig. 8-6, the gigantic eagle hovering in the winter skies above the vacant open space gazes a coffin floating water, implying the catastrophic storm casualties (Fig. 6-P, 8-7-P).

When the flood-prone area remained vacant, elaborately shaped artificial islands/mountains covered with trees/forests in gardens increased effectiveness of multi-buffering hazard mitigation, and man-made ponds connected with canals successfully stored floodwaters and enhanced nursery function of many species of fishes and crustaceans (Fig. 8-7-P). This shoreline was fame for a fine view out to sea and Mount Tsukuba on the horizon (Fig. 8-6). The attractive landscape of the vacant open space was a favorite spot for boat-trips. Pleasure-boats were available for hire, on which geishas played musical instruments and sang, offering the quests food and drink.   

 

‘The tragedy of the commons’ in coastal fisheries: land governance for marine wildlife sanctuaries in Edo

The ‘tragedy of the commons’ in fisheries. In relation to fisheries, the ‘tragedy of the commons’ has long been recognized (e.g., McWhinnie 2009). When individual pursuit of personal gain is allowed, the problems of overuse and consequent degradation can occur easily in natural resources that are in public ownership or to which everyone has access (Hardin 1968). Marine resources are basically common resources that access is open, overfishing and the consequent collapse of fisheries easily occur around the world (e.g., Jackson et al. 2001).

Natural aquaculture and nursery role in the elaborately shaped artificial wetlands. Placement of marine wildlife sanctuaries in Edo was unique. In Fukagwa, elaborately shaped artificial wetlands—a large number of gardens, timber yards, and vacant open space of Jumantsubo—were dotted with seawater-filled ponds (Fig. 8-7). These man-made ponds connected by sea via canals were designed to boost quality/quantity of fisheries resources by trophic transfer in marine food webs. In these man-made ponds, phytoplankton are consumed by marine zooplankton (small crustaceans such as copepods and krill; larva of fish, squid, lobsters and crabs). These smaller herbivorous zooplankton are eaten by larger zooplankters and forage fish (small, schooling, filter-feeding fish such as sardines, anchovies, and herrings). In Edo, vinegared fillets of fish species such as konoshiro (鰶, Konosirus punctatus) and sappa (鯯, Sardinella zunasi) in the family herrings were popular as topping of Edo-style sushi. The forage fish are then consumed by larger predators such as red seabream (鯛, Pagrus major) and flounder (鮃, Paralichthys olivaceus). Notably, high productivity of shrimp of the artificial wetlands plays a pivotal role in enhancing quantity/quality of coastal fisheries resources. The large areas of man-made vegetated wetlands shape natural aquaculture of shrimp, which is important in the diet of almost all species of coastal fisheries at one history or another.

The predator fish of ‘red seabream (鯛)’ was a decorative element in saltwater-filled ponds of gardens in the low-lying gavage-filled up land. Property rights of the artificial vegetated wetlands such as gardens of feudal lords were complete and access to the created aquaculture system was limited as ‘forbidden lands.’   

In Eastern philosophy, contribution to politics for people was considered one of the important duties that the ruling class and wealthy people were obliged. The ruling class and wealthy people were acknowledged that the function of natural aquaculture in the artificial wetlands plays the underlying role in governance of food security for people via boosting quantity/quality of coastal fisheries resources. Therefore, abundant shrimp and fish were released to sea via water gate equipped in gardens, not to be enclosed.

Aware of the importance of coastal wetland in fisheries (Borsch and Turner 1984; Chesney et al. 2000) via learning-based approach, placement of artificial wetlands as marine wildlife sanctuaries was ubiquitous in the Edo period over the whole country of Japan. Although much altered, remnant of seawater-filled moat system still exists today, where the predator fish of ‘red seabream (鯛)’ with vivid red color are swimming, in Takamatu (高松) city (in Kagawa prefecture). 

Fig. 8-1 New Year Sun-rise with Snow at Susaki (Tokyo: 35°40′ N, 139°48′ E; Fig. 6-I, 8-7-I) from the series Famous Places in the Eastern Capital, Hiroshige, originally published 1831. Reclamation works in Edo gradually outspread the area lay beneath the sea from around 1655. Urban wastes (mostly organic substances such as food scraps) were used to fill up the area lay beneath the sea. Fukagawa (深川) is the gavage filled land in the estuary of Sumida-gawa River. Man-made sandbar was called susaki (洲崎). To shape ecological connectivity between sea and intertidal wetland, man-made sandbars that stick out into the sea were often constructed as sea dykes. In the headland, the shrine dedicated to Benzaiten stands behind a torii gate in the thick dense sacred forests along with elaborately placed tidal ponds. Any fishing and shellfish gathering were forbidden in a broad and unbroken coastal sea along the precinct of the Benzaiten shrine, shaping a sanctuary of nursery/feeding habitats for prolific fisheries resources including clams. Sea dykes were intended to stabilize beaches in front of the structure. Numerous irregular-shaped groynes (groins)—man-made sandbars—that extended into sea from earthen sea dyke create calm shallow seawaters, making favorable condition for growth of underwater seagrass meadows. Irregular-shaped tidal flats are formed in the beach, as the engineering structure of wooden piles accelerates sedimentation, contributing shoreline protection.

Fig. 8-2 Gathering shellfish in the sea at the Benten Shrine in Susaki (Fig. 6-I) from the series Famous Places in Edo, Hiroshige, originally published 1854.  The extensive tidal flats in front of the sea dyke form a prolific marine ecosystem. During the spring low tide, the intertidal zone was open to the public for recreational shellfish harvesting. Even in the popular event, people were respectful for the coastal sea sanctuaries of the Benten Shrine. Hiroshige depicts that sea dyke systems are designed to serve the population as the places of numerous pleasurable activities.

Fig. 8-3 Open Garden at Fukagawa Hachiman (Fig. 6-N, 8-7-N) from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the ukiyo-e.org https://johnresig.com/projects/ukiyoe/ by Resig J, the Museum of Fine Arts). In the low-lying gavage filled land of Fukagawa, numerous gardens of temples/shrines, feudal lords, and wealthy merchants were placed, intended to provide the multi-buffering in coastal hazard mitigation similar to the legendary Matsushima Bay. The temple/shrine complex, Fukagawa Hachiman, was famed for its beautiful garden, which was open to the public in early summer. The artificial islands/mountains covered with trees/forests in the gardens were designed to provide buffering form tsunami and/or storm surge like the dotted islands in the legendary Matsushima Bay. A decorative element in seawater-filled pond was swimming predator fish of ‘red seabream (鯛)’ with vivid red color. Seawater-filled ponds connected by sea via canals served as protected habitats supporting shrimp productivity. These artificial wetlands served as nursery grounds for prolific fisheries resources via tropic transfer in marine food webs. Abundant shrimp and fish were released to sea via the water gates equipped in gardens. The abundant released shrimp and fish in turn boosts quantity/quality of coastal fisheries resources. Edo had unique form in establishing coastal protected areas. 

Fig. 8-4 Open Garden at Fukagawa Haciman (Fig. 6-N, 8-7-N) from the series Famous Places in Edo, Hiroshige, originally published Early-mid-1840’s (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). Via learning-based approach, ancient Japanese architects were aware that highly elevated landforms such as mountains/islands covered with forests/trees effectively attenuate wave energy and reduce wave reflection. Hiroshige depicts vegetated artificial high mountain in a typical garden in the low-lying gavage filled land of Fukagawa, as part of coastal multi-buffering. Japanese engineers pursued aesthetic works of effectiveness in coastal hazard mitigation.

Fig. 8-5 Fukagawa Kiba (木場, lumber-yard, Fig. 6-O, 8-7-O) from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the Adachi Institute of Woodcut Prints https://www.adachi-hanga.com/ ). The timber was necessary to build and rebuild after the constant fires and disruption as a result of repeated earthquakes. Lumber-yard was moved several times form the very center of the city, before it settled in 1701 in Fukagawa. The logs were mainly stored in seawater-filled man-made ponds.  In Kiba, numerous wealthy merchants constructed villas with lavished gardens of artificial vegetated islands/mountains and seawater-filled ponds. The timber-yard, occupied an enormous area of 297,000 m² (74 acres), provided nursery grounds for prolific fisheries resources. Urban planning of Edo was unique in establishing coastal wildlife sanctuaries. 

Fig. 8-6 Fukagawa Susaki Jumantsubo (Fig. 6-P, 8-7-P) from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the Adachi Institute of Woodcut Prints https://www.adachi-hanga.com/ ). The Tokugawa shogunate government bought out the waterfront district of Jumantsubo of 333,333 m² (82 acres) and prohibited to construct any buildings, following the catastrophic storm damage in 1791. The gigantic eagle hovering in the winter skies above the vacant open space gazes a coffin floating seawater, implying the catastrophic storm surge casualties. The district previously occupied feudal lords’ mansions and built-up areas turned to a vacant open space of wilderness. Owing to the wilderness policy, artificial islands/mountains covered with trees/forests in gardens enhanced effectiveness of multi-buffering coastal hazard mitigation, and man-made seawater-filled ponds increased efficiency of nurseries to boost prolific fisheries resources. The proactive acquisition of vacant open spaces in flood-prone areas in Edo was unique. The attractive landscape of the vacant open space was a popular spot for boat-trips. Pleasure-boats were available for hire, on which geishas provided the entertainment, offering the quests food and drink.  

Fig. 8-7 The multi-buffering system of coastal hazard mitigation in Fukagawa, data from the Reproduced 1856 Edo Map Verified by Actual Measurement in the Encyclopedia of EDO-MEIJI-TOKYO, edited by Keiji Nakagawa, APP Co., Ltd, 2004, processed by Dr. Sotaro Tanaka. Reclamation works in Edo gradually outspread the area lay beneath the sea from around 1655. Urban wastes were used to fill up the area lay beneath the sea. To protect the low-lying areas from coastal hazards and to enhance quality/quantity of coastal fisheries resources, the multi-buffering coastal protection system was designed: I: unique shape of earthen sea dyke called Susaki along with saltwater-filled canal connected to sea; N: a typical garden as part of the multi-buffering, with constructed artificial islands/mountains to absorb wave energy and reduce wave reflection, and saltwater-filled ponds to store floodwaters; O: lamber-yard, numerous seawater-filled ponds to store logs along with saltwater-filled canal connected to sea; P: Fukagawa Susaki Jumantsubo, a large expanse of the vacant open space of wilderness, placed following the storm surge devastation caused by a typhoon in 1791. Property rights of these man-made seawater-filled ponds connected to sea were complete, shaping sanctuaries of nursery/feeding habitats for prolific fisheries resources. Abundant shrimp and fish were released to the sea via water gate from the man-made vegetated coastal wetlands as the obligation of ruling class and wealthy people, which in turn underpinned the prolific coastal fisheries. Strategical placement of coastal wetlands contributed the governance for food security, due to the importance of vegetated coastal wetlands in fisheries productivity (Boesch and Turner 1984; Chesney et al. 2000), 

4.3 Imposing multi-buffering coastal protection in front of Edo Castle

 

Hama-goten: a sort of outpost

Shiba-ura Embayment (芝浦, Fig. 6-K) is a coastal district along the stretch of shore from the sea opening of moat system of Edo Castle as far as the mouth of Furu-kawa River (Fig. 9-3). Offshore of Shiba-ura, only one route to the ports of Edo Castle for large vessels, had an important attribute in defensive and military strategies.

When Ieyasu settled in Edo in 1590, he immediately started to produce the moat system that ran in a loop gradually approaching the castle and to extend residential areas for feudal lords by the reclamation of the coastal marsh. The soil dug from the moat construction was used to fill up an inlet near the castle. In the coastal fringe of the moat system, a series of man-made islands and/or sandbars was created, and all the sides of shoreline were reinforced with dry stone walls. These fortified islands and/or sandbars, rectangle or rhombus shaped, were allocated to mansions for governors of provinces.

The sea entrance approach of moat system to Edo Castle was of military strategic importance (Fig. 9-6-Z). Therefore, a falconry field of the shogun family was placed in the salt marsh of this zone. In 1654, a lesser branch of the Tokugawa family reclaimed the salt marsh and constructed Japanese traditional wooden palace in the artificial island, along with landscaping garden of artificial islands/mountains and seawater-filled ponds (Fig. 9-1, 9-2).

In 1704, the palace was passed to ruling line of the shogun family, called Hama-goten (浜御殿, seashore palace, Fig. 6-P, 9-6-P). The seashore palace, with the sides around 500 m (0.31 miles) long covered with an area of 250,216 m² (62 acres), served as a villa for the shogun family and used for the reception of noble guests from abroad. Due to the military strategic importance, it served as a sort of outpost defending the approaches to the shogun’s castle. Naval base was situated here in Hiroshige’s time. In 1853, five artilleries were equipped in the ground as a measure of coastal defense caused by Perry’s arrival with the steam frigates.

The estates of feudal lords and the grounds of Hama-goten were surrounded by seawater-filled moats (Fig. 9-1, 9-6). The moat system was intended to defend the approaches to the shogun’s castle. The moat structure was complicated: while some moats were wide in width, others were narrow, with some parts went sudden trapped. These complications made it hard to access Edo Castle, called ‘sea-moat labyrinth.’               

Japan transited from shogunate (military governing dynasty) to an imperial-led government by the Meiji revolution of 1868. In 1869, western-style palace was built as a guesthouse for the reception of noble foreigners. In 1879, former U.S. president and Civil War general Ulysses S Grant met the Emperor Meiji (26 years old at that time) at Hama-rikyu (浜離宮, seashore villa palace) and provided advice/guidance for the future of Japan. Although much altered, this site still exists today, open to the public as Hama-rikyu gardens.

 

Integrative approach to management of fisheries resources and Edo Castle’s defending strategy: Placement of extensive unbroken coastal forests  

The inshore area of Edo Castle’s moat system was strategically defended. Hiroshige depicts a view of Shiba-ura Embayment from offshore (Fig. 9-3, Fig. 6-K).  A large cargo vessel is riding at anchor just offshore. The coastal water was too shallow for large vessels to get closer to shore, vessels dropped anchor just off shore, and small boasts were used to shuttle passengers and/or freight.

At the upper left of the print, between the forests that form two dark masses, a small river—Furu-kawa River, served as a sort of outer moat, enters Edo Bay. A deep forest on elevated river terrace that forms a dark mass at the upper left of the print occupied mansions of feudal lords and high-ranking samurais. Behind the forest, Zojo-ji monastery (Fig. 6-R) lies covered with deep sacred forests. Behind the Zojo-ji monastery’s forests, another extensive coastal forest is depicted far in the distance, which belongs to a series of man-made islands and/or sandbars for residential area of feudal lords including the Hama-goten. The shogun’s castle exists behind the coastal forests of Hama-goten.

In management of fisheries resources, ancient Japanese architects and decision-makers were acknowledged that coastal forests play an important role as critical juncture in biogeochemical connectivity between land and sea (http://harukanoor4.blogspot.com/2022/). Extensive unbroken coastal forests were placed in the inshore district in front of Edo Castle integrated with defending strategy of the shogun’s castle.

The coastal forests supply leaf-litter of slow-decomposition and humus—essential nutrients for marine productivity, besides reduce urban runoff and harmful nutrient loadings (http://harukanoor4.blogspot.com/2022/). Furthermore, seawater-filled moats (Fig. 9-1) and ponds in gardens (Fig. 9-2) served as protected nurseries for many species of fishes and crustaceans. The man-made vegetated wetlands, in turn, enhanced inshore and coastal fisheries productivity. Notably, fairly small shrimp, shiba-ebi (芝海老, Metapenaeus joyneri) were abundant, spawning prolifically, accordingly named after the inshore district of Shiba (芝).

The elaborately shaped landscapes of Shiba-ura formed a complex and prolific marine ecosystem. This complex ecosystem supported abundant and diverse fisheries resources. Therefore, the Shiba-ura Embayment was admired as Osaiura (御菜浦, His excellency’s fishing grounds) and freshly caught fish/shellfish were delivered to the nearby shogun’s court. Edo-style sushi , also known as Edo-mae sushi (江戸前寿司), originates value-added use of freshly caught fish/shellfish in the embayment in front of (mae, 前) Edo  (江戸)  Castle—inshore sea area of the largest metropolis in the world.  

  

Unique reclamation work for coastal fishery communities in creation of diverse and productive habitats

In the outskirts of Edo Castle, a small river—Furu-kawa River flowed. In 1675, natural course of the down-stream Furu-kawa River was deepened and widened for canalization, eventually this canal became an element of importance in Edo’s waterborne transport system. Besides, Furu-kawa River served as a sort of outer moat of the shogun’s castle (Fig. 9-5).

In Fig. 9-3, between the forests that form two dark masses at the upper left of the print, the Furu-kawa River enters Edo Bay. The estuarine area of the Shiba district was reclaimed from marsh lands. Due to defensive and military strategic importance, the Zojo-ji monastery, and mansions of feudal lords and high-ranking samurais were placed. The coastal water was too shallow for large vessels to get closer to shore, vessels dropped anchor just off shore and use small boasts to shuttle passengers and/or freight.

In Fig. 9-3, along the shoreline of the reclaimed marshland, a series of man-made sandbars, which stick out into the bay as parallel each other with a slanted angle, was constructed. These sandbars are fringed with a wide expanse of sandflats and mudflats. The sandbars of elevated topography are tightly packed with houses. Although seashores are prone to storm damage, people associated with fisheries prefer to live in the locations owing to easy access to harvest marine resources along with water amenity and open views.

 To prevent erosion and accelerate deposition of sediments, a number of pine wooden piles are driven into the shallow bottom. A large quantity of wood piles accumulates oysters to grow together forming rock-like oyster reefs that contribute mitigation of erosion. The coastal forests are seen behind the coastal communities and the headlands.

Multi-layered elevated topography of sandbars, placement of dense coastal forests, a wide expanse of fringed sandflats/mudflats, and wood piles formed rock-like oyster reefs provide buffering from wave energy and reducing vulnerabilities of coastal communities. For coastal fishery communities, income sources are derived from coastal ecosystems rich biodiversity and ecological functions (Adger et al. 2005). These buffering structures, in turn, contributed in enhancing capacity of coastal ecosystems rich in biodiversity. The coastal design in Fig. 9-3 shows that decisions are made to reduce vulnerability of coastal hazards and to enhance resilience of ecosystems for fisheries, acknowledged that coastal ecosystems support local societies and economics.

 

Strategic placement of urban forests: elaborately designed inaccessibility to avoid the ‘tragedy of the commons’  

In Fig. 9-3, beyond the large cargo vessel riding at anchor, on the elevated river terrace in the east side of Furu-kawa River (the second dark mass of forests from the left of this print), the Zojo-ji monastery (増上寺, Fig. 9-4; Fig. 6-R)—the most important and influential Buddhist center on the Eastern Capital—lies. It occupied an enormous area of 833,250 m² (206 acres).

As shown in Fig. 9-3 from offshore and Fig. 9-4 viewing sea from a building within the precinct, the monastery was covered with deep sacred forests. To protect from the ‘tragedy of the commons,’ inaccessibility to the forests near the city center was elaborately designed using canals, ponds, and defensive structures of temple buildings.

In urban design of ancient capital Heian-kyo (平安京, today’s Kyoto, 794–1868), mystic defense from evil spirits was carefully considered based on the ancient Chinese beliefs such as Feng sui (Chinese: 風水). According to the Chinese beliefs, such sprits were located to the northern-east (鬼門, evils’ gate) and roamed another passage-way of the southern-west (裏鬼門, evils’ back gate). To confine such sprits, Enryaku-ji  monastery (延暦寺) to the northern-east, and Iwashimizu Hachiman shrine (石清水八幡宮) to the southern-west of the emperor’s palace were placed. These monastery and shrine, both exist today, occupy enormous areas covered with dense sacred forests.

Urban design of Edo was followed the precedent. As a mystic defense, Kanyei-ji monastery in Ueno to the north-east and Zojo-ji monastery in Shiba to southern-west of Edo Castle were constructed. Owing to close ties with the ruling dynasty, six mausoleums of Tokugawa shoguns were at Zojo-ji temple, another six in the cemetery at Kanyei-ji temple in Ueno. Kanyei-ji temple also occupied an enormous area of 1,016,565 m² (around 251 acres), covered with deep sacred forests. These monasteries were obliged to maintain the deep forests with meticulous stewardship.

Cities are supported by appropriate ecosystem areas (Folke et al. 1997; Kaye et al. 2006; Grimm et al. 2008). Essentially, Eastern Philosophy such as Feng sui was flexible formula to harmonize all elements of Nature: 2006; wind (風), water (水), solar radiation, and so on to build environment. For instance, the placement of enormous areas of deep forests was a carefully considered one in terms of urban summer cooling strategies. The northern-east forests shield and absorb intense solar radiation in morning and release cool moisture via transpiration, cooling for the whole city. In afternoon, the southern-west forests shield and absorb intense solar radiation and release cool moisture via transpiration, abating the rising afternoon temperatures in the city.

Tenkai Nankobo (南光坊天海, 1536–1643, a stateman, theologian, and architect), one of the closest advisors of Ieyasu and his two immediate successors, made the schematic plan of Edo. He was referred to as ‘a minister in priestly vestments.’   

In Fig. 9-3, Hiroshige depicts that placement of large coastal forested areas close to city center was intended to generate diverse ecosystem services: protecting low-lying coastal areas from coastal hazards, and providing essential nutrients for marine productivity.

In Eastern philosophy, temples/shrines were designed to serve the population as places of relaxation. Many forms of temple festival with Buddhist performance were held. In Fig. 9-4, visitors are enjoying a view out to sea from a building within the precinct. In all probability, a temple festival was held. The precinct crowded with many visitors in front of the stalls.

 

Urban forest in estate of feudal lord

In Fig. 9-3, beyond the large cargo vessel riding at anchor, dense forests occupy on fluvial terraces along the Furu-kawa river. In the west side of the river, the forests that form a dark mass at the upper left of the print belonged to estates of feudal lords and high-ranking samurais, notably a main office/residence of the Arima family form the north of Kyusyu Island (Fig. 9-5; Fig. 6-S).

In Fig. 9-5, the Furu-kawa river, served as a sort of outer moat of the shogun’s castle, runs alongside the Zojo-ji monastery complex. As so often with Edo’s rivers, it had a local name here—the Akabane-gawa River. This area was known as Akabane (赤羽根). On the opposite bank from the Zojo-ji monastery, there stood the main office/residence of the Arima family from the north of Kyusyu Island. The mansion’s fire-watchtower was constructed in an extensive deep residential forest on the elevated river terrace. The estate of the Arima family was enclosed with multi-family residential building, which was used for residence of retainers. The building with red gates was partitioned vertically into separate households, served as defensive walls.

Families of feudal lords were aware that providing a place of relaxation for the population was one of the duties that the ruling class was obliged. The Arima estate was famous for Suitengu  (水天宮)—the Japanese Shinto shrine, in its grounds. The position of the shrine is indicated by six vertical banners rising inside of the estate. The Suitengu, particularly popular among women seeking to give birth without trouble, was brought by the Arima family from their homeland. On the fifth of each month, there was a shrine festival along with a fair. In Fig. 9-5, a red gate is opened and visitors are allowed to enter the Suitengu’s precinct, and the street is crowded with people in front of the stalls.

Fig. 9-1 Main gate of Hama-goten and backwater moat filled with seawater (Tokyo: 35°39′ N, 139°45′ E; Fig. 6-Q, 9-6). Photo in the Meiji era (Image courtesy of the Open University of Japan Library). In 1654, salt marsh at the sea entrance of moat to Edo Castle was reclaimed. The seashore palace on the artificial island served as a sort of outpost defending the approaches to the shogun’s castle. Complicated moat system—while some parts were wide in width, others were narrow, with some parts went sudden trapped—was called ‘sea-moat labyrinth.’ 

Fig. 9-2 Garden of Hama-goten (Fig. 6-Q, 9-6) in 1863, photo by Felix Beato, via Wikipedia. The landscaping garden in reclaimed marsh is composed of artificial islands/mountains and ponds filled with seawater. The seawater-filled ponds, connected by sea via moats, served as protected nurseries supporting shrimp productivity. The intricately designed vegetated wetlands in turn formed self-organizing natural aquaculture, producing diverse fisheries resources by trophic transfer in marine food webs. The predator fish of ‘red seabream (鯛)’ with vivid red color swimming in the seawater-filled ponds was a decorative element of the garden. Estates of feudal lords and high-ranking samurais occupied a large geographic area in the inshore zone near the shogun’s castle. Their gardens played an important role in food security of Edo via the function of coastal marine sanctuaries. 

Fig. 9-3 Haze on a clear day at Shiba-ura (Fig. 6-K) from the series Eight Views of Environs of Edo, Hiroshige, originally published mid-1830’s (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). Hiroshige depicts a view of inshore district of Shiba-ura from offshore. A large cargo vessel is riding at anchor just offshore. The coastal water was too shallow for large vessels to get closer to shore, vessels dropped anchor just off shore, and small boasts were used to shuttle passengers and/or freight. The inshore area of Edo Castle’s moat system was defended by mansions of ruling class families notably the Arima family’s estate (Fig. 9-5), Zojo-ji monastery, and Hama-goten. Forests in residential area of feudal lords and high-ranking samurais form a dark mass in the upper left of this print, and contiguous to the adjoining forests belong to Zojo-ji monastery, which continue to the forests of Hama-goten. The extensive unbroken coastal forests were placed to enhance inshore and coastal fisheries productivity integrated with defending strategy of the shogun’s castle. Besides, seawater-filled moats (Fig. 9-1) and ponds in gardens (Fig. 9-2) served as protected nurseries for many species of fishes and crustaceans. Accordingly, the Shiba-ura Embayment was admired as Osaiura (御菜浦, His excellency’s fishing grounds), and freshly caught fish/shellfish were delivered to the nearby shogun’s court. Edo-style sushi, also known as Edo-mae sushi (江戸前寿司), originates value-added use of catches from the embayment in front of (mae, 前) Edo  (江戸)  Castle. 

Fig. 9-4 Zojo-ji Temple in Shiba (Fig. 6-R) from the series Eight Famous Places in the Bay Capital, Hiroshige, originally published mid-1830’s (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). In ancient urban planning, large areas of sacred forests were placed in the northern-east and in the southern-west in peri-urban zone as a mystic defense. The enormous areas of deep forests were elaborately designed to achieve effective implementation in urban summer cooling. The Zojo-ji monastery, known for six mausoleums of Tokugawa shoguns, occupied an enormous area of 833,250 m² (206 acres). The large forested area was placed on integrated policy approach: defending strategy of the shogun’s castle, coastal hazard mitigation, management of fisheries resources for food security, and summer cooling for the whole city. Temples/shrines were planned to serve the population as places of relaxation. In the temple festival, visitors are enjoying a view out to sea from a building within the precinct covered with deep sacred forests.

Fig. 9-5 Suitengu Shrine in Akabane (Fig. 6-S) from the series Famous Places in Edo, Hiroshige, originally published 1854 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). In Fig. 9-3, beyond the large cargo vessel riding at anchor, the deep forest that forms a dark mass at the upper left of the print belonged to estates of feudal lords and high-ranking samurais, notably a mansion of the Arima family form the north of Kyusyu Island. To avoid the ‘tragedy of the commons,’ deep urban forests were elaborately protected. The estate of the Arima family, deep forests in its grounds, was enclosed with multi-family residential building, which was served as defensive wall. The Estates of ruling class families were required to play a role in the integrated policy approach: defending strategy of the shogun’s castle, coastal hazard mitigation, management of fisheries resources for food security, and summer cooling for the whole city. Providing a place of relaxation for the population was considered as one of duties that the ruling class families were obliged. The Arima estate was famous for Suitengu shrine (水天宮), particularly popular among women seeking to give birth without trouble. On the fifth of each month, there was a shrine festival along with a fair. In this print, one of the red gates is opened and visitors are allowed to enter the Suitengu’s precinct, and the street is crowded with people. 

Fig. 9-6 The grounds of Hama-goten (Q) and estates of feudal lords surrounded by seawater-filled moats at the sea opening of moat system of Edo castle (Z), data from the Reproduced 1856 Edo Map Verified by Actual Measurement in the Encyclopedia of EDO-MEIJI-TOKYO, edited by Keiji Nakagawa, APP Co., Ltd, 2004, processed by Dr. Sotaro Tanaka. The complicated defensive moat system was called a ‘sea-moat labyrinth.’ The urban forests in Hama-goten and the estates of ruling class families supplied essential nutrients for marine productivity, leaf-litter of slow-decomposition and humus. Similar to the natural vegetated coastal wetlands (Boesch and Turner 1984; Chesney et al. 2000), the intricate seawater-filled moats and ponds in gardens were served as nurseries for prolific coastal fisheries. The forbidden area due to the important military strategic point was protected as a coastal marine sanctuary. Commitment to politics for people was considered one of the important duties that the ruling class was obliged. Therefore, abundant shrimp and fish were released to the sea via water gate equipped in gardens, which in turn played a significant role in governance of food security in the largest metropolis in the world.  

5.     Shaped landscapes of site-specific design in peri-urban and rural areas

 

While cities are supported by a wide variety of goods and services provided by ecosystems from outside the cities (Folke et al. 1997; Kaye et al. 2006; Grimm et al. 2008), the capacity of ecological services in rural regions is increasingly eroded (Hooke et al. 2012). Under current urbanization trends, restoration of resilience of coastal ecosystems in peri-urban and rural areas is more important than ever.  

 

5.1 Man-made long sandbar at river mouth to protect amusement quarter: Shinagawa

 

Shinagawa (品川, Fig. 6-H) was only 8 km (5 miles) from the Nihon-bashi Bridge, the starting point of the main highways that connected Edo with the rest of the country. Shinagawa (Fig. 10-1) was the first staging-post on the Tokaido highway that linked Edo with the imperial capital of Kyoto. In the Edo period, travelling the Tokaido, along the Pacific coast, became fashionable to enjoy beautiful sceneries associated with cultures and customs diverse from coasts to coasts (e.g., Fig. 10-3). In Japan it was customary when seeing someone off on a journey to go part of the way with them. The journey to this first station took a whole day and ended with a farewell banquet often with geishas to provide music and dance. Accordingly, Shinagawa was famous for its amusement quarters, stood numerous teahouses— amusement establishments.

The view in Fig. 10-1 is from the second story of one of the many amusement establishments. In the bottom left-hand corner, a courtesan is looking out to sea from the light-filled room upstairs of a teahouse building. Further off, two of coastal defense installations (daiba, Fig. 5; Fig. 6c-G) are under construction at the upper right of the print.

The area filled with a large number of amusement establishments and shops was protected from risk of coastal hazards by a 500 m (0.31 mile) long man-made sandbar (洲崎, susaki), which ran far out into the sea at the mouth of the Meguro-gawa River (Fig. 6b-H). In Fig. 10-1, irregular-shaped shoreline of the headland was reinforced with dry-stone walls. To mitigate erosion: in front of the masonry where prone to erosion by reflective wave energy action and at masonry base scouring action of waves, a number of pine wooden piles are driven into the ground. The spaces between rocks and wood piles accumulate oysters, forming rock-like reefs. The formed rock-like oyster reefs in turn dissipates wave energy and provide productive coastal habitats.  

On the headland covered with a dense sacred forest, a shrine dedicated to Benzaiten (弁才天, 弁財天), a Japanese goddess of everything that flows, stands behind a torii gate. As the coastal zone of the Benzaiten’s precinct was deemed sacred, any fishing was prohibited. Thereby, a broad and unbroken coastal sea was shaped as sanctuary of nursery grounds for productive fisheries.

 

5.2 Landscape architecture to create a favorable condition for cultivation of edible seaweed species of nori (Neopyropia tenera): Shinagawa Samezu

 

Legend of Samezu (鮫洲, Shark Bar)

In Fig. 10-2, Hiroshige depicts Samezu of southern part of Shinagawa, the stretch of coast around 1.5 km (a mile) long, with a vertical composition culminates in the twin-peaked Mount Tsukuba. Below the mountain, behind the two ships sailing along coast, a view of Shinagawa Susaki (Fig. 10-1) the long man-made sandbar sticks out into the bay is depicted. The sandbar was covered with dense forests, that lie high degree of connectivity from coast toward inland. The coastline of the sandbar, where elaborately formed large expanses of sandflats/mudflats, was one of the two excellent spots for shellfish harvesting during spring low tide (Fig. 1).  

The name Samezu is derived from an ancient legend. In 1251, a local fisherman caught a shark in his net and in its bally he found a wooden sculpture of Kannon (観音, the bodhisattva of mercy and compassion). The story was came to Tokiyori Hojo (北条時頼, 1227–1263), the head of the Kamakura shogunate. He considered it as an auspicious sign and ordered construction of a Zen monastery close to the spot where the shark had been caught. Daolong Lanxi (蘭渓道隆, 1213–1278), a Chinese Buddhist monk born in Sichuan Province, took charge of the construction of the Zen monastery—Kaian-ji temple (海晏寺) —'the Calm Sea Monastery.’ The Kannon statue discovered in such a miraculous way was placed in the monastery as the chief object of veneration. This legend suggests that the history of ‘land governance and coherent coastal national strategy’ in Japan dates back to at least the Kamakura period (1185–1333).

 

Landscape architecture to create a favorable condition of cold brackish seawaters inside of the embayment

The Kaian-ji temple, occupied an enormous area of over 4,840,000 m² (1,196 acres), received cordial protection by the Tokugawa shogunate. In Fig. 10-2, the large forested area belonged to Kaian-ji is depicted as a dark mass at the upper left of the print. The sacred forests, popular place to admire the turning autumn colors of foliage especially the scarlet leaves of maples, are extended contiguously to coastal forests. Along the shoreline, a series of man-made sandbars, which stick out into the bay as parallel each other with a slanted angle, is tightly packed with houses of coastal communities. The man-made sandbars structures were intended to stabilize beaches in front of the structure and to enhance the growth of underwater seagrasses and deep-water kelp forests, which in turn created calm and shallow coastal seawaters. Coastal communities are surrounded by tall dense forests, for a diverse range of functions and values to reduce vulnerability of coastal hazards, to create thermal comfort in the summer season, and to enhance quality/quantity of fisheries resources.

The specialty of Samezu was its cultivations of nori (Neopyropia tenera, frond up to 50 cm/20 inches), an edible seaweed species. In the foreground of Fig. 10-2, seaweed farmers are gathering the harvest by using the boats steering between the rows of standing bundles of tree branches. One type of Edo-style sushi—rolled sushi has been underpinned by the paper-like sheets of dried nori (海苔) by using the Japanese paper manufacturing technique. The huge demand for nori production provided plentiful opportunities and work for the coastal communities.

In Fig. 10-2, Hiroshige features the landscape architecture to create a favorable condition for cultivation of edible seaweed species of nori. The edible seaweed thrives better at cold temperature around 15°C (59°F) in brackish seawaters in winter, and grows on stems of reed, wooden piles, and shells. In Hiroshige’s time, the edible seaweed was cultivated in a unique method. In the autumn, bundles of tree branches were stuck into the shallow bottom in long rows. They became entangled with the edible seaweed as it grew. At low tide in winter and early spring, the harvest was gathered.

On the other hand, in Japanese nori cultivation, the most important point of the uniqueness is the landscape architecture to meet the requirements and needs for growth of nori.

In the ocean, iron (Fe) deficiency is limiting growth of phytoplankton, known as microalgae (Martin and Fitzwater 1988). The macroalgae growth is also restricted by the availability of soluble Fe, which derives from humic substances of forests via the decomposition of leaf litter (Matsunaga et al. 1999). The edible seaweed of nori belongs to algae group. Therefore, growth of the edible seaweed of nori requires soluble Fe that derives from humic substances of forests via the decomposition of leaf litter.

The sacred forests of the Kaian-ji temple and contiguously placed coastal forests provide leaf-litter of slow-decomposition and humus—essential nutrients for growth of microalgae and macroalgae including the edible seaweed of nori.

 

Cold brackish seawaters inside of the embayment

Seawater temperatures, controlled by biological processes supported by land-sea interaction, are in a state of dynamic equilibrium (http://harukanoor4.blogspot.com/2022/).  

Via learning-based approach, ancient Japanese architects and decision makers were aware that brackish seawaters occur inside embayment, besides estuaries where a river meets the sea. Occurrence of brackish seawater inside embayment was attributed to coastal groundwater discharge from the vast expanse of deep forests. Brackish water occurs when freshwater of groundwater discharge meets seawater.

Along the shoreline of Samezu, there was a constant groundwater discharge flowing into the sea. Coastal groundwater discharge plays an important role to procedure brackish seawaters with cold temperature around 15°C (59°F) in winter, in the shallow calm intertidal zone where the edible seaweed of nori grows (Fig. 10-2).

During the autumn, deciduous trees such as maple and oak in temperate forests shed their leaves, and add newly formed layer of leaves on yearly stratification of the leaf-litter—the thick layer of leaves on the forest floor. The decomposition of leaf-litter mainly by microorganisms is a key process of biogeochemical cycles in forests (e.g., Bani et al. 2018).  

Although deciduous trees cease photosynthesis during the winter season, all cells of living trees protected by thick bark including the deeper roots continue cellular respiration to acquire biochemical energy to fuel cellular activity. In addition, all microorganisms in charge of decomposition of leaf-litter acquire biochemical energy via biological processes of cellular respiration.

In cellular respiration—a series of metabolic processes within a cell, glucose (a monosaccharide sugar) is oxidized to carbon dioxide and water. During the winter season, leaf less trees cease transpiration. On the other hand, all cells of living trees and the deeper roots produce considerable amount of water as by-product of cellular respiration. Trees are protected by thick bark, which in turn leads to reduced water loss.

Dead leaves on the forest floor shield solar radiation (e.g., Yoshimura et al. 2010) and reduce evaporation from the forest floor. Cellular respiration by microorganisms in leaf-litter layer produce considerable amount of water as by-product of cellular respiration.

The considerable amount of water produced as by-product of cellular respiration in forest ecosystems permeates the soil and constitutes an important portion of groundwater. A substantial amount of freshwater produced by cellular respiration of temperate forest ecosystems contributes groundwater formation and constant discharge of freshwater to coastal seas.

The water formation by cellular respiration of trees of forests and leaf-litter could occur in the night-time during the spring and summer growing season (Fig. 10-4).

The role of forests in groundwater formation is controversial. The sponge theory—forests act as sponges storing rain water and slowly releasing it to maintain groundwater and streams—have lost credibility. In recent decades, global forest restoration is considered as harmful to maximizing water availability for human use. In the dominant paradigm, forest clearance generally leads to increased water yields, and afforestation leads to reduced water yields due to water losses from transpiration and rainfall interception (e.g., Ilstedt et al. 2016).

However, the historical evidence of ‘occurrence of cold brackish seawaters inside of the embayment’ shows that freshwater produced by cellular respiration in temperate forest ecosystems plays a critical role in formation of groundwater and qualitative restoration of freshwater.

In Eastern philosophy, the sacred forests and high degree of connectivity with coastal forests, tall and dense temperate deciduous forests having thick layer of leaf-litter, were placed and maintained to meet the requirements and needs for growth of nori, which in turn enhanced resilience of coastal communities.

The edible seaweed nori (Neopyropia tenera) is currently listed as an endangered species in Japan. Clearance of deep coastal forests and loss of land-sea interactions lead to habitat loss/degradation for cultivation of nori. Consequently, alternative species such as Neopyropia yezoensis have been used for the edible seaweed cultivation.

 

Distant view of Shinagawa Susaki

Hakkei-zaka Slope—‘the Slope of Eight (i.e., many) Views,’ adorned by a gigantic pine tree of eccentric shape (Fig. 10-3), is noted for its beautiful view of the shoreline: high connectivity of a distant view of Shinagawa, Shibaura, far shore of the Bay Capital of Edo, and further to the Chiba peninsula.

In Hiroshige’s time, the sea came in close to the foot of the hill and the Tokaido highway lay along the shore. Despite a detour of uphill climb, travelers on the Tokaido made a stop here to drink tea in one of the teahouses situated alongside the pine and enjoy a view of the shoreline of the Bay Capital. There was a legend that Hatimantaro Yoshiie (1039–1106), the outstanding military commander of the late Heian period (794–1185), stopped to rest here and hung his armor on the tree, during his campaign to northern Japan.

In Fig. 10-3, Hiroshige depicts distant view of Shinagawa Susaki, the long man-made sandbar, sticks out into the bay on the left-hand side behind the pine tree. The ‘loosely spaced wooden piles’ driven into the seabed served as a sort of breakwater are depicted around the headland. The coastal forests were placed behind the coastal communities tightly packed with houses. The coastline of the man-made sandbar, where elaborately shaped large expanses of sandflats/mudflats, was one of the two excellent spots for shellfish harvesting during spring low tide (Fig. 1).

The far shore of the Bay Capital of Edo, with the peak of the volcano Nikko Mountain range rising above it, is depicted behind the Shinagawa Susaki. Edo Castle was constructed on dry Musashino Plateau, which covered with a thick layer of volcanic ash on the base of an alluvial fan. The Hakkei-zaka Slope is situated on the Musashino Plateau that is extended to the Tama-gawa River (Fig. 12) via Shinagawa.

Fig. 10-1 Shinagawa Susaki (Tokyo: 35°37′ N, 139°44′ E; Fig. 6-H) from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the British Museum: https://w,ww.hiroshige.org.uk/ by Chiappa JN). Shinagawa was famous for its amusement quarters, as the first station on the Tokaido highway that linked Edo and the imperial capital of Kyoto. The area with many amusement establishments was protected from risk of coastal hazards by a long man-made sandbar, which ran far out into the sea at the mouth of Meguro-gawa River (Fig. 6b-H). On the headland reinforced with dry-stone walls, a shrine dedicated to Benzaiten was placed with thick sacred forests. The coastline of the man-made sandbar, where elaborately shaped large expanses of sandflats/mudflats, was one of the two excellent spots for shellfish harvesting during spring low tide (Fig. 1). A broad and unbroken sacred coastal zone along the Benzaiten’s precinct, where any fishing was prohibited, was served as sanctuary of nursery grounds for productive fisheries.  

Fig. 10-2 Minami Shinagawa and Samezu Coast from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the National Diet Library, Japan). Behind the two ships sailing along coast, Hiroshige depicts a view of Shinagawa Susaki from offshore. The man-made sandbar is covered with dense forests, that lie high degree of connectivity from coast toward inland. The specialty of Samezu (鮫洲, Shark Bar) was its cultivations of nori (海苔), an edible seaweed. In this print, seaweed farmers are gathering the harvest by using the boats steering between the rows of standing bundles of tree branches. Hiroshige features the landscape architecture to create a favorable condition for cultivation of edible seaweed species of nori. The edible seaweed thrives better at cold temperature around 15°C (59°F) in brackish seawaters in winter. Via learning-based approach, ancient Japanese architects and decision makers were aware that brackish seawaters occur inside embayment, in a condition that groundwater discharge meets seawater. In cellular respiration—a series of metabolic processes within a cell, glucose (a monosaccharide sugar) is oxidized to carbon dioxide and water. During the winter season, leaf less trees cease transpiration. On the other hand, all cells of living trees and the deeper roots produce considerable amount of water as by-product of cellular respiration. The water formation by cellular respiration of forest ecosystems could occur in the night-time during the spring and summer growing season. Aware that a vast expanse of deep forests plays a critical role in constant adequate groundwater discharge, an ancient policy decision maker placed Kaian-ji temple (海晏寺) —'the Calm Sea Monastery,’ with sacred forests (depicted as a dark mass at the upper left) occupied an enormous area of over 4,840,000 m² (1,196 acres). Owing to the critical importance in marine resources management, the temple received cordial protection by the Tokugawa shogunate.

Fig. 10-3 The Armor-hanging Pine at Eight Views Hill from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). The Hakkei-zaka Slope is associated with a legend of Hatimantaro Yoshiie, a brave warrior in the late Heian period (794–1185). Behind the pine tree on which the warrior hung his armor, Hiroshige depicts a distant view of the coastline of Shinagawa Susaki, one of the two excellent spots for shellfish harvesting during spring low tide (Fig. 1), and the continuous shoreline of Bay Capital of Edo. Travelers on the Tokaido made a stop here to drink tea and to enjoy an open view of the sea. The Edo Castle was constructed on dry Musashino Plateau, which covered with a thick layer of volcanic ash on the base of an alluvial fan. Hakkei-zaka Slope, noted for its beautiful view, is situated on the Musashino Plateau which is extended to the Tama-gawa River (Fig. 12) via Shinagawa. The land governance of the dry fragile plateau in Edo was unique in enhancing quality/quantity of groundwater to create arable land.

Fig. 10-4 In temperate forests, deciduous trees such as maple and oak shed their leaves and cease photosynthesis during the winter season. Whereas, all cells of living trees including the deeper roots continue cellular respiration to acquire biochemical energy to fuel cellular activity. In cellular respiration—a series of metabolic processes within a cell, glucose (a monosaccharide sugar) is oxidized to carbon dioxide and water. Trees are protected by thick bark, which in turn leads to reduced water loss. In addition, all cells of microorganisms in the thick layer of leaf-litter on the forest floor, which plays a pivotal role in biochemical cycles of forest ecosystems (e.g., Ilstedt et al. 2016), continue cellular respiration to acquire biochemical energy. Solar radiation shield properties of dead leaves on the leaf-litter layer (e.g., Yoshimura et al. 2010) lead to reduced evaporation from the forest floor. Consequently, considerable amount of water produced as by-product of cellular respiration permeates the soil and constitutes an important portion of groundwater. The water formation by cellular respiration of forest ecosystems could occur in the night-time during the spring and summer growing season.

As forests age, the amount of cellular respiration increases in response to the accumulating biomass. Due to the higher biomass, tall and dense forest ecosystems, having a higher leaf area index (LAI, i.e., the total area of green leaf surface per unit of ground area), play a pivotal role in retaining moisture levels in land and groundwater formation. Thus, tall and dense forests having a higher LAI greatly contribute to quantitative renewability and qualitative restoration of freshwater. In contrast, soil moisture and a portion of groundwater formation reduce in grasslands and crop lands due to the low LAI (b). Impervious surface, the zero LAI (a), has completely lost the important function in retaining moisture levels in the soil and groundwater formation, due to loss of cellular respiration by vegetation. Therefore, impervious surface expansion and engineered aqueous flow paths have a direct impact in quantitative renewability and qualitative restoration of freshwater. Which in turn leads to reduced water yields for human use.

5.3 The land governance in dry fragile plateau

 

Unique land governance of the dry plateau to create arable land  

Edo Castle (the highest ground elevation: 28 m/92 ft) was built in 1456–1457 on dry Musashino Plateau, which covered with a thick layer of volcanic ash on the base of an alluvial fan. The Musashino Plateau, shaped by cutting action of rivers and streams (e.g., Fig. 11-1), is extended to the Tama-gawa River (Fig. 12) via Shinagawa.

The land governance of the dry fragile plateau was unique in enhancing quality/quantity of groundwater to create arable land. To stabilize fragile soil of the plateau and to ensure groundwater formation, tall and dense forests highly mixed with evergreen conifers and the deciduous broad-leaved tree species were strategically placed as sacred forests of shrines/temples such as Zojo-ji temple in Shiba (Fig.9-3, 9-4) and the Kaian-ji temple (Fig. 10-2). Similarly, tall and dense forests were preserved within the grounds of mansions of ruling class families (Fig.9-3, 9-5).

Furthermore, farmhouses were surrounded by tall dense forests (Fig. 11-1). Deciduous broad-leaved tree species were selected to plant the forests within the grounds of farm houses. One of most common trees planted in the Musashino Plateau was keyaki (欅, Zelkova serrata, Elm family, up to over 30 m/98 ft) for its deeper roots. The wood is a praised timber to make furniture and for construction work where appearance and strength are important. Deciduous oak trees such as konara (小楢, Quercus serrata, Beech family, up to 20 m/66 ft) and kunugi (櫟, Quercus acutissima, Beech family, up to 20 m/66 ft) were commonly planted because of high quality fire wood. These woods are good for producing charcoal, and logs are used mushroom cultivation.

As the man-made forests composed primarily of deciduous broad-leaved trees grow, the phytobiomass increases. In forest floor, large amount of leaf-litter is added each year. As the forest ecosystems grow, the amount of freshwater produced by cellular respiration of trees and leaf-litter increases. The man-made old-growth forests supply moisture in the soil, and enhance quality/quantity of groundwater. In addition, the decomposition of leaf-litter releases essential nutrients for plant productivity including all sorts of cultivated plants. Thus, the strategic placement of the man-made forests converted the dry fragile plateau into fertile arable land.     

In Fig. 11-1, Hiroshige depicts typical man-made forests surrounded farmhouses in the Musashino Plateau. Hiroo (広尾, Fig. 6-T) was a rural locality of the upper part of Furu-kawa River, less than 1 km (0.6 mile) from the Akabane-gawa River in Fig. 9-5. In Hiroshige’s time, Hiroo was a place to enjoy a day trip for inhabitants of Edo. The main attraction was a popular restaurant, the specialty was an eel dish, stood on the right bank of Furu-kawa River. As significant amount of the water flowing rivers comes from groundwater, cool groundwater discharge into rivers creates a favorable condition for freshwater fisheries resources. In terms of river engineering of this small river, irregular-shaped sandbars that extend into river are constructed to shape overflow dams, riffles (瀬), and deep pools (淵), which creates a variety of habitats and preserve land-sea linkage for prolific inland fisheries resources (http://harukanoor4.blogspot.com/2022/). In Hiroo, eel (鰻, Anguilla japonica, catadromous fish migrate from fresh water down into sea to spawn, up to 1 m/3.3 ft) abundance provided plentiful opportunities and work for the local communities.

 

Bluff stabilization and groundwater formation

The Musashino Plateau was noted for the cool groundwater discharges and artesian springs. Since the Musashino Plateau is shaped by cutting action of rivers and streams on the thick layer of volcanic ash on the base of an alluvial fan, there forms fragile bluffs. The springs flow out at the bluffs.

To stabilize the fragile bluff and to enhance groundwater formation, these springs were surrounded by tall dense man-made forests. The tall deciduous broad-leaved tree species were selected to plant.

Besides, unique design of civil engineering technique was developed (e.g., Fig. 11-2, 6b-U). The noted temple of Meguro Fudo is situated at a bluff along the Meguro-gawa River, around 1.5 km (1 mile) from Shinagawa (Fig. 10.1). According to a legend, the Buddhist monk Tenkai, the consultant of the Tokugawa shoguns, instructed to renovate five outlying temples dedicated to Fudo (不動明王, a wrathful Buddhism deity who removes obstacles and destroy evil), to protect Edo by divine forces. Meguro Fudo was the largest of the temples.   

In Fig. 11.1, the temple is surrounded by tall dense man-made forests. Some of visitors perform ritual ablutions. The showering in waterfall, originally a sort of meditation as a religious activity, seems one of the summer-time entertainments for inhabitants of Edo. At the base of the bluff, a pool is placed. Water flows from springs fall into the pool via the sculpture of dragons’ mouths. As for the structure of the pool, the base of the bluff is retained by dry-stone wall. Permeability of dry-stone wall play an important role in providing constant adequate water to support large phytomass of the forests. In addition, dry-stone walling is effective to stabilize the fragile bluff. The spaces between rocks allow groundwater behind the wall to pass through, which in turn lowers the pressure on retailing wall. Furthermore, the deeper roots of the tall dense forests stabilize the fragile bluff. The Meguro Fudo, surrounded by tall dense man-made forests, enhanced groundwater formation via cellular respiration. The constant adequate groundwater discharges underpinned resilience of local communities, that probably Tenkai intended.  

Fig. 11-1 Furu-kawa River at Hiroo (Fig. 6-T) from the series One Hundred Views of Edo, Hiroshige, originally published 1856–59 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN, the Museum of Fine Arts). To stabilize fragile soil of the plateau and to ensure groundwater formation, tall and dense forests were strategically placed as sacred forests of shrines/temples such as Zojo-ji temple in Shiba (Fig.9-3, 9-4) and the Kaian-ji temple (Fig. 10-2). Similarly, tall and dense forests were preserved within the grounds of mansions of ruling class families (Fig.9-3, 9-5). Furthermore, farmhouses were surrounded by tall and dense man-made forests. Deciduous broad-leaved tree species such as keyaki (欅, Zelkova serrata, Elm family, up to over 30 m/98 ft) and konara (小楢, Quercus serrata, Beech family, up to 20 m/66 ft) were selected to plant the forests within the grounds of farm houses. Hiroshige depicts typical man-made forests surrounded farmhouses in the Musashino Plateau in Hiroo (広尾). There stood a popular restaurant, the specialty was an eel (鰻) dish. In this small river, numerous irregular-shaped sandbars that extend into river are placed to shape overflow dams, riffles (瀬), and deep pools (淵), which in turn creates a variety of habitats for catadromous fish of eel. The landscape architecture was intended to shape a favorable condition for abundance of freshwater fisheries resources. In Hiroo, eel abundance provided plentiful opportunities and work for the local communities.

Fig. 11-2 Visiting the Fudo Temple in Meguro (Fig. 6b-U) from the series Famous Places in the Bay Capital, Hiroshige, originally published mid-1830’s to early 1840’s (Image courtesy of the ukiyo-e.org https://johnresig.com/projects/ukiyoe/ by Resig J, the Museum of Fine Arts). The showering in waterfall, originally a sort of meditation as a religious activity, seems one of the summer-time entertainments for people. According to a legend, the Buddhist monk Tenkai, an adviser of the Tokugawa shoguns, instructed to renovate five outlying temples dedicated to Fudo, a wrathful Buddhism deity. Meguro Fudo was the largest of the temples. In the Musashino Plateau, groundwater discharge often flows out from the fragile bluffs. To stabilize the fragile bluff and to boost groundwater formation, these springs were surrounded by tall dense man-made forests. The noted temple of Meguro Fudo is situated at a bluff along the Meguro-gawa River, around 1.5 km (1 mile) from Shinagawa (Fig. 10.1). The temple’s tall dense man-made forests enhanced quality/quantity of groundwater via cellular respiration. The constant adequate groundwater discharges underpinned resilience of local communities.

5.4 Estuarine and river engineering for fisheries resource management of migratory fish: Tama-gawa River

 

Estuarine engineering: An artificial island covered with tall and dense forest along with extensive salt marshes

An artificial island constructed on the shoal at the estuary of Tama-gawa River (Fig. 12-1, 6a-V) had been highly praised as a tsunami mitigation (coastal protection) engineering among ancient Japanese architects and decision-makers for a long time. The Tama-gawa River, its total length is 138 km (86 miles), flows along the edge of fragile Musashino Plateau. Thereby, sediments brought by the river shaped a vast shoal of sand with fan-like coastline at the estuary.   

Japanese engineers often placed man-made islands in entrance of bay and/or river mouth, which served as a sort of caisson breakwater, absorbing wave energy and providing safe harborage (http://harukanoor4.blogspot.com/2022/). In Fig. 12-1, the artificial island, covered with a tall and dense sacred forest mixed with evergreen conifers and the deciduous broad-leaved tree species, is linked to the shore by an irregularly zigzagged causeway. Numerous earthen groynes (groins), sandbars that extend into sea, are constructed from the causeway. The artificial island is also fringed with man-made sandbars that shape extensive salt marshes. On the man-made island, the Shinto shrine dedicated to Benzaiten, a Japanese goddess of everything that flows, stands behind a torii gate. The Benzaiten’s precinct was surrounded a broad and unbroken sacred coastal sea, where any fishing was prohibited, shaping a sanctuary of nursery grounds for productive fisheries.

Salt marshes provide coastal protection from waves and storm surge, as well as from coastal erosion (Barbier et al. 2011). Notably, the highly vegetated artificial island fringed with extensive salt marshes by man-made sand bars was an effective multi-buffering in coastal hazard mitigation. Accordingly, the shrine was particularly popular among wholesale trade merchants and shipping companies providing passenger and freight transportation seeking to give seafaring without trouble.    

　  The Tama-gawa River was noted for its abundance of the high-quality ayu (鮎, Plecoglossus altivelis, river trout, sweet fish, typical maximum size: 30 cm/1 ft, amphidromous fish: moving between coastal sea waters and freshwater rivers) (Fig. 12-2, 12-3). Ayu was one of the staples of the traditional Japanese diet and an ingredient of preserved delicacies such as kanroni (fish simmered in syrup, soy source, and extract of tea leaves). Hiroshige features the civil engineering design to create a favorable condition for maintaining the abundance of high-quality ayu in Fig. 12-1, 12-3 and 12-4.

Although the Tama-gawa River in peri-urban area of Edo was modified by humans, decisions were made to enhance the productivity of ayu. The ayu are born in river estuaries during autumn, then drift into coastal seas. The Ayu in larval/juvenile stages overwinter in coastal seas until migrating back into rivers in spring. Young stages of ayu use the estuaries and coastal seas as ‘nursery grounds,’ where unique coastal engineering structure provides advantage of the protection and abundant food.

The shallow waters associated with marsh provide a refuge for commercially important fishes of critical life history stages from predators (Boesch and Turner 1984; Barbier et al. 2011). In the Japanese coastal engineering (Fig. 12-1), man-made marshes are elaborately created with shallow waters and deep waters that leads to a variety of habitats. Because of complex and tightly packed plant structure of marshes, the constructed shallow waters increase survival of young larval/juvenile stages of migratory fish such as ayu.

Gross primary production (annual amount of photosynthetically fixed carbon dioxide) of terrestrial vegetation is the largest global carbon flux (Beer et al. 2010). Furthermore, it drives several ecosystem functions such as respiration. As forests age, cellular respiration increases in response to the accumulating wood biomass; therefore, tall and dense forests having a higher LAI produce a greater amount of freshwater as by-product of cellular respiration (Fig. 10-4).

The groundwater discharge from the deep forests flowing into the sea influences seawater temperatures, favorable for the blooms of diatoms-dominated phytoplankton, the basis of marine food webs. Coastal seawater temperatures, in a state of dynamic equilibrium, are controlled by biological processes in the integrity of terrestrial and aquatic ecosystems. Placement of enormous areas of deep coastal forests is fundamentally important, because the dynamic equilibrium of cool seawater temperatures is a basic requirement for resilience of fisheries supported by marine food webs.

Hiroshige depicts that the sacred forest is maintained as tall in height along with highly stratified structure of canopy foliage. The tall and dense sacred forest on the artificial island and extensive salt marshes provide a larger amount of essential nutrients such as Fe and Si compounds in the form of humus, leaf litter and detritus, for growth of diatoms-dominated phytoplankton—the basis of marine food webs.

Salt marshes provide water purification or the increase in water clarity via suspended sediments deposition and nutrient uptake (Barbier et al. 2011). Furthermore, large phytomass of the sacred forest and high primary productivity of salt marshes produce considerable amount of water as by-product of cellular respiration. Which in turn contributes to water purification and the increase in water clarity.

Diatoms-dominated phytoplankton, the basis of marine food webs, are flourished in cool, clear, and clean seawaters, with huge amounts of essential nutrients supply (http://harukanoor4.blogspot.com/2022/). The artificial island along with extensive salt marshes at the mouth of Tama-gawa River created a favorable condition for growth of diatoms-dominated phytoplankton. The offshore of Haneda was renowned as one of Osaiura (御菜浦, His excellency’s fishing grounds), because of abundant fisheries. Thus, the estuaries and coastal seas provide ‘forage ground’ for young larval/juvenile stages of ayu.  

In spring, ayu migrate back into freshwater to grow adults. Ayu feed on diatoms-dominated freshwater algae that accumulates on the rocks, scrapping it off the rocks with their saw-shaped teeth (Fig. 12-2). A distinct, sweet flavour with ‘watermelon and cucumber’ aromas of ayu’s flesh is derived from the diet of diatoms-dominated freshwater algae. The diatoms-dominated freshwater phytoplankton, the basis of stream food webs, thrive better in cool, clear, clean, and oxygen rich waters. In Eastern philosophy, unique design of river engineering had been developed to create a favorable condition for maintaining the abundance of high-quality ayu (Fig. 12-3, 12-4).   

Fishing season of ayu is from early summer to late autumn. Despite being 12 km/7 miles from the city center, Futako-tamagawa (二子玉川, Fig. 6a-W) was a popular place for anglers of Edo to enjoy ayu fishing (Fig. 12-3).  

Taking account of fisheries resources management, unique design of river engineering had been developed to flourish the diatoms-dominated freshwater phytoplankton, the basis of stream food webs, and to maintain cool, clear, clean, and oxygen rich waters (http://harukanoor4.blogspot.com/2022/).

 

River engineering of riffle-pool sequence: Flood-water retaining system served as a sort of ‘dam’ not to block river

In the traditional Eastern philosophy, the primary function of river engineering was to retain moisture levels over a large geographic area of land. Therefore, unique design of river engineering had been developed to slow down river flows and to make longer freshwater residence time in land-surface, without continuous levees that force the river to flow more quickly.

During the Edo period, non-contiguous dike system to retain flood-waters in desolate areas was ordinarily adopted in river engineering (e.g., Okuma 1981). In the outskirts of Edo in the upper-stream zone of Sumida-gawa River, extensive areas of flood-water retaining zones were allocated and a series of man-made sandbanks to direct water-flows into low-lying plains were constructed (http://harukanoor4.blogspot.com/2022/).

Besides, riffle-pool sequence system was ordinarily adopted in river/stream engineering in wide range of land and watershed management. Hiroshige depicts numerous landscape prints that feature the riffle-pool sequence system. In Futako-tamagawa (Fig. 12-3; Fig. 6a-W), 10 km (6 miles) from the river mouth, earthen groynes, man-made sandbars constructed nearly perpendicular to the river flows, were placed. These sandbars create a variety of habitats: rapid currents by riffles (瀬), calmer flows, and  deep pools (淵). Man-made riffles serve to aerate the running water by rapid babbling currents, increasing the amount of dissolved oxygen. Which in turn creates a favorable condition for blooms of diatoms-dominated freshwater phytoplankton, the basis of stream food webs.

In the foreground of Fig. 12-3, Hiroshige depicts the structure of an ‘overflow dam’ that looks like a natural landscape. A deep pool, where a fisherman casts a net, is created by the earthen groynes. Another fisherman working in river water in the foreground implies presence of man-made riffles in front of and between the sandbars. Weeping willows (Babylon willow, Salix babylonica, an introduced tree species from China), are planted to stabilize fragile soil of the earthen groynes by the deeper roots. In addition, wooden-framed groynes associated with jyakago (蛇籠, a long sausage shaped basket of woven bamboo filled with stones) are placed on the man-made sand bars. These elaborately shaped groynes: sand bars made from earth and stones, planted trees and shrubs, and wooden frames along with jyakago, reduce velocity of flood-waters and store flood-water temporarily in the pools, thereby decreasing peak discharge. As shown in Fig. 12-3, numerous riffle-pool systems are contiguously placed. The man-made riffle-pool sequence system retains considerable amount of flood-water, thereby serving as a sort of ‘dam,’ not to block river.

Unlike contemporary dams where the water is blocked with a huge wall, the riffle-pool sequence systems preserve free-flowing river flows with high connectivity of river ecosystems that serve habitats/forage grounds for maintaining the abundance of high-quality migratory fishes such as ayu. Typically, the riffle-pool sequence systems were adopted in rapid flows in high-gradient rivers. However, the riffle-pool sequence systems were also placed in fairly low-gradient rivers/streams, because of a sort of ‘dam’ to retain considerable amount of flood-waters, and effectiveness in increasing the amount of dissolved oxygen by rapid currents of riffles.

The man-made riffle-pool sequence system requires large areas of flood plains, as the flood plains are designed to retain flood-waters. Thereby, the large areas of flood plains are intended to enhance the organic matter dynamics by land-sea interaction. In the background of Fig. 12-3, dense riparian forests are placed with high connectivity of mountain forests to facilitate the movement of essential nutrients such as humus and/or leaf litter, toward the sea via river flows.

 

Engineering in lower reaches of rivers

Hiroshige depicts a typical feature of river engineering in lower reaches of a river (Fig. 12-4). The Tokaido highway lay at the lower reaches of Tama-gawa River, 4 km (2.5 miles) from the river mouth of Fig. 12-1. As so often with Edo’s rivers, it had a local name here—the Rokugo-gawa River. In Fig. 12-4, travelers on the Tokaido are crossing the Tama-gawa River on ferries, in a low-gradient stream flow.  

The irregular-shaped elevated river groynes, man-made sandbanks constructed nearly perpendicular to the river flows, are placed on either side of the river (Fig. 12-4). These groynes were shaped by closely spaced wooden piles driven into riverbed. Besides, the shores of groynes are protected by ‘loosely spaced wooden piles,’ which are served as a sort of breakwater preventing the shores from being washed away by the currents. The earthen groynes are covered with the thick dense riparian forests.

As depicted in Fig. 12-4, numerous floodplain wetlands along with reed beds are continuously placed. The man-made floodplain wetlands create a variety of habitats: shallow and/or deep waters; closed, semi-closed and/or open to river flows; still, and/or rapid-running waters, providing non-fragmented breeding/feeding habitats for migratory fish such as ayu. The constructed wetlands provide a refuge from predators because of complex and tightly packed plant structure of reed beds, increasing survival of young larval/juvenile stages of migratory fish such as ayu.

The town of Kawasaki (川崎) being suggested at by a few houses on the left of the print, is protected by highly raised sandbanks along with tall dense riparian forests (Fig. 12-4).

Marine phytoplankton produces nearly half of global net primary production each year (Field et al. 1998). To sustain huge marine primary productions, a large amount of essential nutrients in the forms of humous, leaf-litter, and other plant parts is required from terrestrial vegetation. Rivers are the main transport corridors of the essential nutrients from the terrestrial environment to the oceans (e.g., Milliman 1997).

Architecture of free-flowing river flows (Dynesius and Nilsson 1994; Nilsson et al. 2005) is an underlying requirement in managing fisheries for food security, not only ayu but also other migratory fish: salmon, shad (river herrings, Alosa), sturgeon, striped bass (Morone saxatilis, length up to 90 cm/35 inches), eels, Japanese sea bass (Suzuki, 鱸, Lateolabrax japonicus, length up to 1m/3.3 ft), flathead grey mullet (Bora, 鰡, Mugil cephalus), Shishamo (柳葉魚, Spirinchus lanceolatus), and so on.  

The Tamagawa Benzaiten (Fig. 12-1) was famed as one of the three venerated Benzaiten shrine, along with Enoshima in the province of Sagami (in Kanagawa prefecture) and Itsukushima in Aki province (in Hiroshima prefecture). The artificial island on the shoal of Tama-gawa River was at one time known as Kaname-jima (要島, Fan-pin Island) because it seemed to hold together the fan-like coastline of shoal. The word Kaname (Fan-pin, lit., a critically important part; like a keystone in masonry arch structure) had the hidden meaning. The man-made island structure plays a critical role in consolidation of coastal protection, ecological functions as nursery habitats for fisheries, and community resilience that supported by the harvests from the ecosystems. The island structure had been preserved for hundreds of years by a taboo—destruction of the torii gate will be cursed forever. Ancient Japanese were aware that the demolition of the island structure leads to increase in coastal vulnerability against hazards, collapsed fisheries resulting from habitat loss/degradation, and decline in resilience of local societies and economics. The site is currently occupied by the Hanada Airport (Tokyo International Airport).      

In almost all rivers in Japan, the abundance of ayu migrate back to rivers has drastically declined, due to loss/degradation of habitats and nursery grounds, river fragmentation, and disconnected river ecosystems from the sea by engineering structures. 

Fig. 12-1 Descending Geese at Haneda (Tokyo: 35°32′ N, 139°44′ E; Fig. 6a-V) from the series Eight Views of the Environs of Edo, Hiroshige, originally published mid-1830’s (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). The artificial island covered with a tall dense forest along with widespread salt marshes constructed on the shoal at the estuary of Tama-gawa River had been highly praised as a coastal protection engineering. Gross primary production (annual amount of photosynthetically fixed carbon dioxide) of terrestrial vegetation is the largest global carbon flux (Beer et al. 2010). Besides, tall and dense forest having a higher leaf area index (LAI, i.e., the total area of green leaf surface per unit of ground area) greatly contributes to quantitative renewability and qualitative restoration of freshwater by the considerable amount of freshwater produced as by-product of cellular respiration via gross primary production along with respiration. The tall and dense sacred forest and extensive salt marshes provide a larger amount of essential nutrients such as Fe and Si compounds in the forms of humus, leaf litter and detritus, for growth of diatoms-dominated phytoplankton—the basis of marine food webs. Salt marshes provide ‘nursery grounds’ and ‘refuges’ for commercially important fishes of critical life history stages from predators (Boesch and Turner 1984; Barbier et al. 2011). Ancient Japanese architects built the consolidated structure of coastal protection and productive coastal habitats.

Fig. 12-2 Ayu from the series Grand Series of Fishes, Hiroshige, originally published 1840-42 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). The Tama-gawa River was noted for its abundance of the high-quality ayu (鮎, Plecoglossus altivelis), amphidromous fish moving between coastal sea waters and freshwater rivers. The ayu are born in river estuary during autumn then drift into the coastal sea. The estuarine of the Tama-gawa River, unique coastal engineering structure provides ‘nursery grounds,’ via the protection from predators and abundant food (Fig. 12-1). In spring, ayu migrate back into freshwater. A distinct, sweet flavour with ‘watermelon and cucumber’ aromas of ayu’s flesh is derived from the diet of diatoms-dominated freshwater algae that thrive better in cool, clear, clean, and oxygen rich waters.

Fig. 12-3 Catching Ayu in the Tama-gawa River under the Autumn Moon from the series Snow, Moon and Flower at Famous Places, Hiroshige, originally published 1844-47 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). Futako-tamagawa (二子玉川, Fig. 6a-W) was a popular place for anglers in Edo to enjoy ayu fishing. Architecture of free-flowing river flows (Dynesius and Nilsson 1994; Nilsson et al. 2005) is an underlying requirement in managing fisheries for food security, not only ayu but also other migratory fish such as salmon and eels. Hiroshige depicts riffle-pool sequence river engineering, flood-water retaining system served as a sort of ‘dam’ not to block river. In the foreground, an ‘overflow dam,’ is constructed: A deep pool is created by earthen groynes, man-made sandbars constructed nearly perpendicular to the river flows. Weeping willows (Babylon willow, Salix babylonica, an introduced tree species from China) are planted to stabilize fragile soil of the earthen groynes. Besides, wooden-framed groynes associated with jyakago (蛇籠, a long sausage shaped basket of woven bamboo filled with stones) are placed on the man-made sand bars to reduce velocity of flood-water flows and to store flood-waters temporarily in the pools. Rivers are the main transport corridors of the essential nutrients from the terrestrial environment to the oceans (e.g., Milliman 1997). To enhance the dynamics of essential nutrients by land-sea interaction, dense riparian forests are placed over the large areas of flood plains that are designed to retain flood-waters.

Fig. 12-4 Rokugo Ferry at Kawasaki from the series Fifty-three Stations of the Tokaido Road, known as the Reisho Tokaido from the calligraphy style in the title or Marusei Tokaido from the publisher, Hiroshige, originally published 1847-52 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). Hiroshige depicts the engineering in lower reaches of river, creating non-fragmented nursery/feeding habitats for migratory fish. The irregular-shaped raised sandbanks constructed nearly perpendicular to the river flows along with wetlands are continuously placed on either side of the river. The tall and dense riparian forests having high gross primary productivity provide large amounts of essential nutrients in the forms of humous, leaf litter, and detritus, which in turn enhances onshore and coastal fisheries productivity. 

5.5 Two characteristic man-made islands at entrance of embayment: Yokohama

 

Yokohama (横浜, Fig. 6a-L), near the entrance of Tokyo Bay, is the second largest city in Japan. Yokohama was one of the ports to open for trade with the West following the end of the isolationist foreign policy for a period of 216 years (1639–1854). The port was opened officially in 1859, the year following Hiroshige’s death. The Tokugawa shogunate decided to build port facilities in the fishing village of Yokohama to avoid on the strategic highway of Tokaido. The offshore of Yokohama was well-known as one of Osaiura (御菜浦, His excellency’s fishing grounds), because of abundant fisheries resources. Although Yokohama was a small fishing village, the coastal area was elaborately shaped by humans to enhance the productivity of fisheries resources.

Hiroshige depicts a disappearing sprit of traditional coastal engineering in Fig. 13-1, using the Japanese perspective, which positioned far away Mount Fuji higher on the picture plane behind Mount Oh-yama (elevation: 1,252 m/4,108 ft) in the Tanzawa mountains at the upper right of this print. The fishing village Yokohama, tightly packed with houses along the shoreline of the Noge (野毛) embayment, is surrounded by coastal hills and mountains, including Noge-yama mountains. Thereby, a road to connect to the Tokaido highway was constructed to cut through the coastal hills and mountains. Despite manual labors using traditional tools such as stone hammers and chisels, it took only three months to finish the road construction. The traces of through-cuts of mountains, exposed bare soils, are depicted as an irregularly-formed clay-color belt behind the coastal village in Fig. 13-1. Hiroshige depicts an approaching paradigm shift in Yokohama by the sweeping modernization.

Japanese engineers often placed man-made islands in entrance of bay, which served as a sort of caisson breakwater, absorbing wave energy and providing safe harborage, consolidated with coastal protection and productive coastal habitats. (http://harukanoor4.blogspot.com/2022/). At the entrance of Noge embayment, two characteristic artificial islands, Fig. 13-1 and 13-2, were placed. The name Syukan-jima Island (Syukan, 洲干, lit., reclaimed shoal) in Fig. 13-1 suggests that the artificial island was created on a shoal that was formed sediments brought by two small rivers, Ohoka-gawa river and Nakamura-gawa River, flow into the Noge embayment. Numerous man-made sandbars that run far out into the sea are constructed from the artificial island. Salt marshes control erosion via trapping sediments and protect shoreline by buffering wave energy (Barbier et al. 2011). The man-made sandbars fringed with salt marshes have unique design of coastal defense, it shaped like an elephant’s trunk to protect the coastal communities. The large extents of salt marshes provide breeding and feeding habitats for fishes and invertebrates.

On the artificial island, the Shinto shrine dedicated to Benzaiten, a Japanese goddess of everything that flows, lies behind the cluster of trees. Any fishing was prohibited in the broad and unbroken sacred coastal sea along the precinct, shaping a sanctuary of nursery/feeding habitats for productive fisheries.  

On the opposite side of embayment entrance, a man-made island of rocky reef covered with dense forests was placed (Fig. 13-2). Rocky intertidal areas are one of the important coastal habitats, creating refuges for juveniles and large numbers of species of fish (Moyle and Cech 2004; Sala et al. 2012). The history of large-scale coastal protection civil engineering in Japan dates back to the period of the Kamakura shogunate (1185–1333) (http://harukanoor4.blogspot.com/2022/).      

In Fig. 13-2, the man-made rocky reef island by large-scale civil engineering is linked to the shore by wooden bridges and rocky reef causeway. Along the causeway, the ‘loosely spaced wooden piles’ are driven into the seabed served as a sort of breakwater to absorb wave energy and reduce wave reflection. At the edge of the causeway, a small village tightly packed with houses is protected by the highly raised rocky island covered with dense forests. The products of nori (海苔, Neopyropia tenera) that cultivated in a small embayment formed by the man-made island were highly praised in city market.

In Fig. 13-2, the man-made rocky reef island is depicted from the direction of low-lying village, along with the part of Syukan-jima Island, the man-made sandbars project into the sea in the right of this print. The two characteristic artificial islands at the entrance of Noge embayment are intended to protect low-lying coastal areas from hazards. Besides, the two characteristic artificial islands created a wide variety of habitats/nurseries for abundance of fisheries resources, which in turn leads to resilience of local societies and economics.

In Eastern philosophy, excavation work in civil engineering interfaces with project of using the excavated material, not to waste excavated material and manual labors. Thereby, the excavated material, earth and rocks, from the through-cuts of mountains for road construction (Fig. 13-1) was used to fill up the Noge embayment. The reclaimed land: the Noge embayment and the adjoining wetlands of two artificial islands, was used as the port facilities and residential area for foreign merchants. The series by Hiroshige II were published during 1859–61. As the port of Yokohama was opened officially in 1859, Hiroshige II depicted the disappeared landscape (Fig. 13-2).

Fig. 13-1 Yokohama at Noge in Musashi Province (Yokohama: 35°27′ N, 139°38′ E; Fig. 6a-L) from the series Thirty-Six Views of Mount Fuji, Hiroshige, originally published 1858 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). Yokohama, near the entrance of Tokyo Bay, was one of the ports to open for trade with the West following the end of the isolationist foreign policy for a period of 216 years. In this print, Hiroshige implies an approaching paradigm shift by the sweeping modernization. The port was opened officially in 1859, the year following Hiroshige’s death. To connect to the Tokaido highway, a road cut through the mountains behind the Noge embayment was constructed; The traces of through-cuts of mountains, exposed bare soils, are depicted as an irregularly-formed clay-color belt behind the coastal village. The excavated soil was used to fill up the Noge embayment to construct the port facilities and residential area for foreign merchants. Despite being a small fishing village, two different types of artificial islands are placed at the entrance of Noge embayment, which consolidated with coastal protection and a wide variety of habitats/nurseries for abundance of fisheries resources. The Syukan-jima Island, fringed with numerous man-made sandbars that run far out into the sea with the large extents of salt marshes, are effective multi-buffering to protect low-lying coastal areas from coastal hazards, providing breeding and feeding habitats for fishes and invertebrates. The Shinto shrine dedicated to Benzaiten lies behind the cluster of trees, shaping a sanctuary of nursery/feeding habitats for productive fisheries in the broad and unbroken sacred coastal sea along the precinct of shrine.

Fig. 13-2 Yokohama Noge in Busyu from the series One Hundred Famous Views of in Various Provinces, Hiroshige II, originally published 1859–61 (Image courtesy of the ukiyo-e.org https://johnresig.com/projects/ukiyoe/ by Resig J, the British Museum). On the opposite side of the Syukan-jima Island (Fig. 13-1) at the embayment entrance, a man-made island of rocky reef covered with dense forests is placed. Rocky intertidal areas are one of the important coastal habitats, creating refuges for juveniles and large numbers of species of fish (Moyle and Cech 2004; Sala et al. 2012). The two different types of artificial islands at the entrance of Noge embayment were intended to protect low-lying coastal areas from coastal hazards. Besides, the two characteristic artificial islands created a wide variety of habitats/nurseries for abundance of fisheries resources, which in turn leads to resilience of local societies and economics. At the time this print was published, the Noge embayment was already filled up for the port facilities. A samurai riding horse on the bridge is gazing the past landscape. 

5.6 Man-made rocky reefs: Consolidation cliff erosion mitigation and productive coastal habitats

 

Multiple-buffering of rocky reefs as cliff erosion mitigation

Coastal cliffs, vertical or near-vertical rock faces rising from the sea, occur about 75 % of the world’s coastlines (Bergillos et al. 2020). Cliff erosion on rock coasts is a major global challenge at the beginning of the 21st century. Since rising sea levels and more frequent intensifying storms (e.g., Bhatia et al. 2019) from human-induced climate change have accelerated the cliff erosion, threatening coastal infrastructure and liveliness (Hurst et al. 2016; Shadrick et al. 2022). Therefore, effective measures of cliff erosion mitigation integrated with fisheries resource management are urgently required.   

Japanese engineers placed man-made rock reefs in front of cliffs as the consolidated structure of coastal protection and productive coastal habitats. In Fig. 14-1 (Fig. 6a-X), Hiroshige depicts the coastal engineering work at a coastal cliff facing the Pacific Ocean, using the Japanese perspective, which positioned far away Mount Fuji higher on the picture plane behind Mount Oh-yama in the Tanzawa mountains at the upper right of this print, viewing the coast of Kamakura (where the Kamakura shogunate, 1185–1333, was established) and Enoshima Island in the distance. The two fishing boasts imply that the structure of unique coastal engineering creates excellent fishing grounds.

To provide cliff protection from waves and to reduce erosion, multiple rocky reefs and/or boulders/rocks were placed to shape as multi-buffering coastal protection system like the islands in the legendary Matsushima Bay. The architecture of multi-buffering mitigation system in front of cliffs was based on design and construction principles in Eastern philosophy.

 

Architecture of rocky reefs: Shaping fisheries productive habitats

Despite being exposed to crashing surf, strong currents, and daily exposure to the air, rocky intertidal areas and near-shore rocky bottoms are one of the important coastal habitats, creating refuges for juveniles and large numbers of species of fish (Moyle and Cech 2004; Sala et al. 2012).

Furthermore, the flux of nutrients from deep nutrient-rich waters contributes abundance of fisheries resources at the rocky reefs. When surface waters are pushed offshore by winds, the upward movement of deep, cooler water, known as upwelling, occurs. Coastal upwelling plays a significant part in the oceanic biogeochemical cycles (Falkowski et al. 1998). Besides, localized upwelling around islands and seamounts provides excellent fishing grounds worldwide (e.g., Silva et al. 2021). Since cool, nutrient-rich waters containing a larger amount of essential nutrients such as Fe and Si compounds promote growth of diatoms-dominated phytoplankton—the basis of marine food webs. The blooms of diatoms-dominated phytoplankton lead to abundant and diverse fisheries resources. The abundance of diverse fish and invertebrates in turn attracts large pelagic predators such as tunas. In the open ocean referred as ‘the blue desert,’ the localized upwelling around islands and seamounts offers oases for marine predators, such as tunas, dolphins, and seabirds (e.g., Silva et al. 2021).

Via learning-based approach, ancient Japanese architects and decision makers were aware that the placement of man-made rock reefs in front of cliffs leads to favoring the congregation of marine predators, such as tunas, bonitos (e.g., katsuo, 鰹, skipjack tuna, Katsuwonus pelamis, up to 1 m/3.3 ft, common standard length: 40 cm/1.3 ft), and whales. It is said that the placement of man-made rock reefs in front of cliffs was ubiquitous over the whole country of Japan.  　

 

Material supply for construction of rocky reefs

In Japan, works of civil engineering by people for people were abundant. For instance, a Zen Buddhist monk, Zenkai (禅海) decided to construct a tunnel passage through a bluff along the rapid flow of Yamakuni-gawa River (山国川) in the north of Kyusyu island in 1735, because of so many accidents that villagers and pack-horses fell to death from a passage at the bluff (Fig. 14-2). The independent manual labor by the monk using only stone hammers and chisels took 30 years to cut through the tunnel passage with skylight windows, with the length of 342 m (1,122 ft). Not to waste excavated material and manual labors, excavation work linked project of using the excavated material, earth and rocks. Thus, the material from excavation work was often used to construct rock reefs in front of cliffs.

 

Architecture of ‘hot spots’ of commercially important fisheries resources

Structurally complex habitats of rocky reefs provide shelter from predators and abundant food to a wide range of species, leading to the abundance and diversity of fish species (Eisele et al. 2021). Furthermore, upwelling enhances seaweed nutrient quality, which in turn provides a favorable condition for growth of intertidal herbivore such as urchins (Pulgar et al. 2022).

Via learning-based approach, ancient Japanese architects were aware that the placement of man-made rocky reefs in front of cliffs creates ‘hot spots’ of commercially important marine resources, such as sea urchins (uni; herbivorous, spiny, globular echinoderms in the class Echinoidea, the gonads are culinary delicacies, highly valued for sashimi and/or Edo-style sushi known as uni, 雲丹), abalone (awabi, 鮑, Haliotis, an edible herbivorous sea snail, highly praised for Japanese cuisine sashimi and/or Edo-style sushi), spiny lobsters (ise-ebi, 伊勢海老, Panulirus, praised in high-class Japanese cuisine), and a wide variety of edible sea-weeds.

In Fig. 14-3 (Fig. 6a-Y), Hiroshige depicts rocky reefs and boulders/rocks in front of cliff at the entrance of Edo (Tokyo) Bay in the Chiba peninsula, with Mount Fuji in the background behind the far opposite shore of the Miura peninsula. Sandy beaches are often bounded on the upland side by cliffs. Placement of boulders/rocks and rocky reefs are intended to mitigate erosion of the sandy beach and cliff. In Fig. 14-3, the harvest is gathered by villagers in the shallow seawaters. The fishermen on a fishing boat are casting net. Which implies that the abundant and diverse fishes congregate in the deep seawaters.  　    

To enhance quantity/quality of fisheries resources, strategic placement of large areas of sacred deep coastal forests was ubiquitous over the whole country of Japan. In Fig. 14-3, the name 天神山 (lit., mountains of Tenjin) suggests that a large area of sacred deep coastal forests is placed on the cliff. Tenjin is Japanese Shinto god of scholarship, the deification of Sugawara no Michizane (菅原道真, 845-903, a scholar, excellent poet, and politician) after dying in exile in despair.

The sacred coastal forests contribute to creating a favorable condition for blooms of diatoms-dominated phytoplankton, the basis of marine food webs; and submerged aquatic vegetation (underwater seagrass meadows and deep-water kelp forests), nursery/feeding grounds for commercially important fisheries resources. The essential nutrients such as Fe and Si compounds in the forms of humus, leaf litter and detritus are supplied to coastal sea. Furthermore, cool groundwater discharge from the deep coastal forests has a direct effect on coastal seawater temperatures in a state of dynamic equilibrium, as the considerable amount of cool freshwater produced as by-product of cellular respiration by the tall and dense forest ecosystems. Cool coastal seawater temperature is a fundamental requirement for blooms of diatoms-dominated phytoplankton and resilient submerged aquatic vegetation that support productivity of fisheries. Thus, the landscape architecture, multi-buffering rocky reefs along with sacred deep coastal forests, creates a favorable condition for prolific coastal fisheries resources. In addition, a vast area of submerged aquatic vegetation can dissipate wave energy, which in turn stabilizing coastal cliffs.  

The architecture of multi-buffering system, ubiquitous over the whole country of Japan, was shaped to create a broad range of structurally complex habitats and varied seawater depths, depending upon the available material. In Fig. 14-1, a small islet is constructed by raised soil material on the man-made rock reefs. To stabilize the bare soil, the quick growing plant and tree species tolerant salt spray: such as perennial grasses (Imperata cylindrica), perennial sedges (kobomugi, 弘法麦, Carex kobomugi; koboshiba, 弘法芝, Carex pumila), and Japanese black pine (Pinus thunbergii) are planted. The rocky reef island extending out into the ocean creates intertidal zone behind it, providing excellent fishing grounds. Ancient Japanese architects built the consolidated structure of coastal protection and productive coastal habitats.

It is important to note that the flux of nutrients from deeper, nutrient-rich waters is derived from the healthy blooms of diatoms-dominated phytoplankton. On the other hand, harmful algal blooms modify the flux from deeper waters into the flux of toxins, which in turn leads to persistent and detrimental impacts in upwelling systems (Sekula-Wood et al. 2009; Trainer et al. 2012; Ryan et al. 2017).

Fig. 14-1 The Sea off the Miura Peninsula in Sagami Province (Kanagawa: 38°08′ N, 149°37′ E; Fig. 6a-X) from the series Thirty-Six Views of Mount Fuji (1858 edition), Hiroshige, originally published 1858 (Image courtesy of the ukiyo-e.org https://johnresig.com/projects/ukiyoe/ by Resig J, the British Museum). As mitigation measures for cliff erosion, Japanese engineers placed man-made rock reefs in front of cliffs. To provide cliff protection from waves and to reduce erosion, multiple rocky reefs and/or boulders/rocks were placed to shape as multi-buffering coastal protection system. Rocky intertidal areas and near-shore rocky bottoms are one of the important coastal habitats, creating refuges for juveniles and large numbers of species of fish (Moyle and Cech 2004; Sala et al. 2012). In addition, the flux of nutrients from deep nutrient-rich waters, known as upwelling, contributes abundance of fisheries resources at the rocky reefs. Since cool, nutrient-rich waters containing a larger amount of essential nutrients such as Fe and Si compounds promote growth of diatoms-dominated phytoplankton—the basis of marine food webs. The abundance of diverse fish and invertebrates in turn attracts large pelagic predators such as tunas (e.g., Silve et al. 2021). The two fishing boasts imply that the multi-buffering of rocky reef system creates deeper seawaters, where provide excellent fishing grounds of large pelagic predators such as tunas, bonitos (e.g., katsuo, 鰹), and whales.

Fig. 14-2 Buzen Province: The Tunnel Passage under the Rakan Monastery (Kyusyu: 33°30′ N, 131°10′ E) from the series Pictures of Famous Places in the Sixty-odd Provinces, Hiroshige, originally published 1853–1856 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). In Japan, civil engineering works of site-specific design by people for people were abundant. Hiroshige depicts a tunnel passage under a bluff excavated by a Zen monk. Not to waste excavated material and manual labors, excavation work linked project of using the excavated material, such as earth and rocks. The man-made rock reefs in front of cliffs were constructed using the material derived from excavation works such as canal, moat, roads cutting through hills/mountains, and tunnel. 

Fig. 14-3 The Coast at Tenjinyama in Kazusa Province (Chiba: 35°18′ N, 139°51′ E; Fig. 6a-Y) from the series Thirty-Six Views of Mount Fuji (1852 edition), Hiroshige, originally published 1852 (Image courtesy of the British Museum: https://www.hiroshige.org.uk/ by Chiappa JN). Via learning-based approach, ancient Japanese architects were aware that the placement of man-made rocky reefs in front of cliffs along with sacred deep forests on the cliffs, ubiquitous over the whole country of Japan, creates ‘hot spots’ of commercially important marine resources, such as sea urchins (uni, 雲丹), abalones (awabi, 鮑,), spiny lobsters (ise-ebi, 伊勢海老), and a wide variety of edible sea-weeds. Sandy beaches are often bounded on the upland side by cliffs. Placement of boulders/rocks and rocky reefs are intended to mitigate erosion of the sandy beach and cliff, focusing on marine resource management. The harvest is gathered by villagers in the shallow seawaters. The fishermen casting a net implies that the abundant and diverse fishes congregate in the deep seawaters.

6.     Land governance in coastal zone urban planning

 

The dynamic biological process of photosynthesis in estuarine and coastal zone influences climate, via solar radiation valance, CO₂ sequestration in the deep ocean known as blue carbon, and regulation of atmospheric CO₂ (http://harukanoor4.blogspot.com/2022/). Coastal urbanization, a global trend at an unprecedented rate, destroys the most productive estuarine and coastal ecosystems, which in turn increases vulnerability to coastal hazard such as tsunami and storm surge, and upsurges the negative impact of climate change via altering solar radiation valance, weaking CO₂ sequestration in the ocean and decline of natural sinks on land and the ocean removing atmospheric CO₂ via photosynthesis.

In terms of fisheries resources management, vegetated wetlands in the intertidal zone, underwater seagrass meadows, and deep-water kelp forests play a role of critical importance in fisheries productivity as nursery/foraging grounds. The loss of nursery/foraging grounds leads to decline of fisheries productivity (Unsworth et al. 2018).

Historically, Japan developed unique design of coastal hazard mitigation, ‘multiple-buffering system,’ to protect coastal areas from risk of coastal hazards such as tropical cyclone (typhoon) and tsunami integrated with marine resources management.

The urban areas of Edo were expanded by reclamation works of salt marshes and mud flats. The reclamation works gradually outspreaded the area lay beneath the sea. To protect low-lying coastal areas, multiple-buffering system: earthen dykes, elevated mounds/mountains and artificial islands combined with intertidal wetlands were placed.

The conceptual framework for urban planning and design in Eastern philosophy is unique in architecture of the interconnected biogeochemical networks over land and sea. To close biogeochemical cycles in land-sea connectivity, continuous (non-fragmented) vegetation: deep sacred forests, trees planted on the dykes, and salt marshes, was elaborately shaped. Marine photosynthesis requires huge amounts of essential nutrients such as Fe and Si compounds in the forms of humus, leaf litter and detritus. Since the continuous (non-fragmented) vegetation works as pathway of essential nutrients from land to seas, submerged aquatic vegetation: underwater seagrass meadows and deep-water kelp forests, flourishes, which in turn serves as nursery/foraging grounds—the underlying requirement for fisheries productivity. The multiple-buffering systems were shaped by diverse site-specific design.

In historical eastern philosophy, ecosystem-based management of aquatic resources was considered as a core issue of governance to supply affordable and high-quality animal protein for people. Fisheries played an important role as a major source of food for people in Edo. Coastal harvest marine fish, shellfish and seaweeds, and also inland capture fisheries, were abundant to provide food security to the largest metropolis in the worlds, Edo.

Although most of Japan’s landscapes of traditional engineering have been lost due to recent river engineering and modern land reclamation works, the information of the unique historical design would be beneficial for appropriate planning and implementation of coastal zone restoration. The unique policy and management strategies of Eastern philosophy provide guidance for alternatives and/or solutions of transformative coastal urban governance for the era of climate change. Thereby, a large number of features of Japan’s original landscapes of traditional engineering are shown in this article.

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