A Theory of Integrated Coastal Zone Management in Japan

Masahiko Isobe

Department of Civil Engineering
University of Tokyo


Three functions of the coastal zone environment can be identified: disaster prevention, utilization and ecological. The current status of the Japanese coastal zone environment relative to each of these functions is examined. It has become clear in the area of disaster prevention that the coastal zone has suffered major damage caused by flooding, high waves and tsunamis while at the same time; the coastal erosion has worsened. Furthermore utilization has expanded, reached new levels of complexity and supported economic development, but a drop in the environmental capacity has been witnessed in the area of the ecology. The concept of an environmental foundation, which supports the various functions of the coastal zone, has been introduced to resolve these conflicts, and a proposal for comprehensive coastal zone management has been made, focusing on maintaining the health and stability of the coastal regions. Examples of current day projects, which focus on environmental restoration and the creation of new environments will be introduced from this viewpoint, and a look will be taken at what directions these activities, will move in the future.


EExcecutive Summary
2.Current Status of the Coastal Environment in Japan
2-1 Disaster Prevention
2-2 Human Utilization
2-3 Ecology
3.A Theoretical Framework for Integrated Coastal Zone Management
4.A Theoretical Framework for Integrated Coastal Zone Management
5.Future Integrated Coastal Zone Management in Japan
5-1 ICZM and Mitigation
5-2 Examples of ICZM in Japan

Executive summary

The word "environment" has been interpreted in various different ways depending upon exactly that is using it. A broad definition of environment could be the area that surrounds humans, and that environment would include not only the natural environment, but also structures and systems created by humans to prevent disasters and enhance convenience.

The elements of the environment related to the coastal zone that would be included in a broad definition of the environment are shown in Table 9. A good environment from the human standpoint can be characterized as one in which people are surrounded by lush nature and an ecosystem which is unpolluted and are protected from natural disasters. This environment would also be easy to make use of and provide the foundation for an active, fulfilled life. Thus, in the case of the coastal zone, the ideal can be summed as "lush, safe and vibrant." The elements of the environment corresponding to these concepts have been broken down into disaster prevention, utilization and the ecology in the Table. The borders of the coastal zone are the atmosphere (air sphere), seas (water sphere) and land (earth sphere), and the location at which these three spheres approach the coastline is where they form the coastal zone. The ecology is made up of these three spheres together with the elements of flora and fauna, while disaster prevention encompasses different types of coastal damage, and utilization encompasses various patterns of coastal zone use.

The main factors involved in disasters in the coastal zone are flooding, high waves and erosion of the coast. Japan is located directly in the path through which many typhoons pass, and the southern bay areas frequently incur damage from flooding. In addition, tsunamis caused by earthquakes also often make their way to Japan. The encroachment on the coastal regions has been striking in recent years, and the sand beaches throughout the nation have retreated an average of one meter over a six-year period.

The concentration of people and industry in the coastal zone is also conspicuous from the standpoint of utilization. Despite the fact that the total area of the towns in these regions is only 32% of the total nationwide, they account for 46% of the population, 47% of the industrial shipments and 77% of commercial sales. The utilization of the coastal zone in Japan behind the achievement of these figures cover both a broad spectrum and is quite advanced including transportation, energy, marine industries, industrial zones, commercial zones and recreation.

As a result of these activities, a drop has been witnessed in the ecosystem in the areas where seaweed grows and tidal flats are located together with a drop in plant and animal habitats as evidenced by the creation of artificial coast lines.

The health and safety of the environmental foundation which supports the three areas of disaster prevention, utilization and ecology has to be maintained in areas such as topography, soil quality, water quality and air quality in order to maintain and promote the coastal zone. A smooth flow among the water, soil, energy, flora and fauna is needed to achieve this end. Through this process, the environmental capacity of the coastal zone will be increased, and humans will reap the subsequent benefits.

If we look back from this viewpoint on the projects to restore the environment and create new environments, work to ensure a smooth supply of soil from the upstream to downstream of rivers in the coastal zone have been embarked upon in Japan. These activities can, from a long-term and broad-based viewpoint, be termed environmental restoration. In addition, seaweed sites, dry beaches and sandy beaches have been created as part of projects, which have been undertaken to restore and create habitats. The construction of structures is now planned taking into consideration the habitats of flora and fauna. Technology has been developed which is designed to promote the restoration of the environment and create new environments. Through combining these various different technologies into a coherent system, we should be able to point the way for the restoration and creation of an integrated coastal environment.

1. Introduction

Coastal zone can be narrowly thought of as the "dividing boundary" between sea and land-the coastline-or broadly thought of as the zone in which the three spheres of air (atmosphere), water (hydrosphere), and land (lithosphere) converge-the coastal zone. Coastal regions are intensely dynamic areas, and are of critical important to humans.

Coastal zones contain unique, irreplaceable ecosystems. At the same time, coastal zones are subject to intense use by humans-for transportation activities, resources and energy procurement, industrial uses, and recreation. Furthermore, coastal zones are the first lines of defense against inland disasters. They are buffer zones against the ravages of tsunamis, rough waves, flooding, and erosion. In short, there are three functional aspects-provision of ecological services, disaster prevention, and human utilization-which are part of the human relationship to coastal zones. Each of these aspects is intricately linked. Consequently, humans must monitor and manage these three facets of the coastal zone in an integrated manner to ensure that the human relationship to coastal zones remains harmonious.

In this paper, the current status of the coastal environment in Japan is examined and problem areas identified. Following this, a basic theoretical framework for an integrated coastal zone management (ICZM) scheme in Japan is introduced. Examples of practical experiments in Japan in ICZM are then discussed. Finally, conclusions about the present state of ICZM in Japan are drawn.

2. Current Status of the Coastal Environment in Japan

Japan is part of the Asian temperate monsoon climatic region, and it is bathed by the warm Japan Current on the pacific side and Tsushima Current on the Sea of Japan side of the country. Thus, Japan experiences relatively high sea temperatures and a warm climate given its high northern latitude. The difference in tides at flood stage on the pacific coast is approximately 1.5 meters, and approximately 0.2 meters on the Sea of Japan coast. It is more than four meters on the Ariake Bay coast due to its unique topography.

The total land area of Japan is approximately 378,000 square kilometers (see Table 1). Coastal areas which are 20 meters or less below sea level account for about 31,000 square kilometers, which is approximately 10% of the total land area. The 200-mile exclusive economic zone encompasses an area of about 4.47 million square kilometers. The total length of Japan's coastline is roughly 35,000 kilometers. Japan has 91 meters of coastline per square kilometers of total land area. If small island states are excluded, Japan comes in second in the world behind Denmark (150 meters of coastline per square kilometer of total land area) in coastline length per unit total land area. This fact helps demonstrate the importance of the coastal zone to Japan.

Coastal Zone Facts of Japan

Total Land Area of Japan377,720 km2
Water Depth Area: 0 - 20 m30,880 km2
: 20 - 50 m49,850 km2
: 50 - 100 m79,740 km2
200-mile Economic Zone Area4,470,000 km2
Length of Coastline34,536 km

In the following sections we will examine the current status of Japan's coastal zone relative to the three functional aspects of coastal zones important to humans mentioned above-disaster prevention, human utilization, and provision of ecological services.

2.1 Disaster Prevention

Japan is prone to seaborne natural disasters, including typhoon-induced flooding and high waves, and tsunamis or tidal waves. In addition, Japan's coastline is prone to erosion. Thus, prevention of disasters related to typhoons, tsunamis, and erosion is one important functional aspect of coastal zones that must taken into account in any ICZM schemes developed in Japan.

All of Japan is threatened by flooding and high waves during the typhoon season around September. In addition, the Sea of Japan side of Japan is buffeted by strong winds and rough seas in the winter. Storm conditions combined with High tides can cause especially severe damage. Table 2 lists damage caused by flooding due to typhoons in Japan since 1900. High tides in the three major bays of Tokyo, Ise, and Osaka, as well as in the Ariake Bay, can be amplified by storm winds. A particularly damaging typhoon hit the Tokyo area in 1953. Maximum tide deflection was 3.9 meters in Tokyo Bay. Though it is not included in Table 2, this typhoon lead to the drafting and enactment of the Coastal Act. The worst recorded typhoon-induced damaged was experienced in the Ise Bay Typhoon of 1959 which caused a storm surge anomaly of 3.4 meters and resulted in more than 5000 deaths and damage to almost one million buildings. Damage caused by flooding has diminished in recent years, but it is unclear whether this is a result of efforts to protect the coastline, or the lack of severe typhoons in recent years.

Principal Typhoon-Induced Floods in Japan since 1900

(maximum deflection of 2 meters or more above high tide)

high tide
Totally or
partially destroyed
Water seepage-
flooding in homes
10/1/1917Tokyo Bay2.33.11127(197)(363092)(363092)@
7/18/1930Ariake Bay2.5||(|)||@
9/21/1934Osaka Bay3.13.22702(334)92740401157Muroto Typhoon
9/1/1938Tokyo Bay2.2|201(44)13223158536@
9/3/1950Osaka Bay2 .42.5336(172)56131166605Typhoon Jane
8/17/1956Ariake Sea2.44.233(3)3734110431Typhoon 5609
9/26/1959Ise Bay3.43.94697(401)833965363611Ise Bay Typhoon
9/16/1961Osaka Bay2.52.9194(8)499444384120Muroto Typhoon No.2
9/25/1964Osaka Bay2.12.647(9)7126944751Typhoon 6420
9/10/1965Utsumitobu2.2|67(6)6343649626Typhoon 6523
8/21/1970Tosa Bay2.43.123(4)4865259961Typhoon7010

Information on floods was taken from Miyasaki (1971), information on damage
(from typhoon overall) was taken from the Publication of the Science Table (1972 and 1992).

Tsunamis or tidal waves are also a source of severe damage and loss of life in Japan. Table 3 shows the major tsunamis in Japan over the past 100 years. Tsunamis can hit anywhere in Japan, but they are most common on the Pacific coast. In particular, high-energy tsunamis are frequently experienced in the Sanriku region in the northeast part of the main island of Honshu. Two tsunamis, however, hit the Sea of Japan coast in 1983 and 1993, which underscores the need for vigilance in this area as well.

Major Tsunamis in Japan during the past 100 years
(magnitude of 3 or higher)

height of
Totally or partially
away (units)
Water seepage
-flooding in homes(units>
6/15/1896Meiji Sanriku Tsunami6.8424.4 (Sanriku Cho,
Iwate prefecture)
3/3/1933Showa Sanriku Tsunami8.1323.0 (Ryori Cho,
Iwate prefecture
12/7/1944Southeast Sea
Earthquake Tsunami
7.939.0 (Owase City,
Mie prefecture
12/21/1946South Sea
Earthquake Tsunami
8.036.5 (Shirahama Cho,
Wakayama prefecture)
Earthquake Tsunami
8.548.1 (Noda Cho,
Iware prefecture)
5/26/1983Sea of Japan Chubu
Earthquake Tsunami
7.7313.0 (Hachihama,
Akita prefecture)
7/12/1993Hokkaido Southwest Sea
Earthquake Tsunami
7.8|30.5 (Okushiri Cho,

Taken from Watanabe et al. (1985)

While typhoon-induced floods and tsunamis cause enormous damage in a short period of time, the most serious damage to coastal areas has been wrought by slow coastal erosion over a long period of time. In contrast to typhoons and tsunamis, this damage is not the result of natural forces but human forces. Coastal erosion has been particularly severe since the end of World War II and coincides with Japan's rapid industrialization after the war. Industrial development combined with the severity of sea conditions during typhoons and the fact that Japan has an inadequate natural supply of soil and sand has resulted in a serious coastal zone erosion problem in Japan.

Table 4 shows erosion speeds of sandy coasts as determined by comparing of past and present topographic maps (Tanaka et al., 1993). The table shows that coastal erosion has accelerated in the post-war era. Given that the average erosion speed for sandy beaches is 0.168 m (approximately one-sixth of a meter), and that the average width of these beaches is 30 meters (Ministry of Agriculture, Forest and Fisheries et al., 1990), a simple calculation reveals that at this speed all such beaches will be lost in 180 years.

Changes in of Sand-Pebble Coastal Areas

PeriodChanges in areaTotalWidth of average change
Annual average
loss (ha/yr)
Annual average
loss (m/yr)
1900's to 1970's (70 years)12,5397,4805,059729,499.
1970's to 1980's (15 years)4,6052.2102,3951604.

Created from Tanaka et al. (1993)

A wide variety of structures have been built in Japan with the express purpose of preserving coastal areas against the above-discussed problems of typhoon-flooding, tsunamis, and slow coastal erosion. Table 5 illustrates the magnitude of the effort to preserve the coastline.

The total length of the coastline in Japan as of 1992 was 34,536 km. Approximately one-half of this total, or 15,932 km, requires protection against coastal erosion. Structures have been built along about two-thirds, or 9,382 km, of this portion. In the 30-year period from 1962 to 1992 protective structures were built on about 4,248 km of coast. While it can be said that the coastline has been protected, it can also be said that the coastline is no longer natural. It is an artificial coastline.

Of the protective structures, banks and seawalls were built primarily in the first 10 years of this 30-year period. In the next 10 years, construction of seawalls together with detached breakwaters dominated. In the last 10 years, the focus was primarily on detached breakwaters. This shift was due to the fact that banks and seawalls were limited in their ability to stop the effects of rough seas. Detached breakwaters were found to be more effective in controlling rough seas and coastal beach currents.

Table 5
Coastline Protection in Japan from 1962 to 1992

Survey yearLength of
Length of
main preserved
coastline (km)
Length of
coastline preservation
region (km)
Effective length of
all facilities on
preserved coastline2 (km)
Sea walls
walls (km)
  1. 1963 does not include Okinawa and the Northern territories, and 1973 does not include the Northern territories.
  2. The definition differs slightly.
  3. The figure within the parentheses represents the effective length.
    (Taken from Coastal Statistics (1963, 1973, 1983 and 1993)

Coastal erosion is a problem of utmost importance in Japan because coastal erosion compromises the ability of coastal zones to act as front-line defenses against floods, tsunamis, and rough seas, to provide adequate utilization functions, and to maintain the integrity of shallow water ecosystems. Coastal erosion also, in essence, means that the land of Japan itself is lost.

2.2 Human Utilization

Coastal zone has been used for various human activities from time immemorial. In ancient times they were used by hunters and gatherers as a place to harvest marine resources, today they are used as sites for airports, petroleum exploration, fuel storage and energy generation, industrial and commercial development, waste dumps, and recreation areas.

Figure 1 compares those cities, towns, and villages which border coastlines to those which are landlocked in terms of their area, population, value of industrial shipments, and value of commercial sales. Despite the fact that waterfront municipalities do not exceed 32% of the total area, they account for 45% of the population, 47% of the value of industrial shipments, and 77% of the value of commercial sales. These figures clearly underscore just how central coastal zones are to human activity.

Figure 1

Figure 1: A Comparison of Population and Economic Development in Coastal and Inland Municipalitie

Japan is covered with mountainous regions unsuitable for intense human utilization. Thus, its population and accompanying activities tend to be concentrated in flat areas, especially along the coast. Table 6 shows a comparison of the Tokyo Bay and San Francisco Bay areas. The land area is just about the same, but the ratio of the population density in the drainage basin is 60:1 in Tokyo Bay's favor. This highlights the inescapable need in Japan to make efficient use of its coastal zones.

A Comparison of Tokyo Bay and San Francisco Bay

Tokyo BaySan Francisco Bay
Water area(km2)13801240
Drainage area(km2)7549153000
Average water depth(m)45
Amount flowing in from rivers(m3/s)300500
Drainage basin population
Drainage population density
Reclamation area(km2)249240

*: within the Bay area
**: state of California

2.3 Ecology

Healthy coastal ecosystems are vital to healthy coastal zones. However, coastal erosion and construction of coastal preservation structures are adversely affecting coastal ecosystems. Dry beaches, seaweed beds, and coral reefs are important elements of coastal ecosystems. Table 7 shows changes in the spatial area of dry beaches, seaweed beds, and coral reefs in Japan in the post-war period. The drop in dry beach area in the 1970s is particularly striking. This coincides with increased landfill in bays. These figures underscore the fact that human activity in Japan has reached a level where its impact on coastal zones can not be ignored.

Table 7
Changes in Dry Beach, Seaweed Bed, Coral Reef, and Landfill area in Post-War Japan

Dry beach82,621--(-28,765)53,856 (55,538)*(-4,076)-51,462
Seaweed-184,776(-2,049)182,727 (207,557)*(-6,403)-201,154
Coral-88,972(-1,789)87,183 ---
within bay**

* Figure was not obtained directly from the survey results, but the reduced area was added to the 1992 value.
** This figure stands for the landfill main area, and it is 55% of the total landfill area from 1978 to 1983.
(Created from information from the Environment Agency (1980 and 1992)
and the Japan Port and Harbor Association (1990))

Landfills and coastal preservation structures are causing coastal zones to become increasingly artificial. Table 8 shows some of the changes in natural, semi-artificial , and artificial coastal areas. An artificial coastal area is an area where structures have been erected in shallow waters. Semi-artificial coastal areas are those in which structures are erected but are either on the land side of the high tide shoreline or the sea side of the low tide shoreline. The basic conclusion to be drawn from Table 8 is that as artificial coastline has increased, natural coastline has decreased. Despite a slowdown in the speed of construction of landfill coastline and preservation structures, the trend toward increased artificiality of the coastline remains unchanged.

Table 8-1
Changes in Natural, Semi-Artificial, and Artificial Coastal Areas: Natural coast

Survey yearBeach has developed in coast (sea shore)Beach has not developed
in coast (sea shore)
Mud beachSand quality
(sand beach) coast
(pebble beach) coast

Table 8-2
Changes in Natural, Semi-Artificial, and Artificial Coastal Areas: Semi-natural coast

Survey yearBeach has developed in coast (sea shore)Beach has not developed
in coast (sea shore)
Mud beachSand quality
(sand beach) coast
(pebble beach) coast

Table 8-3
Changes in Natural, Semi-Artificial, and Artificial Coastal Areas: Artificial coast

Survey yearCoast created
by landfill
Coast created
by drainage
Coast created
by other methods

Taken from Environment Agency (1980 and 1984)

3. A Theoretical Framework for Integrated Coastal Zone Management

ICZM schemes must address both the human and natural elements of the total coastal environment. Figure 2 and Table 9 show some of the components of the total coastal environment as it relates to ICZM. Together the figure and table express the basis for a theoretical framework for ICZM in Japan.

Figure 2

Figure 2: Basic Make-Up of Coastal Human and Natural Environment

Table 9
Composition of Coastal Zone Environment

Environmental foundationCoast type (craggy coast, pebble coast and muddy coast) Air sphere (climate, air quality, light, sound and odor)Water sphere (sea climate, sea bottom topography, water quality and bottom quality) Earth sphere (terrestrial phenomenon, topography, soil quality, underground water and surface water)
EnvironmentEcologyEcosystem (physical/energy) Land floral and fauna, sea floral and fauna, benthos, plankton and necton
Disaster preventionCoastal erosion, rough waves, high tides, wind and floodingEarthquakes and tsunamis
UtilizationTransportation (harbors, fishing ports and airports)Energy bases (power generators and energy supply facilities)Resources (petroleum, ore resources, waves, tides, currents, temperature differential energy)Marine industry (fisheries, breeding farms) Agriculture (farm land)Industry (factories), Commerce (offices) Cities (housing) Recreation (sea bathing, low tide gathering, fishing, walking, sightseeing, surfing, yachting, boating, camping, cycling)Space (waste, construction waste and dredging soil waste)
Total environmentLandscape

One objective of ICZM is to preserve the ecological integrity of coastal zone ecosystems. Such ecosystems exist in generally harsh conditions-conditions of strong winds, high salt concentrations, and wide changes in air and water temperature. However, at the same time, nutrient salts supplied from rivers and abundant light in the shallow waters support high primary productivity. Coastal zone management must be sensitive to the nuances of the ecological variables of coastal ecosystems.

A second objective of ICZM is to prevent excess material damage and loss of life from natural disasters such as high tides, high waves, strong winds, flooding, earthquakes, tsunamis, and coastal erosion.

A third objective is to aid in appropriate human utilization of coastal areas. Utilization refers to harvesting of fish, shellfish and seaweed, construction of ports, establishment of sites for industry, building of residential homes, and setting aside of recreation areas.

A final objective is to comprehensively integrate separate efforts undertaken to achieve the first three objectives. The purpose of ICZM is to create an attractive, safe, and vibrant coast; an ecologically sound and inspiring landscape.

Mimura et al. (1996) set down specific items for evaluation in each of the three categories (ecology, disaster prevention, and human utilization) related to the coastal environment, and proposed an integrated evaluation method for judging management schemes relative to these three categories. One of the purposes of Mimura et al.'s method is to overcome one of the biggest problem of ICZM-the trade offs between the ecological, disaster prevention, and human utilization aspects. For example, ecosystems are often damaged when seawalls are constructed.

The basis of ICZM is that it must strive to maintain a healthy environmental foundation. It is upon this foundation that the ecological, disaster prevention and human utilization functions of the coastal zone rest. Coral Reefs, pebble beaches, seaweed beds, muddy beaches, etc. are elements of the natural world which, in their natural state, change slowly. If the environmental foundation is not maintained over long time scales (say, decades), the ecological, disaster prevention, and human utilization functions of coastal zones will suffer. In other words, the status of the environmental foundation determines the health and viability of coastal zones.

If a sandy beach coast is taken as an example, topographic changes occur on the order of thousands of years. When human alter the sandy beach with the motive of improving its disaster prevention capability or human utilization potential, care should be taken that the alterations do not create a state of instability. The objective of ICZM is to achieve a new state of equilibrium without causing destructive instability.

ICZM demands intense monitoring. For instance, to ensure that the construction of structures do not cause a chain reaction of coastal erosion, it is necessary to monitor such variables as supply of sand from rivers and cliffs, movement of coastal sand drifts, airborne transport of sand, and runoff to deep waters (see Figures 3 and 4). For successful sand management, water flow, air flow, energy flow, and soil movement must be appropriately preserved.

Figure 3

Figure 3: Soil and Sand Management in Coastal Zones

Figure 4

Figure 4: Erosion of Inner Coast Caused by Breakup of Coastal Sand Drifts

4. Japan's Present Coastal Zone Management System

Japan's first formal coastal zone management scheme was embodied in the Coastal Act of 1953. Its objective was the prevention of disasters. It was not drafted from the viewpoint of integrated management of the coastal zone. Until recently prevention of disasters has remained a primary focus of Japanese coastal zone management. Japanese coastal law differs from laws in the United States. The state of California, for example, has codified a integrated coastal zone management system. Japanese laws such as the Harbor Act, Fishing Port Act, and the Public Waterfront Landfill Act were set down separately and cover the development and utilization of Japan's coastal zone. The National Parks Act and the Seto Inland Sea Preservation Special Measures Act cover the protection of nature. There is, however, no law that serves to coordinate all the relevant aspects of each of these separate laws.

These different laws result in differing responsibilities by different government agencies. The coastal zone is classified into, for instance, harbors, fishing ports, and reclaimed agricultural lands. Each classified area is overseen by a different ministry such as the Ministry of Transportation, Ministry of Agriculture, Forest and Fisheries, and Ministry of Construction. To achieve true ICZM, establishment of new laws and administrative bodies is desirable.

In the course of actual management, spatial units of the environmental foundation must be designated. The environmental foundation in a given area can be considered as almost a closed flow system, and hence, different environmental classifications are possible. A total of 77 environmental classifications of coastal zone units have already been made. These classifications have been established taking into consideration the unity of coast, and they can be thought of as points of departure for the environmental foundation sub-units.

5. Future Integrated Coastal Zone Management in Japan

5.1 ICZM and Mitigation

Mitigation is a concept important to coastal zone management. Japan has established no legal system for mitigation to maintain the integrity of the coastal zone. The United States, on the other hand, has systematized a mitigation system. The definition of mitigation used in the United States was set down by the Council of Environmental Quality. Also a definition which focuses on what are called avoidance, minimization, and compensatory courses of mitigation action was set down in a 1990 memorandum agreed to by the US Army Corps of Engineers and the Environmental Protection Agency. The U.S. mitigation system vis-a-vis the environment is based on the principle of "no net loss." No net loss means that whenever an act is taken by humans, such as residential development, which negatively affects the environment, the environment must also be restored or a new environment created to offset this damage.

If the ultimate objective of mitigation is the maintenance of a healthy environment, then the preservation of the environmental foundation is extremely important. Artificial changes in the coastal zone which accompany activities such as development must, in the context of mitigation, be done in such a way that they do not destabilize or adversely affect the environmental infrastructure, for example, the topography, soil quality, water quality, or air quality. When planning and executing projects related to human utilization, disaster prevention, and ecological protection, a selection from among the possible plans must be made from the standpoint of maintaining the soundness of the environmental infrastructure.

5.2 Examples of ICZM in Japan

Although no codified system of mitigation exists in Japan, restoration of the environment, creation of new environments, and concern for the environment has been present. These practices can be incorporated in the developing concept of ICZM in Japan. In this section some examples of ICZM are given.

The Dashihira Dam on the Kurobe River in Fujiyama Prefecture was constructed so that sand which accumulated on the upstream side of the dam is expelled through a sand flushgate. This ensures a supply of soil and sand downstream. In addition, a sand control dam was constructed with a sand flushport so that soil is expelled during normal hours. Ensuring a steady supply of soil to the mouth of the river by minimizing the extraction of soil from mid- and downstream can be termed environment restoration and creation in a macro sense.

The maintenance of coastal sand drifts provides another example of ICZM. A sand bypass was employed to maintain what are perhaps Japan's most famous coastal sand drifts-a formation known as Ama-no-Hashidate (Bridge of Heaven) in Kyoto Prefecture.

Projects have been embarked upon to restore and create new beaches by beach nutrishment. Examples include the artificial shore created in the Kasai Waterfront Park, a project aimed at creating natural habitat. In this project, one of two artificial islands that were created is used for recreation while the other is reserved exclusively as a natural sanctuary where people are not allowed to enter.

One specific project which aims to both restore and create habitat is a project to create an artificial tidal flat in Itsukai City in Hiroshima Prefecture. A 24-hectare tidal flat has been created along a breakwater to replace the dry beach at the mouth of a river, which was been lost to harbor development. This dry beach provides a feeding and resting area for birds such as sea gulls, snipes and plovers. The number of birds on the artificial beach rivals the number that was present before its construction. However, there are problems with the dry beach including subsidence of the site and diameter of grains in the bottom sediment.

Methods for creating a base for seaweed to adhere using blocks that have been placed at the bottom of the sea and methods for transplanting seaweed have been employed to create sites for new seaweed beds. A 60,000 square meter seaweed mound was created to replace a seaweed site that was destroyed by the construction of the Ikata power plant in Ehime Prefecture. Natural and artificial seaweed sites have formed in the three years since the start of this plan. Another example is found in Hiaijima in Kumamoto Prefecture where a 19,000 square meter transplant site was created to replace an eelgrass site that was lost with the creation of an artificial recreational beach. Two years after the transplant, the density of the eelgrass was observed to have doubled.

Efforts have been made to shape seawalls and sunken piers to make them into appropriate habitats. It was found that aquatic plants and animals were able to attach themselves easier to a slanted stacked stone seawall , which was built for the Kansai International Airport in Osaka Bay. Monitoring confirmed the adherence of seaweed to the structures and a return of reef fish, which were not present prior to construction. As another example, a block shaped, gently slanted seawall on the Sumiyoshi coast in Miyazaki Prefecture was constructed so that sea turtles could lay their eggs on the beach. Compared to conventional gently slanted seawalls, the block shaped seawall resulted in an increase in the ratio of eggs.

In addition to the examples given above, there are numerous other examples of restoration of the environment and creation of new environments. Significant progress has been in the technology required to put ICZM into practice. Japan has very little marshland in comparison to the United States, thus, compared to the U.S., Japan will focus on creating sand beaches, tidal flats, and seaweed sites.

6. Conclusion

ICZM is absolutely essential to solve Japan's development-related coastal zone problems. Development in the post-war era has resulted in Japan's coastline becoming an artificial coastline. ICZM seeks to integrate the ecological, disaster prevention, and human utilization functions of coastal zones. ICZM seeks to think of coastal management with a long-term and broad-based perspective. Creation of a healthy and stable environmental foundation is the goal of ICZM. To this end, Japan's prowess in technological development can be harness to integrate separate technologies into a coherent mitigation-oriented system of technologies that can enhance the coastal zone environmental foundation.


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