13-Coastline Loss and Natural Restoration Challenges in Kyushu and Kanto (1990s to 2020s)-August 1995-Environmental Destruction

13-Coastline Loss and Natural Restoration Challenges in Kyushu and Kanto (1990s to 2020s)-August 1995-Environmental Destruction

1990s: Crisis and initial response to coastline loss

The 1990s was a period in which the rapid loss of coastlines in Japan became apparent. In addition to natural disasters such as typhoons and storm surges, reclamation and development progressed rapidly, especially in the Kyushu and Kanto regions, specifically Tokyo Bay, Kagoshima Bay, and Sagami Bay. In Japan as a whole, approximately 290 kilometers of coastline were lost in the 10 years between 1984 and 1994. In Tokyo Bay and Osaka Bay, more than 70% of the tidal flats and wetlands were reclaimed as industrial zones expanded. In the Ariake Sea, the reclamation project has disrupted the ecosystem and reduced the migratory bird population by about 30%. The Environment Agency (now the Ministry of the Environment) and academic institutions began sounding the alarm about these problems, and discussions were promoted to preserve the coastal environment, but concrete measures were limited.

2000s: Start of Full-Scale Efforts for Coastal Conservation

In the 2000s, awareness of environmental issues increased, and in 2002, the Law for the Promotion of Nature Restoration was enacted. Based on this law, nature restoration projects were initiated throughout Japan. In the Ariake Sea, the focus was on the restoration of tidal flats. In response to the deterioration of water quality caused by agricultural drainage and the collapse of the ecosystem due to excessive accumulation of sediments, embankments were constructed and dredging was carried out, and the population of migratory birds gradually recovered. In Sanbanse (Chiba Prefecture), approximately 1,000 hectares of tidal flats have been restored, providing habitats for birds and other aquatic life. In Tokyo Bay, the "Green Loop Line Project" was promoted to restore tidal flats and vegetation in coastal areas. As a result, statistics show that biodiversity increased by approximately 20% in the late 2000s.

2010s: Responding to Climate Change and Disasters Become Important Issues

In the 2010s, the effects of climate change became even more pronounced, with sea level rise and coastal erosion caused by extreme weather events. The 2011 Great East Japan Earthquake and Tsunami that hit the Sanriku coastline caused widespread destruction of the coastline. The earthquake triggered an urgent need to strengthen disaster prevention infrastructure against tsunamis and storm surges, and seawalls were constructed throughout Japan. As part of the reconstruction plan, approximately 500 kilometers of levees were constructed at a total cost of more than 3 trillion yen. Vegetation restoration projects were also undertaken along the coasts of Tokyo Bay and Sagami Bay, and the area of sandy beaches preserved increased by approximately 25% over a 10-year period.

2020s: Sustainable Coastal Management and Deepening International Collaboration

In the 2020s, efforts to achieve the Sustainable Development Goals (SDGs) were further strengthened: At COP26, "nature-based solutions" to climate change were the focus of attention, and the Blue Carbon Project, led by the Ministry of the Environment, was launched in Japan. Through this project, seaweed beds and coral reefs are being restored, with the aim of improving their carbon absorption capacity. Specifically, activities are underway in Tokyo Bay, the Seto Inland Sea, and Nagasaki Bay, which are expected to absorb approximately 100,000 tons of carbon dioxide annually.

In addition, "smart coastal protection" utilizing the latest technology is also making progress, with drones and AI-based monitoring systems being introduced. In a project involving Kajima Corporation and Takenaka Corporation, AI is being used to monitor erosion conditions in real time, and conservation activities are being carried out based on precise data. With the introduction of this technology, coastal protection costs are expected to be reduced by about 30% compared to conventional methods. In the Minami-Boso region of Chiba Prefecture and the Shonan region of Kanagawa Prefecture, coastal cleanups and vegetation restoration are being promoted through cooperation between local residents and companies, and the number of projects involving local residents is increasing every year.

Thus, from the 1990s through the 2020s, there has been progress in efforts to address coastline loss and natural recovery, particularly in Kyushu and Kanto, and statistical evidence shows that ecosystems and natural environments are recovering.