Towards a Beautiful, Safe, and Lively Seashore
MASAHIKO ISOBEThe University of TokyoGraduate School of Frontier ScienceDepartment of Environmental Studies
Measures for safety and disaster prevention at coastal areas are important, given the high population density in these areas, and the significant role they play in business and industry. Besides the problems of coastal erosion and land subsidence, coastal areas always face dangers from high waves, flood tides, storms, floods, and tsunamis caused by earthquakes.
The Sea Coast Law was enacted in 1956 for the prevention of such disasters, and coastal areas were viewed as areas to protect. There were various natural disasters before World War II. After World War II, there were several severe natural disasters, such as the Isewan Bay Typhoon in 1953, and the tsunami caused by the Chilean Earthquake in 1960. Such disasters made people work harder on disaster prevention at coastal areas, and accelerated the development of harbors and constructions for shore protection and for building banks. In consequence, shorelines in Japan were gradually changed from natural shorelines to artificial ones.
However, people gradually started to change their consciousness of nature and development and to ask for protection for natural seashores. In this way, The Sea Coast Law was amended in 1999. The law was reviewed further since then, in order to attain the objectives of coastal protection, environmental conservation, and utilization.
There is another significant problem: erosion of shoreline sands. Japanese seashore sand is eroded by some 0.17 meter (ca. 7 inches) each year, because the amount of sand supplied by upper streams is decreasing, due to the construction of dams. At seashores, sand absorbs wave energy, and the decrease in sand significantly decreases a shoreline's protection from high tides.
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