Statistical Analysis of Artificial Modification of Natural Coastline in Japan Since 1960

Abstract

The ratio of artificial to natural coast is considered to be an important index for the study of coastal zone management from an environmental point of view. The amount of natural coast can be used as an index showing the destruction of natural environment in the coastal zone as well. In Japan, however, the ratio of artificial to natural coastline has been examined only in three national coastal environment investigation projects conducted beginning in 1978 by the Environmental Agency of Japan. The authors used the national coastal statistics published every year by the Ministry of Construction to analyze the degree of modification of the Japanese natural coast statistically. The results show that artificial modification of the Japanese coast has progressed since the period of high economic development in Japan in the 1960's. The ratio of artificial to natural coastline continued to decrease from 78% in 1960 to 55% in 1993. The history of the artificial modification of the coastline falls roughly into two phases . The first phase began in 1960 and is characterized by the rapid decrease in natural coastline. The second phase began in 1980 and shows a substantial loss of natural coastline in an area designated by the Coastal Protection Law as needing protection.