MECHANISM OF RAPID CHANGE FROM NATURAL TO ARTIFICIAL COAST IN JAPAN - THE EXAMPLE OF NODE COAST IN KUJYUKURI COASTAL PLAIN

摘要

In the analysis of the shoreline changes on a coast, where continuous longshore sand transport is interrupted by structures and the downcoast is eroded, comparison of the shoreline changes based on the aerial photographs is often used and useful results have been obtained on several coasts. However, the analysis of the shoreline change does not necessarily lead to sufficient understanding of the events occurring on the coasts and rather direct comparison of aerial photographs is useful. The disappearance of the natural coastal sand dune and sandy beach in Japan has been caused not only by the recession of the shoreline due to decrease of longshore sand supply, but also by the excess advance of the coastal forest as a part of the land use change behind the coastline. This study aims at investigating this issue by using the method of direct comparison of aerial photographs taking the Node coast as the example. Finally it is concluded that in order to prevent further devastation of the coastal environment, overall comprehensive management in the widespread coastal zone including the coastal forest is needed.