NARROWING OF NATURAL SAND DUNE TRIGGERED BY BEACH EROSION ASSOCIATED WITH FORMATION OF WAVE SHADOW ZONE AND PROGRESSION OF COASTAL FOREST

AN EXAMPLE OF TERADOMARI AND NOZUMI COASTS

Abstract

The shoreline of the Teradomari and Nozumi coasts extending around the mouth of the new Shinano River, which was a floodway excavated in 1923, had been advanced due to the rich fluvial supply from this river. However, in recent years, natural sand dune was largely narrowed due to the beach erosion associated with formation of wave shadow zone caused by the extension of the breakwater of the Teradomari Port. Furthermore, excess progression of coastal forest occurred. Thus, natural scenery of this coast is rapidly changing to an artificial poor coastline. These situations were analyzed by comparison of aerial photographs and field observation.