A Field Study on the Movement of Sand and Gravel around the River Mouth of the Tenryu River

Abstract

A field investigation was conducted on the eroding coast around the river mouth of the Tenryu River, where the coast covered by sand and gravel experienced severe erosion due to the decrease in sand supply from the river. The movement of gravels was monitored in the period from August to December, 2006, when sand and gravels supplied by a flood in July were transported alongshore. The beach surface was found to be mostly covered by sand under moderate waves. Gravels were found to be predominant only in the vicinity of structures, such as detached breakwaters and a jetty. However, gravel layers were found to be present below the surface sand layer. The role of the gravel layer in maintaining the beach topography around the river mouth was discussed