EFFECT OF LARGE-SCALE LOGGING OF VEGETATION IN THE SHIMANTO RIVER ON THE SUBSEQUENT FORMATION OF THE SWEETFISH SPAWNING GROUNDS

Abstract

The Ministry of Land, Infrastructure, Transport and Tourism has been promoting a natural rehabilitation project including the cutting down of vegetation with the purpose of restoring the gravel and improving the flood control capacity of the Shimanto River. In this research, we extracted the topographic and hydraulic conditions of the river by conducting detailed river topography measurements before and after a flood using the UAV photogrammetry technique, a riverbed penetration survey around the sweetfish spawning grounds, and a two-dimensional analysis of the flow. Moreover, the effects of large - scale logging of vegetation conducted from 2003 to 2009 on the creation of spawning grounds of sweetfish was clarified.