ASSESSMENT OF CHANGES IN THE FLOW OF SMALL RIVER BASINS DUE TO DEPOPULATION USING A DISTRIBUTED RUNOFF MODEL

Abstract

 The purpose of this study was to analyze the runoff in small river basins and to predict the impact of depopulation. Depopulation is expected to promote land-use change and channel change and alter the hydrological processes in the basins. A distributed runoff model evaluated the changes in inflow with forested land use and vegetation cover after no population. The annual maximum flows decreased in the Sukawa and Ohtani Rivers, indicating a decrease in flood risk. In the lack of river management, the risk of inundation increases in the vicinity of the river channel. In addition to land-use change, the inundation processes were evaluated by the flow change. The annual maximum flow was further reduced in the Sukawa and Ohtani Rivers, and runoff was delayed by one hour. The results indicate that the inundation in uninhabited basins may reduce flood risk in the downstream areas.