THE EXAMINATION OF SEDIMENT PRODUCTION ESTIMATION BY THE USLE METHOD IN MOUNTAINOUS BASINS OF JAPAN

Abstract

The steep-slope topographic condition makes Japan to face the problems of high sediment production and yield in many areas. The problems are much severe in comparison with the other part of the world, but slightly less than the East and Southeast Asia and South American areas. However, with many reservoirs which relatively small in size, the sediment depositions in the catchments create very serious problems.
In order to understand the sediment production and yields in the catchments scale, the USLE, the most widely used of Sediment Estimation Model, was applied in the catchments of Arakawa, Daimon, and Hirose reservoirs in the Fuji River Basin. The result indicated that if parameters are properly selected to reflect the regional conditions, the USLE is adequately applicable for estimating long-term mean annual sediment production in the area.
The results couldbe useful to understand the spatial variation in sediment production that is required for erosion and sediment yield reduction management on the basin. While for the short-term or annual sediment deposition calculation, some problems were encountered where the methodology could not explain the observed accumulated sediment in the reservoirs.