OBSERVATION STUDY ON SEDIMENTATION PROCESSES IN A STEEP AND HIGH MOUNTAIN RIVER BASIN

Abstract

It is very important for the prediction of sediment runoff into reservoirs and downstream of rivers to evaluate the behavior of sediment transport in a river basin located at high mountains. However, the difficulty for this study due to steep topographies and extensive research areas have hindered the accumulation of reliable data.This paper discusses characteristics of production, transportation and deposition processes of sediment in failed slopes and streams, and the overall situation of sediment balance of the basin, based on the on-site data such as aerial photographs and slope erosion data obtained from measuring sticks. The study area, Takase Dam basin, is surrounded by mountains higher than 2800 m in elevation. Characterized by steep topography and weak geology consisting of deteriorated granites, the area is one of the major sediment runoff areas in Japan.