Spatial Variation in Specific Sediment Discharge Volume from First-Order Catchment due to Heavy Rainfall and its Factors

Abstract

In this study, we evaluated the variations in sediment discharge between basins from the first- order catchment of the Akatani River watershed, where sediment discharges as a result of heavy rainfall. We tested the correlation between sediment discharge, topography, and rainfall magnitude using LiDAR datasets. The results showed that the specific eroded sediment volume in the first-order catchment was sufficiently greater than the specific deposited sediment volume, and the variation of the specific discharge sediment volume from the first-order catchment was determined by the variation of the specific eroded sediment volume. The spatial variations of specific discharged sediment volumes could not be evaluated solely by topography and rainfall indices; even in the catchment, where the topographic condition and rainfall magnitude were almost the same, the specific sediment discharge varied by more than one magnitude.