Journal of the Japan Society of Erosion Control Engineering, Vol.55,No.6,p.21-32,2003

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Volumetric changes in suspended sediment load and bed load from mountainous catchments

Hoon KIM, Tomomi MARUTANI, Toshitaka MIYAZAKI

Abstract

The aim of this study is to clearly identify the characteristics of suspended sediment load and bed load occurrences in relation to the changes of catchment scales, water discharge and rainfall characteristics in the source area, which plays an important role to plan management strategies in mountainous catchments. Three catchments (i.e. Catchments A, B, and C) with different catchment areas were chosen to investigate the volumetric changes in suspended sediment load and bed load. The result shows that suspended sediment load is significantly related with water discharge rather than rainfall. On the other hand, it is proven that bed load is more closely related with rainfall rather than water discharge. Moreover, in the power function regression (YS=aEQb) of the relationship between cumulative water discharge and suspended sediment load, the coefficient a and the exponent b show the inversely proportional relation. Especially, decreasing rate of b against a in the catchments smaller than 10km2 in area is higher than that in the catchments larger than 10km2. From this result, it is considered that volumetric changes in suspended sediment load become higher with decreasing catchment area in mountainous catchments. In addition, suspended sediment load is account for 40]55 per cent of total load. It means even in mountainous catchments, a large part of total load consists of suspended sediment load.

Key words:bed load, catchment area, mountainous catchment, suspended sediment load, volumetric changes