ダム堆砂に関する研究

Abstract

Sedimentation in reservoirs is very important subject, because it gives a large influence on theprocess of sediment transport and the change in water environment.This paper treats on the annual specific sediment yield, which is very useful index for theprediction of sedimentation, and also on the grain-size distribution of the sedimentation. Re-arrangement of data on sedimentation due to dams in Japan shows that the specific sediment yieldscan be classified to some groups and it is closely related to catchment area for every group.Taking up the data of sedimentation in the Syo River, a method to estimate the specific sedimentyield on the physical background is discussed in detail. The part due to the bed load transportamong the specific sediment yield can be estimated by the bed load formula such as by Ashida andMichiue. The part due to the suspended load transport is proportional to the relative area of land-slides and square of discharge.Some interesting characteristics for the logitudinal variation in grain-size distribution of sedi-mentation due to the dam are also presented from the discussion of the longitudinal variation ofshear stress and grain-size distribution feeded from landslides.