Journal of the Japan Society of Erosion Control Engineering,
Vol.56,No.5,2004
Estimation of the Amount of Sediment Discharge from Steep Mountain Basins Using Sedimentation Data in Sabo]dams
Takeshi MIZUTANI
Abstract
Regression equations for estimating the amount of sediment discharge from steep mountain basins have been derived by using 43 data of sedimentation in sabo]dams in Central Japan. Explanatory variables are topographic properties including mean basin gradient (S), maximum3]hour rainfall intensity (P3) and geological condition which are the major factors affecting the processes of sediment yield and transportation. Topographic properties are measured easily and quickly by using digital elevation data in a 50m mesh. The amount of sedimentation in a sabo]dam per a unit drainage basin area and per year (qs) is proportional to about the fourth power of S and the third power of P3. Geology of studied areas is pyroclastics and volcanic rocks (V), granitic rocks (G), Palaeogene sedimentary rocks (Tp)and Palaeozoic rocks (P). Regression coefficients obtained for geological category are 0.22 for G, 0.35 for Tp and 0.14for P when that for V is set at1.The inverse number of these values indicates the relative registivity to erosion for each geology. Since the determination coefficients are about 0.9, 90%of qs can be explained by these three factors.
Key words:Sedimentation in sabo]dams, Equations estimating sediment discharge, Mean basin gradient, Maximum3]hour rainfall intensity, Geological condition
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