山地流域における侵食と流路変動に関する研究 (2)-流路の側岸侵食機構-

Abstract

The mechanism of bank erosion is discussed for erodible channels composed of cohesive andnon-cohesive materials.An equation is derived for critical shear stress of a sand particle on side slopes composed ofcohesive materials by introducing the cohesive force due to the existence of clay particles into thedynamic balance equation for a sand particle.It is supposed that the rate of particle deposition onto side slope are negligible so long as theshape of side slope is kept constant in a widening process of stream channel. A formula is obtainedfor the erosion rate, by integrating the pick up rate of sand particles from side slopes and bytaking the sand volume sliding down from the regions above water surface into cosideration.The equation is tested by its application to several experiments for bank erosion. The erosionrate is predicted well by this equation for both non-cohesive and cohesive materials.