EROSION RATE OF BED SEDIMENT BY MEANS OF ENTRAINMENT VELOCITY

Abstract

 Methods to evaluate erosion rate of bed sediment composed of very fine materials by means of entraiment velocity are discussed in the present study. It has been revealed that entraiment velocity depends on the Richardson number. To investigate the applicability of entraiment velocity on the estimation of erosion rate of bed sediment, flume experiment is conducted using very fine sediment; pearl-cray sand. As a result of experiment to investigate kinematic viscosity of the mixture body of water and pearl-cray sand, it has been revealed that the kinematic viscosity significantly changes at the concentration around 18-20%. As a result of flume experiment to investigate entraiment velocity, though the entrainment velocity is much less than the values obtained from previous researches in the cases that cohesion is dominant, in the cases with less concentrarion, the results are consistent with previous researches.