Abstract
In meandering rivers, a sediment size distribution on a bed, as well as a flow field and a bed configuration, varies systematically in both a streamwise and a lateral direction due to a relatively strong secondary current. In order to clarify the mechanism of the “sediment sorting”, the numerical model was constructed with no correction coefficients and a least assumption. The validity of this model was confirmed by comparing the predicted results with the meansured ones obtained in a laboratory flume and a natural river. Sediment sorting is found to originate from the region near the side wall and to proceed into a central portion with an extremely low speed.
