STUDY ON THE PROCESSES OF BANK EROSION WITH BAR FORMATION BY NUMERICAL SIMULATION

Abstract

It is very important issue to estimate the place where bank erosion occurs and the scale of bank erosion during floods. We focused on the bank erosion with the transformation of bars. We found two types of bank erosion in a natural river where alternative bars are formed. One type of bank erosion is that the place where the bank erosion occurs moves with bars in a straight channel. Another type is the place is almost fixed with point bars in a meandering channel. By using numerical simulation including bar formation model and bank erosion model, we investigated the process of bank erosion with the transformation of bars. The results from numerical simulation show that both types of the bank erosion occur with developing the bars. Firstly, the place where the bank erosion occurs moves along the riverbank as fast as the bars migratate. Secondly, the migration speed of bars becomes smaller and the place where the bank erosion occurs is almost fixed. The angle of path line and that of the line which connect the deepest points have some relationships with the time when the first stage changes to the second.