Mechanism on lateral widening of alluvial river channel

According to the lateral widening of alluvial river channel, this paper analyzes two kinds of mechanical principles, which cause river channel widening. That is: the widening caused by the direct water erosion and the widening caused by the collapse of river bank. In addition, this paper also summarizes the common methods of lateral widening of simulating river channel (empirical method and hydrodynamics - soil mechanics method), and analyzes the advantages and disadvantages as well as its application ranges of both methods. At last, research expectations have been put forward.