The Function of Flood Control by Vegetation in Stream

近年来，人们对自然的需求似乎在增加。水流中的植被具有一定的沉积作用，在水力学上可以看作是一组粗糙度，从而起到降低水流速度的作用。然而，植被对河流的阻流和沉积作用尚未得到充分的认识。本研究的要点如下：1。河床利用的过渡植被对河床波动的影响植被对防洪的影响研究表明，有植被的水流剪应力是可以准确估算的。因此，当植被占面积百分比较大时，粗糙度系数增大，河床波动减小。因此，植被具有固定河床的功能。

People's demands for nature seem to be on the increase in recent years. It is expected that the vegetation in stream have a function of sedimentation as they can be hydraulically regarded as a group of roughness, thus performing to reduce the velocity of flow.However, the function of the flow resistance and sedimentation by vegetation has not been estimated yet.The points of this study are as below.1. Transition of the river bed utilization2. Influence of the vegetation to fluctuation of river bed3. Influence of the vegetation to flood controlIt became clear that shear stress in the stream flow with vegetation can be estimated accurately.As a result when the percentage of area occupied by vegetation is large, the coefficient of roughness increase and the fluctuatin of river bed is reduced.Therefore it is understood that the vegetation has a function to fix river bed.