河岸与河底相对粗糙度对河道平衡形态的影响研究

边界条件对河流地貌形态具有重要影响,基于河道边界阻力水力半径分割方法,利用变分方法研究河岸与河底相对粗糙度对冲积河流平衡河道形态的影响。结果表明,河岸与河底相对粗糙度对河流达到平衡时的最大输沙率有一定的影响,但对河道平衡形态的影响非常显著。在临界和平均水力几何形态关系式中,随着河岸与河底相对粗糙度的增大,河宽关系式的系数逐渐减小,水深关系式的系数逐渐增大,但控制变量,特别是流量的指数变幅很小。

Study on the influences of the relative roughness of channel banks to bed on equilibrium channel geometry of alluvial rivers

Based on the hydraulic radius segmentation method for segmenting river channel boundary resistance,the variational method is applied to investigate the influences of the relative roughness of channel banks to bed on the channel geometry of an alluvial river when it reaches equilibrium. It is demonstrated that the relative roughness of channel banks to bed exerts influence on the maximum sediment discharge to a degree and yet to a very large degree on equilibrium channel geometry. In the mathematical derived threshold and average hydraulic geometry relationships,an increase in the relative roughness of channel banks yields a smaller value for the coefficient in the width relation,a larger value for the coefficient in the depth relation,and yet insignificant changes in an exponents of the control variables,typically flow discharge.