1 引言明渠不稳定流的水力学公式需要两个边界条件,在缓流(即弗劳德数 F 小于1)的情况下,其中一个边界条件是在河道的下游端。在实际洪水演算中,几乎总是忽略下游控制的影响,洪水演算仅沿下游方向进行。对于低弗劳德数的缓流情况,可将水流方程中的小的对流项在线性运动波基础上近似。这 1 Introduction The hydraulic equations for instability flow in open channel require two boundary conditions, one of which is at the downstream end of the channel with slow flow (ie Froude number F less than 1). In actual flood calculations, the effects of downstream controls are almost always ignored, and flood calculations are performed only in the downstream direction. For the case of low Froude number of slow flow, the small convection term in the flow equation can be approximated based on the linear motion wave. This