大型调水工程渠道设计中有大量的过水建筑物，给开发非恒定模拟计算软件带来了一定的幽难。为此，提出采用虚拟渠道等效糙率的方法，用来模拟各输水建筑物对渠道中的水位和流量的影响。开发了非恒定流计算软件，成功用于南水北调中线工程总干渠渠道的非恒定流过程的模拟计算。

There are many hydraulic structures in large water transferring channels. These structures create rather difficulties for the development of an unsteady flow model for solving Saint-Venant equations. This paper proposed a method of equivalent roughness by using a short virtual channel to replace the actual transitional structure in order to simulate the effect of the structure on the water surface elevation and discharge. Unsteady calculation software was developed and succeeded to simulate transitional progress in the Middle Route of S.N Water Transfer Channel.