南水北调长距离调水中渠首所需水头的探讨

南水北调中线总干渠全长约1270km，主要由明渠、倒虹吸、隧洞、涵洞和暗渠组成，总计沿线布置各类交叉建筑物1715座，不管是沿程水头损失还是水流经过各建筑物的局部水头损失大小，经统计都相当可观。针对该问题，对沿程糙率和局部水头损失系数的取值大小进行了变更比较。计算表明，各值在一定范围变化时，陶岔渠首的水位受局部水头损失系数取值变化影响很小，主要取决丁沿程糙率的大小。此处给出了渠首水位随糙率变化的过程，并得到渠首水位随糙率的变化拟合公式。且表明各建筑物对水位的影响主要集中住所在位置的局部段。

Discussion on the Elevation of Water Surface at the Head of the Middle Route of South-to-North Water Transfer Channel

The length of the Middle Route of Diversion Project from South to North China is about 1270 km and there are 1715 constructions of different types laid along the line. There are great head loss along the line added up and values of coarse rate n and local head loss rates are decisive and sensitive factors. Different values of these parameters are used to calculate the elevations of water surface of the head of the channel. It's indicated that the head elevation is mainly decided by coarse rate n and the influence of local head loss rates is rather small. A drafted formula of the elevation of water surface at the head with coarse rate n is gained. The effect of local head loss caused by conveyance constructions mainly focus on local channel.