不等宽河道型水库动防洪库容近似计算方法

Approximate calculation method of the flood control capacity of the varied width mountainous reservoir

河道型水库由于回水曲线相当部分处于明显高于坝前水位的位置,防洪库容不能完全采用根据地形资料确定的静库容方法计算,应按照考虑基于入库流量的动库容法进行。本文在已有等宽河道防洪库容研究工作基础上,将不等宽河道划分为多个近似等宽子河道,采用恒定非均匀流理论推导了不等宽河道各子河段回水曲线方程和防洪库容近似表达式。通过计算给出了各子河段动静防洪库容关系曲线,然后讨论了动防洪库容计算步骤,最后给出了与数学模型计算的实例比较。结果表明,本文提出的动防洪库容计算方法与采用数学模型的计算结果基本吻合。近似计算方法对于可行性研究阶段或是中小型水库动防洪库容的初步确定具有参考意义。

The flood control capacity of the mountainous reservoir cannot be calculated accurately simply by the storage capacity curve based on the bathymetric information because the water volume can not be neglected when the backwater level is higher than the dam level, so the influence of the inflow should be taken into account. Based on the previous work of the flood control capacity on the equal width river, the general river width is divided into several equal width reach and the water level formula is deduced in each part by adopting the steady non-uniform flow equation and then the expression of flood control capacity is obtained. Relationship curves between the dynamic flood control capacity and the static flood control capacity are given out and the calculation processes are brought forth. An example is demonstrated for comparing between the mathematical model and the approximate method. Results obtained with the approximate method are close to that of the mathematical model. The method presented in the paper can offer a relatively great value especially for the early stage planning of the mountainous reservoir or determination of the flood control capacity in the middle and the small flood control reservoirs.