大型水库群蓄水后下游河道枯水期流量增幅估算

Estimation of downstream river discharge amplification in dry season after upstream large reservoir group construction

随着流域上游大型水库群建设,由于“蓄丰补枯”的调节方式,下游河道枯水期流量增幅明显,对航道条件改善具有重要意义。在金沙江下游控制性水文站历年水文资料的基础上,对不同时期水库群建设后河道枯水期流量变化进行分析,提出一套基于水库群调节库容的下游河道枯水期不同保证率流量增幅的理论计算方法,并定量预测了乌东德、白鹤滩运行后向家坝站95%保证率流量为2 172 m3/s,与实际统计的2 007 m3/s较为接近。此理论计算方法可为其他河流梯级水库群建设后,下游航道枯水期流量的估算提供借鉴。

As large reservoir groups are constructed in the upstream of the watershed, the downstream river discharge increases significantly in the dry season due to the mode of storing water in the wet season and supplying water in the dry season, which is of great significance to improve waterway conditions. Based on hydrological data of the downstream control hydrologic stations of Jinsha River over previous years, we analyze river discharge variations in the dry season during different periods of reservoir group construction and put forward a theoretical method for calculating downstream river discharge amplification under different guarantee rates in the dry season based on reservoir capacity adjustment of reservoir groups. Then we predict quantitatively that the river discharge of Xiangjiaba station under a guarantee rate of 95% is 2 172 m~3/s after two reservoirs are constructed in Wudongde and Baihetan. The value approximates the actual statistic value of 2 007 m~3/s. Therefore, the proposed theoretical method can provide references for estimating downstream river discharge in the dry season after cascade reservoir groups are built in other rivers.