辽河流域丰枯遭遇下水库调度

利用Copula函数分析辽河流域水库入库流量边缘分布及其生态径流量,得出水库可调水范围,在满足生态流量基础上,保障辽河流域城市供水。研究表明:(1)英那河与张家堡水库入库流量以对数正态分布为最佳边缘分布,其余水库入库流量最佳边缘分布均为广义极值分布,同时,Gumbel Copula与Frank Copula函数对水库入库流量拟合效果最优;(2)7组水库组合中有3组水库组合入库流量(白石与锦凌、白石与青山、张家堡与碧流河)丰枯异步概率高于丰枯同步概率,且枯枯遭遇概率较低,分别为13%,12%以及13%。其余4组水库组合枯枯遭遇概率皆高于27%,水库间入库水文过程发生同枯概率可能性较大;(3)使用90%保证率逐月频率计算法所求流量是辽河流域9个水库的最佳生态径流量。(4)枯水月水库间易发生枯枯遭遇,当水库间入库径流皆低于最小生态径流标准,水库无法对各自调水城市进行供水调度,其中,大伙房与桓仁、白石与锦凌、白石与青山主要在1、2月无法对沈阳、凌海和绥中县进行输水,桓仁与清河水库仅在2002年5月无法对开原进行供水,此时需考虑水库提前蓄水以满足城市用水需求。碧流河、英那河和张家堡水库虽两两存在无法输水情况,但可三者联动对大连进行联合调度,缓解无法输水问题。

Reservoir-based ecological water operation in the Liaohe River basin characterized by synchronous occurrence of wet/dry events

Allocation of water resources from river basins draining into reservoirs is a challenging task, particularly, if the ecological water requirement is taken into account. In this study, copula functions were used to analyze hydrologically the possible synchronous occurrence of dry and wet regimes in the Liaohe River. The ecological streamflow requirements were considered during the water resource allocation. The following results were obtained. (1) The probability distribution with the highest goodness-of-fit for the Yinna River and Zhangjiabao reservoir inflow was the log-normal distribution and that for the reservoir inflow of other rivers was the generalized extreme-value distribution. Further, the Gumbel and Frank copulas had the best fitting efficacy for the inflow series of the reservoirs. (2) The synchronous wet/dry events occurred at a higher probability of more than 27% at 4 out of 7 pairs of water reservoirs and at the rate of 13%, 12%, and 13% at the other three pairs of water reservoirs, i.e., Baishi vs. Jinling, Baishi vs. Qingshan, and Zhangjiabao vs. Biliuhe, respectively. Further, the probability of synchronous dry instream events was high in these reservoirs. (3) The method of minimal monthly runoff at 90% guarantee rate suggest the best ecological runoff at the nine water reservoirs. (4) Dry-dry events occurred at a higher frequency during low-flow periods. The water resource allocation or operation cannot be executed when the reservoir instream flow is lower than the minimum ecological streamflow. Joint water operation of the reservoirs based on the occurrence probability of dry-dry events and minimum ecological streamflow can satisfy the regional water requirement.