汛期分期以及分期汛限水位的合理确定,能够较好地协调水库防洪效益与发电效益之间的矛盾,对充分发挥水库的防洪、发电能力,以及提高汛期洪水资源利用率具有重要意义。基于改进的模糊集分析方法并依据金沙江下游乌东德、白鹤滩、溪洛渡、向家坝4个梯级水库入库洪水对其汛期进行分期,通过隶属度与防洪库容的映射关系确定梯级水库分期汛限水位,提出利用跨期选样法对分期结果及汛限水位进行修正。研究结果表明:金沙江下游梯级水库前汛期为6月1日—7月14日,主汛期为7月15日—9月16日,后汛期为9月17日—10月24日,4个梯级水库合理汛限水位分别为962,800,575,374 m。通过不同典型洪水放大的洪水过程检验了分期汛限水位的合理性。研究得到的金沙江下游梯级分期结果及各库分期汛限水位,均能够在满足防洪安全的前提下提高水库发电等经济效益,在一定程度上提高了汛期洪水资源的利用率。

Determining flood season stages and corresponding water levels in flood season stages rationally could help coordinate the contradiction between flood control benefit and power generation benefit of reservoirs, and is also of great significance to give full play to flood control and power generation capacity of reservoirs and improve the utilization rate of flood resources in flood season. In this paper, the flood season of cascade reservoirs(Wudongde,Baihetan,Xiluodu,and Xiangjiaba) in the lower reaches of Jinsha River is divided into stages according to the incoming flood using the improved fuzzy set analysis method, and the staged limit water level of cascade reservoirs is determined through the mapping relationship between membership degree and flood control capacity. The stages and corresponding limit flood levels are revised with intertemporal sampling method. Research results reveal that the pre-flood season of cascade reservoirs in the lower reaches of Jinsha River is July 1-July 14, main flood season July 15-September 16, and post-flood season September 17-October 24. The reasonable limit flood level for the four reservoirs is 962 m, 800 m, 575 m and 374 m, respectively. The staged limit flood levels are verified through the flood process of different typical floods. The staging results obtained in this study and the phased limit flood level of each reservoir could improve the economic benefits of reservoirs' power generation under the premise of flood control safety, and enhance the utilization rate of flood resources in flood season.