密云水库上游径流变化趋势及影响因素

对径流演变规律的认识和研究是水资源得到有效利用的前提。密云水库是北京市唯一的地表水源地,水库的正常运行对北京市供水安全有重要的意义。2015年9月,南水北调的水开始进入密云水库,对密云水库上游径流量的研究可以使南水北调的水与其相互配合,有效补充密云水库的水资源,研究上游河流的径流变化趋势很有必要。以密云水库白河(张家坟站)和潮河(下会站)水文站1960—2014年的月径流数据为基础,采用年内径流不均匀系数、滑动平均法、Mann-Kendall突变检验法、小波分析方法、双累积径流曲线法分析了密云水库入库径流的年内分配特征和年际变化特征,径流变化周期趋势及降雨和人类活动对径流变化的影响。结果表明:密云水库入流径流量主要分布在7—9月之间,占全年径流量的70%;白河流域年内径流变化较为剧烈。50年来白河与潮河径流量有减少趋势,递减率分别为3.24m~3s~(-1)(10a)~(-1)和1.60m~3s~(-1)(10a)~(-1)。白河流域和潮河流域径流量存在周期为7a的变化特征。利用累积径流曲线分析降雨和人类活动对密云水库上游径流量的影响,结果表明人类活动是影响密云水库径流变化的主要原因,为71.36%—91.39%,其中白河流域受人类活动干扰更为剧烈。

Attribution analysis of changes in runoff in the upstream of the Miyun Reservoir

Studying the trends and laws of runoff is fundamental to the proper use of water resources. The Miyun Reservoir is the only surface water source in Beijing and is important to Beijing''s water supply. In September 2015, water from South-North Water Diversion Project (SNWDP) was added to the reservoir. Therefore, studying the runoff of upstream in Miyun Reservoir is more necessary for the proper management of the reservoir than ever before. As the amount of the water from SNWDP should supplement the runoff of the upstream, to know the trend of the upstream is necessary. Accordingly, the study analyzed the multi-temporal scale changes and abrupt change of the runoff, the influence factors of the runoff of Zhang Jiafen and Xiahui stations from 1960 to 2014. The methods of trend analysis, the moving average method, the Mann-Kendall method, wavelet analysis, the flow duration curve, and the double mass curve were used. The results indicated that the runoff in Miyun Basin mainly concentrated in July to September, accounting for 70% of the annual runoff, and runoff in the Baihe Basin changed more significantly than that of the Chaohe Basin. From 1960 to 2014, the amount of runoff slowly decreased at the rate of 3.24 and 1.60m³ s^-1 (10 a)^-1 in Baihe and Chahe respectively, and the runoff in Baihe and Chaohe Basin both showed change period of 7a. The results of double mass analysis indicated that the reduction of runoff in Miyun Basin can mainly be attributed to human activities (71.36-91.39%), and the Baihe Basin was disturbed much greater by human activities.