气候变化和人类活动对密云水库上游流域径流变化的影响

以北京市密云水库上游流域为例,采用非参数检验Mann-Kendall、Sen斜率、小波周期性分析、基尼系数及洛伦兹不对称系数、SCRAQ法,分析了1960~2017年水库上游流域张家坟站、下会站和密云水库入库月及年径流量的趋势、突变、均匀度等,并定量研究了气候变化和人类活动对径流量变化的影响。结果表明,三个站点月径流量所占比例主要集中于7~8月,且变幅较大,从8月开始,径流量开始减少;季度径流量夏季最大,春季和冬季较小;密云水库7~8月月径流总量的平均值为其他月份径流总量的0.94倍,其夏季径流量的平均值为其他三个季节径流总量的1.18倍;下会站在突变点即1997年后径流深出现缓慢的增加趋势,密云水库在突变点即1992年后径流深的减小速率变小,减小了20%,这是由于降水量及南水北调工程向其供水共同影响所导致;三个站点的主周期分别为8年和24年、5年和24年、6年和24年;年径流量的分布主要集中于许多较小的年径流量,其分布的不均匀性是由于少数较大的径流量引起的;降水和人类活动是对密云水库上游流域径流量变化影响最大的因素,其中人类活动是导致密云水库上游入库流量减小的主要原因。

Impact of Climate Change and Human Activities on Runoff Change in the Upper Reaches of Miyun Reservoir

The upstream basin of Miyun Reservoir in Beijing City is taken as the research area. The non parametric tests Mann Kendall, Sen slope, wavelet periodicity analysis, Gini coefficient and Lorenz asymmetry coefficient, slope changing ratio of cumulative quantity (SCRAQ) method are used to analyze the characteristics of the monthly and annual runoff or Zhangjiafen, Xiahui and Miyun reservoir from 1960 to 2017, and the impacts of climate change and human activities on the runoff change are quantitatively studied. The results show that the proportion of the monthly runoff for these stations is mainly concentrated in July August, and its value varies greatly. From August begins, the runoff begins to decrease. The seasonal runoff is the largest in summer and smaller in spring and winter. The average value of the monthly runoff for Miyun Reservoir from July to August is 0.94 times of the total runoff of other months, and its average value of runoff in summer is 1.18 times of the total runoff of the other three seasons. The depth of runoff shows a slow increasing trend after the abrupt change point 1997 for the Xiahui Station. The runoff depth for Miyun Reservoir decreases by 20% after 1992, which is caused by the combined influence of precipitation and water supply from the South to North Water Transfer Project. The main period of the three sites is 8 and 24 years, 5 and 24 years, 6 and 24 years, respectively. The distribution of annual runoff is mainly concentrated in many smaller values, and the non uniformity of its distribution is caused by a few larger runoff. Precipitation and human activities are the factors which have the greatest impact on the runoff change in the upstream basin of the Miyun Reservoir. Among them, human activities are the main reason for the decrease of runoff in the upstream basin of the Miyun Reservoir.