密云水库入库流量变异性及其影响因素

Variability and Potential Impact Factors of Inflows into the Miyun Reservoir

对密云水库流域入库站下会站(潮河)和张家坟站(白河)不同时期的流量变异性进行了研究,分析了降水和土地利用变化与流量变异的关系。借助流量变异分析方法,统计分析了日平均流量过程的脉动数量和脉动持续期,在此基础上分析了不同时期的流量变异和波动。研究结果表明,下会站和张家坟站2002年以后的流量较20世纪80年代均有所减少,且流量过程变化更为平缓。这2个站点的流量变异性主要由降水变化引起。草地增加是流量缓慢变化的一个原因,林地减少使得高阈值流量略有增加,但可能导致总流量有所减少。总的来说,土地利用状况因为在研究时期内变化不大,没有对流量变异产生明显的影响。

Analysis on the variability of inflows into the Miyun Reservoir was performed at both Xiahui（Chaohe River） and Zhangjiafen（Baihe River） stations and the relationships between the flow volumes and precipitation and land use change were addressed.Based on inflow variability analysis,daily pulse number and mean pulse duration were statistically discussed for the estimation of various stream flow thresholds.The results show that the inflows decreased and exhibited less temporal variability at both Xiahui and Zhangjiafen stations during 2002—2006,comparing to those in the 1980s.The variability of the stream flows was mainly affected by precipitation.The increase of grassland area might reduce the inflow velocity,and the decrease of forest increased the high threshold volumes and at the same time could reduce total flow volume.However,land use change had only little contribution to stream flow variations,owing to only insignificant change was detected during this time period.