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密云水库是北京唯一的地表饮用水源地,水库水量的多少直接关系到首都人民的生活。根据密云水库1960—2009年年入库径流量和汛期径流量2类序列,采用随机水文学方法结合序列统计性质揭示了入库径流演变规律,从降雨、人类活动和土地利用变化角度探讨入库径流演变的成因。结果表明:年入库径流和汛期入库径流都呈现减小趋势,1999年以后减小趋势更为明显,年径流减小程度比汛期显著,年际变化有明显的阶段性。受多种因素影响的密云水库入库径流序列包含相依成分,特别是年径流序列相依关系较强。入库径流减少的趋势不是单一由降水造成,流域内人类活动和土地利用变化是径流量锐减的主要原因。
Miyun Reservoir is Beijing’s only source of surface drinking water. The amount of water in the reservoir is directly related to the people’s lives in the capital. According to the annual runoff of flood storage and the runoff of flood season in Miyun Reservoir from 1960 to 2009, the evolution law of runoff was revealed by using random hydrology and the statistical properties of the sequence, and the storage was discussed from the aspects of rainfall, human activities and land use change The causes of runoff evolution. The results show that annual runoff and runoff in the flood season show a decreasing trend, and the trend of decrease after 1999 is more obvious. The annual runoff reduction is more significant than that in flood season, and the interannual variation has obvious stage. Miyun reservoir storage runoff sequences affected by many factors contain interdependent components, especially annual runoff sequences. The trend of decrease of runoff in storage is not caused by precipitation alone. Changes in human activities and land use in the basin are the main reasons for the sharp drop in runoff.