降水变化与人类活动对密云水库入库泥沙量的影响

Impact of precipitation changes and human activities on sediment flux into the Miyun Reservoir of Beijing

近50年来,随着流域降水量减少,以及修建水利水保工程、引水等人类活动的增加,密云水库的入库泥沙量呈显著减少趋势。为了揭示密云水库流域的水土流失状况及变化趋势,分析水利水土保持措施对减少密云水库入库泥沙的实际作用,基于降水—产沙统计模型,定量评估了降水变化及人类活动对密云水库入库泥沙量的影响。结果表明,1966—1979年、1980—1989年、1990—1999年、2000—2005年,水利水保工程措施的减沙作用非常显著,减沙贡献率分别为89.45%、78.86%、86.90%和64.36%;降水变化的减沙贡献率分别为10.55%、21.14%、13.10%和35.64%。以植树造林和水土保持为中心的生态建设对防治密云水库流域的水土流失起了重大作用。

In recent 50 years, the sediment flux into the Miyun Reservoir of Beijing has declined significantly with decreasing precipitation and increasing human activities, such as engineering measures for water conservancy construction and water diversion of the drainage basin. In order to reveal the situation of soil and water loss and its changing trend, and to analyze the actual effects of engineering measures for water conservancy on reducing sediment flux into the Miyun Reservoir of Beijing, the impact of precipitation variations and human activities on sediment flux into the reservoir was evaluated quantitatively based on the rainfall-sediment statistical model. The results showed that the engineering measures for water conservancy contributed to sediment reduction markedly. During 1966-1979, 1950-1959, 1990-1999, and 2000-2005, the contributing rates of human activities to sediment reduction were 89.45%, 78.86%, 86.90% and 64.36% respectively, while 10.55%, 21.14%, 13.10% and 35.64% for precipitation variations. Ecological constructions centered on afforestation and soil and water conservation play a great role in preventing and controlling the soil and water loss of the Miyun Reservoir Basin of Beijing.