气候和土地利用变化对潮河流域产流产沙的影响

为探究气候变异和土地利用变化对流域产流产沙的影响,选择位于北京密云水库上游的潮河流域,对该流域1961-2009年的年径流、年降水、年潜在蒸散发和年输沙量分别进行了非参数检验和突变点分析,结合该流域不同时期的土地利用变化情况,采用水量平衡原理,定量评价该流域土地利用和气候变异对年径流量和年输沙量变化的贡献。结果表明:该流域年径流量在1961-2009年间呈显著减少趋势,并在1999年发生突变,但年降水和潜在蒸散发没有显著变化。该流域年输沙量显著减少,且于2004年发生突变。分析表明该流域气候变异和土地利用变化对年径流量减少的贡献率分别为43.9%和56.1%,而对年输沙量减少的贡献率分别为1.95%和98.05%。土地利用变化是导致该流域年径流量减少,特别是年产沙量减少的重要原因。在全球气候变化的大背景下,通过调整流域土地利用结构、优化土地利用方式,开展以植被恢复为主体的水土流失综合治理,是实现适应性流域管理目标的根本途径。

Effects of climate and land use changes on stream flow and sediment yield in Chaohe river basin

To explore the effects of climate and land use changes on water and sediment yield at multiple temporal scales in the watershed, the non-parametric Mann-Kendall test was used to identify the change trend and change points of annual precipitation, annual potential evapotranspiration (PET) and annual streamflow from 1961 to 2009 in the Chaohe watershed located in the upstream of Miyun Reservoir, Beijing, China. Water balance model was used to quantify the respective contribution of land use and climate changes to annual streamflow. Double mass cure was used to examine their effects on sediment yield reduction. The results indicated that there were no significant changes in annual precipitation and PET from 1961 to 2009. In contrast, the annual streamflow was significantly decreased from 1961 to 2009 with the change points occurred in 1999. Annual sediment yield significantly declined and the change point occurred in 2004. The land use/cover changes contributed 56.1% reduction in mean annual streamflow, while the rest was caused by climate variability. Land use changes contributed 98.05% of reduction for the declining of sediment yield. Land use changes were the main factor for the reduction of water resources and sediment yield. Developing the reasonable land use scenario for utilizing the water and soil resources, implementing the ecological restoration programs were the basic approaches for the adaptive watershed management strategies.