中文摘要：

利用1980年和1996年土地覆被情景分别表征1964年-1979年和1990年-1999年土地利用情况，运用双源蒸散与混合产流的分布式水文模型探讨老哈河流域太平庄集水区土地覆被变化的水文效应，定量分析土地覆被变化对“绿水”和“蓝水”的影响，结果表明1980年到1996年研究区域土地覆被变化总体趋势为草地向林地和耕地转化，上述土地覆被变化导致老哈河流域截留蒸发量和冠层蒸腾能力增加，土壤蒸发能力减小，进而使得蒸散发能力和实际蒸散发量增加，地表径流、地下径流和径流系数减少。1964年-1979年平均地表径流、地下径流、总径流和径流系数分别减少了4．4％、9．5％、8．7％和8．7％。此外，径流模拟除了受土地覆被变化影响外，同时还受到人类生产活动的影响。

英文摘要：

Over the recent 30 years, durative drought has been threatening the environment in northern China, resulting in water resources scarcity, environmental degradation, and desertification. To make an attempt to investigate the effects of land use and land cover changes on hydrological processes in northern China, a distributed hydrological model was developed and applied in the Laohahe catchment. Direct evaporation from intercepted water, potential canopy transpiration, and potential soil evaporation were computed using a physically-based two-source potential evapotranspiration （PET） model, which constituted input to the distributed hydrological model for computation of actual evapotranspiration （AET）. Runoff generation was based on mixed runoff mechanisms of infiltration excess runoff and saturation excess runoff. The Muskingum-Cunge method was adopted for flow routing. Land cover maps of 1980 and 1996 were used for characterizing vegetation cover over the area controlled by the Taipingzhuang hydrologic station in the Laohahe watershed during the periods of 1964-1979 and 1990-1999, respectively. Results of the runoff simulation show that saturation excess runoff generation was dominant in the catchment. The model parameters were calibrated using hydrometeorological and land cover data of the corresponding period. The streamflow simulation was conducted for each period under these two land cover scenarios. Effects of land use/cover change on ＂green water＂ and ＂blue water＂ were quantified by comparing calculated PET, AET, and runoff under different land cover scenarios. Blue water is referred to as visible liquid water moving above and below the ground as surface or groundwater runoff, respectively. Blue water can thus be in the form of surface runoff in rills, gullies and rivers, or water stored in reservoirs and lakes, or water flowing underground, recharging water tables and aquifers. Green water is defined as the invisible vapor moving to the atmosphere, including productive green water, defined a