中文摘要：

土地利用/覆被变化是导致流域水资源发生变化的重要原因.以中国西北地区的洮河流域为研究区,构建适宜于洮河流域的分布式水文模型（SWAT）,在综合考虑流域1985-2000年间土地利用/覆被变化特征的基础上建立多种土地利用/覆被情景,并对不同情景下的水文过程进行模拟,得到以下结论：（1）经校准后的SWAT模型,其验证期的相关系数R2、相对误差R_e和效率系数E_（ns）分别为0.83、-8%和0.68,说明SWAT模型在洮河流域径流量模拟中具有较高的适用性.（2）草地、林地和耕地是洮河流域的主要土地利用类型.林地的壤中流、土壤湿度和产水量最大,耕地的地表径流和蒸散量最大.与1985年相比,2000年土地利用/覆被情景下地表径流增加了1.72%,地下径流和产水量降低了0.8%和0.4%;耕地扩张和城镇建设用地情景下流域地表径流明显增加,生态恢复情景下流域地表径流和产水量均有所降低.（3）从月径流量来看,林草地可以减小最大与最小流量的变幅,而耕地的作用正好相反.与1985年相比,2000年土地利用/覆被情景下汛期地表径流增加1.67%,地下径流减少0.83%,产水量减少0.36%;非汛期地表径流增加1.86%,地下径流减少0.63%,产水量减少0.46%.说明林草地减少对非汛期的影响更大.

英文摘要：

Land-use /cover change is the important reason for water resource changing in a basin.The Taohe River basin in Northwest China is studied with the distributed hydrological model SWAT（Soil and Water Assessment Tool）.Land-use/cover scenarios are constructed based on comprehensive consideration of the variation characteristics of the land-use/cover change from 1985 to 2000.Then the hydrological processes are simulated and the hydrological response in different scenarios at basin scale are discussed.The results show that：（1） After successful calibration verification,the correlation coefficient（R~2）,relative error（R_e） and Nash-Suttcliffe coefficient（E_（ns）） of SWAT model are 0.83,- 8%and 0.68,respectively.It is demonstrated that the calibrated SWAT model can well simulate the monthly runoff,and is thus applicable to study the Taohe River basin.（2）The main types of land-use/cover in Taohe River basin are pasture,forest and farmland.When the interflow,soil moisture and water yield in forest land reach the maximum,runoff and evapotranspiration of farmland reach the maximum.As compared with the land-use/cover scenarios in 1985,under the land-use/cover scenarios in2000 the annual runoff increased 1.72%,but the underground runoff and water yield decreased by 0.8%and0.4%,respectively.The annual runoff of farmland expansion scenario and urban expansion scenario significantly increased surface runoff,but the annual runoff and water yield decreased under ecological restoration scenario.（3） The forest and grassland can reduce the amplitude of monthly runoff between maximum and minimum,while farmland shows an opposite result.As compare with the land-use/cover in 1985,the land-use/cover in 2000 scenario shows that the runoff increased by 1.67%,while underground runoff and water yield decreased by 0.83%and 0.36%in flood season;in non-flood season the surface runoff increased by 1.86%,while underground runoff and water yield decreased by 0.63%and 0.46%.The results demonstrate that forest and grassl