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土地利用和气候变化是流域水资源发生变化的重要原因。以洮河流域为研究区,通过模型率定得到适宜于洮河流域的分布式水文模型(SWAT),在综合考虑流域土地利用和气候变化特征的基础上构建多种情景模式,并对不同情景模式下的水文特征进行模拟,得到以下结论:(1)校准后的SWAT模型,R2、Re和Ens分别达到0.83、-8%和0.68,说明该模型在洮河流域径流模拟中具有较好的适用性。(2)与1976—1995年相比,气候变化使流域产水量增加1.30mm,土地利用变化使流域产水量减少0.77mm。土地利用变化对水文特征的影响小于气候变化,但土地利用变化对流域管理的作用却是不可忽视的。从极端土地利用变化情景可知,与1985年土地利用情景相比,林地、草地和耕地情景中产水量分别变化了18.1%、-7.4%和-10.1%。从气候变化情景可知,当降水量不变,温度分别变化2℃、1℃、-1℃和-2℃时,流域产水量的变化量分别为-4.23%、-2.56%、3.08%和6.70%;当温度不变,降水量分别变化20%、10%、-10%和-20%时,流域产水量的变化量分别为56.32%、30.88%、-23.66%和-45.94%。(3)在土地利用和气候变化共同作用下,地表径流增加的区域主要位于下游的广河县、和政县和康乐县以及上游的碌曲县和夏河县等地,地表径流增加地区的面积约占流域总面积的39%。
Land use and climate change are important reasons for the changes of water resources in the basin. Taking Bahe River Basin as a research area, a distributed hydrological model (SWAT) suitable for the Bahe River Basin was obtained through model calibration. Based on comprehensive consideration of the land use and climate change characteristics of the river basin, a variety of scenarios were constructed, and different scenarios (1) After calibrating the SWAT model, R2, Re and Ens reach 0.83, -8% and 0.68, respectively, indicating that the model has a good applicability. (2) Compared with 1976-1995, climate change increased the water production in the basin by 1.30mm and the land use change reduced the water production in the basin by 0.77mm. The impact of land use change on hydrological characteristics is less than that of climate change, but the role of land use change in river basin management can not be neglected. As can be seen from the extreme land use change scenarios, the water production in the forestland, grassland and cultivated land scenarios changed by 18.1%, -7.4% and -10.1%, respectively, compared with the 1985 land use scenario. According to the climate change scenario, when the precipitation is constant and the temperature changes by 2 ℃, 1 ℃, -1 ℃ and -2 ℃ respectively, the variation of water production in the basin is -4.23%, -2.56%, 3.08% and 6.70 %. When the temperature is the same and the precipitation is 20%, 10%, -10% and -20% respectively, the variation of water production in the basin is 56.32%, 30.88%, -23.66% and -45.94% respectively. (3) Under the combined effects of land use and climate change, the areas with increased surface runoff are located in the downstream areas of Guanghe County, Hezheng County, Kangle County, Luqu County and Xiahe County in the upper reaches, and the area of surface runoff increases Accounting for about 39% of the total basin area.