Impacts of climate variation and land use change on river discharge in the upstream of the Miyun Reservoir

摘要

Both climate variation and change in land use and cover caused by the human activities influence the river discharge. It is necessary to distinguish the impacts of climate variation and the land use and cover change in the analysis of the variation of river discharge and water resources. The study area is the upstream of the Miyun Reservoir, which consists of the Chao River and the Bai River, in northern China. In the present study, a distributed hydrological model-GBHM is used to simulate natural runoff. Corresponding to different Land use types in two different periods (1980s and 1990s), two sets of land surface parameters are used in the models for characterizing the land use and cover changes. We use the fixing-changing method to run the model. First the climate variation factor is fixed, and the land use is changed, then the land use factor is fixed and the climate is changed. The results of model simulation show the quantitative effects of climate variation and land use change on river discharge. It is found that in the study area, the land use change, affects the river discharge and the spatial distribution of the evaporation and runoff.