Quantitative effects of climate variations and land-use changes on annual streamflow in Chaobai river basin

In order to make the quantitative analysis of the impacts of climate variation and land use change on annual streamflow, Chaobai River watershed located in rocky mountain area of north China was selected as research object. AWY model and separation evaluation method were applied to quantify the respective contribution of climate and land use change to annual streamflow of the area from 1956 to 2010. The results indicated that the precipitation among years presented significantly a decreasing tendency, and the annual runoff also had a significant decreasing trend with the change point occurred in 1979. Climate variations was the strongest contributor to the reduction in mean annual streamflow of Chaohe and Baihe watershed, and the contribution rate reached 59.3% and 93.5%, respectively, while the remaining caused by land-use change. The effects of different type of land-use on the reduction in annual streamflow were quite different, for instance, the contribution rates of forest land was about 67%, which was more than the farmland of 18% and the grassland of 15%. The water body and unused land, which have a small proportion and a small change ranges in this region, were not observed to have a clear impact on annual streamflow. The results provide a theoretical reference for basin water resources management and land-use planning in Chaobai river basin.