Quantitative discrimination of impacts of vegetation restoration on runoff components in the upper reaches of the Beiluo River

Quantitative contribution of vegetation restoration and climate change to changes in runoff and its components is largely unknown in semi-arid loess areas. The effect of vegetation restoration and climate change on runoff and its components was evaluated using the elasticity coefficient method for the Beiluo River at Wuqi, Zhidan, and Liujiahe stream gauging stations. Surface and total runoff showed significant decreasing trends at these three stations from 1970 to 2010, surface runoff accounts for 45% to 56% of total runoff; abrupt changes all occurred around 2002—2003. Changes in baseflow on the other hand were not consistent among the three stations. Forest and grassland areas in the upper Beiluo River Basin has increased by 15.1% since 1999. Contributions of vegetation restoration, precipitation, and the potential evapotranspiration to the reduction in total runoff at the three stations were 73%, 19%, and 8%, respectively, on average; and the average contribution to changes in surface runoff were 67%, 19%, and 14%, respectively. The greater the extent of vegetation restoration, the greater its contribution to changes in runoff. Vegetation restoration can significantly reduce surface runoff and total runoff, but may increase the baseflow at the same time. This research has implications for developing and managing water resources for the region.