The determinants of streamflow variability and variation in Three-River Source of China: climate change or ecological restoration?

Exploring the determinant between climate change and ecological restoration for streamflow dynamics is a significant issue in global change research and is essential for restoration policy assessment and climate change adaptation. In this paper, the combination of elasticity method and Budyko framework was applied with the meteorological and hydrological data from 1980 to 2014. The variability and variation of streamflow were explained by individual elasticity coefficient and contribution of climate change and ecological restoration between 1980-1999 and 2000-2014. Results showed that streamflow was more sensitive to climate change in the Yellow River source (YER) than in the Yangtze River source (YZR). Ecological restoration was positively correlated with the variability of streamflow in YER with 7.38% relative change in elasticity coefficients, while it was opposite trend in YZR with a relative change of - 7.41%. However, the impacts of climate change and ecological restoration on the variation of streamflow were not consistent with the variability. In YER, ecological restoration dominated the streamflow reduction with a contribution of 82.43%, whereas, in YZR, climate change mainly contributed to the streamflow increase which could explain 123.72% and the precipitation was the major contributor. By analysis, the difference in two catchments might result from the spatial heterogeneity of precipitation conditions and land use/cover change, especially the conversion of grassland. The results suggest that the implementation of ecological recovery should consider the difference of streamflow change in response to ecological restoration and climate change for the sustainability of water resources.