Quantifying the relative contribution of climate variability and human activities impacts on baseflow dynamics in the Tarim River Basin, Northwest China

Study region: Tarim River Basin (TRB)- the largest inland basin of China and essential part of the water supply to northwest arid region of China. Study focus: Information on baseflow dynamics and attributions is needed to develop sustainable water management strategies in cold and arid regions. The study separates baseflow with multiple separation methods, and analyzes the regional patterns and changes of baseflow and baseflow index (BFI). Furthermore, we quantitatively evaluate response of baseflow and BFI to climate variabilities and anthropogenic activities through the concept of climate elasticity under the water-energy balance framework. The purpose is to understand the dynamics and attributions of baseflow in the TRB. New hydrological insights for the region: We found that climate variabilities play leading roles in the increase of baseflow in the headstreams. Among them, temperature is decisive climatic factor controlling baseflow variation. Changes of potential evapotranspiration have significant negative impacts on baseflow variations across the TRB. Besides, precipitation and inflow possessed great positive impacts on baseflow increasing. However, the decline across the basin BFI is found with increasing precipitation and inflow, indicating the increasing precipitation and inflow can promote more surface runoff, particularly in late spring and early summer. Attribution analysis indicates that climate change and human activities (e.g., engineering construction, agricultural activities, etc.) have the opposite impact on baseflow variation. Human activities are the main factors reducing baseflow in the mainstreams. Furthermore, the combined effects of climate change and human activities have caused the decline of BFI