Attributing climate variability, land use change, and other human activities to the variations of the runoff-sediment processes in the Upper Huaihe River Basin, China

The Wangjiaba (WJB) watershed, located in the upper Huaihe River Basin in China. An attributing framework has been proposed combining the Double Mass Curve (DMC) and the Soil and Water Assessment Tools (SWAT) model to identify the contributions of climate variability, Land use (LU) change, and Other Human Activities (OHA) to the variations in runoff-sediment processes within the WJB. The studied period was able to be separated into three sub-periods ( P 1 : 1981–1991, P 2 : 1992–2009, and P 3 : 2010–2019) using the DMC, and the SWAT model could simulate runoff and Sediment Yields Load (SYL) properly during different sub-periods after calibration. Generally, the runoff, SYL, and Suspended Sediment Concentration (SSC) within the WJB exhibited a decrease trend with a change rate of −1.3 mm a −1 , −8.49×10 4 t a −1 , and −0.01 kg m −3 a −1 , respectively. Substantially, climate variability decreases runoff, SYL, and SSC from P 1 to P 3 ; LU change decreases runoff, SYL, and SSC from P 2 to P 3 ; OHA decreases SYL and SSC from P 1 to P 2 , but increases SYL and SSC from P 2 to P 3 . It should be noticed that the OHA has increased the SYL significantly especially over the downstream of WJB from P 2 to P 3 . It is essential to enhance soil erosion prevention measures in the future under the background of global climate change. • A framework is proposed to quantify the effect of factors on hydrological processes. • Firstly attributing climate, LU, and OHA to the variations of SSC. • The effects of LU and OHA on hydrological processes varied in different regions. • OHA has increased the SYL from P 2 to P 3 within WJB.