Quantifying the impact of climate change and anthropogenic activities on runoff and sediment load reduction in a typical Loess Plateau watershed

Study region: The Huangfuchuan Basin on the Loess Plateau, China. Study focus: Runoff and the sediment load of the Yellow River in China have received substantial attention owing to their marked declines over recent decades. Climate change and intensive anthropogenic activities-soil and water conservation measures on the Loess Plateau-are regarded as the main factors responsible for the dramatic declines. Thus, attribution analysis on the roles of such influencing factors is important for the sustainable management. In this study, annual-scale variations of runoff and sediment load of a typical watershed undergoing intensive change were simulated using three regression algorithms. The impacts of climate change, namely precipitation and temperature, and anthropogenic activities, namely channel measures (check dam construction) and slope measures (terracing, afforestation, grass planting, and closures), on runoff and sediment load variations were quantified continuously for the period 1954-2015.New hydrological insights for the region: Results indicated that the main climate change factor was precipitation reduction, which was attributed to 35% and 34% of runoff reduction and sediment load reduction, respectively. Channel measures caused 32% and 39% of runoff reduction and sediment load reduction, respectively, whereas slope measures caused 33% and 27% of runoff reduction and sediment load reduction, respectively. We recommend that further implications of soil and water conservation measures be studied carefully on the Loess Plateau.