Quantifying the Impacts of Land Use and Cover Change (LUCC) and Climate Change on Discharge and Sediment Load in the Hunhe River Basin, Liaoning Province, Northeast China

Abstract

Assessing the impacts of land use and cover (LUCC) change and climate change on discharge and sediment load is beneficial for the regional management of water resources and the water environment. The Mann-Kendall test and soil and water assessment tool (SWAT) model were applied to analyze the change trends of meteorological and hydrological variables and to quantitatively assess the response of discharge and sediment load to LUCC and climate change, respectively, in the Hunhe River Basin (HRB). The results showed that LUCC changed little during 1980–2009, mainly from forestland (−0.36%) to other land use types, such as urban land (+0.13%) and grassland (+0.13%). Temperature increased significantly (p < 0.01), and precipitation showed a non-significant decreasing trend. Discharge showed a non-significant decreasing trend, and sediment load significantly (p < 0.05) decreased. The Nash–Sutcliffe efficiency (NSE), coefficient of determination (R2), and percent bias (PBIAS) during the calibration and validation periods indicated that good performance was achieved for the discharge simulation (NSE: 0.77–0.79; R2: 0.79–0.84; PBIAS: −9.61–1.48%) and satisfactory performance for the sediment load simulation (NSE: 0.65–0.77; R2: 0.65–0.78; PBIAS: −2.56–8.31%). The calibrated SWAT model was successfully utilized to assess the impacts of LUCC and climate change on discharge and sediment load, finding that the combined impact of LUCC and climate change decreased the annual discharge and sediment load by 22.65% and 31.51%, respectively. Minor changes in annual discharge (+0.08%) and sediment load (−1.33%) were caused by LUCC, and climate change led to a pronounced decrease in annual discharge (−22.69%) and sediment load (−30.61%). These findings indicate that climate change rather than LUCC dominated the hydrological alterations in the HRB. This study provides important information for decision makers to identify the reasons for changes in hydrological alterations and to design adaptive measures.