Integrated assessment of the impacts of climate variability and anthropogenic activities on river runoff: a case study in the Hutuo River Basin, China

Understanding the linear and nonlinear responses of runoff to environmental change is crucial to optimally manage water resources in river basins. This study proposes a generic framework-based hydrological model (Soil and Water Assessment Tool (SWAT)) and two approaches, to comprehensively assess the impacts of anthropogenic activities and climate variability on runoff over the representative Hutuo River Basin (HRB), China. Results showed that SWAT performed well in capturing the runoff trend in HRB; however, it exhibited better performance for the calibration period than for the validation. During 1961-2000, about 26.06% of the catchment area was changed, mainly from forest to farmland and urban, and the climate changed to warmer and drier. The integrated effects of the anthropogenic activities and climate variability decreased annual runoff in HRB by 96.6 mm. Direct human activities were responsible for 52.16% of runoff reduction. Climate (land use) decreased runoff by 45.30% (2.06%), whereas the combined (land use + climate) impact resulted in more runoff decrease, by 47.84%. Land use-climate interactive effect is inherent in HRB and decreased runoff by 1.02%. The proposed framework can be applied to improve the current understanding of runoff variation in river basins, for supporting sustainable water resources management strategies.