Response of runoff to climate change in the Manas River Basin flow-producing area, Northwest China

The inland river basins of northwestern China are structured as mountain-basin systems. Water resources originate in the flow-producing area (FPA), are utilized and operated in the oasis area and are dissipated in the desert area. In this study, a Soil and Water Assessment Tool (SWAT) model was constructed in the Manas River Basin (MRB) FPA. Meanwhile, it simulated climate change and runoff evolution trends in the FPA of the MRB under different four climate change scenarios of Coupled Model Intercomparison Project Phase 5. The main findings showed that (1) the years 1979–1980 were chosen as the model warm-up period, 1979–2000 as the model calibration period and 2001–2015 as the model validation period to complete the construction of the SWAT model for MRBFPA. From 1981 to 2015, three performance parameters indicated that the model accuracy meets the requirements (NSE = 0.81, R 2 = 0.81 and PBIAS = 1.44) and can be used for further studies; (2) the hydrological elements (e.g. runoff, potential evapotranspiration, evapotranspiration, soil water content, snowmelt) in the MRBFPA were analysed by the constructed SWAT model; (3) the climate change in the MRBFPA is close to the RCP 8.5 scenario, and the future changes in water resources under this scenario will range from 659 to 2308 (million)m 3 . Compared to the multi-year historical mean value (12.95 × 10 8 m 3 ), the future fluctuation in the amount of water resources available in this basin is increasing.