Assessment of Climate and Land Use/Cover Change Impacts on Watershed: A Multi-model Ensemble Runoff Simulation Method

Changes in land use/cover and climate could significantly affect hydrological processes of watersheds. In this study, a multi-model ensemble runoff simulation (MERS) approach is developed, which incorporates input data simulated by the CA–Markov model and GCM into the hydrological model (SWAT). The method can not only forecast runoff processes under the influences of land use/cover change (LUCC) and climate change and obtain the possible range of future runoff, but also evaluate the main factors affecting the runoff process in the study area. Then, the method is applied to simulate runoff results under 48 different climate change and LUCC scenarios in the upper basin of Amu Darya River in Central Asia. The results indicate that: (i) the annual average runoff would decrease by 43.33–80.99 m3/s in the future period (2025–2055); (ii) compared with LUCC, climate change is the main contributor to variations in hydrological processes, and its contribution is 83.35–99.00%; (iii) the rising temperature would lead to the reduction of the glacier area, which would further affect the runoff process.