ACKNOWLEDGEMENTS
We sincerely thank the Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Ministry of Education. The authors are grateful to the Editor and anonymous reviewers for their constructive comments and suggestions. This research was funded by the General Financial Grant from the China Post-doctoral Science Foundation (2017M623088), Shaanxi Postdoctoral Science Foundation 2018, National Natural Foundation of China (51679185) and the National Key R&D Program of China (2018YFE0103800). APC was funded by the General Financial Grant from the China Postdoctoral Science Foundation (2017M623088).