1. State Key Laboratory of Eco-hydraulics in Northwest Arid Region of China; Xi'an University of Technology; Xi'an 710048 China
2. Department of Geosciences; University of Oslo; P.O. Box 1022 Blindern Oslo N-0315 Norway
3. Post-doctoral Research Station of Xi'an Chan-Ba National Ecological District; Xi'an 710014 China
4. State Key Laboratory of Water Resources and Hydropower Engineering Science; Wuhan University; Wuhan 430072 China