Center for Dryland Water Resources Research and Watershed Science;
Key Laboratory of West China's Environmental System of Ministry of Education;
Lanzhou University;
Key Laboratory of Arid Climate Change and Reducing Disaster of Gansu Province;
College of Atmospheric Sciences;
Lanzhou University;
College of Earth and Environmental Sciences;
Lanzhou University;
Department of Geography;
Western Michigan University Kalamazoo;
MI 49008-5424;
USA;