1. School of Water Resources and Environment
2. MOE Key Laboratory of Groundwater Circulation and Environmental Evolution
3. China University of Geosciences
4. Beijing 100083
5. P. R. China
6. College of Environmental Sciences and Engineering
7. Peking University
8. The Key Laboratory of Water and Sediment Sciences
9. Ministry of Education
10. Beijing 100871
11. Department of Civil and Environmental Engineering
12. Virginia Polytechnic Institute and State University
13. Blacksburg
14. USA