1. Ph.D. Student, School of Environment, Tsinghua Univ., Beijing 100084, China.
2. Professor, School of Environment, Tsinghua Univ., Beijing 100084, China (corresponding author).
3. Postdoctoral Research Fellow, Centre for Water Systems, College of Engineering, Mathematics and Physical Sciences, Univ. of Exeter, Exeter EX4 4QF, UK.
4. Research Assistant, School of Environment, Tsinghua Univ., Beijing 100084, China.
5. Environmental Engineer, Aurecon, 116 Military Rd., Neutral Bay, Melbourne, NSW 2089, Australia.