1. Engineering Research Center of Eco-environment in Three Gorges Reservoir Region, Ministry of Education; China Three Gorges University; Yichang 443002 China
2. College of Hydraulic & Environmental Engineering; China Three Gorges University; Yichang 443002 China
3. Institute of Hydroecology, Ministry of Water Resources and Chinese Academy of Sciences; Wuhan 430079 China
4. School of Natural Sciences and Mathematics; Ferrum College; Ferrum Virginia 24088 U.S.A.