Research Of The Environmental Flows And Levels For Lakes Based On Ecosystem Health

Urban lakes which influenced by human activities are facing serious stress, such as water pollution, shrinkage of lakeside wetlands, water level dropped (fluctuated), and saltwater intrusion. These stress grievously disturbed the ecological service function of urban lakes, including fresh water supply, sight seeing, and ecological regulation. To figure out environmental flows and levels for lakes and to allocate them correctly can help to improve water quality, maintain ecosystem health, and prevent environment degradation, which are of great importance for ensuring the ecological service function of urban lakes. Basing on analyzing the theories of environmental flows and levels for lakes, we study the environmental flows and levels of Xinglin Bay, a seaside lake in Xiamen, and the results are as follows.(1) Based on the particularity of urban lake tropic state and the research progress in lake ecosystem health evaluation, this thesis deduced that the relationship between ecosystem healthy index (EHI) and trophic state index (TSI) of response and non-response lakes was near quadratic function. The lake ecosystem elasticity coefficient was put forward, and the EHI was improved, which could better reflect the healthy condition of various lakes, and made the theory of Xu et al more perfect and applicable. The improved EHI might be a quantitative computable formula, which was closest to the healthy index concept defined by Costanza as yet and applied successfully in the ecosystem health evaluation of Xiamen Xinglin Bay.(2) This thesis figured out the the key purpose and theory basis of environmental flows and levels, and analyzed its relationship with ecosystem health. The calculation formulas of environmental flows and levels were optimized, and 6 principles and research flow chart were proposed for lakes' environmental flows and levels research.(3) This article took Xiamen Xinglin Bay as case study. Firstly, we analysised the development planning, ecosystem service functions and the main environment problems of Xinglin Bay. Secondly, we calculated the annual water budget and analysised the hydrological characteristics of Xinglin Bay systematically. Thirdly, based on the ecosystem health evaluation, this study figured out relationship between water level and TSI, and then, developed the environmental flows and levels for Xinglin Bay. Finally, to maintain the ecosystem health, and to satifiy the environmental flows and levels of Xinglin Bay, this study put forward the integrated management mode for Xinglin bay and its basins. The mode included management institutions, policies and statutes, public participation, data and information, and finance.