Study On The Application Of Eutrophication Control Criteria For Wuliangsuhai Based On System Dynamics

Water eutrophication is one of the serious global hydro-environmental problems. To thequestion of eutrophication existed in the current situation of Wuliangsuhai, the characteristicsof grass-type lakes are investigated and analysed in this research. Coupled with the eutrophi-cation control concept of "zoning, grading, classification, staging", the ecological dynamicsmodel on macrophytic lakes is used to calculate water environmental carrying capacity ofWuliangsuhai Lake, and finally draws up the plan on grosses pollutant amount controle.Based on the priciples of the lake nutrient sources transportation, the whole system of Wa-tershed-lake was selected as the study object, the system dynamics model coupled with so-cio-economic and water environment was built to quantify the socio-economic developmentand the decision interval for water conservation and pollution control. By scenarios analysison the parameter intevals and its contribution to the nutrient loads, together with fesabilityanalysis on the economy and technology, the the suggested social development mode was putforward for the application of eutrophication control criteria. It is of great significance for thesustainable development of socio-economy in Lake Watershed. The main conclusions are asfollows:a) According to the eutrophication control criteria of Wuliangsuhai in short and longterm were set, and Wuliangsuhai carrying capacity of TN and TP can be allocated were678.60t/a and19.26t/a respectively under the conditions of lake volume322million m3. Theamount of the TN and the TP discharged into the lake were1890and149t/a, respectively, in2008, which exceeded two times of the total quantity control requirements. Moreover, in thepresent development mode, the amount of pollutants discharged into the Lake in2015and2020will be far beyond the environmental capacity of the lake.b) The social, economic, and environmental system dynamics model of Wuliangsuhaiwas built to reveal the relationship between social and economic development and water en-vironment in the lake watershed. Under the total pollutants control the short and long termsocial and economic coordinated development scenario was proposed. c) Under the consideration of social, economic, environmental sustainable developmentin the watershed, the coordinated development scenario was the optimal solution. If a morerigorous control criteria of lake eutrophication, the resource and environment constrainedscenario could be the optimal solution. The total project investment was1.8%of nation GrossDomestic Product (GDP).Finally, some reasonable suggestions to the problems in application of eutrophicationcontrol criteria were put forward.