Liangzi Lake Enclosure Culture Fence Removal Policy Comprehensive Impact Assessment Based On System Dynamics

Liangzi Lake is the demonstration of well protection, development and utilization of freshwater lakes in Hubei Province even the whole country. But in recent years, with the increasing population density and accelerated urbanization process in China, water polution has been becoming more and more serious along with delicate ecological balance, resulting in the decline of natural land carrying capacity in the Liangzi Lake watershed, which has seriously affected the sustainable development of regional economy and society. So how to well protect the ecological environment has calling more awareness from government and public. According to the Ecological Environment Protection Planning of Liangzi Lake(2010-2014), the government has implemented the enclosure culture fence removal policy in the lake district, while the comprehensive impact of the policy desperately needs to be assessed scientifically. So Liangzi Lake enclosure culture fence removal policy was selected as the research object of this paper aiming of evaluating the comprehensive influence on Liangzi Lake water environment and economic activities around the lake.The lake enclosure culture fence removal policy comprehensive impact assessment system is a complex dynamic feedback system which involves many aspects and has numerous influencing factors. System dynamics, one of the commonly used policy simulation analysis methods by the majority of researchers, is good at dealing with nonlinear time-varying complex dynamic feedback system, so it was selected as assessment methods in this paper. The lake enclosure culture fence removal policy comprehensive impact assessment system dynamics model is established after the steps of influencing factors analysis, data collection, index selection, model debugging and so on, which has three subsystem, namely population subsystem, enclosure culture economy subsystem and the Liangzi lake water quality subsystem. Selecting the fence removal area and the amount of compensation as decision points, by using the scenario analysis method, four possible policy scenarios have been set, via the SD model to assess the relevant changes of the population, lake enclosure culture net income and the status of water quality of Liangzi Lake during 2010-2022 based on the data of 2010.The result shows that removal in batches and appropriate increase the compensation fees are relatively reasonable policies. All policy scenarios have equal effects on the water quality and the population changes of the lake district after all the fence is removed. The lake enclosure culture is a relatively high profit industry and the fishermen put a lot of money to buy bamboo pile, seine, fishing boats and other fencing equipment in the early days, so appropriate increase of the compensation fee is conducive to the smooth implementation of the policy. Removal in batches can not only ease the financial pressure on the government, but also give fishermen longer buffer time to maintain their livelihoods.