Health Assessment And Diagnosis Of Lu Lake Ecosystem

Lu Lake is a typical shallow lake with high-intensity agricultural activity in the Jianghan Plain.With the development of aquaculture in partial area, severe disturbance of human activities and the ecological environment is deteriorating.In order to understand the characteristics of ecosystems of Lu Lake and provide theoretical support for watershed management,this paper relying on Key Research Projects of Hubei Provincial Department of Water Resources 2015 about Lu Lake Ecological Environment Investigation and Ecosystem Health Assessment.It has conducted four surveys in December 2014, February 2015, June 2015 and August 2015.Based on the survey data,it publish an analysis of water quality, sediments, plankton, benthic animals and aquatic plants,screen evaluation indexes using principal component analysis and correlation analysis, compares with 5 kinds method of evaluation indexes reference point. It also selects entropy to calculate the index weight and Comprehensive Health Index to evaluate the health of Lu lake ecosystem. Verifying the correctness of the evaluation results as the premise, it presents the main cause of ecological problems of Lu Lake. Combing with current research it attempts to take several countermeasures.The main contributions of this dissertation are described as follows.(1)It shows that the main pollution indicators of Lu Lake are total phosphorus, total nitrogen and permanganate index. Total phosphorus and total nitroen of the lower water are higher than the concentration of surface water in winter and spring, while in summer and autumn it is the opposite. It prompts the blue-green algae blooms in summer and fall in a large scale. Moreover, the aquaculture and intense human activities also leads to a single species of benthic fauna in the Lu Lake,and it is not suitable as an indicator species.(2)Screening evaluation indexes changes with the seasons.Determine the weight of evaluation index using the entropy method could exclude subjective factors interfere. Five different frame of reference include historical data, analogy, indicator species habitat, the optimal index and comprehensive analysis are took into the Comprehensive Health Index method to do analysis.It determines that the optimal index was most suitable for Lu Lake ecosystem health assessment. Factor analysis verifies the results of the Comprehensive Health Index could reflect Lu lake ecosystem health.(3)Combing with the research progress and the development process of domestic and foreign on river ecosystem health and lake ecosystem health,it points out that the lake ecosystem health assessment method and river ecosystem health evaluation method have something in common from the narrow point of view.The health assessment method of Lu Lake applies to a typical river ecosystems and the evaluation results were consistent with some literature.(4) Based on the current research, it presented that ecological problems of Lu Lake mainly performance as water eutrophication, severe disturbance of human activities and low aquatic biodiversity,and,it also try to put forward appropriate measures.