Ecosystem Health Assessment Of Baiyangdian Lake

Baiyangdian Lake is the largest shallow lake in North China.Scientiifical ecosystem health assessment of Baiyangdian Lake is of great scientific significance and practical value for environmental management and ecological restoration.Aiming at the lack of evaluation system for shallow grassy lakes,this paper established and optimized ecosystem health assessment system of Baiyangdian Lake based on "Driving force-Pressure-Status-Impacting-Response"(DPSIR)model combined with the measured results of ecosystem health indicators.And the ecosystem health status was evaluated and predicted based on the evaluation system.The main conclusions are as followings:This paper clarified the spatial and temporal distribution of Baiyangdian Lake ecosystem.By analysing the comprehensive water quality index,it can be found that the general water quality level of Baiyangdian Lake is better than Class IV,and the seasonal variation is significant.In spring,the water quality of Baiyangdian Lake was good except Nanliuzhuang which was inferior to Class III.In summer,the water quality of Baiyangdian Lake was the worst.The water quality of Nanliuzhuang was in Class V which were contributed by TN and TP.The comprehensive nutritional status index indicated that most of the regions of Baiyangdian Lake were in different degrees of eutrophication.The density of phytoplankton in Baiyangdian Lake increased first and then decreased.Cyanophyta-Chlorophyta have become the dominant population in Baiyangdian Lake.The result showed that all the sections of Baiyangdian Lake were in the "sub-health" state.This paper optimized the ecosystem health assessment system based on DPSIR model and evaluated the health status of Baiyangdian Lake.On the basis of DPSIR model,this paper constructed and optimized a 3-level and 15-index ecosystem health assessment index system which could reflect the characteristics of shallow grassy lakes by principal component analysis and correlation analysis.The combined weighting method and interpolation scoring method were used to determine the weight of each index and normalize the index.And we obtained the ecosystem health index(EHI)that was consistent with the characteristics of Baiyangdian Lake.The results showed that all the sections of Baiyangdian Lake were in the "sub-health" state.The EHI of Zaolinzhuang,Shaochedian and Wangjiazhai was between 50?60,and the EHI of Duancun,Caiputai and Nanliuzhuang were only slightly higher than 40,which was close to the "unhealthy" state.This paper pridicted the ecosystem health of Baiyangdian Lake based on "grey wave forecasting"model.The GA-grey waveform model was used to predict the health status of Baiyangdian Lake in the next two years.The results showed that the GA-Grey wave forecasting model is obviously superior to the traditional grey wave forecasting model in matching information sequences.The health index of Baiyangdian Lake would be 45.6 and 50.1 in the next two years,showing an overall upward trend,but there is still a big gap from the ideal state.