The Evaluation Research On The Lake Ecosystem Health Based On Entropy Theory

The health of the lake ecosystem has been a hot problem in the study on ecology and sociology.Now at this stage of the lake ecosystem health,it's a comprehensive problem,covering the natural and social.Thus,the lake ecosystem not only can have ability to meet the reasonable requirements of human society,but also sustain itself ecological survival and development.How to evaluate the lake ecosystem health scientifically has significance to the sustainable development of society.This paper introduced the entropy theory and grey wave forecasting model,set Baiyangdian Lake as the background to explore the lake ecosystem health evaluation.The main researches mage as followings:(1)Based on Schrodinger's theory about the relationship between entropy change and life,this paper introduces the concept of information entropy and establishes a quantitative model.The main body of evaluation system based on the DPSIR model(D showed “Driving force”,P showed “Pressure”,S showed “State”,I showed “Impacted”,R showed “Response”)which covers chemical integrity,physical integrity,biological integrity and social service function integrity four aspects.The analysis method adopted is based on the state of the indicators.At the meantime,the indicators are sorted into positive indicators and negative indicators,both the indicator property and entropy flow direction are being identified.And then balance the health and development to determine the weight.The entropy calculation results indicating that the entire eco-system of Baiyangdian Lake is in the serious situation.To be specific,the degradation trend of hydrology and water resources as well as the "bio" criterion layer is much more serious.Based on the analysis of the stability of the indexes,and through the analysis of related indexes of the two criterion layers,it's easily to get the conclusion that the main factor that influences the health of Baiyangdian Lake is that its ecological water level could not be satisfied for such a long time,which leads to a series of biology as well as water quality declines.(2)In view of the importance of the natural ecosystem of lake into the lake water,then explored the change regular of water.Seen from the long time-series of the nature flow into Baiyangdian Lake,it has a rule of the dry season and the wet season alternating.The grey wave forecasting model is applicable to research the rule's evolutional trend.This paper uses the genetic algorithm(GA)to optimize the first-order grey model's iterative basic value ? and background value coefficient ?.This method takes advantages of GA in efficient convergence and broad select range,basing on the GM(1,1)grey models establish the GA-Grey wave forecasting model,thus use it study the trend of the nature flow into Baiyangdian Lake.The final analysis conclusion is that the GA-Grey wave forecasting model is obviously superior to the tradition grey wave forecasting model not only in matching information sequences but also in finding the changing characteristic of the information sequences,thus better forecast the changing of nature flow into Baiyangdian Lake.It also shows,the nature inflow have eased in recent years,the amount of inflow could reach about 400 million cubic meters and in rising trend.However,still far away from the historical average value 908 million cubic meters.