Calculation For Eco-Environmental Water Requirement Of Nansihu Wetland

As a confluent area of natural and man-made pollutant, Laky wetlands have beendamnified and the ecosystems are destroyed by the lack and pollution of water.It is urgent tosolve the balance of water distribution between society,economy and ecosystem.As the largestlake of Shandong area, Nansihu lake has a strategic significance because of its locating on theEast Route Project of South to North Water Transfer.But water pollution, sullage deposition,diversity decrease of species are becoming severe since the 80th decade.One day Nansihu willdisappear as Beiwuhu Lake.Luckily,people pay more and more importance to the protection and logical usage of thebio-diversity of Nansihu wetland.Water, the most sensitive factor in the regional sustainabledevelopment,must be studied quantificationally and detailedly.The new methods to solve thecalculation of water requirement should be found so that we can make the concerteddevelopment of econmy,society and eco-environment.The author takes part in the projectsponsored by natural science fund of Shandong Province(Y2004E01),the study of and watersafety of Nansihu basin,which makes the first research on the calculation of theeco-environmental water requirement in Shandong area.The conclutions are as follows:(1)Today,the eco-environmental water requirement consists of two segments:ecologicalwater,and environmental water requirement which accounts for the environmentalproblems.The main calculating methods are composed of the exchanging water cyclemethod,minimum water level method,water quantity balance method and ecological functionsmethod, especially the last one is the most popular.The study of Water requirement mostlyfocuses on the optimum and the minimum water requirement.(2)The eco-environment of Nansihu Lake steps down currently,and the whole lake hasentered into the old age.Based on the hydrological analysis of the last 50 years and ecologicalanalysis from 1987 to 2000,the deterioration comes from two factors:natural andartifical,precipitation reduction by 42.54mm/10a, land reclamation around the lake, sullageaggradation and upriver water blocking cut down the quantity in the lake,especially in the late80th decade and the early 21th century,the ecological system undergos two destructive blowsowing to the dryup of the lake.