Water Environment Evaluation And Prediction For The Lake Of Wuliangsuhai

A lake is normally a complicated ecosystem regarding water, aquatic plants, aquatic animals, manyl kinds of microorganisms and nutritional ingredients. The lake of Wuliangsuhai having an open water area of 285.38 km2, is loacated in the Mongolia-Xinjiang altiplano region with a precipitation of 224 mm, which is one of the eight largest fresh water lakes in China. It is not only the unique drainage water receiving basin from the cultivated farmland of Hetao Irrigation Districte, but also has the function in maintaining biodiversity, adjusting the local climate, storing the seasonal floodwater, purifing water quality, and so on. Since the source waters are having been polluted by using more and more fertilizer over the farmland, developing industries within the catchment and receiving sanitary sewage from the towns, a great deal of nutrients are transported into the lake. As a result of this, lake's water has been seriously polluted.The water quality of the lake has been monitored and analyzed for three years. This paper mainly focuses on the water quality evaluation and forecast with respect to the sustainable development point of view. The cataminats were analyzed and the eutrophication indicators were worked out. The index method of synthetical nutrition was used to estimate eutrophication degrees over the open water area. Then, the method of neural network was employed to predicte the change of water quality index in terms of chlorpophyll. The results showed that Chla is one of the most sensitive indicators to characterize eutrophication degrees, the water quality is better in the year of 2007 than 2006 and in the Summer than Spring than Autom within a year.