Three Forks Lake Water Quality Evaluation And Countermeasures To Prevent And Control Pollution

Reservoir is an artificial generate electricity, irrigation and tourism havesome contributions. But in recent years with the rapid development of social economy and the rapid population growth of our country,a large number of without processing waste water straight into to all kinds of natural water,causing water quality to decline. Three Forks Lake is the most important agricultural irrigation water, meanwhile, it have tourism water demand and the water quality impact on the development of regional economy, also effect people’s life and ecological environmental safety and health.There are many different water quality evaluation methods for us to choose, according to the evaluation method can be divided into single factor and comprehensive evaluation, but there are still have not standard method for water quality evaluation. In this paper the fuzzy comprehensive evaluation method has been choosed to evaluate water of Three Forks Lake based on readed a large number of references. Based on the comprehensive consideration of Three Forks Lake, in thispaper selected of DO,CODmn, BOD5,TP, TNand NH3-N as the water quality assessment index. In the process of using fuzzy comprehensive evaluation method, this paper have optimized about it based on the achievement of other’s people. In this paper, using Entropy Methodto quantificate the weights of evaluation factor that to reduce the artificial effect in the process of quantificate the weights, using weight average metho to get the water quality level that to avoid equalization. The paper use general fuzzy comprehensive evaluation method and the optimal fuzzy comprehensive evaluation method for Three Forks Lake water quality level evaluation, and the comparison between the two evaluation results.Through the evaluation results can be concluded that the main pollutants of Three Forks Lakeis total nitrogen (TN) and total phosphorus (TP), many years is more than III kind of water quality standard requirements;Whether before the optimization or after the optimization of the fuzzy comprehensive evaluation method of the evaluation of water quality level results are out there from1989to2000is increasing gradually and water quality become poor year after year, but so far in2001water quality level gradually reduce process, water quality appear signs of improvement;The dam, laoshan bifurcation and LongYun three points water quality level changes have the same trending, also have the same trending with whole lake, but if the three monitoring stations separately, the best one is LongYun water quality level, the dam is the second, and laoshan bifurcation is the worst, this also is consistent with actual situation of Three Forks Lake. At the same time the optimized results is more conservative than the result of before optimization, the water quality level obviously become better. At the last of this paper through analysis the point source, diffuse and sediment release that to confirm the main pollutants of Three Forks Lake, and in the light of the actual situation of the three bifurcation lake to put forward the corresponding prevention and control countermeasures.