Research On The Eutrophication Comprehensive Index Formula Based On Particle Swarm Optimization

Nowadays the lake eutrophication has become a worldwide problem in the area of water pollution control, and it is also a globel environmental problem.Most of the Inland freshwater in Europe and North America are Eutrophic now or later .At present, the problem of lake eutrophication caused by Water pollution is very prominent in our country, which impede the development of enconomy.In our country, "Ninth Five-Year Plan", we have laid a emphsis on the treatment of Taihu Lake, Dianchi and Chaohu.This article discuss the research significance of the comprehensive index formula based on a power function of weighted sums and the status quo of evaluation models home and abroad at first.It also introduce and describe the current states of the lake eutrophication, the characteristics, the harm of the lake eutrophication and the basic principle of particle swarm optimization which is also illustrated in detail. A program based on the basic principle of particle swarm has been designed to optimize the parameters of the universal index formula. Optimization of parameters in formula is carried out using particle swarm optimization to derive a universal formula of evaluation of lake eutrophication suited to multi-index. In order to test the effect of the universal index formula, this article compares the evaluation results of thirty representative lakes in China with the results which are respectively from Randomized evaluation of the law, Fuzzy evaluation and Gray evaluation method .The results show the simplicity for calculation, practicality, generality, comparability and objectiveness.At last, take Shengzhong Reservoir as an example,this article testifies the applicability of the universal index formula.At the same time, this article has given some pieces of advice for the phenomenon of lake eutrophication of Shengzhong Reservoir.