Study On Mechanism And Practice Of Improving Water Quality By Water Diversion On Lake-net

The problem of lake pollution is more and more acute, Nutrient control for restoration of lakes has been a urgent task of the world. The definition of the clean water diversion here is a water resource reallocation method adopted to improve lake water qualityit the water project controlled region by means of maximum use of fresh water resources passing by through functions of engineering arrangements including gates, pumps and ditches to facilitate an oriented and orderly movement of the water body of lake and speed up the water body exchange on the perquisite that flood control, industrial and domestic water use and water environment of critical areas are guaranteed.It is not only an important measure to enhanse the existing lake water environment capacity,but asle a world current of BPEO case with Chinese touch and therefore meet the need for double targets achieving both social and economic development and environment improvement at present situation in China.At present,all the existing foreign and domestic water diversion practices are on river or single lake, still havn't practices about lake-net which maked up with more than one lake and ditches. The water diversion of lake-net exists such problems as multi-waterway, cross infection and diffluence etc.this paper aims for the upper problems, do some tentative research work on the water diversion project of Hanyang lake-net, with the purposes of offering the project scientific dependence, developing the water diversion theory and supplying some references for actual practices.The main contents are as follows:1. Has a brief review and analysis of the history and current status of foreign and domestic water diversion.2. Discusses the mechanism of improving water quality of water diversion. The 'activity water mechanism' is draw out. We all know the dilution mechanism of water diversion,but a large amount of reseaech work indicate that velocity is the key factor to influence the water body's self-cleansing mechanism. It is reflected in the water quality predict model.3.On the bases of the water quality evolution of Hanyang lakes, analyzing the necessity and advantage of Hanyang lakes for water diversion.choose the water source , the water way and the manner of water diversion. There are three reserved water sources can be chosen,The Houguan lake, The YangZi River and The Hanjiang River.It is can be concluded throuth Comparing the three water sources synthetically that TheHanjiang River has abundant water,better water quality, more engineering arrangements and can self-flow throughout the route etc.So choose The Hanjiang River as the water source. It is should comply the principles such as lake-way being longer, ditch-way being shorter, diminishing the dead water zone, avoiding cross infection, rational diffluence, saving money etc.to choose the water way and the manner of water diversion.4. Recommends the best water diversion proposal and confirms the diversion period.this paper combines methods of numerical modeling and engineering situation analysis to forecast the rule of the water-flow and water quality, Compares the effect of every proposal synthetically, and recommends the best water diversion proposal. According the density process line out of each lake, considering four index synthesizly to settle the water diversion period.