The Design Research Of Water Quality Security Engineering Measures In South Lake Of Yueyang

With the social and economic development, a growing number of natural lakeshave been involved in the urban planning and development scope. Compared with thelarge-scale shallow lakes, research with regard to the city-within small shallow lakesis relatively weak. Municipal lakes have comprehensive functions such as excretingstormwater, detention storage, tourism, waterscape, supplying water and so on. Theyare playing a very important role in the urban ecological construction, and the waterenvironmental problems are cannot be ignored.Due to its relative closure, municipal lakes have low flow velocity, and longtime for waters’ replacement cycle, all of which are disadvantageous to pollutant’sdilution and diffusion. Urban lakes mostly located in humanity’s compact distinct,and the destructive power of humanity is far more bigger than those away from thecity. Compared with rivers, municipal lakes also have the following salient features:low water capacity, small catchment area, mild water exchange adjust capability,closely linked to the surrounding environment and have a high risk of pollution.Therefore, it’s rather difficult to maintain and improve the urban water environment.As the largest urban lake in Yuyang, South Lake has the generality of municipallakes. Taking South Lake as a research object, due to the amount of pollutantsentering the South Lake is seriously beyond its self-purification capacity, the waterquality standards cannot reach its functional criteria. This paper proposed a waterquality security method to control the amount of pollutants entering lake, accordingto the limit value of water environmental capacity, some engineering measures to cutdown the amount of pollutants into the water environmental capacity range aredesigned, and the self-purification capacity of water to remove pollutants andimprove water quality should be made full use of.After taking a series of water quality security engineering measures such asregular intercepting initial rainwater, increasing the combined sewer systeminterception ratio, setting up combined sewage overflow regulation and storagestructures, improving the quality standards of sewage treatment plant effluent water,the total amount of pollutants entering South Lake can be greatly reduced, and thereduction rate of COD, TP and TN can respectively reach70.08%,84.84%and78.86%. The water quality monitoring results shows that the governance effect ofSouth Lake is obviously, the water quality of the South Lake has a significantimprovement in a relatively short period of time, and now the South Lake water quality has been improved from the original GradeⅤto Grade Ⅳ, besides, part of thewater has already reached Grade Ⅲ, and the quality of water is in a continuousimprovement process. It can be expected that the whole lake water quality will reachGrade Ⅲ in the near future.The governance practices of South Lake in Yueyang can be used as municipallakes governance design technical basis and reference, and it is expected that throughthis topic research, an applicable water quality protection engineering design methodsfor large-area water, landscape water and slow-flow water bodies could be found.