南水北调东线调度对南四湖水质的影响

The impact of the operation of Eastern Route Project of the South-to-North Water Diversion Project on water quality in Lake Nansi

南水北调东线一期工程2013年通水,必将对南四湖水质产生重大影响.借鉴既有成功理论方法,建立南四湖三维水力调配和水质模型,并经实测值验证.利用该三维模型,模拟南水北调东线一个完整调水期中的南四湖常规、干旱调水工况调度运行过程,分析南四湖上级湖、下级湖的水力和水质变化规律,提出加强和改善南水北调东线调度管理的措施和建议,既可充分发挥南水北调工程效益,又可改善南四湖水质.

Lake Nansi consists of four lakes： the Nanyang, Dushan, Zhaoyang and Weishan Lake. It is a lake in the line of the Eastern Route Project （ERP） of the South-to-North Water Diversion Project （ NSBD）. After the project supply water in 2013, the water quality of Lake Nansi will be affected significantly. Based on the existing theories and methods, a three-dimensional hydrau- lic control and water quality model of the lake is presented. The model is developed under the Environmental Fluid Dynamics Code （EFDC） model. It was calibrated and verified to hydrodynamic and water quality data, using two sets of observed data from Octo- ber 1 to December 31, 2006 and January 1 to June 30, 2007, respectively. The observed data including water surface elevation, water temperature, chemical oxygen demand, dissolved oxygen and ammonia nitrogen from five stations is used as forcing for simu- lations. The model results show that temporal and spatial patterns for hydrodynamic and water quality components are consistent with observed data in the reservoir. Because the direction of the water supply and natural flow is converse, the Lake Nansi is divid- ed into the upper-lake and the lower-lake by Erji dam in the Lake Zhaoyang. Two scenarios of whole supplying water term of the lake were simulated using the model. By the analysis of the variations of the hydraulic control and water quality of the upper-lake and lower-lake,This paper proposed three advices of the ERP operation, which can help the project to give full benefits and im- prove the water quality.