强蒸发抽水型水库水质和水动力耦合模拟研究-以宁夏鸭子荡水库为例

Pumped storage reservoirs are differt from channel type reservoirs,which have uniqe hydrodynamic characteristics. According to the characteristics of strong evaporation in northwest of China, Yazidang reservoir is selected as research object, which is located in arid zone of middle Ningxia. In view of the characteristics of strong evaporation and decrease of water quality, the water quality and the water dynamics of Yazidang reservoir are to be coupling studied. Based on the testing of evaporation, flow velocity and computer simulation, the water kinetics equation of reservoir with strong evaporation will be proposed and the figure of flow field will be achieved. On the basis of the water sampling and water quality analysis, the water quality evaluation of Yazidang reservoir is to be carried out. Integrated with dynamic equation, the coupling relationship between water quality and water dynamics of reservoir with strong evaporation will be promoted, and then the distribution and change tendency of water quality will be analyzed and concluded.The results of this research will serve for water quality prediction and early warning of reservoirs in semi-arid area of northwest of China, and provide reference to water quality management and pollution control of reservoirs.

抽水型水库有别于河道型水库，有着独特的水动力学特征。本项目以宁夏中部干旱带的鸭子荡水库为研究对象，针对水库强蒸发的特点及水质下降问题，开展宁东鸭子荡水库的水质和水动力耦合研究。通过库区蒸发量和流场的测定及计算机模拟，探索蒸发量对模型参数的影响，建立强蒸发抽水型水库在上水期和非上水期的水动力数学模型，获得库区流场图；通过库区水样的采集和分析监测，开展库区水质评价；结合水动力模型，建立强蒸发抽水型水库的水质和水动力学耦合关系，分析主要水质指标在库区的分布规律并预测水质变化趋势。通过本项目研究，为西北地区强蒸发抽水型水库的水质预测和预警提供依据，为水库的水质管理和污染防治提供参考。

宁夏地处西北干旱半干旱地区，区内通过抽取黄河水形成的抽水型水库较多，为宁夏的经济发展提供水资源保证。鸭子荡水库是宁夏宁东基地供水工程的调蓄水库，为典型的抽水型水库。本项目主要完成四个方面的内容，研究结果总结如下：. （1）2014年通过逐月水质监测，对有机污染指标和富营养化指标进行分析可知，鸭子荡水库的有机污染指标中CODCr和DO达到Ⅲ类水体要求，但BOD5均存在超标现象；富营养化指标中NH3-N达标，TP存在部分超标现象，而TN则100%的超标。采用灰色关联法对水库水质进行评价，结果表明鸭子荡水库的水体类别基本属于Ⅲ类水体，并采用了ArcGIS中反距离权重法对鸭子荡水库的三次采样结果进行空间插值分析。. （2）在实测水库地形的基础上，建立水流二维平面模型。按照抽水型水库的运行方式，模拟了鸭子荡水库在上水和不上水时的水流特征，分析了吞吐流和风生流对鸭子荡水库流场的影响。模拟结果表明吞吐流和风生流对鸭子荡水库的流场影响明显，其中风生流是主动力，由此获得鸭子荡水库的水动力机制。. （3）在实验室测定降解系数的基础上，模拟了鸭子荡水库的水质变化，获得上水和不上水两种典型工况的水质变化规律。模拟了吞吐流、风场和进水水质变化对库区COD和NH3-N的空间分布的影响，结果表明吞吐流和风场明显影响库区污染物的浓度分布，而进水水质变化还将影响水库做为饮用水水源地的水体功能。. （4）分析鸭子荡水库的水质控制对策，为水库的水质管理提供参考。. 通过项目研究，分析了鸭子荡水库的水质现状，探讨了库区流场分布的水动力特征，获得水质变化规律及影响因素，为抽水型水库的水质预测和预警提供依据，为水库的水质管理和污染防治提供参考。