【作者】 马莉；

【导师】 桂和荣；

【作者基本信息】 安徽理工大学 ， 环境工程， 2012， 博士

【摘要】 淮河水系凤台至淮南主城区段位于淮河中游,地处安徽省淮南市。淮河自西向东横穿淮南市,在凤台县附近受八公山的阻隔,河道曲折,受自然因素和人工开挖河渠的双重影响,具有二道河、河心洲(上下六坊堤)等地形特点。淮河作为淮南市重要的水上枢纽,是工农业用水、居民饮用水源地,与淮南市的经济发展、百姓的生活息息相关。但是由于气候、地理、历史等方面的原因,淮河中游河段极易发生洪水和干旱,且受人类工农业活动的影响,水质状况也不容乐观,部分监测断面水质甚至达到国家V类水。因此有必要对目标河段的水环境状况展开深入研究,以便全面了解污染物在时间和空间上的影响深度和广度。本文以淮河水系凤台至淮南主城区为目标河段,上游起始断面为淮南市凤台县鲁台子水文站,下游终止断面设为淮南市主城区田家庵区田家庵断面,研究对淮河中游大断面地形资料,部分年份的水文水质观测资料进行了数据统计分析。利用SMS(地表水模拟系统)中二维水动力学模型RMA2和物质输运模型RMA4,对目标河段特定年份丰水期和枯水期的水流水质状况进行了模拟计算。通过本论文的研究,对淮河水系凤台至淮南主城区段水动力学扩散特征、水质要素的扩散输移规律有了一定的认识,具体包括以下几个方面：(1)以特定洪水年2003年的水文资料对目标河段进行糙率率定,率定结果为n=0.02。通过对2004年洪水期和2009年枯水期水位、流速的模拟值和观测值比较,成功模拟了水位和流速的变化过程。相对误差δ、平均误差η、均方根误差σ较小。误差最小二乘法分析显示相关性系数R2平均在0.95以上,模型精确度较高,为污染物输运计算提供了可信的动力场。(2)分汊流水动力学模拟计算得出凤台大桥附近分汉口处南北汊分流比约为4：1,南汊分出的二级支汉南北分流比为约3：1,交汇口处南北汊分流比约3：2。分汊流整体水流流场模拟显示分汉型河道二道河以上河心洲(上六坊堤)分隔的南汊较北汊具有较好的通航条件,二道河以下河心洲(下六坊堤)分隔的南北汊通航能力较均衡。通过对上游不同流量级下交汇口处的流场模拟展示了交汇口处有河心滩出露,且为不稳定滩地,并分析了滩地形成的原因及其演化趋势。(3)水质模拟对目标河段接纳污染源进行了概化处理,对各排污口的排污量和排污浓度采取年平均统计分析方法,以丰水期2004年7月水质资料为基础,对鲁台子断面、平圩大桥断面、田家庵断面污染指标氨氮(NH3-N)、高锰酸钾指数(CODMn)、重铬酸钾指数(CODcr)进行了计算,模拟值和实测值吻合度较好,研究表明丰水期污染物径流输入较大,污染物高浓度区随着颍河向鲁台子推移,各下游断面污染物浓度与颍河排污相关率高。并以氨氮(NH3-N)为例,展示了特定时刻点污染源的时空分布特征。通过对分汊河道六个特征点的污染物动态变化过程计算,显示了丰水期受颍河口动态排污的影响,分汊型河道各汉分污整体均衡,局部存在一定差异,但差异规律不显著。(4)根据1956-2000年的实测流量资料,推求出鲁台子水文站95%、75%保证率下的设计流量,对水动力要素进行预测,结合目标河段沿淮排污口2003年全年排污资料,对凤台大桥断面、平圩大桥断面、田家庵断面的污染指标氨氮(NH3-N)和化学需氧量(CODCr)进行预测,模拟结果分析表明：小流量下(枯水期),当上游来水为《地表水环境质量标准》Ⅲ类水浓度时,水质稳定后下游各特征断面污染指标浓度严重超标。其中凤台排污口排污对下游断面水质“贡献率”较大,尤其对于分汊型河道交汇口不远处的平圩大桥断面(淮南饮用水源区的代表断面),受到上游污水和凤台排污的双重影响,污染物产生聚集效应,难以扩散推移。为体现污染源在河道中分布的时空变化,研究中以P=75%来水条件为例,模拟了不同时刻点CODCr在河道中的扩散状态,得出污染源排污强度和上游来水的水动力条件为制约下游水质的主要因素。更多还原

【Abstract】 Fengtai to Huainan Urban Section of Huaihe River midstream is located in Huainan city of Anhui province. It flows through Huainan city from the west to the east.Because of the double influence of Bagongshan Mountain and artificial excavation,It is a typical braided channel which is composed of Erdaohe and river island(two flood-control dykes divided by Erdaohe).As the water translation, industrial-agricultural water and drinking water,it plays an irreplaceable role in economy and life.However,Owing to the influence of climate,geography and history, Flood and drought occur frequently in the area.Furthmore, under effects of human activities of industry and agriculture, water quality is not optimistic.Water quality of some monitoring sections is classified to V.Therefore,It is necessary to make a deep study on the water environment in this area so as to comprehensively understand the influence depth and rreadth imposed by pollutant, both spatially and temporally.The paper takes Fengtai to Huainan Urban Section as target river,Lutaizi hydrological station and Tianjia’an as the initial and final section. Based on a comprehensive analysis of the history terrain, hydrological and water quality measurement, A two-dimensional hydrodynamic and water quality mumercial model, RMA2and RMA4in SMS(Surface Water Modeling System),are applied to simulation the water flow and water quality in the high water period and low water period of specific years. Through reseach in this paper,The character of hydrodynamic and convective-diffusion of discharge pollutants are understood as follows:(1) Based on the hydrological data in2003, a specific torrent year,Calibration and validation of roughness are developed in the area,the result of calibration is n=0.02, Through comparison between simulation value and observed value of water level and flow velocity in high water period of2004and low water period of2009,the process of water level and flow velocity is simulated smoothly.Relative error8, mean error η and root-mean-square error σ can satisfy computational precision. Error analysis of the least square method shows that correlation coefficient R2is above0.95in average.The model provides an accurate hydrodynamic field for the calculation of pollutant diffusion-transportation.(2) The calibration results of the bitfurcated flow show that flow diversion ratio of South-North-Branch bifurcation near Fengtai Bridge is about4:1,south and north flow diversion ratio of the secondary branch sepatated from south branch is about3:1. flow diversion ratio of South-North-Passage in junction is about3:2.Tributary whole flow field simulation shows that south branch has better navigation condition than north branch above Erdaohe river.Downstream of Erdaohe river, South-North-Branch both have better navigation condition. Flow field analysis of the junction shows there are river island appearing in intersection, exactly unstable bottomland,then expatiates the reason and evolution trends of bottomland formation.(3) Water quality simulation conducts generalization on pollution source of the target stream.An annual average method is applied to calculate discharge capacity and concentration. Based on water quality data in July2004,the water quality model simulates the concentration curve of NH3-N、CODmn、CODCr of Lutaizi section,Pingwei bridge section and Tianjia’an section.The simulated data and measured data show good agreements. Study proves that the runoff input of wet season is rather large and the contaminant concentration of some sections is mainly influenced by Yinghe river.Then take NH3-N for example, study shows spatial and temporal distribution of pollution source in specific moments. Calculation on pollutant dynamic distribution of six feature points in the braided river shows that concentration distribution of each branch is balanced on the whole and exists some difference locally,but the differences are not obvious under the impact of the unsteady flow and dynamic pollution discharge.(4) Based on the flow data between1956to2000,desigh flows of Lutaizi hydrologic station under assurance rate of95%and75%are researched,the velocity fields are forecasted.Combining annual pollution discharge data of drain outlet in2003, NH3-N and CODCr concentration of Fengtai bridge section,Pingwei bridge section and Tianjia’an section are forecasted.The result shows when the water quality of Lutaizi section is classified to Ⅲ, the pollutant concentration of each section in downstream exceeds the standard greatly in low water period. Pollution discharge of Fengtai bridge has a rather large influence on water quality of each section in downstream, especially on Pingwei Bridge section(typical section of drinking water source area in Huainan).Due to the double influence of upstream drainage and pollution discharge of Fengtai bridge,the pollutants in the environment are tend to accumulate.In order to reflect temporal and spatial variation of pollution discharge,in this study,take P=75%for example,the paper simulates CODCr distribution at different moments,and concludes that discharge intensity of pollution source and hydrodynamic condition of upstream are the major restriction factors to the water quality of downstream.更多还原