基于EFDC的密云水库水环境及应急处理模型研究

发布时间：2018-11-22 08:21

【摘要】：密云水库是北京市最大的也是唯一的地表饮用水水源地，随着社会经济的高速发展，密云水库水环境受到污染，水库水质有了下降趋势。掌握库区基本的水文特征、水环境机理，并进行模拟预警，对遏制密云水库水体恶化具有一定的指导意义，为水库环境治理工作提供相关的技术支撑。本文通过收集水库库区及周边的实测数据，对研究区模拟范围的时空进行概化，搭建EFDC密云水库二维水动力—水质模型。通过密云水库水动力模型，得到良好的水位模拟结果，，平均误差约为-0.61%。水温模拟结果客观的反应了密云水库四季温度变化，解释了冬春季湖心水温低、夏秋季湖心温度高的主要原因是由于水库入流受气温影响较库区水体大，且库区水体交换周期长，并且水体的生态转化也会产生热量。在水动力基础上，利用2007-2008年水质数据建立密云水库水质模型并进行模型率定，水质率定模拟结果表明：各项水质指标模拟变化趋势和实测值变化趋势基本相符，模拟效果良好，总体平均误差在可接受范围内：DO平均误差13.34%，氨氮平均误差12%，总氮平均误差11.43%，总磷平均误差12.34%。2008年模拟验证结果表明，各项水质指标模拟变化趋势和实测值变化趋势拟合关系好于率定模拟结果，总体平均误差在可接受范围内，可以满足预报、预警等技术要求。在调试好的水质模型基础上，设置了瞬时排放污染物及连续排放污染物两种情景，并选用衰减系数为1e-8、1e-7、5e-7的人工处理方式并与未考虑衰减系数的情况作为对比，发现：（1）瞬时排放事故发生点位于库区内部，污染物云团运移驱动力主要以风速为主，并沿库区东部、南部所形成的涡旋进行运动扩散；而连续排放事故点位于入流点附近，入流水流则作为主要驱动力影响溶质运移。（2）瞬时排放条件下考虑三种不同衰减系数情况，随着衰减系数增大，同一时刻峰值浓度出现减小趋势。（3）考虑衰减系数下，污染羽范围明显下降。综上所述，使用EFDC模型模拟密云水库水环境并进行污染物突发事件具有一定可行性，可为密云水库治理、防治等工作提供技术支撑。
[Abstract]:Miyun Reservoir is the largest and only source of surface drinking water in Beijing. With the rapid development of social economy, the water environment of Miyun Reservoir is polluted, and the water quality of the reservoir has a downward trend. Mastering the basic hydrological characteristics and water environment mechanism of the reservoir area and carrying out simulation and early warning are of certain guiding significance to curb the deterioration of the water body of Miyun Reservoir and provide relevant technical support for the reservoir environmental control work. By collecting the measured data of reservoir area and its surrounding area, this paper generalizes the time and space of the simulation range of the study area, and sets up a two-dimensional hydrodynamic water quality model of EFDC Miyun Reservoir. Through the hydrodynamic model of Miyun reservoir, good water level simulation results are obtained. The average error is about -0.61. The results of water temperature simulation objectively reflect the variation of four seasons temperature in Miyun Reservoir, and explain the low water temperature in the lake center in winter and spring, and the main reason for the high temperature in the lake center in summer and autumn because the inflow of the reservoir is more affected by the temperature than the water body in the reservoir area. And the water exchange period is long, and the ecological transformation of water will also produce heat. On the basis of hydrodynamics, the water quality model of Miyun Reservoir was established by using the water quality data from 2007-2008 and the model rate was determined. The simulation results of water quality rate indicated that the simulation trend of water quality indexes was basically consistent with that of measured values. The overall average error is within the acceptable range: DO average error 13.34, ammonia nitrogen average error 12, total nitrogen average error 11.43, total phosphorus average error 12.34.2008.The results of simulation and verification show that, The simulation trend of water quality index and the change trend of measured value fit well with the result of rate simulation. The overall average error is within the acceptable range, which can meet the technical requirements of forecast, early warning and so on. Based on the adjusted water quality model, two scenarios of instantaneous discharge of pollutants and continuous discharge of pollutants were set up, and the artificial treatment method with attenuation coefficient of 1e-8, 1e-7 and 5e-7 was selected as a comparison with the situation without considering the attenuation coefficient. The results are as follows: (1) the instantaneous emission accident occurs in the reservoir area, and the main driving force of pollutant cloud movement is wind speed, and moving diffusion along the vortex formed in the east and south of the reservoir area; However, the continuous emission accident point is located near the inflow point, and the inflow flow affects solute transport as the main driving force. (2) considering three different attenuation coefficients under instantaneous discharge conditions, with the increase of attenuation coefficient, The peak concentration decreases at the same time. (3) considering the attenuation coefficient, the range of pollution plume decreases obviously. To sum up, it is feasible to use EFDC model to simulate the water environment of Miyun reservoir and to carry out pollutant emergencies, which can provide technical support for the management and prevention of Miyun reservoir.
【学位授予单位】：中国地质大学（北京）
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TV697;X524

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