基于ECOMSED的太湖悬浮物浓度时空分布模拟研究

发布时间：2018-08-14 11:11

【摘要】：水资源是人们赖以生存的基础。随着中国社会经济的快速发展,水质情况不容乐观,特别是湖泊水体,其富营养化污染一直非常突出。而悬浮物又是影响太湖水质的重要物质,它不仅是藻类的生存基础,同时也会通过改变太湖水体的浑浊程度,从而影响其它水生生物的生存环境。因此,对水质的监测与保护显得非常必要。如今,太湖已经有20多个浮标监测系统,并且其上承载的水质参数监测仪可以实时监测太湖的水质参数,包括浊度数据、叶绿素a浓度等。利用该类系统进行长期监测,可以积累长期连续观测的数据,对水环境遥感研究、水资源管理,都具有重要意义。但是通过浮标监测获取的数据信息,仅能代表观测区域小范围内的水质状况,而无法反映湖泊整体的情况。结合水动力数值模型对影响湖体水质的组分进行输移和分布模拟,则可以弥补常规测量在大面积获取水体数据方面的不足。目前,数值模拟方法被广泛应用在湖泊水质、生态环境的研究中,这对航道清淤工程建设、湖泊资源的可持续利用都有重要意义。其中,利用三维水沙数值模型进行的研究很多,均验证了其在实际应用中的可靠性。但由于湖泊水动力运行机制比较复杂,数值模型的参数众多且数据获取困难,有必要选取模型中典型的主导因素进行敏感性分析,并探讨不同主导因素对模型模拟结果的影响程度与作用机制。同时确定的敏感性区间可以为模型率定提供参考范围,从而在一定程度上起到简化模型的作用。基于此,本文以太湖为研究区域,以悬浮物数据为例,针对太湖悬浮物的空间分布规律,尝试引入三维水沙模型ECOMSED,在研究模型机理与模型构建的基础上,对模型代码进行了修正,并选取模型中的主导因素开展了敏感性分析,在实现监测站点实测数据、太湖悬浮物遥感反演成果数据与ECOMSED相耦合后,进行了模型参数的率定、太湖悬浮物的模拟研究以及太湖悬浮物模型系统的构建。本文的主要研究内容和成果如下:(1) ECOMSED的模型机理研究参考ECOMSED模型的相关资料以及模型公式,在理解水动力和悬浮物输运参数意义的基础上,综合分析它们在模型模拟中起到的作用,同时对模型的构建与运行条件进行了总结。在模型解析过程中发现,ECOMSED无法处理露滩情况,而且只能对全湖悬浮物浓度在空间上赋予唯一值。因此,对原有模型增加了处理干湿边界的代码,并对太湖初始悬浮物浓度进行了空间化处理。(2) ECOMSED模型参数的敏感性分析一个因素对模型结果的影响程度,可以用敏感度系数的大小来判定。敏感度系数愈大,因素对于结果的影响就越为显著。本文选取影响太湖悬浮物模拟结果的3个主导因素(风速、底质特性常数以及再悬浮指数n)进行敏感性分析,以探讨这些典型的主导因素对太湖悬浮物浓度分布的影响程度与作用机制,同时确定的敏感性区间可以为模型参数的率定提供参考范围。(3)太湖悬浮物的数值模拟研究在对ECOMSED模型参数进行率定后,利用ECOMSED水沙模型耦合太湖实测悬浮物数据以及遥感反演成果数据的方法,对太湖悬浮物浓度的分布进行实时模拟。在对太湖流场进行验证的基础上,对太湖监测站点上的实测悬浮物数据以及对应时间的悬浮物遥感反演成果数据进行对比和误差统计分析后发现,太湖西北沿岸以及梅梁湖水域的悬浮物浓度均比较高,而太湖中心地带的悬浮物浓度则介于上述两个水域之间,并集中在40—60mg/L。综上可以得出,ECOMSED模型在模拟太湖悬浮物浓度分布上的可靠性。(4)太湖悬浮物模型系统的构建基于GIS以及可视化技术实现了独立模块的集成,构建了模型数据输入、数据预处理、控制模拟及结果可视化等功能于一体的太湖悬浮物模型系统,实现了太湖悬浮物模型模拟结果(流场和悬浮物浓度分布)的准实时可视化,为太湖水体悬浮物浓度分布规律和水质污染的治理提供决策与支持。
[Abstract]:With the rapid development of China's social economy, the water quality is not optimistic, especially the eutrophication pollution of lakes. Suspended solids are important substances which affect the water quality of Taihu Lake. They are not only the basis of algae, but also the turbidity of Taihu Lake by changing the water quality. Therefore, it is necessary to monitor and protect the water quality. Today, there are more than 20 buoy monitoring systems in Taihu Lake, and the water quality parameters monitors carried on them can monitor the water quality parameters of Taihu Lake in real time, including turbidity data, chlorophyll a concentration and so on. Long-term monitoring can accumulate long-term continuous observation data, which is of great significance to water environment remote sensing research and water resources management. However, the data obtained by buoy monitoring can only represent the water quality in a small area of observation, but can not reflect the overall situation of the lake. At present, numerical simulation method is widely used in the study of lake water quality and ecological environment, which is of great significance to the construction of channel dredging project and the sustainable utilization of Lake resources. Many numerical models have been studied to verify their reliability in practical application. However, due to the complicated hydrodynamic operation mechanism of lakes, the numerous parameters of numerical models and the difficulty of data acquisition, it is necessary to select the typical dominant factors in the model for sensitivity analysis and explore the influence of different dominant factors on the simulation results. Based on this, this paper takes Taihu Lake as the research area, takes the suspended matter data as an example, aiming at the spatial distribution of suspended matter in Taihu Lake, tries to introduce the three-dimensional water-sediment model ECOMSED. Based on the study of the model mechanism and model construction, the model code was modified, and the main factors in the model were selected to carry out sensitivity analysis. After realizing the monitoring site data, coupling the remote sensing inversion results of suspended solids in Lake Taihu with ECOMSED, the model parameters were calibrated, the suspended solids in Lake Taihu were simulated and studied. The main research contents and achievements of this paper are as follows: (1) ECOMSED model mechanism research refers to the relevant data and model formula of ECOMSED model, comprehensively analyzes the role of ECOMSED in model simulation on the basis of understanding the meaning of hydrodynamic and suspended sediment transport parameters, and at the same time analyzes the structure of the model. In the process of model analysis, ECOMSED can not deal with dew beach, and can only give a unique value to the concentration of suspended solids in the whole lake space. In this paper, three main factors (wind speed, sediment characteristic constant and resuspension index n) affecting the simulation results of suspended solids in Lake Taihu are selected to be sensitive. The influence degree and mechanism of these typical dominant factors on the concentration distribution of suspended solids in Lake Taihu are analyzed, and the sensitivity interval determined can provide a reference range for the calibration of model parameters. (3) The numerical simulation of suspended solids in Lake Taihu is carried out after the calibration of ECOMSED model parameters. Based on the verification of the flow field in Lake Taihu, the data of suspended solids measured at the monitoring station of Lake Taihu and the data of remote sensing inversion of suspended solids at the corresponding time are compared and analyzed. It was found that the concentration of suspended solids in the northwest coast of Lake Taihu and Meiliang Lake was relatively high, while the concentration of suspended solids in the center of Lake Taihu was between the two waters, and concentrated in 40-60 mg/L. In conclusion, the reliability of ECOMSED model in simulating the concentration distribution of suspended solids in Lake Taihu can be concluded. (4) The structure of the suspended solids model system of Lake Taihu. Based on GIS and visualization technology, the integration of independent modules is realized, and the suspended matter model system of Taihu Lake, which integrates the functions of model data input, data preprocessing, control simulation and result visualization, is constructed. The quasi-real-time visualization of simulation results (flow field and suspended matter concentration distribution) of the suspended matter model of Taihu Lake is realized. The concentration distribution of suspended solids and the treatment of water pollution provide decision and support.
【学位授予单位】：南京师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X524;X87

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