Spatial And Temporal Distribution Simulation Of Suspended Matter Concentration In Taihu Based On ECOMSED

Water is the foundation of people's survival. With the rapid development of China's social economy, water quality is not optimistic, especially the lake water, its eutrophication pollution has been very prominent; And suspended matter is an important material affecting the water quality of Taihu Lake, it is not only the basis of algae survival but also by changing the turbidity of the Taihu Lake water, thus it will affect the survival of other aquatic organisms. Therefore, the monitoring and protection of water quality is very necessary.Today, Taihu Lake has more than 20 buoy monitoring system, and its water quality parameters on the monitoring instrument can be real-time monitoring of Taihu Lake water quality parameters, including data of turbidity , concentration of chlorophyll a and so on.The use of such systems for long-term monitoring,can accumulate long-termcontinuous observation of data. It can do the great significance for the research of water environmental remote sensing , water management. However, the data obtained by buoy monitoring can only represent the water quality in the small area of the observation area and can not reflect the overall situation of the lake. Combining with the hydrodynamic numerical model to simulate the distribution and distribution of the components influencing the lake water quality, it can make up for the shortcomings of routine measurement of large water resources.At present, the 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.Among them, the use of three-dimensional numerical model of water and sediment for a lot of research, have verified its reliability in practical applications. However, due to the complexity of the lake hydrodynamic operation mechanism, many parameters in the numerical model are difficult to obtain .So it is necessary to select the typical dominant factors in the model to do the sensitivity analysis for exploring the different dominant factors on the model simulation results. The simultaneous determination of the sensitivity interval can provide a reference range for the model rate, which to some extent plays a role in simplifying the model.Based on this, in this paper, Taihu Lake was took as the research area, the suspended matter data was took as an example , and the three-dimensional water-sediment model ECOMSED was introduced for the spatial distribution of suspended matter in Taihu Lake.Based on the study of model mechanism and model construction, the model code was modified, and the dominant factors in the model were selected to carry out the sensitivity analysis. Based on the measured data of the monitoring site, the data of the remote sensing inversion data of Taihu Lake were coupled with ECOMSED, the model parameters were determined, research of the suspended matter in Taihu Lake was did and the suspended matter model system in Taihu Lake was constructed. The main contents and achievements of this paper were as follows:(1) ECOMSED model mechanism researchBased on the relevant data of ECOMSED model and the model formula, the role of hydrodynamic and sediment transport parameters were comprehensively analyzed, and their roles in model simulation were analyzed synthetically. At the same time, the construction and operating conditions of the model were summarized. In the process of model analysis, ECOMSED could not deal with the exposed beach situation, and the suspended concentration of the lake only gave a unique value. Therefore, the processing of dry and wet boundaries of the code was added to the original model, and the initial suspended matter concentration in Taihu Lake was corrected for the spatial treatment.(2) Sensitivity analysis of ECOMSED model parametersThe degree of influence of a factor on the model results can be determined by the size of the sensitivity coefficient. The greater the sensitivity coefficient, the more significant the effect of the factor on the outcome. In this paper, the three dominant factors (wind speed, sedimentation constant and resuspension index n) of the suspended matter in Taihu Lake were selected to analyze the influence degree and mechanism of these typical dominant factors on suspended matter concentration distribution in Taihu Lake , And the determined sensitivity interval could provide a reference range for the rate of the model parameters.(3) Numerical simulation of suspended sediment in Taihu LakeAfter the ECOMSED model parameters were determined, the ECOMSED water and sediment model was used to simulate the suspended matter concentration in Taihu Lake and the remote sensing inversion data. Based on the verification of the Taihu Lake flow field, the data of the measured suspended matter on the Taihu Lake monitoring site and the corresponding time of the suspended matter inversion data could be compared and the statistical analysis could be found in the northwest coast of Taihu Lake and the Meiliang Lake waters suspended matter concentration was relatively high, and the central area of Taihu Lake suspended matter concentration was between the two waters,and concentrated in the 40-60mg/L. In summary, the ECOMSED model could be used to simulate the reliability of suspended matter concentration distribution in Taihu Lake.(4) Construction of suspended matter model system in Taihu LakeBased on GIS and visualization technology, the integration of independent modules was realized, and the model of data collection, data preprocessing, control simulation and visualization of the results were analyzed. The results (flow field and suspended matter concentration distribution) of the suspended matter model of Taihu Lake were realized. It provided decision-making and support for the Taihu Lake water suspended matter concentration distribution and water pollution control.