| With the extensive development of water pollution prevention and control in my country,many cities have planned and launched comprehensive river improvement projects that include various water pollution control measures,and have achieved remarkable results.However,the current post-evaluation on the treatment effect of the comprehensive treatment project of urban rivers is still rare.Carrying out the postevaluation of the treatment effect of the comprehensive river improvement project and the study of water quality control measures will not only help to understand the actual effect brought by the comprehensive improvement project and the contribution of different treatment measures to the reduction of pollution load,but also contribute to the long-term management of the river.The maintenance and management of chemistry has an enlightening effectTherefore,in response to the "clear water and green banks" water quality improvement action in the city’s main urban area,this study selected a river in the main urban area as the research object,summarized its remediation engineering measures,collected water quality monitoring data after remediation,and clarified the main pollution factors that exceeded the standard.The weighted Euclidean distance method is used to comprehensively evaluate the current water quality,analyze the actual effect and contribution of the pollution load reduction after the implementation of the river improvement project measures,and provide theoretical support for the subsequent water quality regulation and the future construction of a smart river management platform.Combining relevant data to investigate the pollution sources of the whole river basin and estimate the multi-source pollution load,and further use the Qual2 K model to simulate the three main pollution indicators of COD,ammonia nitrogen,and total phosphorus in the Jiulongpo section of the river,and clarify that multi-source pollution affects the water quality of each section.Based on this model,the trial-and-error method of the model is selected to estimate the water environment capacity,which is used as an important basis for proposing subsequent river water quality control programs.Finally,a combination of theoretical calculation and model verification is used to analyze the accessibility of the proposed water quality control measures to the water quality target,in order to serve as the theoretical basis for the construction of a smart water platform for long-term water quality control in the post-remediation period of rivers.The main research results obtained in this thesis are as follows:(1)Conduct water quality and quantity monitoring for more than one year on 15 sections in the research section.The monitoring results showed that the three types of indicators of turbidity,ammonia nitrogen,and total phosphorus showed a change pattern of "high in the middle stream-low in the upstream and downstream" along the way.Taking the Grade V water quality as the expected treatment goal of the renovation project,analyze the compliance of each water quality index: the overall level of COD is low,and its compliance rate is as high as 99%-100%;the dissolved oxygen in each section is relatively high,and the compliance rate is more than 90%;about The average ammonia nitrogen concentration of 6 sections exceeded the standard,of which the ammonia nitrogen compliance rate of 2 sections was only 25%;the total phosphorus concentration of three-fifths of the sections exceeded the standard,and about half of the sections had a compliance rate of less than 30%.From this,it can be determined that ammonia nitrogen and total phosphorus are the pollution factors of the Jiulongpo section.The weighted Euclidean distance method was used to evaluate the water quality of the Jiulongpo section.The results showed that 4 sections were inferior to Class V,and only 3 sections reached Class IV and above.It can be seen that the current water quality of the study section has not yet fully reached the expected goal of the renovation project.At the same time,the treatment measures of each section were compared with the water quality index compliance rate and reduction degree before and after the renovation,and it was found that the comprehensive treatment measures of dredging and dredging + ecological bank protection + sewage interception pipe + landscape greening + ecological restoration project have effects on DO,COD,and ammonia nitrogen.The indicator water quality improvement effect is better,and the reduction of total phosphorus is slightly insufficient;the pollution interception pipe project has a strong effect on point source pollution,and the dredging and ecological restoration project has a better effect on the reduction of nitrogen and phosphorus.(2)The survey results of current pollution sources show that the pollution sources in the basin mainly come from point sources and non-point sources.Point source pollution is mainly urban household sewage;non-point source pollution includes urban non-point source and rural non-point source.Among them,rural non-point source pollution comes from rural domestic sewage,rural household garbage,livestock and poultry breeding,agricultural planting,and soil erosion.The point source pollution load is about 3-5 times the non-point source pollution load.Among non-point source pollution,urban non-point source is the main source of COD,accounting for about 83% of the total non-point source pollution.Agricultural planting and urban non-point source contribute significantly to the pollution load of ammonia nitrogen and total phosphorus.Urban non-point source pollution is mainly concentrated in Jiulongpo District,while rural non-point source pollution mainly comes from Dadukou District.(3)Use Qual2 K to construct the water quality model of Jiulongpo section.After parameter calibration and model verification,the goodness of fit is tested.The test results show that the model fits well with the actual situation.Based on the constructed water quality model,with the goal of class IV water quality,the model trial and error method is used to estimate the water environment capacity,and the load reduction calculation is carried out based on the estimated value of pollution load.The results show that the pollution load of ammonia nitrogen and total phosphorus exceeds its water environment capacity.The reduction rate of total phosphorus was once as high as 60-70%,and the average reduction rate of ammonia nitrogen was about 52%;the upstream and downstream COD pollution load does not need to be reduced,and the water After accommodating the pollution load,the environmental capacity has surplus.Only the middle reaches of the river need to be reduced by about 12%.(4)Based on the reduction calculation and the results of previous pollution source investigations,a targeted water quality control plan is proposed,and the accessibility of the water quality target is analyzed through theoretical calculations and model-based model verification.The theoretical calculation results show that the implementation of the measures can be Ensure that the residual pollution load of each river section unit is controlled within the water environment capacity;the model verification results also show that the water quality of the section with more serious nitrogen and phosphorus pollution can meet the requirements of class IV water body after the measures are implemented.The above two methods have verified the feasibility of water pollution reduction programs and treatment measures.Based on the above research results,the paper proposes a method system for longterm water quality maintenance and management of urban rivers,combined with pollution source research results,organically integrates the smart water quality monitoring platform with water quality models,and uses the water quality model as a tool for water quality control program research.It can provide powerful methods and theoretical support for the construction of a smart river management platform in the future. |
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