Study On Comprehensive Control Program And Assessment Method In Laoyunliang River

With the rapid speed of urbanization in China,point source and non-point source pollution discharged into urban water system has increased greatly.In most cities,the constructions of drainage,flood discharge and sewage treatment facilities are seriously lagging behind.Accordingly urban water body is forced to "accept" a lot of pollution load.Because water ecology suffers serious pollution problem,the demand of pollution control and management of urban water environment become more and more urgent.Many types of engineering measurements have been applied to improve water quality of rivers.However,with different applicabilities,construction difficulties and high costs,it is urgent to develop a comprehensive framework to choose appropriate treatment plan considering both economic and remediation goals.This study took Laoyunliang River in the city of Kunming as example.We first built a based on the simulation system of Laoyunliang River and identified main factors of current pollution.Then we selected effective measurements,assessed overall performance,and calculated the total cost with our simulation system.Finally,the alternatives from pareto optimal set of remediation programs were provided for decision-making.This research analyzed pollution condition of the Laoyunliang River based on monitoring data.The results were showed as follows.Firstly,the degree of contamination in the river upstream and midstream were relatively more serious than that in the downstream;and NH4-N was the primary pollutant of the whole river.Secondly,the concentration of CODcr,TN,NH4-N and TP fluctuated in a certain range with no obvious cyclicity.Thirdly,because of drainage system lack of storage capacity,urban runoff resulted from rainfall could bring in impact on the pollutant concentration,with increasing the load flowing into the Dian Lake.Finally,the concentration of TN and NH4-N in tail water from the sewage plant was that were severely higher than the remediation goals.There are four reasons resulting the serious pollution problem of the Laoyunliang River,including no clean water flowing into the upstream,sewage flowing into along the way,severely impact from non-point pollution in rainy season,and the exceeded concentration of TN and NH4-N in tail water from the sewage plant.Parameter estimation and model validation results showed that hydrology and water quality simulation data,which comes from the Regulation Schemes Simulation System of the Laoyunliang River built in this study,matched well with the monitoring data.In the Roofing and Liangyuan Model,value of NS used to compare with the simulation and monitoring of flow was greater than 0.4,and most of them were greater than 0.7;value of RM used to compare with the simulation and monitoring of quality was less than 50% and most of them were less than 35%.In this study,six major measurements were proposed according to four main factors of river pollution.Assessments of single measurement showed that the performance of intercepting sewage,upgrading sewage plants,supplying water,construction of storage tanks,construction of constructed wetlands and construction of ecological river decreased gradually.Program comprehensive evaluations showed that only intercepting sewage,upgrading sewage plants and construction of storage tanks were put forward to definite request in the 136 practical and effective solutions.Based on this evaluation,28 pareto optimal solutions were screened out for decision-makers to choose by their preference in the all river comprehensive remediation programs.