Water Quality And Ecological System Monitoring And Treatment Evaluation Of The Typical Dianchi Urban Rivers

Dianchi lake is one of the most polluted lakes in China.However,the main cause of Dianchi lakepollution is the pollution of inflowing rivers in Dianchi watershed.In order to treat pollution,the government invested heavily in carrying out comprehensive improvement project,especially in the urban inflowing rivers.To researching the effect of the comprehensive improvement project,this thesis selected two typical urban rivers,through one-year tracking investigation and monitoring,analyzed the water quality and water ecological system of urban rivers to response water environment present situation.On the basis of the survey data and the monitoring results and combined with the characteristics of the urban rivers,based on the analytic hierarchy process?AHP?to estiminate the health condition of the rivers.Thus it is more comprehensively and objectively to evaluate the influence of comprehensive improvement project on water ecological restoration,provide a basis for the subsequent treatment of the urban rivers,to ensure the quality of river water environment effectively and continuous improved,and provide experience for the governance of urban inflowing rivers.The research conclusions of this paper are as follows:?1?The water quality and water ecological system of inflowing rivers after been comprehensive treated.Results show that the water quality of Cailian River improved obviously.Compared with 2007,the concentration of CODcr,BOD₅,NH₃-N,TN and TP in lake inlet decreased by 56%,48%,50%,47.5%and 67.6%,the main reach achieved the surface water class IV standard.The species numbers,average density and biomass of zooplankton in Cailian River were 91,812.29 ind/L and 821?g/L respectively;The species numbers,density and biomass of zoobenthos were 14,1008.7 ind/m² and 13.40 g/m² respectively.The results indicate that the comprehensive regulation project brings notable environmental benefit for the treatment of urban rivers.The vegetation coverage rate on both sides reached 51.07%;As Jiancao River,compared with 2008,the concentration of CODcr,BOD₅,NH₃-N,TN and TP decreased by 51.0%,52.8%,54.13%,62.17%and 76.0%;The species numbers,average density and biomass of zooplankton in Jiancao River were 70,3827.4 ind/L and 460?g/L respectively;The species numbers,density and biomass of zoobenthos were 14,1141 ind/m² and 6.09 g/m²respectively.The species numbers of planktonic algae was 109;On both sides the vegetation coverage rate reached 35.12%.?2?The health condition of the rives and suggestions for treatment.Based on the survey data and the monitoring results,combined with the characteristic of urban inflowing rivers in Dianchi watershed,determined the health assessment index structure of type urban rivers,the element layer indexes werewater amount,water quality,riparian zone,river morphology,aquatic organisms and 20 factors.The results show that,the upstream and middle reaches of Cailian River were both in a state of mild lesion,the downstream in a state of severe lesion;the upstream of Jiancao River was in critical condition,middle reaches was under severe lesion,downstream was in a state of mild lesion.The results provide a basis for the subsequent treatment of the two rivers,to ensure the quality of river water environment effectively and continuous improved.