Situation Assessment Of Water Pollution Control For The Typical Dianchi Inflowing Rivers And Its Follow-up Treatment Scheme Construction

Dianchi is one of the most polluted lakes in China.The main reason of its serious pollution is Dianchi inflowing rivers'(DIRs)pollution.Thus,DIRs' treatment is an important work for water pollution control of Dianchi watershed during the period of 11 th five-year plan.In order to study the influence of projects on water environment quality,two typical different types of DIRs,urban river—Xinyunliang River and suburban combination river—Panlongjiang River,were selected to analyze environmental features after treatment from the respects of water quality,microorganism,sediment and riparian through field investigation and study.On this basis,an evaluate system for river ecology recovery effect was established,and Xinyunliang River and Panlongjiang River were taken as case studies,then proposing targeted solutions.Meanwhile,according to Dianchi watershed features and the evaluate results,a new technology scheme for DIRs treatment was constructed,providing basic data for formulation of technical guide,specification and policy of DIRs' follow-up treatment.The main contents and conclusions are as follows:(1)Analyzing treatment effect of DIRs.The results show that water environment quality of Xinyunliang River and Panlongjiang River has been improved obviously.In Xinyunliang River,the situation of black water and bad smell has been alleviated;biomass,species and density of zoobenthos and plankton have been increased,diversity index has showed growth trend;vegetation coverage reaches to 45.87%,which are all artificial vegetation;concentration of organic matter in sediment has showed increasing trend from upstream to downstream;ecological risk degree of heavy metals are all at lower level,ecological risk degree of Cd has been decreased,which was at highest level before treatment,and Pb become the focus of the treatment in future.In Panlongjiang River,water quality has been reached III class water quality standards;species of zoobenthos and zooplankton are 24 and 95,its Shannon-Weiner diversity index has showed growth trend;phytoplankton species are 117,average density of Chlorophyta is the highest level,and Pyrrophyta is the lowest level,its Margalef diversity index reaches 5.54;vegetation coverage reaches to 71.47%,the artificial vegetation accounting for 93.04%;average concentration of organic matter in sediment is 54mg/L;ecological risk degree of heavy metals are all at lower level,ecological risk degree of Hg has been decreased to lowest level from highest level before treatment,and As become the focus of the treatment in future.(2)Establishing an assessment system for DIRs' ecological restoration effect.Based on comprehensive survey and monitoring results of DIRs,assessment system of ecological restoration effect for DIRs with method of AHP was constructed according to characteristics of the river and treatment projects.This system contains five aspects,including water quality,ecological function,river morphology,hydraulic characteristic and riverside landscape,the evaluation system with 16 detailed index by the actual investigation and expert consultation was establised,which can relatively accurate and objective evaluate river treatment effect.(3)Evaluation and application the assessment system.Comprehensive score of ecological restoration effect of Xinyunliang River is 3.14,its remediation effect is at satisfaction level.Comprehensive score of ecological restoration effect of Xinyunliang River morphology reaches 4.48,which is at great satisfaction level;Comprehensive evaluate scores of hydraulic characteristic,riverside landscape and aquatic organism are 3.67,3.57 and 3.37,which are at satisfaction level;water quality are at acceptable level.Comprehensive evaluate scores of Panlongjiang River is 3.81,its remediation effect is at satisfaction level.The scores of hydraulic characteristic,river morphology and aquatic organism are 4.67,4.56 and 4.07,which are at very satisfaction level.Comprehensive evaluate scores of riverside landscape is 3.85,which is at satisfaction level,and evaluate effect of water quality is at acceptable level.The results show that water quality is the major influencing factor of effect of river ecological restoration,especially total nitrogen.Thus,target suggestions were proposed to solve the problem,including sewage interception,estuarine wetland and sewage advanced purification.Furthermore,water recharging as a common problem for most DIRs treatment,choosing a useful way is the key to solve the problem.(4)Constructing and practising technology scheme for DIRs' treatment.The commonly used treatment technology in different types o f DIRs and concisely screens six main categories(point source,non-point source,sediment,water recharging,water quality repair and ecological restoration)and 14 terms of technologies systems of pollution treatment which are suitable to be applied in DIRs was systemized.The technology scheme includes one generic treatment technologies for point source pollution,four for non-point source pollution,two for water recharging,one for sediment,three for water quality repair and three for ecological restoration.And taking the new technology scheme apply to Xinyunliang River and Panlongjiang River,providing target technology scheme for their follow-up treatment.Meanwhile,combing with the research content,suggestions were proposing to formulate the technical guide,specification and policy for DIRs' follow-up treatment,trying to provide a useful reference and guidance for DIRs' treatment.