Establishment And Application Of Water Environment Security Aeeessment For River Network And Lakes In Taihu Lake Basin

Water Environment Security Assessment is the premise and basis of water environment safety management and regulation.With changes of rivers and lakes which from a single management environment pollution prevention and remediation projects to multiple environmentally safe management combined with hydrology,ecology and water quality,water Environment Security Assessment concepts to be presented and attracted more and more attention.Taihu Lake Basin is a typical plain river network area,river and lake is an important channel for material recycling.It not only provides an important habitat and ecological corridor for the living organisms and also provides effective support for regional social and economic development.But in recent years,the water environment status significantly decreased by human disturbance.In this paper,selected the Taihu Lake Basin Water Environment Security as the main line,cross-viewing from the hydrology,water quality and aquatic ecosystems multidisciplinary and Discussing water safety evaluation theory,methods and practice of the Taihu Lake Basin to complete the environment safety evaluation theory and method for the protection and restoration of water environment.This paper systematically reviews the domestic and international water safety concepts and analysis the connotation of development of water environment safety.On the basis of water quality,hydrology,water ecological surveys and research on the Taihu Lake Basin,we analyze the main problems in Taihu Lake Basin Water Environment Security.From the main problems in the Taihu Lake basin,we studied environmental safety evaluation index system,the evaluation criteria and weighting,evaluation methods and basic procedures.Empirical research of Taihu lake and river basin typical environmental safety assessment carried out in the field investigation and document research.Evaluating the typical of the harsh environmental safety to verify the scientific method and provide theoretical support and practical significance for environmental watershed restoration.The research content and results are summarized as follows:(1)Combined with domestic and foreign scholars on environmental safety,water safety,water safety concept of research evaluation,Analysis of the content of the Taihu Lake Basin Water Environment Security Assessment:Guarantee the physical structure of water-safety,water quality,water quantity sufficient supply,natural ecosystems protected properly,the hydraulic scientific scheduling to ensure a virtuous cycle of water and water-carrying capacity of the environment,national and social interests are not compromised.(2)Based on the connotation of the Taihu Lake Basin Water Environment Security,Analysis the water environment situation and trend from four physical structure,water quality,water ecology and hydrology.Currently the following results threat Taihu Lake Basin:Regional land use types upheaval lead to soil self-purification capacity decreased,degradation of buffering capacity;TP and TN is far more than carrying capacity of water environment capacity.Cyanophyta was the dominant species,structure simplification of benthic invertebrates and large animal community,stain high proportion of species and aquatic vegetation wither away;the ecological water level is difficult to protected by hydrological regulation.(3)Construction of water environment safety index for the program level,the physical structure of the safety,quality of the safety,water ecology safety,hydrology safety guidelines layers of multi-level and multi-factor River-Lake Water Safety Evaluation Index System.riparian buffer strips of vegetation coverage,the artificial channels of coastline length ratio;Water security,including TP,TN,NH3-N,DO,CODMn;Water ecological security,including Shannon-wiener index,Goodnight-Whitley index;Eco-hydrology security,including level guaranteed rate,connectivity.The physical structure of the lake system security includes vegetation cover lakeside buffer zone;Water security,including SD,TP,TN,NH3-N,Chl-a,CODMn;Ecological security including benthic fauna Shannon-wiener index,Goodnight-Whitley index of blue-green algae cells,aquatic vegetation coverage rate;Eco-hydrology security,including elevel guaranteed rate,entrance patency rate.(4)Based on the Taihu Lake Basin riverr-lake water environment safety system,using the background value method,the reference standard method,planning objectives,landscape effect threshold method as an indicator standard determination method,expert scoring method and AHP constructed judgment matrix as weights method,mathematical model method to quantify the data,standardized method as Taihu Lake Basin river-lake water security evaluation methods.determined the security status of the water environment through the water environment safety index(WESI).Water safety state is divided into five levels:insecurity[0,20),unsafe[20,40),the general[40,60),safer[60,80),safety[80,100].(5)Selected Wu Yi canal,Ge Lake to determine the water environment security status,The results showed:Wu Yi canal WESI index was 32.6,the security status of the water environment characterized as unsafe,physical structure and water quality are in a state of insecurity,The main indicators were the ratio of the length of coastline,TN,TP and NH3-N,water ecology and hydrology in general state.Gehu water environment safety index(WESI)was 41.1,physical structure,water quality is in unsafe condition.The main indicators were Lakeside buffer zone of vegetation coverage,TN,TP,water ecology and hydrology were under relatively safe conditions.The results showed that water safety indicator system and assessment method established in this study not only to determine security status of the water environment,identify characteristic factor for carrying out environmental management,but also to provide clear guidance about water environment restoration.