Ecosystem Health Assessment Of Lianhuadang River Basin And Dagang River

Lianhuadang river basin and Dagang River,two major rivers into Western Taihu the lake,are located in Dingshu town of Yixing.Renovation project of intensive livestock and poultry breeding had been implemented to improve the environment of them since 2015.In order to evaluate the effectiveness of the regulation project,The temporal and spatial distribution characteristics of water quality and ecological health assessment of Lianhuadang river basin and Dagang River were studied in this paper.Based on monitoring data of the water quality during 2014-2017,the temporal and spatial variation of water quality in Lianhuadang river basin and Dagang river was studied.The results showed that,the DO and CODMn met Class ? of Surface water environmental quality standard(GB3838-2002).The CODMn was more stable and average concentration was 5.37mg/L in the year,and the DO was obvious with the seasonal variation.The concentration of NH4+-N and TN was 4.19 mg/L,6.72 mg/L.The average concentration of total phosphorus was 0.24 mg/L.After the implementation of the project in 2015,the water quality was gradually improved.Exeept that total nitrogen was still inferior class V,the other indexes met class ?.In space,the water quality of Lianhuadang river basin and downstream Wuxi village were poorer.The water quality of Dagang river were good as a whole.Except for total nitrogen,other indexes meet class ?.The concentration of DO and NH4+-N had obvious seasonal changes.From the upstream to downstream,the water quality gradually deteriorated.Using the multi-index comprehensive evaluation method,16 specific indicators were selected from the five aspects of hydrology,water quality,biology,riparian zone,and river form,and the ecological health evaluation index system for the Lotus Watershed and the Dagang River was constructed,based on existing national standards and related Study the criteria for dividing the selected indicators,use the analytic hierarchy process to determine the weights of each indicator,and combine the concepts of subordination and fuzzy mathematics to establish an ecological health assessment method that is applicable to the Lotus Water System and the Dagang River.The results of the ecological health of the Lianhuadang river basin and the Dagang River indicate that all the sections in the first quarter of 2015 were seriously ill.In June 2015,the whole section of the third quarter was healthy after the rectification of the dredging and intensive livestock and poultry industry,and the 90%section of the fourth quarter reached a healthy state.The evaluation results in 2016 were improved compared with the same period in 2015.On the whole,the ecological health status of Lianhua water system had obvious seasonal changes,and the overall situation was improving year by year.The ecological health status of Dagang River gradually decreased from upstream to downstream,and the membership of health gradually decreased from 0.733 to 0.273.The main factors affecting the chemical integrity of Lianhuadang river basin and Dagang river system are the water quality index TN.The main factors affecting the biological integrity of the lotus sway system are benthic zoobenthos,the high pollution resistant benthic species and the improvement of the condition of the benthic zoobenthos after restoration.The main factors affecting the physical integrity of Lianhua water system are velocity and buffer habitat type.