城市景观水体水质时空分布特征及其评价方法适用性研究

Study on the Spatial and Temporal Distribution Characteristics of Urban Landscape Water Quality and the Applicability of Evaluation Methods

为探究城市景观湖泊水质特征及其水质评价的适用性方法,以兴庆湖为研究对象,选取5个采样点,根据2018年1月至2020年9月水体逐月pH值及TP、NH_(3)-N、DO、COD浓度监测值,采用单因子评价法、综合水质指数评估法、水质健康综合评估法和熵权-TOPSIS法对兴庆湖水质进行评价。结果表明:兴庆湖水质指标存在时空分布差异,水体进入兴庆湖后,除氨氮外,其他水质指标值增大;pH值春夏两季高于秋冬两季,TP质量浓度夏秋两季高于春冬两季,COD、NH_(3)-N质量浓度秋冬季高于春夏季;4种水质评价方法对兴庆湖水质评价结果有差异,经综合比较分析,熵权-TOPSIS法不受指标数量、数据分布等的限制,减少了主观因素的影响,能准确反映水体水质情况。

In order to explore the water quality characteristics of urban landscape lakes and the appropriate evaluation methods for water qual⁃ity,taking Xingqing Lake as the research object,5 sampling points were selected,and the monthly water quality indexes of pH,TP,NH_(3)-N,DO and COD were monitored from January 2018 to September 2020.The water quality of Xingqing Lake was evaluated by single factor evaluation,WQI,ETI and entropy⁃weight TOPSIS,and the spatial⁃temporal variation characteristics of pH,TP,NH_(3)-N,DO and COD of Xingqing Lake were studied to reveal the water quality changes and driving factors in different periods.The results show that the water quality indexes of the lake are different in spatial and temporal distribution.From the inlet area to the outlet area,the other water quality index values increase except NH3-N.The pH index and TP index values are higher in spring and summer than that in autumn and winter,while the COD index and NH3-N index values are opposite.The results of water quality evaluation of Xingqing Lake by four methods are different,the entro⁃py weight⁃TOPSIS method is not limited by the number of indexes and the distribution of data.It can reduce the influence of subjective factors and accurately reflect the water quality.