水质标识指数法的缺陷分析及修正

Defect analysis and correction of water quality identification index

现行的水质标识指数法存在的缺陷包括溶解氧计算有遗漏,数字修约不恰当,水质级别易被误导,评价指标选择不全面。针对以上问题提出建议:(1)增加溶解氧的计算公式;(2)通过单因子水质标识指数小数点后第一位数字9的尾数只舍不入的办法解决因数字修约导致跨水质类别问题;(3)综合水质级别不一定代表水质类别;(4)利用主成分分析法可以弥补综合水质标识指数受单因子指标数量影响的缺陷。选取20年时间间隔的相同监测点位数据进行验证分析,使修正后的水质标识指数法计算方法更为严谨,分析结果更为直观,评价结论更为合理。

The current water quality identification index method had defects including omissions in the calculation of dissolved oxygen,improper revision of figures,misleading water quality grade and incomplete selection of evaluation indexes.Suggestions were made in response to the above issues:(1)Added dissolved oxygen's calculation formula.(2)Solved the problem of cross-water quality categories caused by removing the number after 9 from first digit after decimal point of single factor water quality identification index.(3)Pointed out that the comprehensive water quality level did not necessarily represent the water quality category.(4)It was proposed that the principal component analysis method can be used to make up for the shortcomings of the comprehensive water quality identification index being affected by the number of single factor indicators.At the same time,the same monitoring point data with a 20-year time gap were selected for verification and analysis,so that the revised water quality identification index method calculation method was more rigorous,the analysis results were more intuitive,and the evaluation conclusions were more reasonable.