Application Of Improved Nemerow Index Estmation Method Used In The Water Quality Estmation Of The Dongfanghong Wetland

Nemero index estimation is the water quality estimation method recommended in GB/T14848—93,and it is massively applied for its simple calculation,but the calculation results are limited : the estimated values of a single index is not continuous,mutation phenomenon of water quality estimation results exists,the water quality estimation results are smaller,the utilization ratio of water quality classification chart is low.This paper,from the theoretical and practicing aspects,deeply analyzes the existing defects of Nemero index estimation and presents improvement measures by innovatively introducing the piecewise linear interpolation method to make the evaluation factors obtain reasonable values,effectively solving the existing problems and impro ving Nemero index estimation method.The conclusions draws are as follows:(1)The estimated values of a single index can be continuously selected.With the application of piecewise linear interpolation,in the classification range defined by internationa l standard,the measured values of each single index are linearly calculated to obtain the linear estimated values of all the indexes.Within the classification range no fixed value is selected,meanwhile,when the measured values at the classification range boundary varies,the estimated values can be transited smoothly to realize its continual value selection of the single index.(2)Mutation phenomenon of water quality estimation results can be effectively resolved.Since the estimated values of the single index can be continuously selected,its measured values vary slightly at the different classification range boundary,causing no mutation to estimated values,so the mutation phenomenon can be thoroughly resolved.(3)The utilization ratio of water quality classification chart is enhanced.The improved estimation method realizes the even continual distribution of water quality estimation results,whose value ranges are continuously distributed in the water quality estimation classification chart,and for seriously polluted water,worse than V type,can be given estimation values,effectively enhancing the utilization ratio of water quality classification chart.(4)The water quality estimation results are more reasonable.With the reasonable value selection of the single index,the comprehensive estimation values of water quality estimation are corrected,the problem of smaller water quality estimation results with Nemero index estimation is improved and the attribution degree of each estimation index for water quality pollution is objectively calculated,so water quality is reflected more real and the estimation results are more reasonable.Theoretically and practically,it is proved that by introducing piecewise linear interpolation an improved Nemero index estimation is realized,the fundamental problems in the estimation are resolved,and it presents to be scientific and practical.The improved Nemero index estimation is applied to estimate the water quality of Dongfanghong wetland,effectively verifying the scientificalness of the estimation results and reflecting water quality in a more real manner.This paper,under the condition of original calculation complex hardly increasing,introduces a simple and direct method to resolve a series of existing problems of the original method,and the improved method is simple,clear,feasible and effective,providing new ideas for further optimization and improvement of water quality estimation method.