Abstract:

ased on representative samples,a comparative study was carried out for seven typical comprehensive water quality assessment methods including single factor assessment method,pollution index method,fuzzy method,grey system method,analytic hierarchy process method,artificial neural network method,water quality identification index method.The study conclusions are:(1) The single factor assessment method selects the worst water quality class of water quality indices to be the comprehensive water quality class,and gives a overemphasizing result.(2) The pollution index method can qualitatively judge whether the comprehensive water quality meets the specified water function objective,but it can’t judge comprehensive water quality class.(3) The other five methods including fuzzy method,grey system method,analytic hierarchy process method,artificial neural network method and water quality identification index method present the nearly identical comprehensive water quality assessment results for the samples of comprehensive water quality class Ⅰ~Ⅴ,which prove the rationality of five methods for comprehensive water quality classⅠ~Ⅴ.(4) For the comprehensive water quality of inferior class Ⅴ,the fuzzy method,grey system method,analytic hierarchy process method,artificial neural network method underestimate the comprehensive water quality,by comparison,the water quality identification index method can give a scientific conclusion due to the consecutive depiction of water quality inferior class Ⅴ.Further,a qualitative and quantitative assessment of class Ⅰ~Ⅴ,inferior class Ⅴ while no blackness and stink,inferior class Ⅴ while blackness and stink,is scientifically and completely achieved based on water quality identification index method. 

Key words: comprehensive water quality assessment, pollution index method, fuzzy method, grey system method, analytic hierarchy process method, artificial neural network method, water quality identification index