FUZZY CLUSTERING ANALYSIS IN WATER QUALITY ASSESSMENT:A CASE STUDY FOR DIANSHAN LAKE,SHANGHAI,CHINA

Water quality assessment has been one of the most important fields in Environmental Impact Assessment(EIA)for federally funded projects.Since 1964,when Horton devised and implemented the first water quality index(WQI),consideration has been placed on the development of index methods:The WQI allows measurement of constituents to be transformed into a common unit eg.the aggregated measuring score on a WQI scale for overall classification.The critical issue for most WQI designers is to know how a WQI can be constructed in a simplistic way so that the right information can be extracted from the measurements,and then to illustrate its spatial variation and changes with time.According to some reviewersofEIA methods,the weighing technique in the EIA processing has not been solved yet,and more powerful methods other than"judgment"need to be identified and tested.This paper presents a method of fuzzy clustering analysis of water quality evaluation for Dianshan Lake,Shanghai,China.Fuzzy clustering analysis may be used whenever a composite classification of water quality incorporating multiple parameters occurs.In such a case,fuzzy clustering analysis may be used as a complement or an alternative for comprehensive assessment of water quality.