Integrated Water-Quality Assessment of the Huai River Basin in China

Abstract

The traditional indicator method for water-quality assessment is subjected to uncertainties in assessing water quality and quantity due to different subjective evaluations of the quality and determination of errors in the measured data set. In this study, a water-quality assessment based on the integrated measures of the fuzzy set for water-quality indicators is applied to the Huai River Basin (HRB) in China in order to avoid unnecessary errors. The single-factor method usually overestimates or underestimates the degree of risk of the comprehensive water quality since the class of the water quality is determined based only on the worst indicator. Whereas the fuzzy integrated risk assessment can indicate not only the highest grade of water pollution, but also the possible ranges of water-quality-assessment classification. There is some uncertainty, but this method provides more practical and in-depth indicators than the traditional single-factor method on water pollution risk. The final results, based on the water-quality monitor used in 2006, which collected the most representative and complete data set from 71 sites with 37 indicators in recent years, show that the comprehensive water quality in the HRB falls into Grade V (risky), and almost half of the sampling sites along the HRB have a water-quality grade of V or worse. In addition, the final integrated water-quality risk assessment shown on a geographic information system (GIS) risk map is straightforward and can be easily utilized by management decision makers.