Classification of water bodies into various classes of water use is a multi-criteria decision-making problem. Water Quality Index (WQI) and Analytic Hierarchy Process (AHP) were successfully used to assess overall water quality, but are not able to evaluate level of acceptability of water for specific use. Our objective is to develop a method of water quality assessment to evaluate the level of acceptability of a water body for specific use and to provide degree of potential effect of individual parameter on its overall quality. Here, AHP was modified and used to rank water bodies based on their quality. Modified AHP gave acceptable ranking of water bodies; but it failed to identify the reasons for what a waterbody got its corresponding rank. Therefore, a new approach of water quality assessment, named ‘Deviation from Standard Quality (DSQ)’ was developed. Calculation of positive or negative deviation from the desired threshold of water quality parameters is the key method of this approach. It denotes whether water could be used directly for the desired purpose or for which parameters and to what extent purification is required. We found inclusion or exclusion of any parameter had low sensitivity in evaluating ranking of the waterbodies by the DSQ method. This method was statistically validated. Empirical validation was done considering the field data obtained from Saraswati sub-watershed, Hugli, West Bengal.
alternative, analytic hierarchy process, deviation, index, parameter, water quality, waterbody, wateruse
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