Water quality has been considered as one of the major challenges in water resource management. The main reason of degradation of water quality over the years is anthropogenic activities. Also, the monitoring of surface water bodies is a tedious as well as expensive process. For the depiction of water quality in simple and easy to understand terminology Water Quality Index (WQI) is found to be one of the widely used tool. It provides a transparent picture of the status of the pollution of a

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... body that is why it has been widely accepted by policy makers as well as other concerned authorities. Many WQI models have been developed throughout the world, using various water quality parameters, different techniques to generate subindices and also involving various mathematical techniques for aggregation of subindices. This paper deals with the comparison of various water quality models-based om number of parameters used, methods to generate subindices, aggregation techniques as well as their application and uses.