Evaluation of Water Pollution Index using Physicochemical Characteristics in Coastal Water of Sutrapada, Gujarat, India

Abstract

Water quality in coastal environments is influenced by natural processes and human activities, and regular assessment is needed to support sustainable management. This study evaluated the water quality status of the Sutrapada coastal waters, Gujarat, India, using physicochemical characteristics and the Water Pollution Index (WPI). Surface water samples were collected monthly from five sampling stations from June 2025 to January 2026. Fourteen physicochemical characteristics, namely temperature, pH, salinity, dissolved oxygen, biochemical oxygen demand, turbidity, electrical conductivity, total hardness, total dissolved solids, total suspended solids, total solids, ammonia, phosphate and nitrate, were analysed using standard methods and compared with seawater quality standards. The results showed seasonal variation associated with climatic conditions, freshwater inflow, tidal fluctuations and anthropogenic activities. The pollution index values were below unity for most characteristics, including temperature (0.9996), pH (0.9888), salinity (0.9765), dissolved oxygen (0.9996), biochemical oxygen demand (0.8692), turbidity (0.9595), electrical conductivity (0.9860), total hardness (0.6340), total dissolved solids (0.9720), total suspended solids (0.9333), total solids (0.9809) and ammonia (0.7778). However, phosphate (1.0513) and nitrate (1.0551) exceeded unity, indicating nutrient enrichment. The overall WPI value of 0.9356 classified the Sutrapada coastal waters as moderately polluted. The findings provide baseline information for continued water quality monitoring and sustainable coastal management.