Evaluation of water quality using water quality index (WQI) and GIS in Beira Lake, Sri Lanka

The impact of anthropogenic disturbances on urban lakes can be significant due to their size, depth, and stagnancy. Increased population, urbanization, and modernization are causing sewage disposal issues and contamination of surface waters bodies. The study established three goals to determine the current state of selected physio-chemical parameters in Beira lake’s surface and deep water. Creating a map to demonstrate the distribution of water quality parameters identifies the correlation between water quality parameters and calculatesthe water quality index. The interpolation map for each parameter was created using the inverse distance weighted (IDW) interpolation method. The weighted arithmetic water quality index approach calculates the water quality index of the Beira lake’s surfaces and deep water. Pearson linear correlation shows the relationship between water quality parameters, including temperature, salinity, pH, electrical conductivity, total dissolved solids, phosphate, nitrate, nitrite, and ammonia. According to the weighted arithmetic WQI technique, it can say that the quality of Beira lake is unfit for drinking and irrigation. It is incredibly polluted and receives an “E†rating. The findings reveal a strong positive relationship between electrical conductivity and salinity and TDS with salinity and electrical conductivity. It can be concluded that Beira lake is in terrible condition and that water treatment will be costly. As a result, immediate action is compulsory to prevent the inflow of contaminated water and restore the lake’s overall water quality.