GEOSPATIAL ANALYSIS OF EFFECTS OF URBANIZATION ON SURFACE WATER QUALITY OF MAHAWELI RIVER, KANDY CITY, SRI LANKA

Abstract

River water quality can be identified as a factor that has greatly affected the healthy life of both aquatic life and humans. Increased population and industrial activities in urban areas significantly impact the river water quality, resulting in aquatic ecosystem degradation and increased human health risks. In Sri Lanka, urban-induced river water pollution has a significant impact on the drinking water supply, especially in the Mahaweli River which is the longest river in Sri Lanka. Measuring the water quality of the Mahaweli River, which flows through the city of Kandy, has become a pressing need at present. Therefore, this study mainly identifies and assesses the water quality near and of the point source pollution sites in the Kandy city area. Forty water samples were taken from the systematically selected locations in the river to assess the water quality. Seven water quality parameters, such as pH, temperature, acidity, electrical conductivity, total phosphate, total coliform, and dissolved oxygen, were measured. The values obtained were analysed using the Weighted Arithmetic Water Quality Index. The spatial interpolation technique was used for data visualization. The study identifies five major point source sites that adversely affected the water quality of the Mahaweli River. These sites are a site where the Kandy Meda Ela joins the Mahaweli River, where the Piga Oya joins the Mahaweli River, near the Katugastota Railway Bridge, near the Guhagoda Waste Management Site and the Peradeniya Bridge. According to the WQI, the overall water quality of the Mahaweli River is very poor and entirely unsuitable for drinking purposes or other daily activities.