Assessment of Surface Water Quality using the Water Quality Index(WQI) : A Case Study of the Dharatana River, Bagerhat

It is indisputable that all life forms on Earth are dependent on water for survival. However, water sources such as rivers, lakes, ponds, glaciers, and rainfall are threatened by urbanization, population growth, household refuse, and industrialization. The Dharatana River plays an essential role in meeting the diverse water requirements of the surrounding communities, including those for bathing, irrigation, domestic use, and fishing. However, the rapid expansion of minor industries and poultry farms may threaten the river's water quality. Therefore, a thorough evaluation regarding the river's water quality or various purposes is required. The influx of pollutants has had a significant impact on the Dharatana River, resulting in a progressive decline in its water quality. For data collection, a 10-kilometer segment of the river from Narasingh Datterber to Rastar Mhatha Launch Ghat, five sampling points were established. Monthly water samples collected and analyzed in a laboratory throughout 2022. Twenty water quality parameters, including physical, chemical, and biological aspects, were investigated using standard procedures. Twelve of these parameters were discovered to exceed the Bangladeshi drinking water standards. The purpose of this research is to evaluate the water quality of the Dharatana River by collecting water samples from five sampling sites and analyzing them in a laboratory. Temperature, pH, turbidity, conductivity, and color are some of the twenty water parameters. Other parameters include alkalinity, hardness, TS, TDS, BOD, COD, manganese, TSS, phosphate, nitrite, nitrate, chloride, DO, fecal coliform, and total coliform were among the twelve essential water quality parameters measured. The obtained values of the parameters were compared to WHO Standard and ECR'97 drinkable water standards. Calculating the WQI according to the National Sanitary Foundation (NSF) method, the water quality was evaluated. The correlations between chloride, IDS, and conductivity were identified as significant by the research. This correlation analysis aids in the management and monitoring of water Quality. The 2014 average WQI indicated comparable water quality in both the temporal (12-month) and spatial (5- station) dimensions, with scores near to one another. Five stations along the Dharatana River yielded water samples with WQI values of 66.80, 64.50, 67.80, 68.50, and 65.50 indicatingmoderate water quality. In 2014, the average WQI was 64 based on temporal analysis and 65 based on spatial analysis, indicating similar trends. The river water is undrinkable without purification. While the WQI simplifies complex variables, it is unable to differentiate between sources of pollution. Effective water management strategies are indispensable for enhancing the Dharatana River's water quality and suitability for a variety of purposes