Evaluation of Water Quality Through Water Quality Index at Sorbhog Beel, a Critical Ecotone Along Indo-Bhutan Boundary

The present study is conducted to assess the water quality of Sorbhog Beel for determining its usability for different activities. In order to understand the overall surface water quality of the Beel, water samples were collected from four sampling stations (S1, S2, S3 and S4) which are located at equal distances from each other. Sampling of the Beel was carried out for a period of one year from December 2020 to November 2021, covering four seasons of the year. Water samples were analyzed for eleven important physicochemical parameters viz. pH, Total Dissolved Solids (TDS), turbidity, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Total Hardness (TH), calcium, magnesium, chloride, nitrate and sulphate. Results of the physicochemical analysis were compared with the standard limits prescribed by Bureau of Indian Standard’s specification for drinking water, which showed that physicochemical parameters at all the four sampling stations were within the permissible limits except for TDS. Parameters except Nitrate displayed significant positive and negative correlation among each other. Based on the calculated values of the physicochemical parameters, Water Quality Index (WQI) value of the Beel ranged between 63.59 in pre monsoon season to 71.14 in monsoon season, indicating that water samples were of ‘poor’ quality throughout the year in all the four stations, with maximum deterioration at station S1. The water of the Beel, therefore, cannot be utilized for drinking purpose without prior treatment, however, it can be used for other purposes such as irrigation and industry.