ASSESSMENT OF WATER QUALITY OF DHEPA AND ATRAI RIVER OF DINAJPUR FOR IRRIGATION AND FISH PRODUCTION

Abstract

River water samples were collected from two rivers (Dhepa and Atrai) of the Dinajpur Sadar Upazilla, Dinajpur, Bangladesh in the months of August, December and April of the year 2014-2015 and analyzed for its quality and suitability for agricultural and aquatic purposes. Analyses were included pH, EC, temperature, dissolved oxygen (DO), alkalinity cations (Ca2+, Mg2+, Na+ and K+ ), anions (Cl- , HCO3 - , PO4 2- and SO4 2- ) and TDS (total Dissolved Solids). Several variables such as SAR (Sodium Adsorption Ratio), SSP (Soluble Sodium Percentage) and hardness were also computed. Overall we found that the river water were acidic to neutral in nature (pH varied from 5.3 to 7.1) and could be suitable for agricultural and aquatic uses. River water samples contained Ca2+, Mg2+ and Na+ as the dominant cations and HCO3 - and Cl- were the dominant anions. According to TDS and SAR value, all samples were classed as “fresh water” and “excellent” categories. The soluble sodium percentage (SSP) of all water was under ‘excellent’ and 'good' classes. All samples were within 'soft' class regarding hardness. Based on SO4 2- , Cland PO4 2- all river water samples were within the 'safe' limit for irrigation. The DO concentration was suitable for fish production but more DO level should be present for all aquatic life especially for fish production. However, water quality parameters of pH, temperature and DO are dominant factors to affect the growth of fish although BOD and Chemical Oxygen Demand (COD) parameters are not meeting the criteria.