Description

The rivers are the major sources of water for drinking, industrial uses, agriculture and other purposes. Anthropogenic influences, geochemical factors, the chemical composition of the river basin and natural processes like interaction of water with lithogenic structure degrade the river water quality. The evaluation of the water quality of freshwater is essential because of the extreme demand and vulnerability to pollution in developing countries and also for the concern of being diminished in the near future. Mahananda River is an important river in India and Bangladesh, as the people of both countries use the water extensively, without sufficient and reliable information about water quality and pollution status. The main objectives that were set for this study are discussed under three sub-categories and the objectives For this study water samples from fourteen sampling stations in each season were collected in pre-monsoon and post-monsoon seasons in 2015 and 2016. Fourteen sediment samples from fourteen sampling stations in two seasons were collected from this hardly researched river and evaluated various aspects through index analysis. WQI values designated two sampling stations S-2 and S-8 out of fourteen sampling stations as 'very bad' category and another two sampling stations S-1 and S-14 as 'bad' category. The pH values of some sampling stations slightly exceeded the upper permissible limit. USSL diagram analysis put the samples either in C1S1 or C2S1 category which indicates a low salinity/low sodium or medium salinity/low sodium type water. Magnesium hazard values of four sampling stations in post-monsoon season in 2016 exceeded the 50% limiting value suggesting not suitable for irrigation. However, some indices like sodium percent (Na%), residual sodium carbonate (RSC) and residual sodium bicarbonate (RSBC), Kelly's index (KI), permeability index (PI) and potential salinity allow the water for use in irrigation purposes. Langelier Saturation Index (LI) and Aggressive Index (AI) values designate the water as moderately aggressive or non-aggressive. Ryznar Stability Index (RSI) values designate the water as 'aggressive' or 'very aggressive' indicating unsuitability for industrial uses. Sampling stations S-1, S-2, S-8 and S-14 need special attention.