Water quality assessment of a tropical river using water quality index (WQI), multivariate statistical techniques and GIS

Abstract

Mahananda River is an important river in India and Bangladesh, as the people of both the countries use the water extensively, without sufficient and reliable information about water qualities and pollution status. The purpose of this study is to evaluate the water quality of the river and to analyse the suitability for drinking, agricultural and industrial uses. This is why this study on the Mahananda River is extremely important for the region. For this study, samples from fourteen sampling stations were collected in pre-monsoon and post-monsoon seasons in 2016 and water quality index (WQI), agriculture and industry-related indices were computed. WQI values designated two sampling stations out of fourteen sampling stations as ‘very bad’ category and another two sampling stations as ‘bad’ category. The pH values of some sampling stations slightly exceeded the upper permissible limit. USSL diagram analysis classified two samples of pre-monsoon season in C2S1 category which indicates a medium salinity and low sodium water. Magnesium hazard values of four sampling stations are above 50% suggesting not suitable for irrigation. However, some indices like sodium per cent, residual sodium carbonate and residual sodium bicarbonate, Kelly’s index, permeability index and potential salinity allow the water for use in irrigation purposes. Langelier Saturation Index and aggressive index values designate the water as moderately aggressive or non-aggressive. Ryznar Stability Index 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.

Quality reassessment using water quality indices and hydrochemistry of groundwater from the Basement Complex section of Kaduna Basin, NW Nigeria

“…The WQI is a remarkable technique that offers a broader outlining of water quality conditions [10,20,21,49,50]. It represents the magnitude that reflects the collective consequence of various physicochemical parameters.…”

“…Concerns about different hydrochemical characteristics consequent of variation in geology and geography are possible and require the application of WQIs [8]. Water quality comprises the esthetic, radiological, biological, chemical, and physical qualities of the water [9,10]. The evaluation of groundwater quality is beneficial owing to increasing demand and degradation of groundwater aquifers in emerging economies and pollutant generation from multiple sources such as industry, agriculture, and urban discharges.…”

“…This enables the appraisal of water quality status. It is easy to comprehend as a single rated parameter [10].…”

“…Individual countries and agencies have incorporated various parameters of water quality to create local WQI. Most of the indices created are built on the American National Sanitation Foundation index [10]. Hydrochemical analysis of groundwater using WQI is widely conducted in many parts of the world.…”

“…Despite the tremendous research works on groundwater quality in Kaduna Basin [25][26][27][28][29][30], these studies are characterized by reports on individual physicochemical elements of water quality, instead of the application of WQI for the appraisal of the quality status of aquifers. Studies around the world are increasingly employing water quality indices [10,11,15,20,22,[31][32][33][34][35][36], for the evaluation of groundwater suitability for drinking. Appraisal of the quality status of groundwater using WQI helps to classify groundwater sources and became an essential topic in third world nations; hence, continuous monitoring of sources of drinking water is important.…”