Assessment of groundwater quality in Khulna city of Bangladesh in terms of water quality index for drinking purpose

Asif Mahmud,Jagadish Chandra Joardar,Shraboni Sikder

doi:10.1007/s13201-020-01314-z

Abstract

Valuation of water quality index (WQI) is one of the simplest, easily understandable, and efficacious techniques to evaluate the quality and suitability of water for drinking as well as other purposes. This research was aimed to investigate the drinking water quality of tube wells from different areas in Khulna City, Bangladesh, by developing the WQI. Water samples from 59 tube wells were collected from different locations during the pre-monsoon time. pH, electric conductivity (EC), dissolve oxygen (DO), total dissolved solid (TDS), chloride (Cl−), nitrate (NO3−), and total hardness of the collected water samples were analyzed for the calculation of WQI. The mean value for pH, EC, DO, TDS, Cl−1, NO3−, and total hardness was 7.30, 1650 μS/cm, 1.60 mg/l, 1188.7 mg/l, 414.6 mg/l, 0.029 mg/l, and 52.03 mg/l, respectively. The calculated WQI values for individual places were distributed spatially through mapping by using ArcGIS software. Based on the WQI values, the drinking water was categorized into excellent, good, poor, very poor, and unfit for drinking purposes. The calculated WQI values ranged from 40.11 to 454.37 with an average value of 108.94. Among all the groundwater samples, 11.86% were excellent, 54.24% were good, 23.73% were poor, 1.69% were very poor, and 8.47% were unfit for drinking purpose based on WQI. The results showed that the groundwater quality of most of the studied areas of Khulna city could be considered safe and suitable for drinking barring the elevated EC and chloride content in some areas. Since Khulna city is situated in the southwestern part of Bangladesh and gradually approaches toward the base level of the Bay of Bengal which might be the source of salt concentration in the groundwater of Khulna city, Bangladesh.

Highlights

From the dawn of earth to the present, water is one of the essential factors that contribute to sustaining every form of life
water quality index (WQI) depicts the combined effect of different water quality parameters and transfers water quality information to the public and government decision-makers
WQI is a single value to represent the water quality of a source along with decreasing the larger number of parameters into a simple countenance resulting in easy understanding of water quality observing data

Summary

Introduction

From the dawn of earth to the present, water is one of the essential factors that contribute to sustaining every form of life. Due to the growing demand for water worldwide, the assurance of adequate supply of drinking water by maintaining standard water quality has become a significant challenge (Mekonnen and Hoekstra 2016; Sawyer et al 2003). Water and Environment Discipline, Khulna University, Khulna 9208, Bangladesh earth which is used by one-third of the entire world’s population for drinking purposes (Foster and Chilton 2003; Nickson et al 2005). Climate changes, GW recharge, subsurface geochemical reactions, surface water characteristics, geographical locations, atmospheric precipitation, and anthropogenic activities are the most critical factors that affect the quality and quantity of GW directly and indirectly (Collin and Melloul 2003; Kumar et al 2014; Ramakrishnaiah et al 2009). The intrusion of saline water into the coastal area is one of the leading causes responsible for the deterioration of GW quality (Karro et al 2004; Kim et al 2006)

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