Groundwater (GW) in shallow aquifer is a major source of drinking and irrigation water in Bangladesh. Contamination of GW resulting from inherent composition of aquifer material or from human activities reduces the supply of safe drinking...
moreGroundwater (GW) in shallow aquifer is a major source of drinking and irrigation water in Bangladesh. Contamination of GW resulting from inherent composition of aquifer material or from human activities reduces the supply of safe drinking water, posing a threat to public health and thereby posing a great challenge to water managers and policy makers. However, GW quality maps are helpful for identifying locations that involve the threat of contamination. The present study describes the application of geographic information system (GIS) technology for mapping GW quality in shallow aquifer for drinking and irrigation purposes. A small catchment covering two upazillas (Nawabganj Sadar and Shibganj) located in Nawabganj district under northwest region of Bangladesh has been considered for this study. GIS mapping is generated based on different GW quality parameters of shallow aquifer in the study catchment from a total of 122 monitoring locations collected from Groundwater Hydrology Circle (GWHC) of Bangladesh Water Development Board (BWDB). ArcGISv9.3 software package along with water quality data is used to assess the pollution within the catchment. Locations of monitoring wells used for GW sampling are presented by using their location coordinates in the framework of ArcGIS software. In this study, different water quality indices such as sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium bi-carbonate (RSBC), magnesium adsorption ratio (MAR), Kelly's ratio (KR), total hardness (TH), permeability index (PI), sodium percentage (% Na) defining irrigation water characteristics are calculated. The analysis shows that all the GW quality indices show suitable to moderate values for all 122 monitoring locations except percent sodium (% Na). However, in some locations, the value of % Na is in the doubtful to harmful range. Finally, the GW quality map and indices map are prepared, which delineates different GW zones as desirable or undesirable for drinking and irrigation purposes. The developed spatially integrated drinking water quality map demonstrates that GW in 85 percent of the study area is desirable for drinking and irrigation purposes. By contrast, the produced irrigation water quality map shows that over 95 percent of the study area can be considered suitable for irrigation activities.
