Utilizing geographic information system and indexing to evaluate irrigation suitability of groundwater in Kalihati Upazila, Bangladesh

The aim of this research was to evaluate groundwater quality for irrigation in Kalihati Upazila, Bangladesh, a region that is significantly reliant on groundwater for crop development, especially during dry periods. By combining hydrochemical analysis and Geographic Information System (GIS), the research examined the physicochemical attributes and their spatial distribution. Fifteen groundwater samples from various locations were analyzed to measure parameters such as sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), magnesium adsorption ratio (MAR), electrical conductivity (EC), total dissolved solids (TDS), total hardness (TH), Kelly's ratio (KR), permeability index (PI), and potential salinity (PS). The pH of the groundwater ranged between 5.51 and 7.53, indicating slightly acidic to moderately alkaline conditions suited for irrigation. The EC ranged between 115.7 and 458 μS/cm, mostly falling into the "excellent" or "good" categories. Groundwater displayed irrigation suitability with TDS below 182 ppm and low SAR values, but variable RSC and MAR values indicated localized water quality issues. Based on the irrigation water quality index, all samples were within the "permissible" range. However, GIS-generated maps showed disparities in groundwater quality across the study area. Correlation matrices revealed significant links between various factors. Both the Piper and Gibbs diagrams displayed a prevalent Ca-HCO3 groundwater type influenced by geological formations. Overall, the study confirmed groundwater's appropriateness for irrigation while recommending periodic evaluations due to a few uncertainties. In conclusion, the study found that hydrochemical analysis, GIS mapping, and correlation matrices reveal groundwater quality and spatial trends, allowing for sustainable water resource management and agricultural advancement.