Suitability of water quality index methods for assessing groundwater quality in the Ganges River basin area

This study considered three different water quality indices (WQIs) for groundwater data collected from the middle-west part of Bangladesh, and the quantitative results were justified with the globally accepted water quality guidelines. It compared the results between the Canadian WQI with the Weighted Average WQI, and the Canadian WQI and Mierels WQI for drinking and irrigation purposes, respectively. The results revealed that the Canadian method categorized water as ‘fair’ quality while the Weighted WQI model results showed ‘unsuitable’ for drinking usage. Besides, the Meireles method showed that the water quality is classified as ‘good’ to ‘excellent’, while the categorization of the groundwater using the Canadian method was ‘fair’ to ‘good’ for the suitability of irrigation. The comparison results of the Canadian method with the Weighted Average technique for drinking, the latter one gave the abnormal results; and pair difference statistics showed the significant negative correlation (r=−0.91) between them. Similarly, the analysis for the two methods (Canadian and Mierels) for irrigation use exhibited that there was no statistical variance between the two techniques at a significant correlation matrix (r=+0.71). The study concluded that the Canadian WQI for drinking and Mierels WQI for irrigation would deliver better results.