Assessing irrigation water quality in Faridpur district of Bangladesh using several indices and statistical approaches

摘要

Several water quality indices, i.e., salinity hazard (SH), sodium percentage (Na%), sodium adsorption ratio (SAR), permeability index (PI), magnesium hazard (MH), Kelly's ratio (KR) and irrigation water quality (IWQ) indices are applied to assess the irrigation water quality using 60 groundwater samples collected from the study sites. This study reveals that groundwater samples are mainly Ca-MgHCO3 types. The IWQ of groundwater with various classifications are also followed to assess the water suitability for irrigation purposes. Based on IWQ index, it is observed that 68.33% of the water samples (41 locations) belong to high suitability water type, whereas 30% (18 locations) samples exhibit low suitability type for irrigation purposes in the study area. Results of the classification (EC, SH, Na%, SAR, PI, MH, and KR) indicate that groundwater in the study areas are mainly fit for irrigation uses. Besides the above findings, Na+ and Cl- concentrations reveal the positively skewed and are regarded to be extreme. Furthermore, results shows that groundwater mineralization process and rock-water interaction are mainly controlled with bivariate plots of major ions in the study areas. Subsequently, these results are validated using multiple regression models and correlation analysis. The spatial distribution of irrigation indices is carried out by geostatistical modeling. The results of semivariagram model show that most of the irrigation indices have weakly spatial dependence, suggesting agricultural and residential influences. However, it has been expected that this paper helps to give insights for a better management of the groundwater resources for the agricultural purposes in the study area.