Hydrochemical characteristics and quality assessment of shallow groundwater under intensive agriculture practices in arid region, Qena, Egypt

Abstract

Monitoring groundwater quality and analyzing geochemical processes are very crucial in dry environments, especially in areas with intense agriculture and inadequate irrigation management systems. A total of forty-one groundwater samples were collected from the study area and analyzed for major ions chemistry. The results of the geochemical analyses are used to investigate the geochemical processes and make groundwater assessments. The hydrogeochemical characteristics of the groundwater samples revealed a highly mineralized Na+–Cl− water type, implying that the majority of the samples are chemically unfit for human consumption. Based on the water quality parameters analyzed for the groundwater samples collected in this study, such as sodium adsorption ratio (SAR), soluble sodium percentage (SSP), residual sodium carbonate (RSC), magnesium hazard (MH), permeability index (PI), and Kelley's ratio (KR), the suitability of groundwater samples for irrigation purposes is good to moderately good. Also they may reflect some alkaline hazard threats to the soil as indicated by the SSP and KR. The salinity hazard is recognized as high and expected to increase with the expansion of irrigation; hence, special salinity control management for groundwater in the study area is required. Nitrate is widely recognized as a contaminant in the study area. The nitrate concentrations range from 0.1 to 256.8 mg/L, with more than 30% of the samples exceeding the safe drinking water limit of 50 mg/L. The main concern is that the average nitrate concentration will likely continue to increase in the groundwater of the study area. Groundwater monitoring, in terms of both quality and quantity, is essential for sustainable groundwater management.