Groundwater vulnerability, water quality, and risk assessment in a semi-arid region: a case study from the Dier al-Balah Governorate, Gaza Strip

Groundwater pollution threatens human health in the Gaza Strip as most of the residents use groundwater as drinking water in the Gaza Strip; hence, groundwater is one of the most precious natural resources in the Gaza Strip. The quantity and quality of available groundwater vary spatially and temporally and are influenced by multifaceted natural and anthropogenic factors, including climate, hydrogeology, management practices, pollution, etc. In this study, the groundwater vulnerability to contamination is derived by applying the DRASTIC methodology in the Dier al-Balah Governorate. Almost 85% of the study area is moderately vulnerable to contamination. Moreover, we investigated the groundwater quality in the Dier al-Balah Governorate. Water samples were collected from 19 municipal wells in April 2014 and analysed for physicochemical parameters (pH, TDS, Ca2+, Mg2+, Na+, K+, Cl-, SO42-, HCO3-, and NO3-). The results depict that all water samples are very saline due to the intrusion of the Mediterranean seawater in the coastal aquifer. More than 52% of the study area has water that is unfit for human consumption, with the rest of the study area with poor and very poor water quality. This research also produces a risk estimate of groundwater contamination based on the study area's vulnerability and water quality class using qualitative-risk assessment. More than 93% of the groundwater in the study area is at high to extreme risk. Hence, groundwater managers, engineers, planners, policymakers, and the concerned authorities can use the outputs of this study to make better-informed judgments to minimise the risk to groundwater.