Abstract
Groundwater contamination is a major problem in the Gaza Strip. In this study we investigate the groundwater quality in the Dier al-Balah Governorate. Water samples were collected from 19 municipal wells in April 2009 and April 2014 and analyzed for physio-chemical parameters (pH, TDS, Ca2+, Mg2+, Na+, K+, Cl−, SO42–, HCO3− and NO3−). The aim of the research is to determine the groundwater quality and to produce groundwater quality maps using the water quality index (WQI) method and geostatistical analysis. The results show that all water samples are very saline due to the intrusion of Mediterranean seawater in the coastal aquifer. Differences in chemical composition between 2009 and 2014 indicate that about 1% more seawater was mixed with the groundwater in this period. The majority of the observed chemical parameters of all wells are well above the WHO water quality standards and all WQI values indicate that the water quality is problematic. The spatial variation of the WQI scores is modelled by a deterministic component expressing a linear dependence on the distance to the coastline and a stochastic residual described by an exponential variogram with a practical range of 3000 m. The mapping of the WQI scores and derived water quality classes is achieved through regression-kriging. The results indicate that the groundwater in a large area along the coastline is unsuitable for human consumption and comparison of the maps of 2009 and 2014 shows that this region further expanded by about 700 m inland in a period of 5 years. The results of this study are worrying, but they also contribute to a better understanding of the factors that determine the groundwater quality and can help authorities and stakeholders with sustainable development.
Highlights
Groundwater is an important source of fresh water for human consumption, irrigation and industrial use in many countries of the world
Residential, industrial, commercial, agricultural and other anthropogenic activities together with natural conditions often lead to a deterioration in groundwater quality [1,2]
Water quality assessment includes an evaluation of the physical, biological and chemical properties of water in relation to the natural quality, intended use and human effects that can influence the health of aquatic systems [3]
Summary
Groundwater is an important source of fresh water for human consumption, irrigation and industrial use in many countries of the world. Water quality assessment includes an evaluation of the physical, biological and chemical properties of water in relation to the natural quality, intended use and human effects that can influence the health of aquatic systems [3]. More than 90% of the population in the Gaza Strip is dependent on the municipal drinking water network, while the remaining 10% of the population rural areas is dependent on private. The quality of groundwater in the Gaza Strip is influenced by many processes, including return flow from irrigation, wastewater leakage, upconing of underground brine water and sea water intrusion [5,6]. Shomar [4] found that only 10% of the municipal wells meet WHO drinking water standards; in particular the chloride, nitrate and fluoride concentrations are 2–9 times higher than
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