Chapter 3 - A comparison between the geochemical properties of coastal, near-shore and offshore groundwater in an arid region: A case study from Kuwait

Abstract

Kuwait is located in an arid region that is characterized by harsh climatic conditions and the absence of natural water resources. To secure its freshwater needs, Kuwait heavily relies on seawater desalination via numerous desalination plants that are erected along the coast of the Arabian Gulf. Though limited in quantity and quality, groundwater is a major source of water for the country that is used for blending with desalinated seawater to make it potable, in irrigating nonedible crops, and in increasing well pressure during oil exploration activities. In an arid country like Kuwait, the interaction between groundwater and seawater is a key factor governing coastal groundwaters. This study was carried out to assess the possible source(s) of the geochemical ions in the coastal groundwater and the adjacent seawater in Kuwait and to draw a comparison between the geochemical properties of both water types. Water samples were collected from seawater along the shore, groundwater, and offshore. The collected samples were analyzed for major ions, trace elements, and other physiochemical parameters. The obtained results indicated that the electrical conductivity values of the collected groundwater samples were higher than those collected from the adjacent seawater at a few locations. The results also showed that, in general, the EC values of the water samples collected from the Kuwait Bay area were higher compared to those collected from the open sea except for water samples collected from the main premise of the Kuwait Institute for Scientific Research (KISR) which could be attributed to perched freshwater discharge that is believed to have resulted from the intense rainfall of the last rainy season of 2020 in Kuwait. The groundwater samples were predominantly Na-Ca-Cl-SO4 type. These results also demonstrate that the Kuwait Bay area is generally influenced by anthropogenic pollution, submarine groundwater discharge, and natural geochemical processes. Statistical analysis of the interrelationship between the ions of the collected seawater and groundwater samples suggests that a correlation is more pronounced in the collected seawater samples compared to groundwater samples, indicating the complex nature of the geochemical processes governing the groundwater system of Kuwait. The obtained results also showed that V, Ni, and Cu were higher in the seawater samples compared to the groundwater samples, while Cr and Zn were lower in the seawater samples compared to the groundwater samples. No distinct trend of the variation in trace metal concentrations could be developed for the seawater samples. The degree of contamination with respect to metals indicated that both groundwater and seawater samples were polluted. However, the impact of pollution was more significant in the near-shore seawater compared to that of the offshore, especially in the Kuwait Bay area.