An integrated approach for the identification of potential shallow groundwater zones in west-central Saudi Arabia

Abstract

This study aimed to identify groundwater resources at Harrat Khaybar to meet the increasing demand for groundwater for drinking and other purposes, including agricultural and industrial activities. Aquifers were assigned based on integrated electrical resistivity tomography (ERT) and hydrogeological data. Twenty-three ERT profiles ranging 590–890 m long distributed across Harrat Khaybar were acquired. The ERT data were processed to obtain 2D subsurface geoelectrical sections that indicated a variable depth for groundwater as 6–280 m. To investigate water quality, 69 groundwater samples were collected from intensively pumped wells distributed throughout the Harrat. The depth to groundwater measured in these wells ranged 1.5–80 m. It was concluded that Harrat Khaybar is composed of basaltic lava flows underlain by alluvial deposits, which represent two significant water-bearing formations: sub-basaltic alluvial deposits and basalt flows. The depth to the groundwater abruptly deepened from 1.5 to 80 m in the northeast and southwest directions, which could be due to groundwater-bearing formations dipping in these directions or northwest-orientated tension faults. The groundwater quality was assessed in terms of total dissolved solids (TDS), which ranged from 225 to 8340 mg/l, and a TDS-drilling zone encountered in the western part of the Harrat, the following similar most likely resulted from groundwater mineralization. The concentration of TDS generally decreased toward the east in the groundwater flow direction. The pH (6.5–8.1) of the samples indicated that the groundwater pH meets quality standards for domestic and irrigation purposes. It is concluded that, the application of both methods will be of great benefit to identify the groundwater sources and its quality as well.