Hydrogeophysical Study of Sub-Basaltic Alluvial Aquifer in the Southern Part of Al-Madinah Al-Munawarah, Saudi Arabia

Mohamed Metwaly,Fathy Abdalla,Ayman I Taha

doi:10.3390/su13179841

Abstract

Groundwater is extremely important in a water-scarce country such as Saudi Arabia, where permanent surface water resources are absent. Sustainable and future developments plans are essentially relying on the clear understanding of water resources. To evaluate the water resources in arid countries, the groundwater should be quantified through either traditional or scientifically advanced techniques. Aquifer characteristics, particularly the hydraulic conductivity and transmissivity, are essential for the evaluation the aquifer properties as well as the management and development of groundwater modelling for specific aquifers. The present study aims to evaluate the sub-basaltic alluvial aquifer in the northern part of Harrat Rahat, south of Al-Madinah city, and then estimates the principal aquifer’s hydraulic parameters based on the interpreted 1D resistivity-depth models along the study area. For that, 49 Vertical Electrical Soundings (VES’s) utilizing a Schlumberger electrode array were performed along the southern part of Al-Madinah city. The resistivity of the water-bearing formation, thickness, porosity, hydraulic conductivity, and transmissivity parameters were calculated along the measured longitudinal profile from the interpreted VES data. The estimated porosity, hydraulic conductivity, and transmissivity were achieved along the whole profile with average values of 0.2, 3.5 m/day, and 369.6 m2/day, respectively. The resulting transmissivity values from the VES models were compared with those of previous pumping test measurements carried out in the area and a reasonable correlation between the two data sets was observed. These results indicate that surface geoelectrical resistivity techniques may provide an alternative, rapid, and cost-effective method of estimating the aquifer hydraulic parameters where pumping data is rare or unavailable.

Highlights

Water is one of the essential natural resources for life on earth
Sustainable and future developments plans are essentially relying on the clear understanding of water resources in such arid area the groundwater
As the area is almost covered with basaltic flow from an early volcanic eruption, it is not easy to carry out pumping test measurements to cover the whole area because it is expensive, time consuming, and only shows the information along the borehole location

Summary

Introduction

With increasing the earth populations in arid areas and limited water resources, it is subjected to threat for pollution and over exploitation. Al-Madinah Al-Munwarah is an example of the megacities in Saudi Arabia, where the surface water is scarce, while it is subjected to a water stress consumption due to the rapidly increasing population, either from local migrations or as seasonal visitors (Figure 1) [2]. This forced the governmental authorities to pump out/the fossil groundwater extensively to cover the increasing water demands for agricultural, industrial, and human activities [3].

Methods

Results

Discussion

Conclusion