Combining Resistivity and Aeromagnetic Geophysical Surveys for Groundwater Exploration in the Maghnia Plain of Algeria

Djamel Boubaya

doi:10.1155/2017/1309053

Abstract

The Maghnia plain in western Algeria is filled by Plio-Quaternary and Miocene sediments that rest unconformably on a basement of Jurassic rocks. Electrical sounding (VES), magnetic data, well information, and hydrogeological data have been used to explore for groundwater potential in the Maghnia plain. The interpretation of Schlumberger sounding data was first calibrated with the lithology of available nearby wells. Four geoelectrical layers were identified within the study area. They are a thin near surface topsoil layer with variable resistivities, a moderate resistive aquifer (15–30 ohm-m), a resistive aquifer (40–70 ohm-m), and a conductive clay layer (1–10 ohm-m). Near Sidi Mbarek, the geoelectric section is reduced to three layers: a topsoil layer, a conductive layer corresponding to the Miocene marls, and a deep resistive layer that correlates with the Oxfordian sandstones. The interpretation of VES data and the enhancement techniques of magnetic data enabled the identification of a number of unmapped faults that occur near recharge zones close to adjacent mountains. This study enabled us to study the extension of the known Plio-Quaternary aquifer of the Maghnia plain and to explore the possible existence of a second deep groundwater aquifer in Oxfordian sandstones.

Highlights

The study area (Figure 1) is located in the west of the Maghnia plain close to the Algerian-Moroccan border
This study demonstrates the important contribution of the resistivity and the aeromagnetic techniques as effective geophysical tools for exploring deep aquifers, a principal source of groundwater in the Maghnia plain of western Algeria
The validity of the hydrogeological interpretation of the geophysical data is proved by several agreements between the resistivity distribution with depth and the aquifer characteristics

Summary

Introduction

The study area (Figure 1) is located in the west of the Maghnia plain close to the Algerian-Moroccan border. The Maghnia plain is the eastward extension of the Angad plain in Morocco, with the study area above the transboundary aquifer of the Angad plain [1]. The subsurface Tertiary sedimentary infill, the limit between Miocene and Plio-Quaternary under the Maghnia plain, is not well understood compared with the surface outcrop exposed in the bordering mountains. Knowledge of the subsurface structure of this area is very important for groundwater exploration because an important transboundary Plio-Quaternary aquifer occurs in a graben in the study area. In the remote Maghnia plain near the Algerian-Moroccan border, groundwater aquifers provide the only significant way to store water during rainfall years and make it accessible during drought years for the population in this semiarid region

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Conclusion