2D Audio-magnetotelluric (Amt) Data Inversion of the Al-jaww Plain Area (Al-ain, United Arab Emirates) for Groundwater Investigations

Abstract

Abstract The United Arab Emirates (UAE) lies within the arid climate zone due to its low annual rainfall rates. The country’s freshwater is located primarily in shallow groundwater aquifers. Understanding the depth and extent of such aquifers is an important issue for UAE local governments and environmental agencies to ensure water supply needs are met. The hydrogeological conditions of the UAE are strongly related to its topographic features, which are dominated by a mountain range in neighboring Oman on the eastern margin of the Arabian Platform. Alluvial plains, such as the Al-Jaww Plain (eastern Al-Ain city), are an important potential groundwater source for the Al-Ain region. Al-Jaww Plain is a large, flat area consisting of gravel and sand outwashes from the Al-Hajar Mountains. The main objective of this research is to investigate the study area’s electrical resistivity distribution and locate groundwater aquifers. In this research, the audio-magnetotelluric (AMT) method was applied, with measurements from 10 AMT stations recorded along an 11 km east–west profile in Al-Jaww Plain. The AMT method is a high-resolution, non-seismic geophysical technique that measures variations in the Earth's natural electromagnetic fields to detect subsurface electrical resistivity variations at shallow to intermediate depths. A two-dimensional resistivity inversion model was developed for the AMT data from the east–west profile. This model contains three main geo-electrical layers from the surface to 5 km depth, as follows: (1) a shallow layer with low resistivity (0–15 Ohm.m), representing the groundwater aquifer zone from the ground surface to a 1 km depth, (2) a moderately resistive layer (15–250 Ohm.m) beneath the first layer, and (3) the Hawasina Complex (> 250 Ohm.m) beginning at 2.5 km and extending to 5 km. The results of this study will support local government and water agencies to better manage groundwater resources in Al-Ain in the future.