Mapping sea water intrusion in coastal area using time-domain electromagnetic method with different loop dimensions

Abstract

Time Domain Electromagnetic (TDEM) method has been widely used in mapping and assessment of groundwater resources and sea water intrusion along coastal alluvial plains. TDEM soundings were used to define aquifer zones in the alluvial aquifer at Al Khoud coastal area in North Oman. The main aquifer zones, composed of clean gravels, clayey gravels, and cemented gravels, could be identified, along with the basal contact of the aquifer. The TDEM data were also used to map the depth to the interface between freshwater and saline-water along the coast. The inland extents and thickness of the saline water intrusion zone were mapped along two sets of TDEM profiles. The depth to the intrusion zone was investigated using different transmitter loop sizes. Quality assurance of the data was done by comparing the resistivity distribution derived from TDEM with the electrical conductivity and resistivity logs from available well logging data in the study area. TDEM proved to be a successful tool for mapping saline zones and fresh water in arid environment with high depth of penetration and speed of field operation.