Details of the abstract
Title of paper | 3D modeling and inversion of ground-based TEM data, a case study of seawater intrusion on the eastern coast of the Gulf of Aqaba, Jordan |
List of authors | Abu Rajab, J., El-Kaliouby, H., Al Tarazi, E., Al-Amoush, H. |
Affiliation(s) |
The Hashemite University, National Research Center, The Hashemite University, Al al-Bayt University |
Summary | The research describes the ground-based transient electromagnetic (TEM) survey design and modeling/inversion scheme used to recover detailed geoelectrical structures at seawater intrusion in coastal areas. We analyzed the simulated and experimental TEM data along the profile using side-to-side 25 m × 25 m loop dimensions, conducted perpendicular to the coastal line. In addition, a coarse grid of experimental TEM loops of 100 m ×100 m dimensions was also evaluated for deeper investigation in view of the 3D inversion scheme conducted along the coastal area. In our 2D and 3D simulated models, we created multiple simplified geoelectrical structures that approximated seawater intrusion in sandy aquifers while allowing for topographical variations. The transient responses of the saline zone (seawater 1 Ω•m), the mixing zone (brackish water 3 Ω•m) and the fresh zone (freshwater 100 Ω•m) were calculated based on the modified Druskin-Knizhnerman finite-difference algorithm. Modeling of an inclined seawater interface of less than 45° shows subparallel horizontal layering; however, a wedge-like structure becomes more visible at a higher angle. In the presence of two zones (saline and brackish) and three zones (saline, brackish, and fresh), the geometry of inland intrusion is fairly determined using 1D inversion, but the resistivity values among intrusion phases are severely overestimated, and the transient transformation images provide minimum information about intrusion characteristics like depth to boundaries and lateral extension. However, 3D inversion along the TEM profile yields improved geometrical characteristics of intrusion, particularly for resistivity values. A 3D inversion of experimental TEM data distributed along profile and across the seawater interface reveals that resistivity values and interface structure agree much better with the inclined wedge-like structure. A 3D inversion of experimental grid TEM data spread along the seawater interface allows for high contrast at major contacts like brackish water-bearing sediments and saline water-bearing sediments, and the recovered model is comparable to reference sites like total dissolved solids measurements from well data. |
Session Keyword | 3.0 Exploration, Monitoring and Hazards |
File upload |
3.0_3d_modeling_and_inversion_abu rajab_18.pdf
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