Offshore aquifer systems are known as unconventional sources of potable water around the world, especially on islands and populated coastal regions. CSEM methods are effective tools to explore offshore groundwater bodies since electrical resistivity of sub-seafloor is primarily controlled by pore-water salinity and porosity of the sediments. In the Marine Electromagnetic group, we employ a seafloor towed system consisting of a transmitter dipole and several electric field receivers (three to five receiving units) to acquire CSEM data to investigate offshore groundwater systems.

In addition to 1-dimensional and 2-dimensional (Figure 1) inversion methods, we implement a trans-dimensional Bayesian inversion algorithm to assess electrical resistivity probability density and consequently to estimate uncertainty of pore-water salinity. This approach enables us to evaluate hydrogeological model parameters with their uncertainties by generating an ensemble of models (Figure 2).

SMART

MARCAN

TAN1703

RV Hercules

SO277

Aaron Micallef, Mark Person, Christian Berndt, Claudia Bertoni, Denis Cohen, Brandon Dugan, Rob Evans, Amir Haroon, Christian Hensen, Marion Jegen, Kerry Key, Henk Kooi, Volker Liebetrau, Johanna Lofi, Brian J. Mailloux, Renée Martin‐Nagle, Holly A. Michael, Thomas Mueller, Mark Schmidt, Katrin Schwalenberg, Elizabeth Trembath‐Reichert, Bradley Weymer, Yipeng Zhang, Ariel T. Thomas (2020). Offshore freshened groundwater in continental margins, Reviews of geophysics, doi.org/10.1029/2020RG000706.

Amir Haroon, Andrei Swidinsky, Sebastian Hölz, Marion Jegen, Bülent Tezkan (2020). Step-on versus step-off signals in time-domain controlled source electromagnetic methods using a grounded electric dipole, Geophysical Prospecting, doi.org/10.1111/1365-2478.13016.

Bradley Weymer, Phillipe Wernette, Mark Everett, Potpreecha Pondthai, Marion Jegen, Aaron Micallef (2020). Multi-layered high permeability conduits connecting onshore and offshore coastal aquifers. Frontiers in Marine Science, 7, 531293.  doi.org/10.3389/fmars.2020.531293.

Potpreecha Pondthai, Mark Everett, Aaron Micallef, Bradley Weymer, Zahra Faghih, Amir Haroon & Marion Jegen (2020). 3D Characterization of a Coastal Freshwater Aquifer in SE Malta (Mediterranean Sea) by Time-Domain Electromagnetics. Water 2020, 12, 1566. https://doi.org/10.3390/w12061566

Aaron Micallef, Mark Person, Amir Haroon, Bradley A. Weymer, Marion Jegen, Katrin Schwalenberg, Zahra Faghih, Shuangmin Duan, Denis Cohen, Joshu J. Mountjoy, Susanne Woelz, Carl W. Gable, Tanita Averes & Ashwani Kumar Tiwari. 3D characterisation and quantification of an offshore freshened groundwater system in the Canterbury Bight. doi.org/10.1038/s41467-020-14770-7.

Amir Haroon, Klaus Lippert, Vladimir Mogilatov, Bülent Tezkan (2018). First application of the marine differential electric dipole for groundwater investigations: A case study from Bat Yam, Israel. Geophysics 83(2), pg. B59–B76. https://doi.org/10.1190/geo2017-0162.1