More than buried valleys: Do tunnel valleys serve as conduits for preferential freshened groundwater flow within the North Sea?
German Research Foundation: 524639242
Principle Investigator: Dr. Arne Lohrberg
Co-Investigators: Dr. Amir Haroon, Prof. Dr. Sebastian Krastel, Prof. Dr. Nils Moosdorf
The role of large subsurface landforms produced during glaciations of the Pleistocene is poorly understood with respect to groundwater flow. In particular, so-called tunnel valleys (TVs) formed beneath ice sheets acted as drainage systems of glacial melt water. Due to their mechanism of formation, the fill of buried TVs often consists of highly permeable sands and gravels in their lower part and fine-grained deposits at their top. Such a configuration promotes their role as preferential flow pathways for groundwater sealed from the Holocene saltwater above. This project aims to better understand the potential of TVs as preferential flow pathways of offshore freshened groundwater in the southeastern North Sea.
Gulf of Corinth Groundwater
RV Meteor Cruise – M196: GEOMAR, HCMR, University of Malta, HIGP
Principle Investigators: Dr. Marion Jegen, Dr. Thomas Müller, Dr. Amir Haroon
In many regions of known OFG occurrences, this lack of spatial understanding materializes from an insufficient database consisting of either point-scale information (e.g. deep boreholes) or spatial information (e.g. geophysical investigations). Few studies exist that effectively combine the point-scale ground-truthing data with regional measurements to adequately constrain the spatial extents of OFG.
Moreover, questions regarding OFG connectivity to its terrestrial counterpart remain largely unanswered. Here, we propose a marine hydrogeological survey at a newly-discovered OFG site within the Gulf of Corinth, Greece. The proposed cruise will acquire electromagnetic and geochemical data to derive the spatial extents of OFG in the region, and understand if this low-salinity anomaly is due to present-day recharge through karstic aquifer system or, alternatively, a remnant of past sea-level low stands.
Adriatic Sea Groundwater
ISMAR – CNR; University of Bologna; GEOMAR; HIGP
Principle Investigators: Dr. Claudio Pellegrini, Prof. Dr. Bruno Campo, Dr. Amir Haroon
Offshore freshened groundwater (OFG) and fresh submarine groundwater discharge (SGD) play significant roles in coastal hydrologic systems. Despite the importance of these offshore groundwater systems and their interactions with onshore systems along global coastlines, a lack of understanding persists due to limitations in geophysical methodologies. Controlled-source electromagnetic (CSEM) techniques are one promising noninvasive avenue for identifying and characterizing OFG and SGD. We introduce SWAN, a low-cost, modular, surface-towed hybrid time-frequency domain CSEM system capable of detecting OFG and SGD up to water depths of 100 m. A field test conducted in the central Adriatic Sea showcased the system’s capabilities at water depths ranging from several tens to approximately 160 m. SWAN’s ability to provide continuous measurements has proven effective in acquiring high-quality data while operating at towing speeds of 2.5 to 3 knots. The system’s data coverage allows for the detection of subsurface resistivity variations to depths of approximately 150–200 m below the seafloor.