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Electromagnetic imaging of Submarine Canyon freshwater plumes

PIs:  A. Paldor and H. Michael (University of Delaware)

co-PIs:  E. Attias (UTIG), A. Harron (HIGP), E. Aharonov (The Hebrew Univ. of Jerusalem), 
A. Lazar (Israel Oceanographic and Limnological Research Institute)


The water cycle in coastal phreatic aquifers is largely unknown across the “white ribbon” transition zone, where groundwater flows from land to the ocean. On a global scale, these subsea aquifers may transport and store vast amounts of freshwater under the ocean, referred to as active Offshore Freshened Groundwater reservoirs (OFGs). Active OFGs are increasingly recognized as prominent worldwide, but their geological/hydrological functioning remains understudied. Besides OFGs’ potential as a renewable source of fresh water, they have a pivotal role in coastal biogeochemical cycles, which impact marine ecological systems.

 Achziv, Israel: The Achziv nearshore area accommodates an active submarine freshwater 


The ESCAPE project focuses on two active OFG systems with distinctly different geologic settings: (1) the Achziv submarine canyon offshore Israel and (2) the offshore West of Hawaii. ESCAPE is a "swapping" methods experiment where we will apply 3D hydrogeological modeling techniques in Hawaii (conducted in Israel in 2016–2018) and 2D marine CSEM Offshore Israel (performed in Hawaii in 2018). We will also collect multiple oceanographic and biogeochemical data from both study locations. ESCAPE aims to elucidate the mechanism of actively transporting terrestrial freshwater to the ocean environment manifested by large-scale freshened plumes in the water column in Israel and Hawaii.


 Survey sites: Israel & Hawaii geologic settings 

A map of the two proposed study sites. In the Israeli site, existing hydrographic surveys (solid green line) conducted by Paldor et al., (2020) mark the thalweg of the Achziv submarine canyon, and the proposed geophysical measurements (dashed pink lines) are further up, along the continental shelf. Existing geophysical measurements (solid pink lines) in the Hawaiian site showed freshened groundwater (Attias et al.,  2020, 2021). Here, we propose to run hydrographic surveys (dashed green lines). For both sites, 3D groundwater models will be designed to support the research cruises and thoroughly study the hydrologic functioning of the two systems.


Achziv shoreline terraces: Parallel to the submarine canyon

Achziv submarine canyon: The map shows the bathymetry with the submarine canyon and the location of the geological cross-section

Achziv submarine Canyon: coastline image taken by a drone


A 2D hydrogeologic model of the Achziv submarine canyon,  Israel (Paldor et al., 2020). Onshore-offshore hydraulic connectivity is facilitated by a subsea confined aquifer (shaded area) that outcrops to the Mediterranean Sea along the Achziv submarine canyon several km offshore.

Simulated salinity in models of equivalent homogeneous and volcanic (representative of the Hawaiian system) coastal aquifers. The continuous and laterally connected features of the volcanic system conduct freshwater offshore, showing the importance of geologic features on the extent of OFG (adapted from Kreyns et al., 2020). Slices are shown from 3D models.

Achziv coastline: Geomorphological features 




 NSF (HS and OCE)-BSF #2426447: Pending 




Cruise location:  Israel (IL) and  Hawaii (HI)

Ship HI: R/V Makani'Aha
Seagoing days: 30 (IL, 2 cruises) & 16 (HI)
Months range: August & March (IL); May (HI)
Years: 2024