Submarine groundwater discharge (SGD) is considered as an important source of chemical substances to the oceans. Investigations of SGD need to consider varying spatial and temporal scales. They remain a challenge and require the application of different complementary detection and quantification methods. Our study focuses on the identification of fresh SGD (FSGD) in intertidal zones using the Königshafen Bay on the island Sylt, Germany, as an example case. We applied geophysical, remote sensing and in-situ pore water measurements to develop a suitable combination of survey methods for an efficient detection of FSGD. Our results provide detailed information on the occurrence and spreading of FSGD at scales ranging from meters to kilometers. We propose a stepwise approach to identify FSGD in intertidal zones as follows: First, orthophotos from unmanned aerial vehicles (UAVs) can highlight distinct tidal flat features characterized by brighter surrounding sediments and typical plant growth at possible FSGD sites. These can be mapped by large-scale electromagnetic induction (EMI), where possible FSGD patches appear as areas of higher electrical resistivity. Ground penetrating radar (GPR) can then be used to check the possible FSGD patches directly on the surface with high lateral resolution. The deep structure of FSGD can then be explored with Electrical Resistivity Tomography (ERT) on targeted profiles to detect fresh water in the sediment through the zone of increased electric resistivity. Additional Nuclear Magnetic Resonance (NMR) measurements from the surface will help to estimate the water content of the sediments and to distinguish between clay layers and salt water containing sand layers. Finally, the geophysical results are verified by in-situ measurements of pore water salinity. Using this approach, 17 significant areas with FSGD sites in the Königshafen bay could be efficiently identified. These areas have a diameter of 30–60 m and are characterized by increased electrical resistivities of 5 Ωm to 30 Ωm and decreased salinity of 0–10 PSU with respect to the surrounding saltwater-saturated areas.
Erkul E., Wunderlich T., Wilken D., Igel J., Müller-Petke M., Ronczka M., Splith T., Fischer S., Gilfedder B., Böttcher M.E., Ehlert von Ahn C.M., Gründling R., Hoffmann J., Jenner A.-K., Lu E., Oehler T., Rabbel W., Sander L., Scholten J., Schulze F., Moosdorf N. and Mallast U. (2025) Submarine groundwater discharge into a temperate tidal basin: Mapping and characterization by a multi-method and multi-scale approach. 324: 109445. 10.1016/j.ecss.2025.109445
@article{Erkul2025,
Title = {Submarine groundwater discharge into a temperate tidal basin: Mapping and characterization by a multi-method and multi-scale approach},
Author = {Erkul, Ercan and Wunderlich, Tina and Wilken, Dennis and Igel, Jan and Müller-Petke, Mike and Ronczka, Mathias and Splith, Tobias and Fischer, Simon and Gilfedder, Benjamin and Böttcher, Michael Ernst and Ehlert von Ahn, Cátia M. and Gründling, Ralf and Hoffmann, Jasper and Jenner, Anna-Kathrina and Lu, Erman and Oehler, Till and Rabbel, Wolfgang and Sander, Lasse and Scholten, Jan and Schulze, Franz and Moosdorf, Nils and Mallast, Ulf},
Editor = {},
Year = {2025},
Pages = {109445},
Volume = {324},
Doi = {10.1016/j.ecss.2025.109445},
Abstract = {Submarine groundwater discharge (SGD) is considered as an important source of chemical substances to the oceans. Investigations of SGD need to consider varying spatial and temporal scales. They remain a challenge and require the application of different complementary detection and quantification methods. Our study focuses on the identification of fresh SGD (FSGD) in intertidal zones using the Königshafen Bay on the island Sylt, Germany, as an example case. We applied geophysical, remote sensing and in-situ pore water measurements to develop a suitable combination of survey methods for an efficient detection of FSGD. Our results provide detailed information on the occurrence and spreading of FSGD at scales ranging from meters to kilometers. We propose a stepwise approach to identify FSGD in intertidal zones as follows: First, orthophotos from unmanned aerial vehicles (UAVs) can highlight distinct tidal flat features characterized by brighter surrounding sediments and typical plant growth at possible FSGD sites. These can be mapped by large-scale electromagnetic induction (EMI), where possible FSGD patches appear as areas of higher electrical resistivity. Ground penetrating radar (GPR) can then be used to check the possible FSGD patches directly on the surface with high lateral resolution. The deep structure of FSGD can then be explored with Electrical Resistivity Tomography (ERT) on targeted profiles to detect fresh water in the sediment through the zone of increased electric resistivity. Additional Nuclear Magnetic Resonance (NMR) measurements from the surface will help to estimate the water content of the sediments and to distinguish between clay layers and salt water containing sand layers. Finally, the geophysical results are verified by in-situ measurements of pore water salinity. Using this approach, 17 significant areas with FSGD sites in the Königshafen bay could be efficiently identified. These areas have a diameter of 30–60 m and are characterized by increased electrical resistivities of 5 Ωm to 30 Ωm and decreased salinity of 0–10 PSU with respect to the surrounding saltwater-saturated areas.},
}
TY - JOUR
AU - Erkul, Ercan
AU - Wunderlich, Tina
AU - Wilken, Dennis
AU - Igel, Jan
AU - Müller-Petke, Mike
AU - Ronczka, Mathias
AU - Splith, Tobias
AU - Fischer, Simon
AU - Gilfedder, Benjamin
AU - Böttcher, Michael Ernst
AU - Ehlert von Ahn, Cátia M.
AU - Gründling, Ralf
AU - Hoffmann, Jasper
AU - Jenner, Anna-Kathrina
AU - Lu, Erman
AU - Oehler, Till
AU - Rabbel, Wolfgang
AU - Sander, Lasse
AU - Scholten, Jan
AU - Schulze, Franz
AU - Moosdorf, Nils
AU - Mallast, Ulf
TI - Submarine groundwater discharge into a temperate tidal basin: Mapping and characterization by a multi-method and multi-scale approach
PY - 2025
SP - 109445
VL - 324
DO - 10.1016/j.ecss.2025.109445
AB - Submarine groundwater discharge (SGD) is considered as an important source of chemical substances to the oceans. Investigations of SGD need to consider varying spatial and temporal scales. They remain a challenge and require the application of different complementary detection and quantification methods. Our study focuses on the identification of fresh SGD (FSGD) in intertidal zones using the Königshafen Bay on the island Sylt, Germany, as an example case. We applied geophysical, remote sensing and in-situ pore water measurements to develop a suitable combination of survey methods for an efficient detection of FSGD. Our results provide detailed information on the occurrence and spreading of FSGD at scales ranging from meters to kilometers. We propose a stepwise approach to identify FSGD in intertidal zones as follows: First, orthophotos from unmanned aerial vehicles (UAVs) can highlight distinct tidal flat features characterized by brighter surrounding sediments and typical plant growth at possible FSGD sites. These can be mapped by large-scale electromagnetic induction (EMI), where possible FSGD patches appear as areas of higher electrical resistivity. Ground penetrating radar (GPR) can then be used to check the possible FSGD patches directly on the surface with high lateral resolution. The deep structure of FSGD can then be explored with Electrical Resistivity Tomography (ERT) on targeted profiles to detect fresh water in the sediment through the zone of increased electric resistivity. Additional Nuclear Magnetic Resonance (NMR) measurements from the surface will help to estimate the water content of the sediments and to distinguish between clay layers and salt water containing sand layers. Finally, the geophysical results are verified by in-situ measurements of pore water salinity. Using this approach, 17 significant areas with FSGD sites in the Königshafen bay could be efficiently identified. These areas have a diameter of 30–60 m and are characterized by increased electrical resistivities of 5 Ωm to 30 Ωm and decreased salinity of 0–10 PSU with respect to the surrounding saltwater-saturated areas.
ER -
