Project

SMART - Sustainable Management of Offshore Groundwater Resources

Goal: Groundwater resources in coastal regions are facing enormous stress caused by population growth, increased pollution and climate change, with the recent crisis in Cape Town - a city with 4.5 million inhabitants that just escaped a total shutdown of fresh water supply - being just the latest prominent example. Offshore aquifers (OAs) - freshwater bodies located beneath the seafloor - have been proposed as an alternative source of freshwater. However, there are a number of first-order questions that need to be addressed before OAs can be exploited sustainably. These include a lack of understanding of the location, nature, geometry and architecture of OAs, their connectivity with onshore aquifers, and their evolution in response to potential exploitation and predicted climate change. Here we introduce the project SMART, which will lead to a step change in the methodology used to characterise OAs and in our understanding of how they can be used sustainably. Specifically, we will (1) Develop a best practice guide on how to combine geophysical measurements with geochemical characterisation to detect, characterise and monitor OAs, (2) Quantify the hydrologic budget of OAs, and (3) Predict how OAs will change in response to extraction and sea level rise associated to climate change. SMART will entail a unique integration of innovative concepts and techniques from terrestrial and marine geology, geochemistry, geophysics, and hydrogeology to reach the project objectives. The outcomes of the SMART project will be shared with a wide range of stakeholders via scientific publications, conference communications, website, social media, interviews and press releases, public understanding of science activities, workshops and a best-practice guide. The project will bring together five scientists from GEOMAR and two scientists from the University of Malta (UoM), in addition to four newly appointed junior researchers. This team will conduct the project and build up an international centre for offshore groundwater research. This will increase GEOMAR’s international visibility and puts groundwater research onto GEOMAR’s POFIV agenda as one of the grand challenges that is not being addressed by its present POF program. The cooperation and capacity building activities planned by GEOMAR and UoM include advanced training schools, exchange programs, mutual participation in advisory bodies, joint sessions at international conferences, and joint scientific publications.

Links:

https://smart.geomar.de/home

https://www.geomar.de/en/news/article/suche-nach-grundwasser-im-ozean/

https://www.helmholtz.de/en/current_topics/press_releases/article/artikeldetail/first_selection_phase_for_helmholtz_european_partnering_new_impetus_for_the_european_research_area/

Date: 1 January 2019 - 31 December 2021

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Project log

Amir Haroon
added 3 research items
First reported in the 1960s, offshore freshened groundwater (OFG) has now been documented in most continental margins around the world. In this review we compile a database documenting OFG occurrences and analyze it to establish the general characteristics and controlling factors. We also assess methods used to map and characterize OFG, identify major knowledge gaps, and propose strategies to address them. OFG has a global volume of 1 × 106 km3; it predominantly occurs within 55 km of the coast and down to a water depth of 100 m. OFG is mainly hosted within siliciclastic aquifers on passive margins and recharged by meteoric water during Pleistocene sea level lowstands. Key factors influencing OFG distribution are topography‐driven flow, salinization via haline convection, permeability contrasts, and the continuity/connectivity of permeable and confining strata. Geochemical and stable isotope measurements of pore waters from boreholes have provided insights into OFG emplacement mechanisms, while recent advances in seismic reflection profiling, electromagnetic surveying, and numerical models have improved our understanding of OFG geometry and controls. Key knowledge gaps, such as the extent and function of OFG, and the timing of their emplacement, can be addressed by the application of isotopic age tracers, joint inversion of electromagnetic and seismic reflection data, and development of three‐dimensional hydrological models. We show that such advances, combined with site‐specific modeling, are necessary to assess the potential use of OFG as an unconventional source of water and its role in sub‐seafloor geomicrobiology.
Carbonate lithologies host considerable quantities of the Earth's freshwater resources and partially supply a quarter of the global population with drinkable water. In addition, carbonates constitute substantial amounts of the global coastlines, yet it is not known if and how they can sustain freshened groundwater offshore. Here, we use controlled‐source electromagnetic, seismic reflection, and core sample data to derive a lithological model for the eastern margin of the Maltese Islands and identify four distinct resistivity anomalies within the Upper Coralline and Globigerina Limestone formations. The anomalies hosted in the former are likely associated with low porosities, whereas the anomaly within the latter is indicative of pore fluid freshening. Hydrogeological modeling suggests that freshened pore fluids, emplaced during sea‐level lowstands and preserved in low permeability units, are potentially still found within carbonate shelves. However, resource potential is low due to its relict nature and low permeability host environment.
Aaron Micallef
added a research item
The effects of changes in climate predicted for 2100-reduction in recharge, increase in water demand and sea-level rise-on groundwater volume and saltwater intrusion have been quantified in the Maltese Islands, an archipelago located at the center of the Mediterranean Sea. A three-dimensional density dependent and heterogeneous model, working in transient conditions, was developed based on morphological and geological information. The hydraulic conductivity and porosity of the lithological formations were derived from previous tests and studies conducted on the islands. The complex fault system intersecting the area has also been included in the model. The results show that among the three considered factors affecting groundwater resources, the most significant is the increase in water demand, which is closely followed by the decrease in groundwater recharge. Sea-level rise plays a marginal role. The 80-year simulation period showed that these combined impacts would cause a loss of more than 16% of groundwater volume.
Amir Haroon
added a research item
Electromagnetic (EM) geophysical methods are well equipped to distinguish electrical resistivity contrasts between freshwater-saturated and seawater-saturated formations. Beneath the semi-arid, rapidly urbanizing island of Malta, offshore groundwater is an important potential resource but it is not known whether the regional mean sea-level aquifer (MSLA) extends offshore. To address this uncertainty, land-based alongshore and across-shore time-domain electromagnetic (TDEM) responses were acquired with the G-TEM instrument (Geonics Ltd., Mississauga, Ontario, Canada) and used to map the onshore structure of the aquifer. 1-D inversion results suggest that the onshore freshwater aquifer resides at 4–24 m depth, underlain by seawater-saturated formations. The freshwater aquifer thickens with distance from the coastline. We present 2D and 3D electromagnetic forward modeling based on finite-element (FE) analysis to further constrain the subsurface geometry of the onshore freshwater body. We interpret the high resistivity zones that as brackish water-saturated bodies are associated with the mean sea-level aquifer. Generally, time-domain electromagnetic (TDEM) results provide valuable onshore hydrogeological information, which can be augmented with marine and coastal transition-zone
Bradley A Weymer
added a research item
Groundwater resources in coastal regions are facing enormous pressure caused by population growth and climate change. Few studies have investigated whether offshore freshened groundwater systems are connected with terrestrial aquifers recharged by meteoric water, or paleo-groundwater systems that are no longer associated with terrestrial aquifers. Distinguishing between the two has important implications for potential extraction to alleviate water stress for many coastal communities, yet very little is known about these connections, mainly because it is difficult to acquire continuous subsurface information across the coastal transition zone. This study presents a first attempt to bridge this gap by combining three complementary near-surface electromagnetic methods to image groundwater pathways within braided alluvial gravels along the Canterbury coast, South Island, New Zealand. We show that collocated electromagnetic induction, ground penetrating radar, and transient electromagnetic measurements, which are sensitive to electrical contrasts between fresh (low conductivity) and saline (high conductivity) groundwater, adequately characterize hydrogeologic variations beneath a mixed sand gravel beach in close proximity to the Ashburton River mouth. The combined measurements-providing information at three different depths of investigation and resolution-show several conductive zones that are correlated with spatial variations in subsurface hydrogeology. We interpret the conductive zones as high permeability conduits corresponding to lenses of well-sorted gravels and secondary channel fill deposits within the braided river deposit architecture. The geophysical surveys provide the basis for a discharge model that fits our observations, namely that there is evidence of a multilayered system focusing groundwater flow through stacked high permeability gravel layers analogous to a subterranean river network. Coincident geophysical surveys in a region further offshore indicate the presence of a large, newly discovered freshened groundwater system, suggesting that the offshore system in the Canterbury Bight is connected with the terrestrial aquifer system.
Melly Lupita
added an update
On the 14th of August 2020 the SMART team started a cruise called OMAX (Offshore Malta Aquifer Exploration) in the Mediterranean Sea. OMAX will be carried out on the R/V SONNE. R/V SONNE's worldwide operation is coordinated by the German Research Vessel Coordination Centre at the University of Hamburg. The R/V SONNE will sail from the Port of Emden and come back on the 3rd of October 2020 to the same port. 
During the cruise the scientists will conduct marine geophysics (active source seismology, controlled-source electromagnetics (CSEM)) and marine geochemistry (porewater, sediment, water column) experiments. The purpose of these experiments is to determine the location, geometry and dynamics of offshore groundwater aquifers along the Maltese coast. In addition, the team will also publish the activities and updates from the cruise on OMAX blog (https://www.oceanblogs.org/omax/).
OMAX is the first detailed study of an offshore carbonate aquifer and will lead to a step change in the methodology used to characterize OAs and how they can be used sustainably. OMAX will entail a unique integration of innovative concepts and techniques from terrestrial and marine geology, geochemistry, geophysics, and hydrogeology to reach the SMART project objectives. The data to be acquired within this cruise will serve to address two of the overarching goals of the SMART project, which are: a) To develop a best practice guide on how to combine geophysical measurements with geochemical characterisation to detect, characterise and monitor OAs, and b) To quantify the hydrologic budget of OAs.
As an arid area, groundwater is the only source of freshwater in Malta and the periods of highest demand (e.g., agricultural and tourist seasons) coincide with the periods of lowest recharge from precipitation. Malta is representative for a large part of the Mediterranean coast line, and is also one of the ten poorest countries globally in terms of water resources per inhabitant. OMAX will support the principal aim of the SMART project to enable the Maltese Islands (and other Mediterranean countries) to sustainably use offshore groundwater as an alternative source of freshwater.
 
Melly Lupita
added an update
The results of the discovery of freshwater body off the New Zealand Canterbury coast from MARCAN project have been published in the international journal Nature Communications. MARCAN is a research project that investigates the role of offshore groundwater in the geomorphic evolution of continental margins. Some of the SMART project team also contribute to this project which started in January 2017.
The article for this study can be accessed in the journal Nature Communications through https://www.nature.com/articles/s41467-020-14770-7 and a press release (https://www.geomar.de/de/news/article/trinkwasser-unter-dem-meeresboden/) is also available on GEOMAR website.
 
Melly Lupita
added an update
The SMART Summer School was held on July 1-5, 2019 at the University of Malta Msida Campus. The Summer School aims to provide junior scientists with a comprehensive view on coastal groundwater research. This year, the focus is on using geophysics as a tool to map the location and quantify the geometry and volume of onshore/offshore aquifers as a potential resource to relieve water stress in coastal communities.
The lectures were given by seven professors and researchers from GEOMAR, the University of MALTA, and Texas A&M University. Nine graduate students at either the Master’s or PhD level from different countries and various academic backgrounds participated in this event. Besides classroom lectures, the participants also had a chance to conduct an onshore geophysical survey using an electromagnetic instrument. The field excursion took place in Pembroke, Malta which was chosen to discover how the fault in the site interacted with the groundwater system.
Photos: Bradley Weymer/GEOMAR
 
Bradley A Weymer
added a project goal
Groundwater resources in coastal regions are facing enormous stress caused by population growth, increased pollution and climate change, with the recent crisis in Cape Town - a city with 4.5 million inhabitants that just escaped a total shutdown of fresh water supply - being just the latest prominent example. Offshore aquifers (OAs) - freshwater bodies located beneath the seafloor - have been proposed as an alternative source of freshwater. However, there are a number of first-order questions that need to be addressed before OAs can be exploited sustainably. These include a lack of understanding of the location, nature, geometry and architecture of OAs, their connectivity with onshore aquifers, and their evolution in response to potential exploitation and predicted climate change. Here we introduce the project SMART, which will lead to a step change in the methodology used to characterise OAs and in our understanding of how they can be used sustainably. Specifically, we will (1) Develop a best practice guide on how to combine geophysical measurements with geochemical characterisation to detect, characterise and monitor OAs, (2) Quantify the hydrologic budget of OAs, and (3) Predict how OAs will change in response to extraction and sea level rise associated to climate change. SMART will entail a unique integration of innovative concepts and techniques from terrestrial and marine geology, geochemistry, geophysics, and hydrogeology to reach the project objectives. The outcomes of the SMART project will be shared with a wide range of stakeholders via scientific publications, conference communications, website, social media, interviews and press releases, public understanding of science activities, workshops and a best-practice guide. The project will bring together five scientists from GEOMAR and two scientists from the University of Malta (UoM), in addition to four newly appointed junior researchers. This team will conduct the project and build up an international centre for offshore groundwater research. This will increase GEOMAR’s international visibility and puts groundwater research onto GEOMAR’s POFIV agenda as one of the grand challenges that is not being addressed by its present POF program. The cooperation and capacity building activities planned by GEOMAR and UoM include advanced training schools, exchange programs, mutual participation in advisory bodies, joint sessions at international conferences, and joint scientific publications.
Links: