The Impact of Predicted Climate Change on Groundwater Resources in a Mediterranean Archipelago: A Modelling Study of the Maltese Islands

Biase, Michele De; Chidichimo, Francesco; Maiolo, Mario; Micallef, Aaron

doi:10.3390/w13213046

Cited by 7 publications

(6 citation statements)

References 48 publications

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“…iii. Faults have been shown to play an important role in controlling the groundwater flow regime of the Maltese Islands, primarily by enhancing or slowing down groundwater flow, depending on the flow direction (De Biase et al, 2021). Faults, and their influence on groundwater flow, have not been considered in either of our models.…”

Section: D Modeling Resultsmentioning

confidence: 99%

“…Onshore geological data for the Maltese Islands comprised: (i) a digital elevation model of the entire Maltese archipelago (1 m cell size; acquired during a 5.5 h flight in February 2012 using an IGI LiteMapper 6800 LiDAR system as part of the project "Development of Environmental Monitoring Strategy and Environmental Monitoring Baseline Surveys" funded by ERDF-156), (ii) a surface geological map (Pedley et al, 1976), and (iii) legacy and recent borehole logs (Costain and Messers, 1957;De Biase et al, 2021). Offshore geological data included: (i) multibeam echosounder data acquired offshore the eastern coast of the Maltese Islands during a number of expeditions (Micallef et al, 2013(Micallef et al, , 2019, (ii) >400 km 2 of bathymetric data acquired with a Hawkeye IIb bathymetric LiDAR sensor and an interferometric swath system (Kongsberg GeoSwath), collected as part of the project "Development of Environmental Monitoring Strategy and Environmental Monitoring Baseline Surveys" funded by ERDF-156, (iii) bathymetry from the remaining seafloor derived from EMODnet Bathymetry (https://www.emodnet-bathymetry.eu/), (iv) multichannel seismic reflection profiles, and (v) offshore boreholes and seafloor samples (as described in Micallef et al, 2019;Haroon et al, 2021).…”

Section: Geological Datamentioning

confidence: 99%

“…Such contrast is thought to play an important role in extending freshened groundwater offshore Malta. The Globigerina Limestone formation is actually made up of three members separated by conglomerate beds, so the hydraulic conductivity across the formation can vary by two orders of magnitude (De Biase et al, 2021). The impact of this variation on the extent of OFG is explored with our model.…”

Section: Simulation Scenariosmentioning

confidence: 99%

“…The Maltese Islands, located in the central Mediterranean Sea, are a carbonate archipelago that has the highest population density in Europe and is one of the poorest countries globally in terms of water resources per inhabitant (FAO, 2003). Groundwater supplies ∼50% of the potable water, and >16% of its volume is predicted to be lost due to climate change by 2100 (De Biase et al, 2021). Controlled-source electromagnetic and seismic reflection data from the seafloor offshore the SE of Malta were used to identify resistivity anomalies that were interpreted as indicative of OFG (Haroon et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Sources: DeBiase et al (2021),Haroon et al (2021), andKuang et al (2020). * Average value fromNicholson (2001) andYeh et al (2000).a prescribed concentration of 35 g/L was set for entering fluxes and model calculated concentrations are applied for outcoming water flows.…”

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confidence: 99%

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Past and future evolution of the onshore-offshore groundwater system of a carbonate archipelago: The case of the Maltese Islands, central Mediterranean Sea

et al. 2023

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Offshore freshened groundwater (OFG) is groundwater with a salinity below that of seawater that is stored in sub-seafloor sediments and rocks. OFG has been proposed as an alternative solution to relieve water scarcity in coastal regions and to enhance oil recovery. Although OFG has been documented in most continental margins, we still have a poor understanding of the extent and flow characteristics of OFG systems, and their evolution through time. In view of the general absence of appropriate field data, paleohydrogeological models have been used. The majority of these models are based on 2D approaches, and they rarely consider the future evolution of OFG systems, especially in response to predicted climate change. Here we utilize recently acquired geological, geophysical and hydrogeological data from onshore and offshore the Maltese Islands, and employ 2D and 3D numerical models, to: (i) reconstruct the evolution of the onshore-offshore groundwater system during the last 188 ka, (ii) predict the evolution of the OFG system in response to climate-related changes. We show that the mechanisms emplacing OFG include a combination of active meteoric recharge at present as well as at sea-level lowstands. The Maltese onshore-offshore groundwater system is relatively dynamic, with 23% of groundwater being preserved in the last 18 ka. The control of geology is expressed by the more prevalent distribution of OFG north of the Great Fault, which is associated to the occurrence of low permeability units, and the asymmetry of the groundwater lens during the 18 ka lowstand. A 30% decrease in recharge predicted in the coming 100 years will diminish OFG extent by 38%, whereas sea-level rise will play a negligible role. At present the estimated volume of OFG is 1 km3, which could potentially provide an alternative supply of potable water to the Maltese Islands for 75 years. Exploitation of OFG with minimal salinization of onshore groundwater bodies would require locating pumping wells close to the coast.

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Section: D Modeling Resultsmentioning

confidence: 99%