Hydrogeological and Hydrochemical Characterization of Coastal aquifers with Special reference to Submarine Groundwater Discharge in Uttara kannada, Karnataka, India

Submarine groundwater discharges to the coastal ecosystems have been recognised as a source of dissolved chemical substances that cause chemical and ecological effects on sea waters. Groundwater, in many coastal areas, becomes contaminated or at least enriched with a variety of chemical substances and can have higher concentrations of dissolved solids than river water. As a result SGD makes a larger contribution to the ﬂux of dissolved chemical compounds than river run-off. Therefore, the present investigation has been carried out to understand the process of submarine groundwater discharge based on hydrological, hydrogeological and hydrochemical components. Accordingly water balance components were evaluated based on hydrological and hydrogeological investigations. Hydrochemical parameters were also evaluated to understand the impact of seawater intrusion during both pre-monsoon and post-monsoon seasons of 2019. Study revealed that, there are signatures of considerable quantity of submarine groundwater discharge in parts of Honnavara, Kumta, Ankola and Karwar talukas. The influence of seawater in coastal aquifers is quite rare all along the coast of Uttara kannada district which is attributed to high groundwater recharge(15-20%) occurring in catchment areas.

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In-situ radionuclide characterization of a submarine groundwater discharge site at Kalogria Bay, Stoupa, Greece

Journal of Environmental Radioactivity ◽

10.1016/j.jenvrad.2011.08.005 ◽

2012 ◽

Vol 108 ◽

pp. 50-59 ◽

Cited By ~ 23

Author(s):

Christos Tsabaris ◽

Dionisis L. Patiris ◽

Aristomenis P. Karageorgis ◽

George Eleftheriou ◽

Vassilis P. Papadopoulos ◽

...

Keyword(s):

Submarine Groundwater Discharge ◽

Groundwater Discharge ◽

Submarine Groundwater ◽

Discharge Site

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Hydrogeological processes and near shore spatial variability of radium and radon isotopes for the characterization of submarine groundwater discharge

Journal of Hydrology ◽

10.1016/j.jhydrol.2019.124192 ◽

2019 ◽

Vol 579 ◽

pp. 124192 ◽

Cited By ~ 6

Author(s):

Carlos Duque ◽

Karen L. Knee ◽

Christopher J. Russoniello ◽

Mahmoud Sherif ◽

Usama A. Abu Risha ◽

...

Keyword(s):

Spatial Variability ◽

Submarine Groundwater Discharge ◽

Groundwater Discharge ◽

Submarine Groundwater ◽

Near Shore ◽

Radon Isotopes

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Seawater Intrusion into Coastal Aquifers

Water ◽

10.3390/w13192719 ◽

2021 ◽

Vol 13 (19) ◽

pp. 2719

Author(s):

Eyal Shalev

Keyword(s):

Seawater Intrusion ◽

Coastal Aquifers ◽

Submarine Groundwater Discharge ◽

Groundwater Discharge ◽

Climate Variations ◽

Special Issue ◽

Groundwater Exploitation ◽

Major Constraint ◽

Highly Sensitive ◽

Submarine Groundwater

This editorial presents a representative collection of 11 papers presented in the Special Issue on Seawater Intrusion into coastal aquifers. Coastal aquifers are one of the most important water resources in the world. In addition, the natural discharge of freshwater to the sea as submarine groundwater discharge (SGD) has an important role in the ecology of marine environments. The dynamics of seawater and freshwater within coastal aquifers are highly sensitive to disturbances, and their inappropriate management may lead to the deterioration of water quality. In many coastal aquifers, seawater intrusion has become the major constraint imposed on groundwater utilization. Groundwater exploitation and climate variations create dynamic conditions, which can significantly increase seawater intrusion into aquifers and may result in the salinization of wells.

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Technical Note: Groundwater flow modeling in coastal aquifers – the influence of submarine groundwater discharge on the position of the saltwater–freshwater interface

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-12-3753-2015 ◽

2015 ◽

Vol 12 (4) ◽

pp. 3753-3785 ◽

Cited By ~ 2

Author(s):

H. A. Shishaye

Keyword(s):

Submarine Groundwater Discharge ◽

Groundwater Discharge ◽

Analytic Solutions ◽

Technical Note ◽

Flow Modeling ◽

Interface Position ◽

Aquifer Systems ◽

Submarine Groundwater ◽

Interface Location ◽

The Impact

Abstract. An investigation of the impact of submarine groundwater discharge on the position of saltwater–freshwater interface is presented in this manuscript. Two conceptualizations were considered and analyzed using both analytic and numerical techniques, for comparison purposes. The first conceptualization assumes that the tip of the saltwater–freshwater interface occurs at the shoreline, and the second conceptualization allows for the tip to extend off-shore. Analytic solutions exist for both conceptualizations, i.e., Strack (1976) for conceptualization 1 and Bakker (2006) for conceptualization 2. Results from both analytic and numeric analysis for the two conceptualizations are presented. Results from the first conceptualization were found to overestimate the inland distance to the interface toe, compared to the second conceptualization, for it ignores the influence of submarine groundwater discharge on the interface location. Moreover, results from the analytic solutions as a whole were found to overestimate the interface location compared to the numerical modeling results, for analytic solutions are based on the sharp interface approximations. Therefore, an empirically derived dispersion factor should be used to correct the analytic solution results so as to compare them with the numerically simulated values. Furthermore, offshore model extents should be incorporated when modeling coastal aquifer systems to include the influence of submarine groundwater discharge on the saltwater–freshwater interface position.

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Saltwater Intrusion and Submarine Groundwater Discharge: Acceleration of Biogeochemical Reactions in Changing Coastal Aquifers

Frontiers in Earth Science ◽

10.3389/feart.2021.600710 ◽

2021 ◽

Vol 9 ◽

Author(s):

Willard S. Moore ◽

Samantha B. Joye

Keyword(s):

Sea Level ◽

Coastal Aquifers ◽

Submarine Groundwater Discharge ◽

Saltwater Intrusion ◽

Groundwater Discharge ◽

Chemical Species ◽

Oxidative Capacity ◽

Fluid Mixture ◽

Submarine Groundwater ◽

Subterranean Estuaries

Intrusion of saltwater into freshwater coastal aquifers poisons an essential resource. Such intrusions are occurring along coastlines worldwide due largely to the over-pumping of freshwater and sea level rise. Saltwater intrusion impacts drinking water, agriculture and industry, and causes profound changes in the biogeochemistry of the affected aquifers, the dynamic systems called subterranean estuaries. Subterranean estuaries receive freshwater from land and saltwater from the ocean and expose this fluid mixture to intense biogeochemical dynamics as it interacts with the aquifer and aquiclude solids. Increased saltwater intrusion alters the ionic strength and oxidative capacity of these systems, resulting in elevated concentrations of certain chemical species in the groundwater, which flows from subterranean estuaries into the ocean as submarine groundwater discharge (SGD). These highly altered fluids are enriched in nutrients, carbon, trace gases, sulfide, metals, and radionuclides. Seawater intrusion expands the subterranean estuary. Climate change amplifies sea level variations on short and seasonal time scales. These changes may result in higher SGD fluxes, further accelerating release of nutrients and thus promoting biological productivity in nutrient-depleted waters. But this process may also adversely affect the environment and alter the local ecology. Research on saltwater intrusion and SGD has largely been undertaken by different groups. We demonstrate that these two processes are linked in ways that neither group has articulated effectively to date.

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Controls on submarine groundwater discharge in an urbanized bay of the southern Baltic Sea: An isotope and trace metal perspective.

10.5194/egusphere-egu21-2470 ◽

2021 ◽

Author(s):

Catia Milene Ehlert von Ahn ◽

Jan Scholten ◽

Christoph Malik ◽

Peter Feldens ◽

Bo Liu ◽

...

Keyword(s):

Coastal Waters ◽

Water Samples ◽

Coastal Aquifer ◽

Submarine Groundwater Discharge ◽

Surface Sediments ◽

Groundwater Discharge ◽

Water Interface ◽

Mixing Zone ◽

Submarine Groundwater ◽

The Impact

Submarine groundwater discharge (SGD) acts as a source of fresh water and dissolved substances for coastal ecosystems. Evaluation of the actual controls on SGD and corresponding chemical fluxes require a closer understanding of the processes that take place in the mixing zone between SGD and the coastal waters. It is hypothesized that artificial infrastructures, like sediment channeling, may ease the hydrological connection between coastal aquifer and coastal bottom water. The resultant, increase of SGD, changes the residence time in the mixing zone, and thereby, reduces the impact of early diagenesis. The present study focuses on the distribution of SGD, including the characterization of different mixing zones in the urbanized Wismar Bay (WB), southern Baltic Sea. Short sediment cores were retrieved for geochemical porewaters and sediment analyses. Surface sea water samples were collected along across-shore transects in the WB.&#160; Besides major ions, Ba, Fe, and Mn, the water samples were analyzed for nutrients, dissolved inorganic carbon (DIC), stable isotopes (H, O, C, S), and Ra isotopes. Sediments were analyzed for C, N, S, Hg contents as well as reactive components (e.g. Fe, Mn, P) by HCl extractions. Organic matter mineralization rates, DIC, and SO4 fluxes for the sediment-water interface were modeled from porewater profiles. Shallow seismic techniques were applied to identify potential litho-morphological controls on SGD. Geochemical porewater data allow identification of active SGD sites in the WB. In the central part, the freshening of porewaters in the top surface sediments indicates the upward flow of SGD originating from a coastal aquifer. The acoustic profiles show that the bottom sediments in the central bay are under local impact of excavation, reducing the sediment thickness above the coastal aquifer. Overall, the impact of SGD on the coastal water body of the WB is diffuse and promoted by local anthropogenic activity. The water isotope composition of porewaters at this site are close to the local meteoric water line at Warnem&#252;nde (located 50 km east of the WB), suggesting a discharge of relatively modern fresh waters. The (isotope) hydrochemical composition of the fresh water discharging is controlled by water-rock interactions in the aquifer and modulated by intense diagenesis in the brackish surface sediments. Furthermore, the SGD facilitates the upward migration of elements and enhances their fluxes across the sediment-water interface, e.g. DIC concentrations in the fresh groundwater are further enhanced in the mixing zone, indicating that SGD is a potential source of excess CO2 in the investigated coastal waters.The investigations are supported by the DAAD, DFG RTS Baltic TRANSCOAST, KiSnet project, BONUS SEAMOUNT, FP7 EU Marie Curie career integration grant, DAM-MFG, and IOW.

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