Vertical Saltwater Intrusion in Coastal Aquifers Driven by Episodic Flooding: A Review

Cantelon, Julia A.; Guimond, Julia; Robinson, C. E.; Michael, Holly A.; Kurylyk, Barret L.

doi:10.1029/2022wr032614

Cited by 55 publications

(28 citation statements)

References 148 publications

(348 reference statements)

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“…Considering different cases of topography and bathymetry could foster future extensions of this study, for instance, uncovering trends in storm‐surge impacts on diverse atolls worldwide. Yet, overcoming the challenges of this study requires more detailed simulations using actual physical parameters measured on‐site, which are generally inadequate (Cantelon et al., 2022). Therefore, in situ measurements of the hydrogeological parameters of atolls are crucial for a more realistic representation of groundwater flooding on atolls through numerical simulations.…”

Section: Resultsmentioning

confidence: 99%

Groundwater Flooding on Atolls Caused by Storm Surges: Effects of the Dual‐Aquifer Configuration

Tajima,

Brunner,

Liu

et al. 2023

Water Resources Research

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Storm surges associated with tropical cyclones endanger atolls through groundwater flooding, wherein groundwater is discharged from the land surface at elevated sea levels. Atolls are characterised by a ‘dual‐aquifer’ configuration, where recent Holocene sediments unconformably overlie highly permeable Pleistocene limestone creating an interface called a ‘Thurber discontinuity.’ This study aimed to quantitatively analyse how the dual‐aquifer configuration of atolls controls the temporal dynamics of groundwater flooding caused by storm surges. To this end, we ran surface‐subsurface coupled synthetic numerical simulations using the HydroGeoSphere code and compared 12 scenarios with different Thurber discontinuity elevations and hydraulic conductivities of the Pleistocene aquifer (KP). The results showed that the shallower the Thurber discontinuity and the higher the KP, the higher the maximum water depth in the freshwater swamp on the atoll during the storm surge and the longer the flooding duration. Despite the effects of the different dual‐aquifer configurations, the initial water table elevation and salinity distribution were almost identical in all simulation cases. These findings suggest that accurate information on the dual‐aquifer configuration is necessary to evaluate the potential risk of groundwater flooding in atolls accompanying storm surges. Furthermore, the results indicate that groundwater flooding caused by storm surges substantially contributes to cyclone‐driven flooding on atolls, and hence, it should not be neglected in flood predictions to avoid underestimation.This article is protected by copyright. All rights reserved.

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Section: Resultsmentioning

confidence: 99%

Groundwater Flooding on Atolls Caused by Storm Surges: Effects of the Dual‐Aquifer Configuration

Tajima,

Brunner,

Liu

et al. 2023

Water Resources Research

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“…All the data needed to evaluate the results presented in this paper are archived on Borealis (Cantelon et al., 2023; https://borealisdata.ca/dataset.xhtml?persistentId=doi:10.5683/SP3/XQVTSU). For each data type (time domain, frequency domain, and piezometer) a “read me” file explains the files.…”

Section: Data Availability Statementmentioning

confidence: 99%

“…Further, small islands experience more frequent natural disasters, including violent storms, and many are at risk of becoming uninhabitable due to seawater intrusion (SWI) into aquifers (Noy, 2016; Storlazzi et al., 2018). Island aquifer salinization and flushing processes have not been well captured with existing monitoring infrastructure; however, documenting the spatiotemporal scales and drivers of salinization is critical to quantify emerging threats to water security on islands and along continental coastlines worldwide (Cantelon et al., 2022).…”

Section: Introductionmentioning

confidence: 99%

“…Groundwater flow and salinity patterns in coastal aquifers are complex as aquifer dynamics are influenced by hydraulic properties, vegetation, topography, ocean hydrodynamics, hydrometeorology, and coastline morphology across a range of temporal and spatial scales (Housego et al., 2021; Paldor, Frederiks, & Michael, 2022). Much of the scientific literature on SWI focuses on a single driver, such as groundwater pumping (Bear et al., 1999) or rising seas (e.g., Ketabchi et al., 2016), and either lateral or vertical intrusion pathways (Cantelon et al., 2022; Werner et al., 2013). However, different SWI drivers are often interrelated.…”

Section: Introductionmentioning

confidence: 99%

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Morphologic, Atmospheric, and Oceanic Drivers Cause Multi‐Temporal Saltwater Intrusion on a Remote, Sand Island

Cantelon,

Robinson,

Kurylyk

2023

Water Resources Research

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Small‐island populations disproportionately rely on fresh groundwater resources, which are increasingly threatened by salinization from changing ocean and climate conditions. This study investigates island groundwater dynamics and salinization over multiple timescales in response to marine, atmospheric, and morphologic drivers. To address this, new geophysical and hydrological datasets were collected on a remote sand island in the Northwest Atlantic Ocean between 2020‐2022 and compared to historical baseline data from the 1970s.Data reveal saltwater intrusion due to multi‐decadal erosion, seasonal climate patterns, tidal forcing, and episodic flooding from Atlantic hurricanes. Long‐term dune erosion has caused the freshwater lens to thin and become asymmetrical; however, a lagged groundwater response causes the freshwater lens to be in disequilibrium with present island morphology. The maximum vertical lens thickness is seasonally constant, but the lateral transition zone along the coast thickens and moves seaward in spring when the water table is high from precipitation and frequent beach flooding. Groundwater level and electrical conductivity along low‐lying beaches significantly increase following Atlantic hurricanes due to seawater flooding, and reach a maximum of 1.93 m above sea level and 38 mS/cm, respectively. While groundwater levels recover quickly, conductivity (salinity) remains elevated due to the short intervals between winter flood events that outpace freshening from meteoric recharge. Results emphasize the importance of multi‐temporal groundwater dynamics and feedbacks between coastal flooding, erosion, and salinization. Field‐based studies considering multiple drivers and timescales of saltwater intrusion are critical for understanding and managing coastal freshwater resources in an age of rapid environmental change.

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“…Rapid intensification is also linked to the development of higher intensity storms (Benedetto & Trepanier, 2020). Strong winds and low atmospheric pressures in a hurricane drive storm surges that in turn cause coastal flooding (Cantelon et al., 2022), erosion (Leaman et al., 2021), and infrastructure damage (Robertson et al., 2007). The magnitude and extent of coastal flooding caused by hurricanes depends not only on the storm intensity, but also on the timing and speed of the storm (Thomas et al., 2019).…”

Section: Introductionmentioning

confidence: 99%

Local and Remote Storm Surge Contributions to Total Water Levels in the Gulf of St. Lawrence During Hurricane Fiona

et al. 2023

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Post‐tropical Hurricane Fiona generated a large storm surge that resulted in pronounced flooding and coastal erosion in Atlantic Canada in September 2022. In this study we apply a regional barotropic storm surge model in the Gulf of St. Lawrence, a semi‐enclosed sea, to demonstrate a method of evaluating different contributions to the total water levels. These include the surge generated over the ocean, the surge generated by the cyclonic winds over the gulf, and the tides. The results indicate that the highest storm surge occurred in the southeastern region, a combination of locally and remotely generated components. The surge that entered from the ocean was greater than the surge generated over the gulf; however, these were not in phase. To investigate the case where the local and remote surges are coincident, we shift the wind field relative to the timing of the boundary conditions and find the near “perfect storm” with significantly higher storm surge elevations. These findings highlight the importance of basin morphology and storm conditions in controlling the interactions of surge components, and this approach can be applied to simulate a range of storm‐driven hazard outcomes for future extreme events.

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Vertical Saltwater Intrusion in Coastal Aquifers Driven by Episodic Flooding: A Review

Abstract: Fresh groundwater is a critically important resource in coastal zones as it supports the water demands of dense and rapidly growing coastal populations (

Cited by 55 publications

References 148 publications

Groundwater Flooding on Atolls Caused by Storm Surges: Effects of the Dual‐Aquifer Configuration

Groundwater Flooding on Atolls Caused by Storm Surges: Effects of the Dual‐Aquifer Configuration

Morphologic, Atmospheric, and Oceanic Drivers Cause Multi‐Temporal Saltwater Intrusion on a Remote, Sand Island

Local and Remote Storm Surge Contributions to Total Water Levels in the Gulf of St. Lawrence During Hurricane Fiona

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