Small atoll fresh groundwater lenses respond to a combination of natural climatic cycles and human modified geology

Briggs, Martin A.; Cantelon, Julia A.; Kurylyk, Barret L.; Kulongoski, Justin T.; Mills, A.L.; Lane, John W.

doi:10.1016/j.scitotenv.2020.143838

Cited by 20 publications

(24 citation statements)

References 35 publications

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“…The impacts of seasonal factors on aquifer recovery emphasize the importance of using event-representative recharge for model boundary conditions instead of average recharge conditions to ensure satisfactory representation of antecedent conditions and recovery behavior (Gingerich et al, 2017). These model findings examining the effects of seasonal changes in recharge also have implications for the impact of natural climate oscillations, such as El Niño and La Niña (Briggs et al, 2021), on aquifer recovery.…”

Section: Flushing Processesmentioning

confidence: 99%

“…(e.g., Sherren et al, 2021). For instance, even minor groundwater salinization along the coast can result in the deterioration or transgression of ecosystems (e.g., ghost forests) or crops (Briggs et al, 2021;Guimond & Michael, 2021), and can render fresh groundwater resources unfit for human consumption, forcing the closure of pumping wells for industrial, agricultural, and domestic purposes (Michael et al, 2017). Anthropogenic climate change is driving sea-level rise and changing the frequency, intensity, duration, and spatial extent of extreme coastal storms that already impact thousands of kilometers of coastline annually (Bevacqua et al, 2020;Bhatia et al, 2019;Emanuel, 2013;IPCC, 2021;Kossin, 2018;Peduzzi et al, 2012).…”

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confidence: 99%

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

Cantelon

Guimond

Robinson

et al. 2022

Water Resources Research

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Section: Flushing Processesmentioning

confidence: 99%

mentioning

confidence: 99%

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

Cantelon

Guimond

Robinson

et al. 2022

Water Resources Research

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“…

Residential and commercial activities on small islands are often constrained by the growing stress and needs of freshwater resources due to the lack of natural reservoirs (Yoshimoto et al, 2020). Such situations have been exacerbated in past decades due to climate change and more frequent extreme weather events (Briggs et al, 2021;Chesnaux et al, 2021). Groundwater in surficial coastal aquifers often provides primary freshwater supplies for island inhabitants (Babu et al, 2020;Dose et al, 2014;Stoeckl et al, 2015).

…”

mentioning

confidence: 99%

Analytical Solutions for Fresh Groundwater Lenses in Small Strip Islands With Spatially Variable Recharge

Tang

Yan

Wang

et al. 2021

Water Resources Research

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Groundwater lens may provide the primary freshwater supply for the inhabitants of small islands. The lens profile and volume are sensitive to spatially variable recharge caused by topography, soil type, land cover, evapotranspiration and human activities. We derive analytical solutions based on the sharp‐interface approximation to describe transient and steady‐state lens profiles for spatially variable recharge rates in small strip islands. The derived solutions are validated by a steady‐state solution for simple spatial recharge patterns and numerical simulations. Numerical investigations show that the spatial recharge pattern has a significant impact on the lens profile. For a given constant total recharge, smaller recharge areas or a more concentrated recharge rate can result in a larger lens volume. The volume increase can be over 20% compared with the lens volume of a uniform recharge. For the steady‐state lens profile corresponding to a point recharge, the squared lens thickness peaks at the recharge location and linearly decreases to the boundary, resulting in a triangle shape for the profile of squared lens thickness. Moreover, compared with recharges in other locations, recharge in a small area at the domain center has the greatest impact. Uncertainty analysis can be conveniently implemented based on the derived analytical solution to investigate the lens behavior under spatially variable recharge with uncertainties. Results show that the lens volume tends to have a larger variance for a recharge rate with a higher variance and longer correlation length.

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“…Holocene sediments were divided into 12 model layers: 1-3 layers represent coral clastic medium sand, with the horizontal hydraulic conductivity (K) of 60 m/d; 4-7 layers represent coral clastic gravelly sand, with the horizontal hydraulic conductivity (K) of 110 m/d; 8-12 layers represent coral breccia, with the horizontal hydraulic conductivity (K) of 150 m/d. Pleistocene limestone, which has good permeability because of many pores and dissolution cavities of different sizes, includes 10 model layers (13)(14)(15)(16)(17)(18)(19)(20)(21)(22), and the horizontal hydraulic conductivity (K) is 1000 m/d [26]. The effective porosity (n e ) is 0.25-0.45 and the specific yield (S y ) is 0.1-0.2.…”

Section: Numerical Modelmentioning

confidence: 99%

“…Vincent et al [12] developed a script-based numerical groundwater model of a freshwater lens to evaluate the potable water supply management scenarios. Briggs et al [13] used numerical simulation to research the driving factors of freshwater lens dynamics observed in Palmyra Atoll National Wildlife Refuge from 2008 to 2019. Numerical models have also been used to research the formation, evolution, and dynamic process of freshwater lenses in coral islands [7,[14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Pumping Well Layout Scheme Design and Sensitivity Analysis of Total Critical Pumping Rates in Coral Island Based on Numerical Model

Wang

Shu

et al. 2021

Water

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Groundwater on small coral islands exists in the form of freshwater lenses that serve as an important water resource for local inhabitants and ecosystems. These lenses are vulnerable to salinization due to groundwater abstraction and precipitation variation. Determination of the sustainable yield from freshwater lenses is challenging because the uncertainties of recharge and hydrogeological characteristics make it difficult to predict the lens response to long-term pumping. In this study, nine pumping well layout schemes along a line are designed using the orthogonal experimental design method, and an optimal well layout scheme is determined by multi-index range analysis and comprehensive balance analysis method. The total critical pumping rates of the freshwater lens corresponding to different schemes are calculated by numerical simulation, and the sensitivity of the total critical pumping rates to hydrogeological parameters is analyzed. The results show that the calculation of the total critical pumping rates needs to be combined with the specific well layout scheme with consideration to the length of well screens, the number of wells and the distance between wells. The difference in total critical pumping rates between different schemes can be up to three times. The uncertainty of hydrogeological parameters has a great impact on the total critical pumping rates. Within the range of a 30% reduction in parameters, α and K are the key risk factors of pumping; within the range of a 30% increase in parameters, α, ne and K are the key risk factors; α-ne combined changes had the greatest impact. The management of freshwater lenses and the assessment of sustainable yield will continue to be important tasks for coral islands in the future, and this study can help with the sustainable exploitation of island freshwater lenses.

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Small atoll fresh groundwater lenses respond to a combination of natural climatic cycles and human modified geology

Cited by 20 publications

References 35 publications

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

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

Analytical Solutions for Fresh Groundwater Lenses in Small Strip Islands With Spatially Variable Recharge

Pumping Well Layout Scheme Design and Sensitivity Analysis of Total Critical Pumping Rates in Coral Island Based on Numerical Model

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