Investigation of transient freshwater storage in island aquifers

Bedekar, Vivek; Memari, S. S.; Clement, T. Prabhakar

doi:10.1016/j.jconhyd.2019.02.004

Cited by 16 publications

(12 citation statements)

References 24 publications

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“…The selected field site is Dauphin Island, a barrier island located to the west of Mobile Bay in Alabama, USA. Further geographical details of this field site are discussed in other published studies (Bedekar et al, a; Chang et al, ). The western end of Dauphin Island has an elongated strip of land, which is approximately 19 km long and about 400 m wide with a total area of 7.6 km 2 .…”

Section: Comparison Of Freshwater Storage Potential In Field‐scale CImentioning

confidence: 98%

“…Since saltwater will intrude from all directions in a circular island, as opposed to just two sides in a linear strip island (Bedekar et al, a; Dose et al, ), one would intuitively expect the island geometry to play a significant role in controlling the rate of intrusion. In order to understand these differences, we simulated the transient location of intruding and receding wedges in a similar type of circular and strip island sand tank models.…”

Section: Comparison Of Transient Saltwater Wedge Transport Dynamics In Lab‐scale Circular and Linear Strip Island Test Problemsmentioning

confidence: 99%

“…Saltwater intrusion is a process where the dense saltwater from the ocean will naturally intrude into groundwater aquifers located along the coastline. In narrow strip islands, the intrusion will occur from two directions, and in some cases, the two wedges could coalesce forming a floating freshwater lens (Bedekar et al, a; Stoeckl et al, ). In circular islands, intrusion will occur radially from all directions pushing the saltwater wedge toward the geometric center.…”

Section: Introductionmentioning

confidence: 99%

“…Noorabadi et al () and Abdoulhalik and Ahmed () completed laboratory experiments and modeling studies to investigate the dynamics of saltwater wedge upconing processes in linear coastal aquifers. Bedekar et al (a) presented an experimental study to investigate the impacts of wet and dry recharges cycles on freshwater storage changes in linear strip islands.…”

Section: Introductionmentioning

confidence: 99%

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Laboratory and Numerical Investigation of Saltwater Intrusion Processes in a Circular Island Aquifer

Memari

Bedekar

Clement

2020

Water Resources Research

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A novel radial flow experimental system to study saltwater intrusion processes in an island aquifer is presented. The study investigated steady state and transient scenarios involving advancing and receding saltwater wedges in a circular island. The experimental results were simulated using the density‐coupled version of the MODFLOW‐USG code. The experimental data along with the model simulation results are employed to develop a new radial benchmark problem for testing density‐coupled models used for simulating saltwater intrusion processes. The experimental data for transient changes in toe position and freshwater storage level indicated an asymmetric pattern where the intrusion time scale is greater than the recession time scale. Numerical experiments were completed to further investigate this asymmetric effect and to intercompare the associated transient transport processes in circular and linear strip islands. We also analyzed the sensitivity of island geometry in controlling the freshwater storage levels under different recharge conditions. Modeling results show that for similar‐sized systems, circular islands are more efficient in storing freshwater than linear strip islands.

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Section: Comparison Of Freshwater Storage Potential In Field‐scale CImentioning

confidence: 98%

Section: Comparison Of Transient Saltwater Wedge Transport Dynamics In Lab‐scale Circular and Linear Strip Island Test Problemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Laboratory and Numerical Investigation of Saltwater Intrusion Processes in a Circular Island Aquifer

Memari

Bedekar

Clement

2020

Water Resources Research

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“…Different from coastal aquifers where seawater intrudes into freshwater from one direction only, seawater intrusion occurs from two directions for narrow strip islands and from all directions for circular islands. Over the past few decades, seawater intrusion in oceanic islands has been extensively investigated in multiple ways, either directly by field observations (e.g., Röper et al, 2013;Post et al, 2019), or indirectly by experimental measurements (e.g., Stoeckl et al, 2015;Bedekar et al, 2019;Memari et al, 2020), numerical simulations (e.g., Lam, 1974;Gingerich et al, 2017;Liu & Tokunaga, 2019), and analytical solutions (e.g., Fetter, 1972;Ketabchi et al, 2014;Lu et al, 2019). Among these, analytical solutions are effective tools to assess the extent of seawater intrusion, despite that they cannot incorporate complex factors (e.g., dispersive mixing and transient oceanic dynamics) (Werner et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Effects of aquifer geometry on seawater intrusion in annulus segment island aquifers

Luo

Kong

Shen

et al. 2021

Preprint

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Abstract. Seawater intrusion in island aquifers is considered analytically, specifically for annulus segment aquifers (ASAs), i.e., aquifers that (in plan) have the shape of an annulus segment. Based on the Ghijben-Herzberg and hillslope-storage Boussinesq equations, analytical solutions are derived for steady-state seawater intrusion for ASAs, with a focus on the freshwater-seawater interface and its corresponding watertable elevation. These analytical solutions, after comparing their predictions with experimental data, are employed to investigate the effects of aquifer geometry on seawater intrusion in island aquifers. Three different geometries of ASA are compared: convergent (smaller side facing the lagoon), rectangular and divergent (larger side facing the sea). The results show that the predictions from the analytical solutions are in well agreement with the experimental data for both recharge events. In addition, seawater intrusion is most extensive in divergent aquifers, and conversely for convergent aquifers. Accordingly, the watertable elevation is lowest in divergent aquifers and highest in convergent aquifers. Moreover, the effects of aquifer geometry on the freshwater-seawater interface and watertable elevation vary with aquifer width and distance to the no-flow boundary. Both a larger aquifer width and distance to the no-flow boundary weaken the effects of aquifer geometry and hence lead to a smaller deviation of seawater intrusion between the three geometries.

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Groundwater mapping and locally engaged water governance in a small island terrain: Case study of Karainagar island, Northern Sri Lanka

Karthiga,

Rameshwaran,

Ketheesan

et al. 2023

World Water Policy

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Groundwater is a vital resource under threat in island communities. Karainagar, a 22 km2 island, is one of seven islands off the coast of Jaffna in Northern Sri Lanka, with its population of just about 11,000 persons, experiences seasonal water shortage, and salinity in groundwater as twin threats impacting on their lives. This paper reports on a 3‐year study (October 2019 to September 2022) to map groundwater dynamics of Karainagar island spatially and seasonally and discusses the patterns revealed in terms of community needs, policy implications, and governance ideas that could already be considered by relevant authorities and citizens jointly. Thirty‐six dug wells used for drinking, domestic, agricultural, and public purposes were selected, and water level, salinity, and pH changes recorded along with daily rainfall. This paper offers a thorough description of the geography, land use, distribution of wells, and water bodies, followed by discussion of the current status of the groundwater in Karainagar island. Year‐to‐year differences in rainfall pattern resulted in different rates of change and range in water level with a corresponding reverse pattern seen in salinity with some exceptions across the island. Cumulative rainfall required to reach full capacity of wells ranged from 652 to 892 mm over the 3 years with an average figure of 739 mm of rain. This implies that any further rainfall during early phase of the main rainy season is potential surface water for storage and runoff. Practices such as unregulated pumping and construction of tube wells are argued to be contributing to increase in salinity levels with health implications for residents. A participatory governance approach that overcomes limitations of the existing institutional approach is proposed. Its success based on broad stakeholder engagement, improved equity, and transparency when supported by adequate policies and village level aquifer monitoring will enable sustainability of groundwater resources in Karainagar.

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Investigation of transient freshwater storage in island aquifers

Cited by 16 publications

References 24 publications

Laboratory and Numerical Investigation of Saltwater Intrusion Processes in a Circular Island Aquifer

Laboratory and Numerical Investigation of Saltwater Intrusion Processes in a Circular Island Aquifer

Effects of aquifer geometry on seawater intrusion in annulus segment island aquifers

Groundwater mapping and locally engaged water governance in a small island terrain: Case study of Karainagar island, Northern Sri Lanka

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