A simplified equation of approximate interface profile in stratified coastal aquifers

Rathore, Saubhagya Singh; Tang, Yuening; Lu, Chunhui; Luo, Jian

doi:10.1016/j.jhydrol.2019.124249

Cited by 12 publications

(7 citation statements)

References 21 publications

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“…Due to density differences, fresh groundwater usually floats as a lens above the saltwater in coastal aquifers (Post et al., 2019). An accurate delineation of the lens shape and quantification of its volume and thickness are critical for sustainable groundwater resources management in coastal aquifers (Lu et al., 2009, 2013, 2019; Lu & Luo, 2010; Rathore, Tang, et al., 2020; Yan et al., 2021).…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…Previous analytical studies (Rathore et al, 2019; Strack & Ausk, 2015) adopted the Dupuit‐Forchheimer approximation of horizontal flow to compute an analytical solution for the interface profile in stratified coastal aquifers. Rathore et al (2019) assumed no seepage face ( x = 0, ζ = B ), a common assumption in many analytical studies (e.g., Bear, 2013; Bear & Dagan, 1964), and revealed that the local transmissivity field is the factor governing the interface profile.

x = \frac{1}{α ()(, - Q_{x})} (][, T_{ζ} ()(, y_{cζ} - ζ))

where α [−] is the ratio of the freshwater density to the density difference between seawater and freshwater.…”

Section: Semianalytical Methodsmentioning

confidence: 99%

“…Water Resources Research transmissivity field above the seawater wedge (Rathore et al, 2019), which entails that the region of single density flow (landward of the toe position) and the region under the transition zone are less significant in determining the extent of SWI. To verify this finding, we conduct numerical experiments using realization 1 in Figure 3.…”

Section: Effect Of 2-d Heterogeneity On Swimentioning

confidence: 99%

“…In this study, we present for the first time a semianalytical method to compute the steady interface profile in 2‐D heterogeneous aquifers, which is significantly faster and requires much lower computational effort compared with the variable‐density flow and transport simulations. Our method is based on the insight provided by Rathore et al (2019), that is, the interface profile is governed by the transmissivity field above the interface (local transmissivity field). The proposed method does not offer any insights into mixing because of the assumption of the sharp interface.…”

Section: Introductionmentioning

confidence: 99%

“…Rathore et al (2018) identified a new parameter, transmissivity centroid elevation (TCE), governing the interface toe position and groundwater discharge rate in stratified coastal aquifers. Rathore et al (2019) further derived a concise equation for the interface profile in stratified coastal aquifers by directly applying the Dupuit-Forchhimer approximation at the outset and found that the interface profile is governed by the local centroid elevation and total transmissivity of the flow-domain above the interface. Toller and Strack (2019) extended the comprehensive discharge potential theory from the stratified aquifer (Strack & Ausk, 2015) to vertically varying hydraulic conductivity.…”

Section: Introductionmentioning

confidence: 99%

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A Semianalytical Method to Fast Delineate Seawater‐Freshwater Interface in Two‐Dimensional Heterogeneous Coastal Aquifers

Rathore

Luo

2020

Water Resources Research

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The freshwater-seawater interface is one of the most important regions in coastal aquifer systems, delineating the subsurface into zones with distinct fluid density and biogeochemical properties. Heterogeneity in hydraulic conductivity is inherent to geological formations, resulting in distinct interface profiles. Currently available analytical solutions are limited to homogeneous and stratified aquifers, and numerical simulations of variable-density flow and transport are the only option to characterize the interface in a two-or three-dimensional heterogeneous aquifer. This study presents a novel semianalytical method to fast delineate the steady seawater-freshwater interface in a two-dimensional, confined, heterogeneous aquifer with a constant flux inland boundary and indistinct seepage face at the vertical coastal boundary. The heterogeneous domain is conceptualized as a series of thin columns of stratified aquifers with the horizontal flow in each of them. The proposed approach is based on the concept of local transmissivity parameters and shows high accuracy in the interface delineation. Leveraging the ability to delineate the interface rapidly along with the Monte Carlo approach, we numerically investigate the stochastic behavior of the interface profile. The uncertainty in seawater intrusion is heavily influenced by the degree of heterogeneity and weakly influenced by the scale of heterogeneity. To homogenize the aquifer, we found that geometric mean generally underestimates the seawater intrusion and cannot be used as an effective parameter. We also showed that the near-coast, near-top region of the aquifer is the most influential region and should be characterized at a higher resolution to reduce uncertainties in estimating seawater intrusion.

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Development of groundwater lens for transient recharge in strip islands

Tang

Rathore

et al. 2020

Journal of Hydrology

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A simplified equation of approximate interface profile in stratified coastal aquifers

Cited by 12 publications

References 21 publications

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

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

A Semianalytical Method to Fast Delineate Seawater‐Freshwater Interface in Two‐Dimensional Heterogeneous Coastal Aquifers

Development of groundwater lens for transient recharge in strip islands

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