Impact of hydrogeological factors on groundwater salinization due to ocean-surge inundation

Yang, Jie; Zhang, Huichen; Yu, Xuan; Graf, Thomas; Michael, Holly A.

doi:10.1016/j.advwatres.2017.11.017

Cited by 38 publications

(28 citation statements)

References 19 publications

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“…Besides the thickness of the unsaturated zone, hydraulic properties of the aquifer, i.e., hydraulic conductivity, and geological heterogeneities also exert control on the recovery of the FWL [22]. For instance, Yang et al [36] conducted a modeling study and showed that a low horizontal permeability and a high vertical permeability increase the aquifer vulnerability during inundation events. Infiltrating seawater may appear as descending saltwater fingers due to density differences between the fresh-and saltwater, causing a rapid downward migration of the intruded saltwater after inundation events resulting in an acceleration of the recovery of the upper parts of the FWL, but a long-lasting deterioration of the deeper parts [22,25,32,33,[37][38][39].…”

Section: Introductionmentioning

confidence: 99%

Modeling the Evolution of a Freshwater Lens under Highly Dynamic Conditions on a Currently Developing Barrier Island

et al. 2019

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The drinking water supply on barrier islands largely depends on freshwater lenses, which are also highly relevant for island ecosystems. The freshwater lens presented in this study is currently developing (since the 1970s) below the very young eastern part of the North Sea barrier island Spiekeroog, the so-called “Ostplate.” Due to the absence of coastal protection measures, formation, shape, and extent of the freshwater lens below the Ostplate are unaffected by human activities but exposed to dynamic changes, e.g., geomorphological variations and storm tides. The main aim of this paper was to reconstruct the evolution of the freshwater lens over several decades in order to explain the present-day groundwater salinity distribution. In addition, the study assessed the impact of geomorphological variations and storm tides on the freshwater lens formation. Detailed field observations were combined with a transient 2-D density-dependent modeling approach. Both field observations and simulations show an asymmetric freshwater lens after ~42 years of formation, whereby the horizontal extent is limited by the elevated dune area. The simulations indicate that the young freshwater lens has nearly reached quasi-steady-state conditions mainly due to the continuous mixing with seawater infiltrating during storm tides, which inhibits further growth of the freshwater lens on the narrow island. The findings further show that (i) a neglection of storm tides results in a significant overestimation of the freshwater lens extent, and (ii) the modeled present groundwater salinity distribution and shape of the freshwater lens are predominantly determined by the position and extent of the elevated dune area at the past ~20 years. Hence, annual storm tides have to be directly implemented into numerical models to explain the groundwater salinity distribution and the extent of young freshwater lenses located in highly dynamic tidal environments.

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Section: Introductionmentioning

confidence: 99%

Modeling the Evolution of a Freshwater Lens under Highly Dynamic Conditions on a Currently Developing Barrier Island

et al. 2019

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“…Leaving out overwash events has negligible impact on the simulated OFGVs because the temporal impacts of these events on the groundwater salinity are likely limited to decades which is beyond the temporal resolution of our SEAWAT modeling approach. However, these events can have a relatively large influence on the inland domain of the local groundwater salinity profiles Yang et al, 2018) and should be considered when building local models with higher temporal resolution. The influence of rivers on groundwater recharge in the inland part of the model domain was also omitted in our study.…”

Section: Seawat Modeling Of Ofgvsmentioning

confidence: 99%

“…In past decades, an increased pressure is observed on both shallow and deep (modern and fossil) inland fresh groundwater resources which results in depletion and quality deterioration (e.g., due to rising salinity), especially in arid regions (Custodio, 2002;Gleeson et al, 2017). These fragile fresh water sources are also threatened by natural hazards such as seawater-overwash events (Yang et al, 2013(Yang et al, , 2018Cardenas et al, 2015;Chui and Terry, 2015;Yu et al, 2016;Gingerich et al, 2017) and sealevel rise (Carretero et al, 2013;Rasmussen et al, 2013;Sefelnasr and Sherif, 2014;Mabrouk et al, 2018), further stressing the need to adjust water management strategies and find potential additional sources of fresh water. According to the latest IPCC report (Masson-Delmotte et al, 2018), the past decade has seen a record-breaking number of such natural disasters (seawater overwash events such as storm surges) while sea-level rise predictions are increasingly alarming (e.g., Pollard and Deconto, 2016).…”

Section: Introductionmentioning

confidence: 99%

Geological Heterogeneity of Coastal Unconsolidated Groundwater Systems Worldwide and Its Influence on Offshore Fresh Groundwater Occurrence

et al. 2020

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Numerous coastal areas worldwide already experience fresh water shortages due to overexploitation and salt water intrusion. Future climate change and population growth will further intensify this threat in more areas in coming decades. Therefore, it is necessary to explore any potential fresh water source, such as offshore fresh groundwater, that could alleviate this fresh water shortage and provide valuable time for adaptation measures implementation and changes in water management strategies. Recent evidence suggests that a disproportionally large portion of human population living in coastal areas relies on groundwater resources stored in underlying unconsolidated groundwater systems. These systems are often very heterogeneous, combining numerous high permeability aquifers interlaid with low permeability aquitards with varying total thickness. This heterogeneity is a major control on the fresh groundwater volume and groundwater salinity distribution within such systems. Thus, the quantification of geological heterogeneity is often the limiting factor when estimating fresh groundwater volumes, both inland and offshore, along the global coastline. To overcome this obstacle, we combine conceptual geological models with available state-of-the-art global datasets to derive a set of geological heterogeneity parameter distributions quantifying geological heterogeneity of coastal unconsolidated groundwater systems (CUGSs) as formed over last 1 Ma. These are then used in an algorithm designed to build synthetic heterogenic parameterizations of CUGSs along the global coastline. These, in turn, provide key input for modeling variabledensity groundwater flow and coupled salt transport to analyze changes in groundwater salinities and offshore fresh groundwater volume (OFGV). Such an analysis is performed over one full glacial-interglacial cycle (the last 0.13 Ma) to account for oscillating sealevel conditions and shifts in coast-line positions and salinity incursions. Our simulation results show a close match between the modeling scenarios and values presented by literature sources demonstrating the potential of the hereby presented methodology to be applied in similar future studies.

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“…The first process (lateral SWI) has been extensively studied over many decades, focusing on the effects of pumping and sea-level rise (e.g., Croucher & O'Sullivan, 1995;Henry, 1959;Huyakorn et al, 1987;Paldor et al, 2019;Volker & Rushton, 1982;Werner et al, 2013). However, the importance of the vertical salinization mechanism has been recognized only recently and the environmental controls on it are investigated in several recent studies (Ataie-Ashtiani et al, 2013;Mahmoodzadeh & Karamouz, 2019;Yang et al, 2013Yang et al, , 2015Yang et al, , 2018Yu et al, 2016). Ataie-Ashtiani et al (2013) solved analytically two scenarios of sea-level rise, with and without considering land surface inundation and the associated vertical infiltration.…”

mentioning

confidence: 99%

“…Yu et al (2016) simulated various types of synthetic topographies and demonstrated the importance of surface characteristics such as connectedness and surface depressions to the impact of a given storm surge on the salinization of coastal aquifers. Yang et al (2018) tested the sensitivity of surge-induced salinization to aquifer characteristics (hydraulic conductivity (K), recharge, anisotropy), and showed that for isotropic aquifers, those with higher K are more vulnerable to vertical salinization in terms of salt penetration depths and flush times. Apart from storm surges, overwash from tsunami events have similar potential to induce vertical salinization.…”

mentioning

confidence: 99%

Storm Surges Cause Simultaneous Salinization and Freshening of Coastal Aquifers, Exacerbated by Climate Change

Paldor

Michael

2021

Water Resources Research

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Nearly half of the world population inhabits coastal environments, and for these communities, groundwater is commonly the primary resource for drinking water. The highly dynamic nature of these settings dictates enhanced vulnerability to both natural and anthropogenic environmental stresses, leading to water scarcity and degradation (Michael et al., 2017). For coastal groundwater resources, the greatest threat is most often salinization due to seawater intrusion. Generally, there are two processes that can introduce seawater into coastal aquifers. The first is lateral saltwater intrusion (SWI) in which the position of the subsurface freshwater-saltwater interface moves landward due to reduction in the land-sea hydraulic gradient

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Impact of hydrogeological factors on groundwater salinization due to ocean-surge inundation

Cited by 38 publications

References 19 publications

Modeling the Evolution of a Freshwater Lens under Highly Dynamic Conditions on a Currently Developing Barrier Island

Modeling the Evolution of a Freshwater Lens under Highly Dynamic Conditions on a Currently Developing Barrier Island

Geological Heterogeneity of Coastal Unconsolidated Groundwater Systems Worldwide and Its Influence on Offshore Fresh Groundwater Occurrence

Storm Surges Cause Simultaneous Salinization and Freshening of Coastal Aquifers, Exacerbated by Climate Change

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