Applicability of a sharp-interface model for estimating steady-state salinity at pumping wells—validation against sand tank experiments

Shi, Lei; Cui, Lei; Park, Namsik; Huyakorn, Peter S.

doi:10.1016/j.jconhyd.2011.01.005

Cited by 47 publications

(19 citation statements)

References 21 publications

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“…Shi et al . () validated a numerical sharp‐interface model against experiments conducted in two small scale sand tanks. They studied the salinity of water extracted from pumping wells.…”

Section: Introductionsupporting

confidence: 94%

Discussion about the validity of sharp‐interface models to deal with seawater intrusion in coastal aquifers

Llopis-Albert

Pulido-Velázquez

2013

Hydrological Processes

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Abstract:Analytical models have been exhaustively used to study simple seawater intrusion problems and the sustainable management of groundwater resources in coastal aquifers because of its simplicity, easy implementation, and low computational cost. Most of these models are based on the sharp-interface approximation and the Ghyben-Herzberg relation, and their governing equations are expressed in terms of a single potential theory to calculate critical pumping rates in a coastal pumping scenario. The GhybenHerzberg approach neglects mixing of fresh water and seawater and implicitly assumes that salt water remains static. Therefore, the results of the analytical solutions may be inaccurate and unacceptable for some real-complex case studies. This paper provides insight into the validity of sharp-interface models to deal with seawater intrusion in coastal aquifers, i.e. when they can be applied to obtain accurate enough results. For that purpose, this work compares sharp-interface solutions, based on the Ghyben-Herzberg approach, with numerical three-dimensional variable-density flow simulations for a set of heterogeneous groundwater flow and mass transport parameters, and different scenarios of spatially distributed recharge values and spatial wells placement. The numerical experiment has been carried out in a 3D unconfined synthetic aquifer using the finite difference numerical code SEAWAT for solving the coupled partial differential equations of flow and density-dependent transport. This paper finds under which situations the sharp-interface solution gives good predictions in terms of seawater penetration, transition zone width and critical pumping rates. Additionally, the simulation runs indicate to which parameters and scenarios the results are more sensitive.

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“…Shi et al . () validated a numerical sharp‐interface model against experiments conducted in two small scale sand tanks. They studied the salinity of water extracted from pumping wells.…”

Section: Introductionsupporting

confidence: 94%

Discussion about the validity of sharp‐interface models to deal with seawater intrusion in coastal aquifers

Llopis-Albert

Pulido-Velázquez

2013

Hydrological Processes

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“…[], Rhodamine WT (fluorescent FWT Red dye, ENVCO, Australia) with concentration of 500 mg/L was used as a visual tracer of saltwater movement in the tank. Rhodamine WT has been widely and successfully used in sand‐tank models previously [e.g., Schincariol and Schwartz , ; Werner et al ., ; Jakovovic et al ., ; Shi et al ., ; Jakovovic et al ., ]. Saltwater density ( ρ s [ M / L 3 ]) and freshwater density ( ρ f [ M / L 3 ]) were 1018.3 and 998.1 kg/m 3 , respectively (determined using a pycnometer and mass‐volume measurements), and a saltwater concentration ( C s [ M / L 3 ]) of 26.4 kg/m 3 was calculated.…”

Section: Experimental Methods and Materialsmentioning

confidence: 99%

Water table salinization due to seawater intrusion

Badaruddin

Werner

Morgan

2015

Water Resources Research

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Seawater intrusion (SWI) is a significant threat to freshwater resources in coastal aquifers around the world. Previous studies have focused on SWI impacts involving salinization of the lower domain of coastal aquifers. However, under certain conditions, SWI may cause salinization of the entire saturated zone of the aquifer, leading to water table salinization (WTS) in unconfined aquifers by replacing freshwater within the upper region of the saturated zone with seawater, thereby posing a salinity threat to the overlying soil zone. There is presently limited guidance on the extent to which WTS may occur as a secondary impact of SWI. In this study, physical experiments and numerical modeling were used to explore WTS associated with SWI in various nontidal, unconfined coastal aquifer settings. Laboratory experiments and corresponding numerical simulations show that significant WTS can occur under active SWI (i.e., the freshwater hydraulic gradient slopes toward the land) because the cessation of freshwater discharge to the sea and the subsequent landward flow across the entire sea boundary eventually lead to water table salinities approaching seawater concentration. WTS during active SWI is larger under conditions of high hydraulic conductivity, rapid SWI, high dispersivity and for deeper aquifers. Numerical modeling of four published field cases demonstrates that rates of WTS of up to 60 m/yr are plausible. Under passive SWI (i.e., the hydraulic gradient slopes toward the sea), minor WTS may arise as a result of dispersive processes under certain conditions (i.e., high dispersivity and hydraulic conductivity, and low freshwater discharge). Our results show that WTS is probably widespread in coastal aquifers experiencing considerable groundwater decline sustained over several years, although further evidence is needed to identify WTS under field settings.

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“…Nevertheless, several experimental studies have investigated SWI for an array of different problems in synthetic homogeneous aquifers without quantifying the WMZ (Goswami and Clement, 2007;Werner et al, 2009;Luyun et al, 2011;Shi et al, 2011;Jakovovic et al, 2012;Stoeckl and Houben, 2012;Morgan et al, 2013;Clement, 2012, 2013;Dose et al, 2014). Werner et al (2009) investigated laboratory scale saltwater upconing at extraction wells and compared the results to an analytical sharp interface solution.…”

Section: Introductionmentioning

confidence: 99%

Experimental saltwater intrusion in coastal aquifers using automated image analysis: Applications to homogeneous aquifers

Robinson

Ahmed

Hamill

2016

Journal of Hydrology

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This paper presents the applications of a novel methodology to quantify saltwater intrusion parameters in laboratory-scale experiments. The methodology uses an automated image analysis procedure, minimizing manual inputs and the subsequent systematic errors that can be introduced. This allowed the quantification of the width of the mixing zone which is difficult to measure in experimental methods that are based on visual observations. Glass beads of different grain sizes were tested for both steady-state and transient conditions. The transient results showed good correlation between experimental and numerical intrusion rates. The experimental intrusion rates revealed that the saltwater wedge reached a steady state condition sooner while receding than advancing. The hydrodynamics of the experimental mixing zone exhibited similar traits; a greater increase in the width of the mixing zone was observed in the receding saltwater wedge, which indicates faster fluid velocities and higher dispersion. The angle of intrusion analysis revealed the formation of a volume of diluted saltwater at the toe position when the saltwater wedge is prompted to recede. In addition, results of different physical repeats of the experiment produced an average coefficient of variation less than 0.18 of the measured toe length and width of the mixing zone. KeywordsSaline water intrusion; Intrusion angle; Width of the mixing zone; Light to concentration conversion.

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Applicability of a sharp-interface model for estimating steady-state salinity at pumping wells—validation against sand tank experiments

Cited by 47 publications

References 21 publications

Discussion about the validity of sharp‐interface models to deal with seawater intrusion in coastal aquifers

Discussion about the validity of sharp‐interface models to deal with seawater intrusion in coastal aquifers

Water table salinization due to seawater intrusion

Experimental saltwater intrusion in coastal aquifers using automated image analysis: Applications to homogeneous aquifers

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