Engineered nanomaterials (ENMs) have shown promise for remediation of groundwater contaminants and the potential application relies on the delivery of aqueous solutions of ENMs to a targeted subsurface location or region. Thus, the ability to accurately predict nanoparticle transport and retention in saturated porous media is one of the most technical challenges faced by the design and assessment of potential field-scale environmental applications. Here, a prior prediction model was presented by coupling the effect of Derjaguine-Landaue-Verweye-Overbeek (DLVO) interaction, Brownian diffusion, hydrodynamics and interception. Characteristics used in the model were medium size, porosity, injection velocity, size distribution of particles, attachment efficiency, single-collector contact efficiency. The direct comparison of parameterized prior model predictions to experimental measurements was proposed to thoroughly understand deposition mechanism of polydisperse ENM. The model predicted deposition rate coefficient quantitatively very close to measured rates. When the particle diameter (d_p) of ENM excessed 1.2080 mm, it was retained in the porous medium by interception; When d_p < 0.1737 mm, ENM would deposite in the porous medium if the kinetic energy (E_k) it possessed is less than the depth of the secondary energy minimum; When 0.1737 mm < d_p < 1.2080 mm, deposition occurred where adhesive torques (T_A) was in excess of hydrodynamic drag torgues (T_H) particles subject to. Further, deposition rate was positive correlated with injection concentrations among the range of 0.34 g/L~1.70 g/L. Besides, low deposition rates were observed with injection velocities around 0.69 cm/min.

How to cite: Ren, L., Qin, B., and Cao, F.: Exploring the deposition mechanism in saturated porous media for polydisperse composites of XG and nZVI@rGO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-247, https://doi.org/10.5194/egusphere-egu24-247, 2024.

Few analytical or semi-analytical models simulating the transport of sequentially decaying reaction products affected by nonequilibrium sorption in the groundwater have been presented considering decay or degradation reaction occurring exclusively in the dissolved phase in the literature. However, the process of decay in the sorbed phase, which is important for the transport of decaying contaminants, has been neglected in previously developed analytical models. This study is thus designed to develop a novel semi-analytical model for simulating the multispecies transport of decaying contaminants subject to a nonequilibrium sorption process simultaneously coupled in both the dissolved and sorbed phases. For this purpose, a set of first-order reversible kinetic sorption reaction equations that respectively represent the nonequilibrium sorption processes between the dissolved and sorbed phases, are coupled to a set of advection-dispersion equations, to illustrate the decay process which occurs in both the dissolved and the sorbed phases. By including the decay in the sorbed phase both the parent sorbed concentration and daughter sorbed concentration coexist in a set of first-order reversible kinetic sorption reaction equations, which absolutely complicate the theoretical derivation of the analytical solution.
 Recursive analytical solutions are derived to account for the concentration distribution of arbitrary transformation products with the aid of the Laplace transform and generalized integral transform. The correctness of the solutions is confirmed through a comparison of our newly derived recursive analytical solution with an existing model which considers an equilibrium sorption process. The newly developed recursive analytical solution is then applied to investigate how the decay in the sorbed phase affects the nonequilibrium transport of a four-member radionuclide decay chain. The result clearly predicts a lower radioactivity concentration of the first nuclide (238Pu), with decay in the sorbed phase, than the simulated results obtained using a model without decay in the sorbed phase. For other daughter elements (234 U, 230 Th, 226 Ra) of the radionuclide decay chain, neglect of decay in the sorbed phase leads to overestimation of the radioactivity concentrations. The result of large differences found in dissolved radioactivity concentration between the decay and no decay in sorbed phase may alter the decision of health risk assessment in the performance of radioactive waste disposal site. The implication is that the decay reactions of contaminants in the sorbed phase are important mechanisms that should be taken into accounts for accurately simulating and assessing the nonequilibrium multispecies transport of decaying contaminants.

How to cite: Chen, J.-S., Ho, Y.-C., Liang, C.-P., Suk, H., Nguyen, T.-U., and Liu, C.-W.: Recursive analytical solution for nonequilibrium multispecies transport of decaying contaminants simultaneously coupled in both the dissolved and sorbed phases, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2369, https://doi.org/10.5194/egusphere-egu24-2369, 2024.

Chlorinated solvents can degrade to generate transformation products sequentially. The presence of such transformation products must be considered for the health risk assessment. Recently, we have developed a software package MUSt (MUltiSpecies transport Analytical Models) in which FORTRAN executable files based on our newly developed multispecies transport analytical solutions are equipped with an interactive graphical user interface (GUI). The multispecies transport analytical solutions embedded in MUSt have been further combined with health risk module for more reasonable health risk assessment. This study assesses the health risk for chlorinated solvent contaminated groundwater in northern Taiwan. The geographical distribution of non-carcinogenic and carcinogenic health risk is depicted for appropriate action for reducing groundwater concentration level of chlorinated solvent contaminants and protecting human health.

How to cite: Liang, C.-P., Chen, J.-S., and Laio, Z.-Y.: Assessing Non-Carcinogenic and Carcinogenic Health Risk for Chlorinated Solvent Contaminated Groundwater Using MUSt Software Palckage: Case Study  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2373, https://doi.org/10.5194/egusphere-egu24-2373, 2024.

Transient forcing, such as tidal fluctuations, enhances mixing within aquifers [1, 2]. This study focuses on two pivotal characteristics of typical aquifers—heterogeneity in hydraulic conductivity (K) and compressible properties, represented by the log-hydraulic conductivity variance (σ_f²) and specific storage (S_s), respectively. Previous research has individually addressed the influence of these parameters on solute dynamics [3, 4, 5], yet their combined effects remain inadequately understood. Here, we explore how heterogeneity and compressibility (finite storage) in combination governs solute transport in aquifers under transient forcing. To this end, this study employs Monte Carlo particle tracking simulations, providing a comprehensive representation of K heterogeneity. The simulations yield temporal evolutions of the centre of mass and spatial concentration variance. These results are compared with those derived from analytical solutions applicable to homogeneous compressive porous media (σ_f² = 0, S_s ≠ 0)  [5]. Our findings reveal that increasing values of σ_f² and S_s result in a delayed temporal evolution of the centre of mass compared to the predictions of the homogeneous analytical solution. In addition, the homogeneous analytical solution with zero local dispersion predicts a consistently zero concentration variance, whereas our heterogeneous simulations demonstrate an increasing concentration variance over time. The simulations also show that the higher σ_f² and S_s, the faster the temporal evolution of the concentration variance. These insights offer a deeper understanding of transport dynamics under transient forcing conditions, providing valuable information for accurate assessments of tidal impacts on salinity distributions in coastal aquifers.

References

[1] Oberdorfer, J. A., Hogan, P. J., and Buddemeier, R. W. (1990). Atoll island hydrogeology: flow and freshwater occurrence in a tidally dominated system. Journal of Hydrology 120, 327-340.

[2] Inouchi, K., Kishi, Y., and Kakinuma, T. (1990). The motion of coastal groundwater in response to the tide. Journal of Hydrology 115, 165-191.

[3] Dagan, G., Bellin, A., and Rubin, Y. (1996). Lagrangian analysis of transport in heterogeneous formations under transient flow conditions. Water Resources Research 32, 891-899.

[4] Dentz, M., and Carrera, J. (2003). Effective dispersion in temporally fluctuating flow through a heterogeneous medium. Physical Review E 68, 036310.

[5] Pool, M., Dentz, M., and Post, V. E. A. (2016). Transient forcing effects on mixing of two fluids for a stable stratification. Water Resources Research 52, 7178-7197.

How to cite: Tajima, S. and Dentz, M.: Solute transport in heterogeneous compressible aquifers under transient forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4470, https://doi.org/10.5194/egusphere-egu24-4470, 2024.

Chlorinated ethenes (CEs), such as perchloroethene (PCE) and trichloroethene (TCE), are pervasive groundwater contaminants. Owing to their toxic properties, there is a considerable effort for their remediation. In this context, in situ CE chemical reduction using zero-valent iron (ZVI) materials represents a promising strategy. However, the intrinsic low electron selectivity of pristine ZVI often results in its rapid surface corrosion and passivation in subsurface environments. In the last years, sulfidation has emerged as an effective means to enhance the reactive lifetime of ZVI. Despite the efficiency of sulfidated ZVI (S-ZVI) in dechlorinating TCE and trans-1,2-dichloroethene (trans-DCE), a notably lower reactivity has been typically observed for PCE and cis-1,2-dichloroethene (cis-DCE). The mechanisms governing the variable reactivity of S-ZVI with different CEs remain poorly understood.

To shed more light on the mechanisms controlling S-ZVI selectivity, we calculated the dechlorination barriers of various CEs at multiple S-ZVI surface models using density functional theory (DFT). Specifically, we focused on the electron transfer-controlled β-elimination reactions, identified as the predominant pathway for CE dechlorination with S-ZVI. Reactions of PCE, TCE, and both cis- and trans-DCE isomers were investigated at different S-ZVI surface sites, including surfaces with varying sulfur coverage. 

Our calculations revealed that CE dechlorination reactions are both kinetically and thermodynamically more favorable at Fe sites compared to S sites. This finding indicates that the overall promoting effect of ZVI sulfidation on CE degradation is indirect, primarily involving the protection of the ZVI surface from corrosion in water. Sulfur coverage was identified to significantly influence the S-ZVI selectivity for individual CEs. Under low S coverage, the reactivity of Fe sites followed the order trans-DCE ≈ TCE > cis-DCE > PCE, with PCE degradation hindered by steric effects from nearby S atoms. Conversely, at high S coverage, Fe sites were sterically hindered for all CEs, and reactivity was controlled by S sites. In this scenario, energy barriers correlated with the energy of the lowest unoccupied molecular orbital (E_LUMO) of CEs in the order PCE < TCE < DCE isomers. These findings demonstrate that the experimentally observed trends in S-ZVI selectivity for individual CEs can be explained by the interplay between the affinity of CEs for electron transfer and steric effects of S atoms at the ZVI surface.

Acknowledgments

This work was funded by the Austrian Science Fund (FWF), project M 2892-N. The Vienna Scientific Cluster (project no. 70544) is gratefully acknowledged for providing computational resources.

How to cite: Brumovsky, M. and Tunega, D.: Mechanistic Insights into the Selectivity of Sulfidated Zero-Valent Iron Materials in Chlorinated Ethenes Removal: A DFT Study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5135, https://doi.org/10.5194/egusphere-egu24-5135, 2024.

Chaotic advection can enhance mixing processes in porous media by increasing the solution-solvent interface available for diffusion. While the pore structure can generate chaotic advection at the pore scale, transient flow fields can lead to chaotic advection at the Darcy scale. This concept can be applied to groundwater remediation, as the flow field can be engineered using injection-extraction systems. This study investigates two injection-extraction systems known to exhibit chaotic structures: a source-sink dipole and a rotated potential mixing. Using Lagrangian particle tracking combined with random walk we solve the stochastic differential equation to simulate solute transport. The pulsed source-sink system is parametrized by the pumping rate, while for the rotated potential mixing system, we use the rotation angle and the rotation frequency to change the flow properties. Using a grid search over the parameter spaces of both systems, we test different configurations. We quantify the temporal increase in dilution and the mixing enhancement with the dilution index by using a novel approach of selecting the optimal grid size with minimal approximation error for each particle density estimation. Furthermore, we analyze the corresponding flow structure to identify Kolmogorov-Arnol'd-Moser (KAM) islands, non-mixing regions that arise around elliptic points of the flow. We find that the parameters of the system control the occurrence and size of KAM islands, which consequently affect the increase in dilution by limiting the chaotic area in the domain. Overall, our results show that not all chaotic systems lead to the same maximum mixing enhancement. Therefore, it is important to properly assess the uncertainty in the design parameters of injection-extraction systems to effectively engineer chaotic advection.

How to cite: Feistner, C., Basilio Hazas, M., Wohlmuth, B., and Chiogna, G.: Impact of Chaotic Advection on Solute Transport in Porous Media, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5154, https://doi.org/10.5194/egusphere-egu24-5154, 2024.

This study presents the treatability tests and modeling aimed at dimensioning of an in-situ reactive multibarrier, designed to purify an aquifer contaminated with a range of chlorinated organic compounds and arsenic, with 1,2-dichloroethane (1,2-DCA) presenting a significant resistance to conventional treatments.
The remediation strategy involves the implementation of a reactive multibarrier system comprising  two series-connected reactive filters: the first filled with millimetric zerovalent iron (ZVI) to remove arsenic and most of the chlorinated hydrocarbons through abiotic reductive dehalogenation, and the second with granular activated carbon (GAC) to adsorb 1,2-DCA and other residual organic contaminants.
To optimize the site-specific design and sizing of the reactive filters, groundwater treatability tests were conducted in the laboratory. Initial batch tests compared various ZVI and GAC types to select the most effective materials. Subsequent column tests assessed the treatment chain's efficacy under flow conditions and determined the longevity of the reactive materials. 
The results demonstrated the multibarrier's high effectiveness, with the ZVI filter removing 99.9% of several chlorinated solvents and all arsenic, and GAC achieving complete removal of the remaining contaminants to meet water quality standards. Mathematical models were employed to interpret the experimental findings and provide quantitative parameters essential for designing a large-scale multibarrier, such as kinetic constants for contaminant removal, reactive material longevity, and reagent volumes. A multicomponent adsorption model specifically aided in designing the GAC filtration step. he preliminary results of the pilot test, which is still ongoing, confirmed the potentiality of the reactive multibarrier to effectively remediate groundwater in site-specific conditions.

How to cite: Sethi, R., Magherini, L., and Bianco, C.: Laboratory tests and modeling of a reactive multibarrier for the remediation of a contaminated aquifer system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6503, https://doi.org/10.5194/egusphere-egu24-6503, 2024.

Chlorinated solvents are prevalent and persistent contaminants, classified as dense nonaqueous phase liquids (DNAPLs) in both soil and groundwater systems.  They have been identified at numerous sites globally, significantly impacting our environment.  The subsurface distribution of DNAPLs creates a source zone with complex geometry, strongly influenced by the specific characteristics of soil textures and stratification.  Accurately defining the location and extent of DNAPL source zones at contaminated sites poses a considerable challenge due to these complexities.

The aim of this study is to delineate the spatial distribution and persistence of trichloroethylene (TCE) in the subsurface for a long-term period of TCE leakage.  The studied area is situated at a factory in Taiwan.  Employing the T2VOC module within PetraSim 2019 software, we analyzed TCE movement and distribution in the subsurface over a 42-year timeframe which encompasses a 22-year period of TCE leakage and an additional 20-year period preceding remedial activities.  Field data from site investigation and remediation reports were incorporated into the analysis, encompassing information on groundwater table contours, soil layers, lithologies, permeabilities and the historical usage of TCE.  Relevant parameters, such as relative permeability, liquid residual saturation, capillary pressure and fluid saturation relationships, were determined based on literature sources.

Results show that TCE infiltrates to a depth of 13 m, reaching a low permeability zone below the ground surface.  However, the site investigation only extended to a depth of 10 m (the lower bound of a high-permeability zone).  Significant TCE residuals persist in both the upper and lower layers of the high-permeability zone after the 42-year simulation period.  The dissolved phase of TCE follows the groundwater flow, extending up to 80 m downstream with notable concentration levels.  However, if considering volatilization of TCE (resulting in an 80% reduction in leakage) and an 80% reduction in the leakage area, it becomes improbable for TCE to infiltrate to the lower low-permeability layer.  This suggests a potential underestimation of the current assessment of TCE usage.  Moreover, the study underscores the influence of groundwater velocity and TCE residual saturation on the retention and persistence of TCE in the soil layers.  This emphasizes the importance of investigating hydrogeological environment and assessing TCE residuals in various soil textures at such contaminated sites.

How to cite: Fen, C.-S. and Zhuang, Y.-Y.: Assessing source zone distribution and persistence at a trichloroethylene contaminated site, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6985, https://doi.org/10.5194/egusphere-egu24-6985, 2024.

Apart from the health risks associated with the consumption of contaminated water, the suitability of water, based on its visual appeal, taste, and odor, is a matter of paramount importance. Elevated levels of Iron (Fe) and Manganese (Mn) lead to the discoloration of sanitary wares and laundry, besides resulting in deposits within distribution systems and contributing to an undesirable taste in drinking water. The mobilization of Fe and Mn in groundwater is predominantly governed by redox processes. In this study, we conducted an analysis of shallow groundwater (n=145) in the Brahmaputra River Plains (BRP), India, which shows that 85 percent (n=123) and 80 percent (n=116) of the groundwater exceed the WHO acceptable limit of Fe (0.3 mg/L) and Mn (0.1 mg/L), respectively. The highest concentration of Iron (II) is 7 mg/L with a median value of 3 mg/L (n=35). However, they are heterogeneously distributed among the Piedmont deposits, Older Alluviums, and Younger Alluviums. Spearman’s correlation shows that total Fe has a strong correlation (0.89) with Fe (II), and a comparison between them reveals that Fe (II) is the dominant species. The reducing nature of the groundwater with low dissolved oxygen and a high dissolved organic carbon suggests reductive dissolution of Fe and Mn oxyhydroxides as a possible mechanism of Fe and Mn release in the groundwater. Therefore, there is a need to mitigate the high Fe and Mn levels in the groundwater-sourced drinking water to avoid health and suitability concerns. Treatment facilities, including the use of iron-removal sand filters and aeration, have been installed across the region to mitigate the problem. Investigation of Fe (II) concentrations in the treated household-supplied water shows a considerable decrease in the Fe (II). Implementing effective mitigation measures, such as the use of iron-removal filters, is crucial to ensure the provision of safe drinking water.

How to cite: Aind, D. A. and Mukherjee, A.: High Iron and Manganese in Groundwater of Brahmaputra River Plains: concerns for drinking water quality and remediation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7282, https://doi.org/10.5194/egusphere-egu24-7282, 2024.

Hydraulic tomography (HT) is an innovative method for characterizing the heterogeneous properties of aquifers. This technique involves sequential pumping/injection tests using a network of wells, with simultaneous measurement of groundwater pressure variations. The resulting pressure data is then transformed into hydraulic heterogeneity using a geostatistical approach. Traditional HT tests utilize wells with screens at a single target depth, limiting pressure data collection to specific depth ranges. In contrast, a multilevel well-monitoring system (MLMS) employs multiple open screens at different depths, separated by packers, to prevent vertical flow connections. This configuration significantly increases the amount of pressure data compared to traditional wells. In this study, we implemented a novel multilevel well system based on fiber Bragg grating (FBG) technology for conducting HT at a contaminated site in Taiwan. A comparative analysis of hydraulic conductivity profiles obtained from HT with FBG MLMS and electrical resistivity was undertaken to validate the effectiveness of the FBG MLMS in HT applications. The results demonstrate the reliability and practicality of using an FBG multilevel well system for hydraulic tomography, highlighting its potential for enhanced data collection in heterogeneous aquifer characterization.

How to cite: Tsai, J.-P., Yeh, T.-C., Wang, B.-T., Chang, C., and Liang, C.-W.: Delineating Hydraulic Heterogeneity Using Fiber Bragg Grating Multi-Level Well and Hydraulic Tomography – A Case Study in Taiwan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9021, https://doi.org/10.5194/egusphere-egu24-9021, 2024.

The escalation of industrialization and population growth in recent decades has increased the prominence of groundwater pollution in environmental concerns. However, accurate prediction of the contaminant migration through the fractured aquifer is still an arduous task. The current research is dedicated to evaluating the predictive accuracy of three models: the Advection Dispersion Equation (ADE), Advection Dispersion Equation with Retardation (ADE-R), and Single Rate Mobile-Immobile (MIM) model. Constant dispersivity is assumed for all the models. These models were employed to predict the migration of the solute, particularly NaCl, within a single fracture characterized by a 0.3 cm aperture and 1000 cm length and filled with fine sand. The study maintained non-Darcian flow conditions throughout the experimental runs. The simulated BTCs exhibited a non-Fickian trend and were subsequently subjected to fitting using the ADE, ADE-R, and MIM models. Notably, the MIM model proved the most adept at fitting the simulated BTCs, effectively capturing both early arrival and long tails. Conversely, the ADE-R model excelled in predicting the early arrival but fell short in fitting the long tails of the BTCs.

Keywords: ADE model; ADE-R model; Breakthrough curves; filled-single fracture; MIM model; non-Darcian flow

How to cite: Pandey, S. and Sharma, P. K.: Empirical and computational study on conservative tracer migration through a single fracture, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11221, https://doi.org/10.5194/egusphere-egu24-11221, 2024.

Aerobic bioremediation combined with electrolytic enhancement, stimulating the indigenous subsurface microflora to degrade TCE, in the recirculating system of groundwater and solute induced by tandem circulation well (TCW) is a novel in-situ remediation method which has been gradually valued for its great application prospects due its  environmental and economic advantages. Previous investigations have been limited to few laboratory experiments, and neither the evaluation of remediation efficiency nor the improvement methods in application were fully understood. This study developed a reactive transport model for in-situ TCE bioremediation, simulating TCW-induced groundwater recirculating system, aerobic biodegradation process of TCE and electrolytic enhanced oxygen supply. A regionalized sensitivity analysis (RSA) was conducted based on the experimental data to quantify the influences of parameters, reduce the number of parameters inverted and provide the value of reactive kinetic parameters for this model. Different simulation cases were conducted to investigate influence of operating parameters and well spacing for remediation efficiency. The results show that increase in both current and pumping rate can improve the degradation efficiency but has a maximum degradation capacity due the limitation of saturated DO concentration in wellbore. Through a quantitative characterization of solute mixing, the model demonstrated an optimal operating parameters index (α_optimal), helping to find the optimal ratio of current and pumping rate. The results of the influence of well spacing indicate that too close an injection/extraction well distance is detrimental to degradation efficiency and the current and pumping rate need to increase in the same proportion with the increasing remediation area to remain the optimal efficiency.

How to cite: Yang, S., wen, Z., Zhu, Q., Yuan, S., and Li, Y.: Model-based evaluation of efficiency of electrolysis-enhanced in-situ bioremediation for trichloroethylene using tandem circulation well, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14458, https://doi.org/10.5194/egusphere-egu24-14458, 2024.

Disposal methods for storing high-level radioactive waste deep underground are being researched and implemented worldwide. In constructing a high-level radioactive waste disposal facility, groundwater reaction front moves and geochemical buffering capacity may be changed, affecting the long-term storage stability. Although various studies have been conducted in this regard in Korea, field-scale studies are still in shortage, in cases compared to overseas cases. This study aims to establish a long-term solute migration experiment system and experimental method for deep depths, to identify the migration and retardation characteristics of released nuclides in the deep underground environment.

For field-scale tests, KURT(KAERI Underground Research Tunnel) was constructed in 2006 and in-situ solute migration tests were conducted. However, that was conducted in shallow depth, which has limitations in realizing an actual disposal environments. Therefore, the long-term solute migration experiment to be designed in this study targets underground depths, where reduced-state groundwater exists and disposal site construction is considered, to get empirical data in deep depth. The in-situ solute migration experiment system designed in this study is composed of an injection part and an extraction part. The injection unit was designed to be in charge of injecting simulated nuclides into the injection borehole. The extraction unit was designed to extract groundwater, including the injected tracer, to obtain a sample for analysis and to measure the properties of groundwater flowing through fractured rock in real-time. Both sorbing and non-sorbing tracers are used in long-term solute migration experiments. The non-sorbing tracers are suitable such as Eosin B, fluorescein sodium, and potassium bromide. The sorbent tracers which can simulate the behavior characteristics of radionuclides are suitable such as rubidium, nickel, zirconium, and samarium. Using the solute migration experiment system and experimental method designed in this study, a long-term solute migration experiment will be carred out in the deep depths around KURT, to obtain the results of the radionuclides’ migration and retardation characteristics for the deep depths.

How to cite: Park, J., Ahn, J.-Y., Yi, J.-H., Cheon, J.-Y., Yi, M.-J., and Jun, S.-C.: Design of system and method on field-scale solute migration experiment for evaluating radionuclide’s migration properties at a deep borehole, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15489, https://doi.org/10.5194/egusphere-egu24-15489, 2024.

Pervasive salinity in soil, surface water and groundwater is a significant challenge in many coastal poldered areas of Bangladesh. These areas are characterized by their vulnerability to cyclone-induced surge inundation due to the low-lying flat topography and their concave coastal profile. The surge water leads to the areas being inundated, which may result in elevated salinity levels in surface water and groundwater. High salinity can affect the availability of potable water and have a serious impact on agriculture, ecosystems, and the health of coastal communities. To effectively address the issue of groundwater salinity in these coastal areas, a comprehensive understanding of the contributing causes is required. A 3D model, HydroGeoSphere, was developed to examine the effect of surge inundations on surface and groundwater salinities. This model coupled surface and subsurface domains, using surge levels data from Chittagong station and a digital elevation model from USGS Earth Explorer. Evaporation and monsoon data were collected at the pond of the DAB site (Dacope, Khulna, Southwest coastal Bangladesh). The results show that even one year after the storm surges, salinity levels in the surface and near-surface areas remained elevated. The high salinity levels near the surface area may be primarily due to the surge water being trapped in depressions, as well as the effects of evaporation reducing the water content of the soil, leaving concentrated salt behind. Also, low-permeable sediments in the area may contribute to the persistent high salinity levels. The modelled groundwater salinity distributions showed good agreement with the measured groundwater salinity distributions derived from electrical conductivities obtained in 14 tube wells at various depths and locations along a cross-section.

How to cite: Tsai, C. S., Mo, H., and Butler, A. P.: The effect of surge inundation on shallow groundwater salinity in the coastal low-lying poldered area of southwest Bangladesh-a 3D model investigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7175, https://doi.org/10.5194/egusphere-egu24-7175, 2024.