HS8.2.2 | Physics-Based Modelling of Groundwater Flow and Solutes/Energy Transport
EDI
Physics-Based Modelling of Groundwater Flow and Solutes/Energy Transport
Convener: Alper Elçi | Co-conveners: Nadim Copty, Elif Aysu BatkanECSECS, Carolina Guardiola-Albert
Orals
| Mon, 28 Apr, 10:45–12:30 (CEST)
 
Room 2.44
Posters on site
| Attendance Mon, 28 Apr, 08:30–10:15 (CEST) | Display Mon, 28 Apr, 08:30–12:30
 
Hall A
Orals |
Mon, 10:45
Posters on site
Mon, 08:30
Groundwater flow and pollutant transport modeling has developed into a vital tool for the analysis of aquifers at different scales, from the pore to the global scales. Numerous applications employ modelling, such as risk assessment, water resource management, decision support systems, and remediation activity guidance. The hydrogeochemical and biological processes affecting flow and transport in heterogeneous porous media are extremely complex, as numerous studies have demonstrated. Since these processes frequently depend on one another, coupled flow and solutes transport modeling is essential.
The objective of this session is to discuss the state-of-the-art and future directions in groundwater flow modeling and simulation of solutes fate and transport in the saturated zone. It provides a special opportunity to promote inter-disciplinary studies and the sharing of knowledge and experiences related to analytical and numerical, physics-based approaches.
We invite researchers, academics, and consulting professionals at all career levels to present their work on the following topics:
• Groundwater flow modelling studies at the global, regional and watershed scale
• Case studies using numerical models such as MODFLOW, FEFLOW, MT3DMS, SEAWAT, SUTRA
• Pore-scale modeling of flow and transport
• Modeling of unsaturated/saturated flow and transport (also in the context of managed aquifer recharge systems)
• Simulation of subsurface flow-surface water interaction
• Modeling the impact of climate change on groundwater resources
• Variable-density flow, and seawater intrusion modeling studies
• Multi-phase flow and contaminant transport modeling in support of groundwater remediation (especially for problems where the flow and transport are highly coupled)
• Modeling of coupled physical, hydrogeochemical and biological processes
• Modeling the impact of subsurface heterogeneity on flow and transport
• Reactive transport modeling (chemical, sorption, bio-mineralization processes in porous media)

Orals: Mon, 28 Apr | Room 2.44

Chairpersons: Nadim Copty, Alper Elçi
10:45–10:50
5-minute convener introduction
Solute and/or Heat Transport Modeling
10:50–11:00
|
EGU25-7383
|
On-site presentation
Large scale flow and dispersion in heterogeneous karst aquifers under laminar and turbulent flow conditions     
Marco Dentz, Philippe Gouze, Juan Hidalgo, and Jannes Kordilla

Non-linear flow and dispersion in fractured and karstic media are key issues in different fields of science and engineering, ranging from the assessment of groundwater vulnerability and flood risks to geothermal energy and speleogenesis. Spatial variability in the physical medium properties lead to scale effects in the flow and dispersion processes that manifest in non-Fickian transport and non-Darcian flow behaviors. We study the mechanisms of flow and dispersion in two- and three-dimensional heterogeneous networks. Flow is modeled by the Darcy-Weisbach equation, which for low Reynolds numbers describes laminar and for high Reynolds numbers turbulent flow conditions. Due to spatial heterogeneity, the Reynolds number and thus the flow conditions may strongly vary in  space. That is, laminar flow regions alternate with regions of dominantly turbulent flow. The aim is to understand and predict large scale flow and dispersion in such media by understanding their relation to medium geometry and heterogeneity. To this end, the flow fields are characterized statistically in terms of the distribution of Eulerian and Lagrangian flow velocities and their correlation properties with emphasis on the relation between network heterogeneity and flow statistics. We find that large scale flow can be characterized by a Darcy-Weisbach law in terms of a  large scale friction factor that depends on the medium heterogeneity. Solute dispersion is measured in terms of particle breakthrough curves and displacement statistics. We observe broad distributions of particle arrival times and non-linear evolution of the displacement variance, which are manifestations of memory processes that occur due to broadly distributed flow velocities and mass transfer rates. These behaviors are linked to the medium structure and Eulerian flow statistics. Based on this analysis, we propose a stochastic time domain random walk approach to quantify the impact of the network heterogeneity on large-scale flow and dispersion.     

How to cite: Dentz, M., Gouze, P., Hidalgo, J., and Kordilla, J.: Large scale flow and dispersion in heterogeneous karst aquifers under laminar and turbulent flow conditions    , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7383, https://doi.org/10.5194/egusphere-egu25-7383, 2025.

11:00–11:10
|
EGU25-1973
|
On-site presentation
New heat tracer transport models to improve understanding of Groundwater-surface water interactions
(withdrawn)
Quanrong Wang, Wenguang Shi, Tuanji Gao, Hongshan Yan, and Zhe Li
11:10–11:20
|
EGU25-2913
|
ECS
|
Virtual presentation
|
Flow and hydrogeochemical model of the Yucatán groundwater flow system 
Martha Edith Castro Zarate, Selene Olea Olea, Eric Morales Casique, Iris Neri Flores, Citlali Salas Barrena, and Ismael de Jesús Mariño Tapia

The study area is located within the Yucatán Flow System in the south of Mexico,  a coastal karstic system characterized by rapid infiltration of rainwater into the subsurface. Groundwater flow in this system can be considered laminar and/or turbulent, with limited contaminant retention in the soil.

In Yucatan, groundwater is the sole source of water supply for human use and ecosystems. It is essential to manage its use through studies that enhance our understanding dynamics of flow systems. This study aims to develop a coupled flow model with the hydrogeochemistry of the groundwater flow system to identify transport and hydrogeochemical processes.

For the hydrogeochemical analysis, physicochemical parameters were measured, and groundwater samples were collected in May 2023 for analysis of major ions and trace elements. A conceptual model was developed based on sample classification concerning chemical quality, hydrogeochemical diagrams, and a flow network created using field measurements of static water level depth and bibliographic information. The coupled flow and hydrogeochemistry model will be developed using PHAST software (PHREEQC and HST3D), which simulates groundwater flow, solute transport, and geochemical reactions.

Preliminary results identified three components of the flow system:

The local component is the shallowest and is influenced by the current climate.
The intermediate component is located along of a fault zone; its more evolved nature suggests that the fault acts as a preferential conduit for groundwater flow.
The regional component is primarily located along the coastline.
Groundwater flow generally moves from south to north, but two geomorphological features alter this flow direction: the Ticul Fault and the Cenote Ring, both of which serve as preferential conduits for groundwater.

The Yucatán Flow System is a complex system due to its karstic nature and its discharge into the sea. Therefore, addressing its geomorphological, hydrogeochemical, and flow complexities is crucial to achieving reliable results that can inform effective groundwater management in Yucatán.

How to cite: Castro Zarate, M. E., Olea Olea, S., Morales Casique, E., Neri Flores, I., Salas Barrena, C., and Mariño Tapia, I. D. J.: Flow and hydrogeochemical model of the Yucatán groundwater flow system, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2913, https://doi.org/10.5194/egusphere-egu25-2913, 2025.

Discussion Post a comment
11:20–11:30
|
EGU25-3164
|
ECS
|
On-site presentation
|
Experimental and modeling assessment of slug tests in the presence of coupled hydraulic, thermal, and solute transport effects 
Xiaosong Dong, Yanrong Zhao, Yong Huang, Monica Riva, and Alberto Guadagnini

Assessment of hydrogeological parameters such as aquifer permeability, thermal conductivity, and dispersion coefficients is critical for comprehensive groundwater resource assessment. In this context we provide experimental analyses of slug tests performed upon considering a confined groundwater system where hydraulic, thermal, and solute transport processes take place. Design and execution of experiments are supported by a detailed numerical modeling analysis taking into account the intimately coupled nature of these mechanisms.

The study investigates coupling mechanisms among (Darcy scale) flow, thermal, and chemical fields across the aquifer. In this sense, groundwater flow directly influences rates of heat and solute transport. Temperature impacts groundwater dynamics upon altering, e.g., water density and viscosity. Our numerical simulations are grounded on the well known and broadly tested COMSOL suite. We also explore the potential of a Physics-Informed Neural Network (PINN) approach to provide characterize complex coupling conditions of the type we analyze, thereby complementing model evaluation and parameter estimation accuracy. Doing so enables us to estimate the set of model parameters through numerical simulations performed according to two diverse strategies and anchored on experimental data.

A dedicated indoor experimental platform is then developed. Slug tests associated with coupled flow and (chemical/thermal) transport conditions are designed on the basis of preliminary numerical simulations performed using both the COMSOL-based fully coupled model and the PINN approach. The platform is equipped with excitation devices and a high-frequency, high-precision automatic data collection system tailored to meet the requirements of hydraulic-thermal-chemical coupling associated with slug tests. In this context, NaCl is employed as a tracer, its concentration being monitored through electrical conductivity signals. A cylindrical container filled with homogeneous fine sand is designed to represent the porous domain. The top is sealed with an insulating film and cement, simulating ideal confined aquifer conditions. One-dimensional column tests are also performed to enable cross-validation of interpretive modeling and parameter estimation. By integrating data such as water level, temperature, and electrical conductivity under various experimental conditions, the study qualitatively examines the temporal and spatial variations in groundwater flow, heat transport, and solute transport. These experimental results are then quantitatively employed in the context of model-based parameter estimation. The latter is performed through the full system model (as implemented in the COMSOL suite) as well as through the PINN approach. 

How to cite: Dong, X., Zhao, Y., Huang, Y., Riva, M., and Guadagnini, A.: Experimental and modeling assessment of slug tests in the presence of coupled hydraulic, thermal, and solute transport effects, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3164, https://doi.org/10.5194/egusphere-egu25-3164, 2025.

Discussion Post a comment
Catchment/Field-Scale Flow Modeling
11:30–11:40
|
EGU25-11272
|
On-site presentation
What can we learn with barometric and earth tide induced groundwater level fluctuations ? From aquifer conceptualization to K and Ss assessment 
Rémi Valois, Gabriel Rau, and Jean-Michel Vouillamoz

Methods for understanding and predicting the impacts of groundwater extraction generally lack detailed spatial and temporal knowledge of subsurface hydromechanical properties. Estimating subsurface hydraulic properties using groundwater response to earth tides (ET) and atmospheric pressure is an alternative approach to pumping tests or “slug-tests”. These methods can be described as passive, since they use the forces of nature, as opposed to active methods requiring human intervention. These passive and inexpensive investigative techniques deserve to be developed to make analysis easily accessible. In this way, the hydromechanical properties of subsurface systems could be obtained with unprecedented spatial and temporal resolution, adding further value to commonly acquired groundwater and atmospheric pressure data.

However, assumptions concerning conceptual models, parameterization of the hydromechanical problem and the influence of drilling on the results are given little consideration. This inverse problem can also benefit from Earth diurnal tides, and not just semi-diurnal as in the literature, to identify the right models to use and to reduce uncertainties in the estimated hydromechanical parameters (K, Ss). The amplitude ratio of diurnal to semi-diurnal waves and the phase shift sign are indicators of the conceptual model to be used, and the estimated transmissivities are in agreement with those of the pumping tests in the case study. In this context, we have shown that the amplitude of terrestrial tidal signals alone cannot be used to estimate the storage coefficient Ss.

We aslo showed that barometric tides can be used to estimate the hydraulic conductivity K of aquifers when the barometric and piezometric sampling time step is adapted to the hydraulic conductivity. When permeability is not very high, there is indeed a phase shift between the tidal wave in the aquifer and that in the borehole, and this can be related to K using slug-test models, with a clear signature on both synthetics and real data. 

We thus demonstrate the potential of natural drivers induced groundwater fluctuations to better conceptualize the hydrogeological model (unconfined, leaky, confined), as well as to assess hydraulic properties such as hydraulic conductivity and specific storage.

How to cite: Valois, R., Rau, G., and Vouillamoz, J.-M.: What can we learn with barometric and earth tide induced groundwater level fluctuations ? From aquifer conceptualization to K and Ss assessment, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11272, https://doi.org/10.5194/egusphere-egu25-11272, 2025.

11:40–11:50
|
EGU25-9913
|
ECS
|
On-site presentation
Integration of hydrologic and groundwater models: Is it profitable?
(withdrawn)
Diego Meléndez-Saldaña and Félix Francés
11:50–12:00
|
EGU25-13475
|
ECS
|
On-site presentation
Quantification of inter-aquifer flow in a Multi-Aquifer System Using Regional Groundwater Modeling: Northwestern Desert, Egypt 
Mahmoud Abdelhamid Ahmed, Sherif Alaa Ibrahim, and Ahmed Emam Hassan

Under severe water stress, intensified by the lack of rainfall and upstream regulation of freshwater, Egypt has little choice but to turn to alternative water resources, such as groundwater. However, the largest groundwater source—the Nubian Sandstone Aquifer—is non-renewable, and its connections to other aquifers are complicated and remain insufficiently studied. Modeling such an aquifer—one of the largest in the world, spanning approximately 2 million square kilometers across Egypt, Sudan, Chad, and Libya—is a complex task, with existing studies largely limited to local scales.

 

This study aims to quantify inter-aquifer flow in the multi-layered hydrogeological system of the Northwestern Desert, Egypt, on a regional scale covering part of the Nubian Sandstone Aquifer. The system comprises five aquifers and two aquitards, namely the Marmarika Limestone and Moghra Aquifers, separated from the Eocene Limestone Aquifer by the Al-Dabaa Shale Aquitard. The Eocene Limestone Aquifer is horizontally connected to the Shallow Nubian Aquifer and underlain by the Abu-Rawash Shale Aquitard, which separates it from the Deep Nubian Aquifer. A three-dimensional regional groundwater model was developed using a comprehensive dataset of lithology, water level, and extraction data. Calibration with over 1,000 historical measurements spanning five aquifers yielded aquifer properties and recharge estimates.

 

The model reveals the presence of vertical connectivity between the Eocene Limestone and Nubian Aquifer and interaction between Siwa lakes and the Limestone Aquifer. Results showed that discharge to Siwa lakes in 1960 was approximately twice the aquifer’s recharge from the Nubian Aquifer but has since declined by 30%, while recharge from the Nubian Aquifer increased by 10% by 2023. Flow from the Nubian Aquifer accounts for about 30% of current extraction from the Limestone Aquifer, indicating over-extraction in the region. Horizontal connectivity between the Limestone and Shallow Nubian Aquifers is minimal, contributing less than 2% of extraction in West Minya. This explains stable water levels in the Shallow Nubian Aquifer at Al-Bahariya despite significant extraction from the Limestone Aquifer at West Minya. The results offer valuable insights into the connections between the aquifers, supporting the development of future local models and clearly highlighting the risks of water salinization and aquifer depletion in the event of overextraction.

How to cite: Ahmed, M. A., Alaa Ibrahim, S., and Hassan, A. E.: Quantification of inter-aquifer flow in a Multi-Aquifer System Using Regional Groundwater Modeling: Northwestern Desert, Egypt, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13475, https://doi.org/10.5194/egusphere-egu25-13475, 2025.

12:00–12:10
|
EGU25-20277
|
ECS
|
Virtual presentation
A water-energy-food-carbon nexus optimization model for sustainable groundwater development in the lower Ain river basin 
Mayank Bajpai, Shreyansh Mishra, and Shishir Gaur

Groundwater management within the water-energy-food-carbon (WEFC) nexus is inherently interdisciplinary, particularly in regions with significant groundwater-surface water interactions. Effectively balancing trade-offs and synergies among nexus components is critical for socio-economic and environmental sustainability. This study presents an integrated many-objective simulation-optimization (S-O) framework to address WEFC nexus management challenges in the lower Ain River basin (LARB), a typical alpine basin with intensive agricultural activities and river-aquifer (R-A) interactions.

The approach integrates a transient groundwater flow model (MODFLOW) to simulate the flow budget and R-A exchanges. These outputs inform the optimization process, which employs the NSGA-III metaheuristic algorithm to evaluate conflicting objectives, including groundwater supply, agricultural yield, energy consumption, and total carbon emissions from agricultural practices. The Pareto optimal front generated by this framework highlights sustainable withdrawal scenarios that minimize environmental degradation while balancing competing objectives. Three scenarios were developed to enhance decision-making based on nexus trade-offs, R-A exchanges, and carbon emissions. Results demonstrate that the optimized solutions achieve improved nexus outcomes, significantly reducing total carbon emissions while maintaining water supply and agricultural productivity. This many-objective S-O framework offers a robust tool for managing the WEFC nexus in river basins characterized by groundwater-dependent agriculture and complex R-A interactions, supporting sustainable resource management and climate resilience.

How to cite: Bajpai, M., Mishra, S., and Gaur, S.: A water-energy-food-carbon nexus optimization model for sustainable groundwater development in the lower Ain river basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20277, https://doi.org/10.5194/egusphere-egu25-20277, 2025.

12:10–12:20
|
EGU25-3739
|
ECS
|
On-site presentation
Testing of MODFLOW related packages to simulate flow patterns to horizontal wells in shallow porous aquifers for effective catchment-scale groundwater modelling 
Tania Stefania Agudelo Mendieta, Max Rudolph, Marcus Genzel, Paul Franke, Andreas Hartmann, and Zhao Chen

Horizontal wells are an interesting alternative to vertical wells for water supply in shallow aquifers and have been successfully implemented at many different water supply sites worldwide. However, the flow patterns to horizontal wells are much more complicated than those to vertical wells, making their mathematical treatment more demanding. In previous studies, some numerical approaches have been introduced and used to represent horizontal wells in numerical groundwater models, but there is no "one size fits all" solution that can be identified. In order to develop a practice-oriented guideline for the appropriate implementation of horizontal wells in MODFLOW based groundwater models, we designed a comprehensive numerical experiment with four different synthetic aquifer models of increasing complexity in terms of hydraulic properties and boundary conditions in the current work. Four different MODFLOW related packages, including WEL, Drain, MNW2, and CFPy, were tested and evaluated for their performance under steady and transient conditions at catchment scale. The advantages and limitations of these four tested MODLFLOW packages were systematically analyzed and compared in terms of performance metrics, computational efficiency, and numerical stability. The results indicate that while both CFPy and MNW2 deliver hydraulically representative simulations, CFPy demands 40–80% higher computational effort compared to MNW2. In contrast to the WEL package, which oversimplifies flow dynamics, and the Drain package, which struggles to represent lateral flow patterns effectively, MNW2 captures variable inflow rates along the well and incorporates essential factors such as skin effects and wellbore storage. Consequently, MNW2 emerges as the preferred choice for practical and more complex applications due to its ease of use, reliable simulation of well-aquifer interactions, and sufficient accuracy for flow modelling at the catchment scale. The outcomes of this study provide actionable guidelines for selecting appropriate modelling approaches for horizontal wells based on specific project requirements. Furthermore, the methodology used in this study and its combination with synthetic aquifer experiments, multiple complexity levels, and comparative package evaluations is transferable to other regions and applications. By offering insights into horizontal well representation, the findings support improved groundwater management and water supply planning in both research and operational contexts.

How to cite: Agudelo Mendieta, T. S., Rudolph, M., Genzel, M., Franke, P., Hartmann, A., and Chen, Z.: Testing of MODFLOW related packages to simulate flow patterns to horizontal wells in shallow porous aquifers for effective catchment-scale groundwater modelling, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3739, https://doi.org/10.5194/egusphere-egu25-3739, 2025.

12:20–12:30
|
EGU25-7996
|
On-site presentation
Finite Land Reclamation at Coastal Region: Impact of Heterogeneity on Groundwater and Seawater Extent 
Jia Zhang, Chunhui Lu, and Jiazhi Sun

Land reclamation provides available land for various purposes of development at coastal region. The filled sediments having different permeability with original land leads to the heterogeneity effects on groundwater regimes including groundwater head, seawater extent and so on, which were evaluated by several studies that unanimously adopt cross-section to represent entire aquifer (i.e., 2-D reclamation model). This study develops analytical solution for the response of groundwater system to size-limited land reclamation, investigating the permeability effects of reclaimed land. Laboratory experiment and numerical modelling were performed for the verification of derived solution and underlying assumptions, involving situations that hydraulic conductivity of created area is lower, same or higher than/with that of original land. Application of analytical solution in an illustrative aquifer found that the heterogeneous finite land reclamation induces less groundwater level rise than 2-D model, especially for inland constant-flux boundary condition, which would be attributed to the along-shore movement of flow. Moreover, less permeable filling material significantly reduces the flux and extends the travel time of groundwater within reclaimed land, invalidating its benefits of alleviating seawater intrusion from decreasing permeability. The analytical solution presented provides a suitable tool for preliminary prediction of changes to seawater extent and flow distribution caused by finite land reclamation.

How to cite: Zhang, J., Lu, C., and Sun, J.: Finite Land Reclamation at Coastal Region: Impact of Heterogeneity on Groundwater and Seawater Extent, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7996, https://doi.org/10.5194/egusphere-egu25-7996, 2025.

Posters on site: Mon, 28 Apr, 08:30–10:15 | Hall A

Display time: Mon, 28 Apr, 08:30–12:30
Chairpersons: Alper Elçi, Nadim Copty
A.46
|
EGU25-932
|
ECS
|
The effect of the permeability heterogeneity on the extension of wellhead protection area based on synthetic simulation and a case study in Hungary 
Bence Molnár, Attila Galsa, and István Garaguly

Sustainable water extraction and the vulnerability of aquifers require the accurate definition of wellhead protection area (WHPA) around both production and injection wells. Although the WHPA definition is different in every country, they have a common feature that the protected area is defined by groundwater travel time. The assumption of a homogeneous medium is the general simplification in modelling of WHPA, although, heterogeneity can have a significant effect on its size in the hydrogeological environment.

In this study, we investigated the effect of permeability heterogeneity on the size of the WHPA in synthetic two- and three-dimensional finite element models with COMSOL Multiphysics software at the time points used in the Hungarian legislation (t=20 d, 180 d, 5 yr, 50 yr). Heterogeneous permeability distributions with different heterogeneity scales (i.e. correlation length R=5 m, 10 m, 20 m) were created in SGeMS geostatistics software using unconditional Sequential Gaussian Simulation (SGS). 20–20 realizations were generated for each value of R in order to get statistically stable solutions for the simulations. The temporal evolution of the concentration front (minimum - rmin, average - rav and maximum - rmax distances from well) was used to monitor the size of the WHPA at the respective time points.

Among the results, the following main conclusions can be drawn based on 2D simulations. Although the average distance (rav) in heterogeneous media is approximately equal to the homogeneous solution, the maximum distance (rmax) is significantly greater in heterogeneous media, because the water travels larger distances in a heterogeneous medium through the channels of zones with good permeability. Therefore, a larger protection area should be expected compared to the homogeneous approach. Water travels up to 25–75% farther depending on the scale of heterogeneity, where the increment rate decreases over time. Based on the 3D simulations, only small differences are detected between the 2D and 3D results. The maximum distances (rmax) in 3D models are 1.05–1.47 times greater than those in 2D models. Besides, the ratio decreases with time, which indicates that the differences are relevant especially on short time scales, and there is no significant difference after 50 years.

The research provides useful results in terms of the size of the WHPA, which is important for geothermal applications and sustainable water management. In this light, the findings from synthetic model calculations are used in a geothermal project area in Hungary where the heterogeneity scale is estimated from seismic attributes (sweetness, amplitude anomaly) and a 3D hydrodynamic model of the heterogeneous hydrogeological environment is evaluated in FEFLOW software.

Project no. KT-2023-900-I1-00000975/0000003 has been implemented with the support provided by the Ministry of Culture and Innovation of Hungary from the National Research, Development and Innovation Fund, financed under the KDP-2023 funding scheme.

How to cite: Molnár, B., Galsa, A., and Garaguly, I.: The effect of the permeability heterogeneity on the extension of wellhead protection area based on synthetic simulation and a case study in Hungary, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-932, https://doi.org/10.5194/egusphere-egu25-932, 2025.

A.47
|
EGU25-1016
|
ECS
|
A Simplified Approach to Modelling Groundwater Dynamics in Complex, Data-Scarce Semi-Arid Basins 
ankush kaundal and sekhar muddu

Groundwater is a vital component of the global hydrological cycle, supporting stream flows, vegetation, and serving as a critical water source during droughts. In semi-arid regions, where rainfall is erratic and surface water resources are limited, groundwater plays a key role in sustaining agriculture and economic activities. However, these regions face compounded challenges due to climatic variability and human activities, leading to significant groundwater stress. Large-scale hydrological models offer insights into broad-scale dynamics but often lack the resolution needed to address region-specific issues, particularly in data-scarce areas where human influences like groundwater extraction significantly alter the hydrological cycle. These limitations underscore the need for localized models that integrate detailed information on human water use and extraction to enhance understanding of groundwater dynamics. The semi-arid Noyil River Basin, characterized by intense human activity and climatic stress, is used in this study to demonstrate the proposed modeling methods. Developing groundwater models in this data-scarce environment is particularly challenging due to insufficient data on recharge and extraction, as well as the complexity of accounting for diverse land-use types. To address these challenges, this study employs a water table fluctuation-based conceptual model (AMBHAS-1D) to estimate recharge and groundwater draft. The outputs from this model are then integrated into numerical transient groundwater model built using MODFLOW, enabling detailed simulations of aquifer responses to climatic and anthropogenic pressures. The study demonstrates how calibrated time series outputs from a simple 1-D model can serve as effective inputs for a more sophisticated transient numerical model. The transient model operates without additional calibration, relying solely on the 1-D model’s outputs, making it particularly suitable for data scarce basins with unpredictable rainfall and significant groundwater reliance. The approach allows for detailed analysis of groundwater dynamics, including flow behavior during dry periods and the impacts of human extraction and climatic variability. The study highlights the importance of incorporating fine-scale human water use, which is often overlooked in data-limited regions. By addressing the challenges of modeling in data-scarce, water-stressed basins, this study provides a framework for more effective groundwater management, particularly in regions where groundwater serves as the primary water source during drought periods.

How to cite: kaundal, A. and muddu, S.: A Simplified Approach to Modelling Groundwater Dynamics in Complex, Data-Scarce Semi-Arid Basins, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1016, https://doi.org/10.5194/egusphere-egu25-1016, 2025.

Discussion Post a comment
A.48
|
EGU25-2263
A Study on Prediction of Saltwater Instrusion in Costal Aquifer using LSTM Algorithm 
Woochang Jeong

In Korea, groundwater is used as the main water resource, and there is a high possibility of groundwater pollution from saltwater intrusion caused by various groundwater developments and overexploitation. In this study, time series data such as daily average sea level, groundwater level, upper and lower electrical conductivity, rainfall, upper and lower water temperature, and LSTM algorithm was used to forecast the electrical conductivity, which is an indicator of seawater intrusion, for four stations in Kyungnam Haeun, Kyungnam Mokdo, Gangwon Joyang, and Incheon Sungyeo, which are severe level stations in the coastal areas of each area, in the rural groundwater management system. A time lag of 3 to 10 days was applied to each area, and out of a total of 3,438 univariate data, 2,406 days (70%) were trained, and 1,032 days (30%) were forecast and evaluated, with LSTM layers ranging from 8 to 256, batch size from 5 to 50 epochs, and parameters from 10 to 150. As one of the best forecasts, RMSE = 0.0066 and R2 = 0.9827 were performed in Gangwon Joyang. Afterward, RMSE = 0.0603 and R2 = 0.9856 were performed with the same parameters when predicting using the Shuffle technique.

How to cite: Jeong, W.: A Study on Prediction of Saltwater Instrusion in Costal Aquifer using LSTM Algorithm, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2263, https://doi.org/10.5194/egusphere-egu25-2263, 2025.

A.49
|
EGU25-2309
|
ECS
Application of THMC Model with User-Friendly Interface in Addressing Saltwater Intrusion 
Yu-Chieh Ho, Yung-Yu Tai, Yen-Pu Hsu, Jui-Sheng Chen, and Gour-Tsyh Yeh

THMC(Thermal-Hydrology-Geo-Mechanics-Chemical), developed by the internationally renowned hydrologist Prof. Gour-Tsyh Yeh, is an advanced physical-based FEM model for simulating fully coupled processes in saturated and unsaturated subsurface environment. Designed to address a broad spectrum of water-related issues, THMC offers unparalleled capabilities in carbon sequestration, geothermal energy, nuclear waste disposal, groundwater resource management and groundwater remediation.

Recent advancements in THMC model emphasize enhanced simulation accuracy and computational stability, consolidating its standing as a leading solution in international subsurface software market. Furthermore, CAMRDA from National Central University, Taiwan, has improved the model’s accessibility and usability by designing a Windows-based, user-friendly interface platform. The platform supports fully 3D operations, enabling seamless simulation workflows with interactive visualization tools and intuitive model-building features. Its self-developed 2D/3D mesh generation engine allows users to construct detailed conceptual models and simulation-ready meshes efficiently.

To overcome the domain knowledge barrier, the software integrates a comprehensive database of frequently used parameters, including material coefficients and chemical equations, simplifying setup processes and shortening the learning curve for new users. With these enhancements, THMC has become a competitive and versatile tool for researchers and practitioners tackling complex environmental and engineering challenges.

In this study, we consider the Henry's saltwater intrusion problem as a case example to perform a simulation using THMC software. The simulation results closely align with those from the previous study (Cheng et al., 1998), serving as a reliable benchmark in the issue of saltwater intrusion. With the THMC platform, users can proficiently execute modelling and interpret the results of simulation, providing a scientific basis for decision-making analysis.

How to cite: Ho, Y.-C., Tai, Y.-Y., Hsu, Y.-P., Chen, J.-S., and Yeh, G.-T.: Application of THMC Model with User-Friendly Interface in Addressing Saltwater Intrusion, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2309, https://doi.org/10.5194/egusphere-egu25-2309, 2025.

A.50
|
EGU25-5449
|
ECS
|
Applications of Modeling Non-point Source Pollution in Groundwater  
Zhendan Cao, Giorgos Kourakos, and Thomas Harter

Modeling non-point source (NPS) pollution in groundwater is a critical yet challenging task, particularly at large regional scales, due to the high computational costs and the need for detailed loading data across the entire area. This work focuses on the development and application of the novel Non-Point Source Assessment Tool (NPSAT), a physically based and computationally efficient framework for simulating groundwater flow and diffuse pollution/tracer transport processes. By integrating regional-scale hydrologic models, high-resolution landscape recharge and pollution/tracer loading models and high-resolution well placement models with particle-tracking and reactive transport frameworks, the NPSAT addresses complexities such as spatial variability and anthropogenic influences on groundwater transport across local to large regional scales. Two key applications are highlighted: groundwater age modeling, which refines our understanding of aquifer porosities and flow velocities, and nitrate transport modeling, which evaluates contaminant movement and attenuation under varying agricultural practices. These advancements demonstrate the potential of cutting-edge groundwater modeling approaches to tackle emerging issues in water resource sustainability and pollution mitigation.

How to cite: Cao, Z., Kourakos, G., and Harter, T.: Applications of Modeling Non-point Source Pollution in Groundwater , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5449, https://doi.org/10.5194/egusphere-egu25-5449, 2025.

Discussion Post a comment
A.51
|
EGU25-7811
A novel semi-analytical solution of over-damped slug test in a three-layered aquifer system 
Mengxiong Cao and Zhang Wen

The slug test has been commonly used to estimate aquifer parameters. Previous studies on the slug test mainly focused on a single-layer aquifer. However, understanding the interaction between layers is particularly important when assessing aquifer parameters under certain circumstances. In this study, a new semi-analytical model on transient flow in a three-layered aquifer system with a partially penetrating well was developed for the slug test. The proposed model was solved using the Laplace transform method and the Goldstein-Weber transform method, where the semi-analytical solution for the model was obtained. The drawdowns of the proposed model were analyzed to understand the impacts of the different parameters on the drawdowns in a three-layered aquifer system. The results indicated that groundwater interactions between the layers have a significant impact on the slug test. In addition, a shorter and deeper well screen as well as a greater permeability ratio between the layers creates a greater interface flow between them, leading to a higher drawdown in the slug test. Finally, a slug test in a three-layered aquifer system was conducted in our laboratory to validate the new model, which indicated that the proposed model performed better in the interpretation of the experimental data than a previous model proposed by Hyder et al. (1994). We also proposed an empirical relationship to qualitatively identify the errors in the application of single-layer model for the analysis of response data in a three-layered aquifer system.

How to cite: Cao, M. and Wen, Z.: A novel semi-analytical solution of over-damped slug test in a three-layered aquifer system, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7811, https://doi.org/10.5194/egusphere-egu25-7811, 2025.

A.52
|
EGU25-9930
|
ECS
Effects of Railway and Port Infrastructures on the Quantitative and Qualitative State of an Urban Coastal Aquifer 
Carles Pérez-Castro, Daniel Fernandez-Garcia, Núria Ferrer-Ramos, and Carme Barba

Currently, approximately 40% of the world’s population is concentrated in coastal cities, and this figure is expected to continue increasing. In this context of demographic concentration in maritime cities, coastal aquifers constitute strategic water resources, particularly in arid or semi-arid regions and especially during drought periods. These aquifers are subjected to various anthropogenic and climatic pressures that affect the quantitative and qualitative state of their water resources. Among the anthropogenic actions, the increasing construction of underground infrastructure, such as tunnels for rail networks, stands out for its hydrogeological impact. Many of these structures are built between retaining walls and/or incorporate drainage systems that distort the natural flow network of the aquifer, while simultaneously reducing its resources. Additionally, the construction of inner docks involves a displacement of the coastline further inland. The combined effects of these actions on a coastal aquifer can exacerbate the advancement of saline intrusion, making it essential to quantify these impacts.

This study evaluates the combined quantitative and qualitative cumulative impact of infrastructure tunnels and an inner dock on the main aquifer of the Llobregat Delta (Spain) over the period 1966–2024. The conceptual and geological model of the aquifer was reviewed, followed by the construction and calibration of a 3D variable-density flow and chloride transport model in MODFLOW 6. The model discretization was designed to accurately reproduce the real geometry of the tunnels, their retaining walls, and the geological units.

Two simulations were conducted: one representing the current state with infrastructure and another reflecting a potential state without these structures. Differences were calculated between the mass balance, chloride concentration maps, and piezometric level maps of both scenarios. Preliminary results indicate that the construction of the dock in a geologically unfavorable area, combined with the piezometric depression caused by a high density of tunnel and basement drainage systems, were determining factors in the rapid salinization and high salinity levels of the western hemidelta.

The contribution of this study is a methodology for quantifying these effects in other coastal aquifers, while highlighting the importance of geological knowledge, the implementation of best construction practices, and the strategic location of such infrastructure to preserve the water resources of an urban coastal aquifer.

How to cite: Pérez-Castro, C., Fernandez-Garcia, D., Ferrer-Ramos, N., and Barba, C.: Effects of Railway and Port Infrastructures on the Quantitative and Qualitative State of an Urban Coastal Aquifer, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9930, https://doi.org/10.5194/egusphere-egu25-9930, 2025.

A.53
|
EGU25-10968
|
ECS
Managed Aquifer Recharge as an Adaptation Strategy to Climatic and Hydrological Extremes 
John Craven, Abdelrahman, Abdelrahman Ahmed Ali, Margarita Saft, and Irina Engelhardt

Climatic and hydrological extremes increasingly pose a challenge to the successful management of water resources in the Lower Spree catchment in Brandenburg Germany, near Berlin. To increase the resilience to such extremes this study explores managed aquifer recharge (MAR) as a potential management strategy to address these challenges.  In this study we present the development and calibration of a high-resolution (approximately 2.65 million active model cells) groundwater model (MODFLOW)  in a complex geological setting, an assessment of MAR source water availability, identification of optimal recharge locations through a multicriteria site selection process, and preliminary results of an optimized recharge scheme based on a multi-objective optimization. The findings provide a decision support tool that stakeholders can utilize to evaluate MAR as part of an integrated water resources management strategy.

How to cite: Craven, J., Abdelrahman Ahmed Ali, A., Saft, M., and Engelhardt, I.: Managed Aquifer Recharge as an Adaptation Strategy to Climatic and Hydrological Extremes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10968, https://doi.org/10.5194/egusphere-egu25-10968, 2025.

A.54
|
EGU25-12892
|
ECS
Investigating Multispecies Reactive Transport in Porous Media: A Simulation and Moment Analysis Approach 
Kumar Rishabh Gupta and Pramod Kumar Sharma

Contaminant migration in subsurface environments critically threatens groundwater, particularly near chemical and nuclear repositories. This study employs both the Finite Difference Method (FDM) and COMSOL for two-dimensional multispecies reactive transport modeling in saturated porous media. The models simulate advection, dispersion, and first-order decay and are validated against analytical solutions with excellent accuracy. A key feature is the incorporation of three dispersivity scenarios of constant, linear, and exponential distance-dependent dispersivities which is applied to radionuclide (RN) decay chains and chlorinated solvents (CS). A novel contribution of this work is the comparative analysis of these dispersivity scenarios, revealing their influence on solute plume mobility and retardation factors. Significant differences in retardation factors for RN and CS highlight the applicability of the model across diverse environments. Spatial moment analysis demonstrates that the species with the largest plume may not dominate subsurface migration. The application of effective dispersivity in interpreting tracer breakthrough curves significantly improves numerical precision and field relevance. The integration of FDM and COMSOL allows for cross-validation of results, offering a robust and reliable framework for modeling reactive transport. This approach provides enhanced insights into the long-term environmental impacts of reactive contaminants and aids in the development of effective remediation strategies. By integrating these numerical methods, the study delivers a valuable insight to mitigate contamination risks in sensitive environments, with broad applicability for safeguarding groundwater near chemical and nuclear repositories.

How to cite: Gupta, K. R. and Sharma, P. K.: Investigating Multispecies Reactive Transport in Porous Media: A Simulation and Moment Analysis Approach, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12892, https://doi.org/10.5194/egusphere-egu25-12892, 2025.

A.55
|
EGU25-12994
Estimation of Aquifer Connectivity Metrics from Pumping Tests Data 
Nadim Copty, Buse Yetişti, Paolo Trinchero, and Xavier Sanchez-Vila

Subsurface flow parameters, such as transmissivity or storativity, are intrinsically heterogeneous and characterized by complex patterns of spatial variability. In the case of transmissivity, the presence of spatially connected flow channels can have significant impact on groundwater flow and contaminant transport. In this study, we investigate numerically the impact of point-to-point flow connectivity on radially convergent flow in constant rate pumping tests, focusing on how connected features influence the estimation of hydraulic parameters. Multiple heterogeneous aquifer systems with different levels of connectivity are synthetically generated and then used to simulate pumping tests. Different pumping test interpretation methods are used to estimate the flow parameters from the time-drawdown data and to investigate how the estimated parameters relate to the underlying heterogeneous distribution of aquifer parameters. In particular, the relations between the estimated parameters and static measures of connectivity, that are independent of the flow pattern, are examined. Results indicate that the estimated transmissivity value approaches the geometric mean of the transmissivity field irrespective of the level of aquifer connectivity. On the other hand, the estimated storativity is seen to be strongly influenced by aquifer point-to-point flow connectivity; yet, this influence is obscured as estimated storativity is also dependent on the spatial distribution of the transmissivity and the relative locations of the observation and pumping wells. The implications of these findings on the interpretation of constant rate pumping tests are discussed.

How to cite: Copty, N., Yetişti, B., Trinchero, P., and Sanchez-Vila, X.: Estimation of Aquifer Connectivity Metrics from Pumping Tests Data, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12994, https://doi.org/10.5194/egusphere-egu25-12994, 2025.

A.56
|
EGU25-15707
Study on the Optimization of Monitoring Well Placement Using Bayesian Model Averaging and Bayesian Maximum Entropy 
Tai-Sheng Liou, Yao-Ming Kuo, Tung-Ching Sun, and Chih-Tse Wang

　　Certain limitations arise when utilizing the Monitoring Efficiency Model (MEMO) and Monitoring and Remediation Optimization System (MAROS) to evaluate monitoring well placement at contaminated sites. MEMO is restricted to one-dimensional groundwater flow analysis, while MAROS can only handle two-dimensional spatial distribution of contaminants. These constraints hinder the ability to account for variability in the three-dimensional spatial distribution of contaminants, leading to suboptimal monitoring well configurations. In particular, factors such as geological heterogeneity and contaminant characteristics (e.g., biodegradation, chemical degradation, and physical adsorption) may lead to contaminant omissions or inappropriate monitoring well density distribution, ultimately limiting the efficiency and accuracy of monitoring well placement.

　　To address these challenges, this study proposes an optimized approach for monitoring well placement at three-dimensional groundwater contamination sites. The method integrates Bayesian Model Averaging (BMA) and Bayesian Maximum Entropy (BME) to delineate contaminant plumes more accurately and provide optimal recommendations for monitoring well placement. BMA, utilizing Markov Chain Monte Carlo (MCMC) simulations and Bayesian inference, calculates the posterior distribution of multiple potential Conceptual Site Models (CSMs) by evaluating discrepancies between observed and simulated contaminant concentrations.

　　Using the weighted CSM, the relative positions between existing monitoring wells and the contaminant plume can be evaluated. During the numerical simulation process, virtual observation points are added to enhance the richness and completeness of data distribution within the contaminated area, further improving the interpolation accuracy of BME. Through this improvement, BME can integrate simulated data with existing monitoring data to precisely predict the locations of additional monitoring wells, supplement critical monitoring data, and optimize the overall monitoring well placement strategy.

　　Additionally, this study incorporates monitoring well-installation costs, the value of information (VOI), and trans-information entropy (TE) into a multi-objective optimization framework. By minimizing the objective function, Pareto-optimal solutions are obtained. The Preference Ranking Organization METHod for Enrichment Evaluations (PROMETHEE) is then applied to rank these solutions, enabling decision-makers to balance monitoring efficiency with cost considerations and implement flexible and effective monitoring configurations. It also verifies the feasibility of retaining a significant portion of critical monitoring information through VOI-based quantitative analysis, even with a reduced number of monitoring wells.

　　The proposed optimization method has been validated through numerical simulations, demonstrating improved model accuracy under complex site conditions. The results offer adaptable, site-specific solutions that maximize both monitoring efficiency and economic viability.

 

Keywords: Bayesian Model Averaging, Bayesian Maximum Entropy, groundwater contaminant transport, optimization of monitoring well placement

How to cite: Liou, T.-S., Kuo, Y.-M., Sun, T.-C., and Wang, C.-T.: Study on the Optimization of Monitoring Well Placement Using Bayesian Model Averaging and Bayesian Maximum Entropy, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15707, https://doi.org/10.5194/egusphere-egu25-15707, 2025.

A.57
|
EGU25-16178
Regional scale simulation of integrated surface-groundwater model for a basin along the west coast of India 
Manikandan Shanmugarajasekaran, Bruno Majone, Diego Avesani, and Alberto Bellin

An integrated hydrological model plays a crucial role in maintaining and ensuring the sustainability of water resources. This study presents a test case for the development of an integrated surface-groundwater model using MODFLOW 6, the latest version of MODFLOW, and FloPy to simulate major hydrological processes and support sustainable water management in a tropical basin where the demand for fresh water is increasing at an alarming rate.

The model incorporates the Unsaturated Zone Flow (UZF), Streamflow Routing (SFR), and Water Mover (MVR) packages to simulate groundwater recharge, surface water dynamics, and interconnections between hydrological components. Input datasets include precipitation, PET, land use, soil, and hydrogeological properties to reflect the basin’s hydrological complexity.

The simulated model was calibrated and validated against observed streamflow and groundwater head data to ensure accuracy and reliability. We showed that the model effectively reflects key hydrological processes, such as monsoon-driven recharge and surface-subsurface interactions. These findings show the model’s ability to guide water resource planning in the basin.

This study illustrates the applicability of MODFLOW 6 and FloPy for hydrological modeling in tropical basins and provides a foundation for assessing climate change impacts on regional water resources.

 

How to cite: Shanmugarajasekaran, M., Majone, B., Avesani, D., and Bellin, A.: Regional scale simulation of integrated surface-groundwater model for a basin along the west coast of India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16178, https://doi.org/10.5194/egusphere-egu25-16178, 2025.