In the European Union, 38 billion m3 of groundwater are extracted every year for municipal water supply, contributing 2/3 of the drinking-water supply. Industrial groundwater extractions are on the same order of magnitude, whereas the groundwater demand for irrigation agriculture is about 15 billion m3 (1, 2). The main threats for groundwater resources are overexploitation and contamination, with strong regional differences: Groundwater resources in the Mediterranean are affected the most by unsustainable extraction for agriculture, whereas regions with poor chemical status of groundwater coincide with those of intensive agriculture (modulated by soil type) or a long history of industry. Climate change and population growth increase the pressure on water resources. A comprehensive understanding of groundwater resources and competing usages is of crucial importance for its sustainable management, and thus for future water supply and ecosystem functioning.
The proposed session will cover current developments and innovations on the assessment of groundwater resources, projections of future supply and demand, and strategies for sustainable groundwater management. The session will address all aspects of groundwater quantity and quality, ideally with its coupling, relevant for long-term management. Contributions may focus on integrative assessing that includes specific threats (e.g. agricultural contamination, excessive withdrawals, pathogens, seawater intrusion), future projections, the challenges of allocating water to different purposes (municipal water supply, industry, agriculture, ecology). We also welcome contributions on assessing emerging demands (e.g., thermal use of aquifers) and on method developments (e.g., integrative modelling, new monitoring approaches, bio-indicators, isotopic tracers). Technical solutions (e.g., artificial groundwater recharge, in situ treatment ) and management strategies including stakeholder involvement, participatory approaches and the consideration of governance and economic requirements are also welcome.
Integrative contributions will be given preference.
(1) European Environment Agency (EEA), 2022, Europe’s groundwater - a key resource under pressure, doi: 10.2800/629513
(2) https://data.apps.fao.org/aquastat, data for 2021
Temperature is a critical factor at the interface between water and energy stakeholders. It plays a vital role in enabling them to sustain and develop their activities without competing for resources, particularly during periods of crisis. Both surface water bodies and subsurface compartments (<200 m), essential for maintaining aquatic ecosystems and supporting human adaptation to global changes, are utilized for a range of purposes. These include low-impact thermal energy production (e.g., river uses and shallow geothermal energy), drinking water supply, irrigation, and industrial applications.
However, these diverse uses by water and energy stakeholders, along with their associated infrastructures, lead to thermal interferences. These interferences are superimposed on broader climatic variations and trends, further complicating resource management.
In the Seine basin, observed trends are projected to persist and intensify. These include rising average temperatures, decreasing summer rainfall, and the increasing frequency and severity of extreme events such as floods, droughts, and heatwaves. The sustainable management of water resources will hinge on our collective ability to anticipate and mitigate the effects of these changes.
To better predict the Seine basin’s responses to climate change, it is crucial to deepen our understanding of heat transfers between the atmosphere and the various compartments of the hydrosystem. This knowledge will be key to developing strategies that balance the needs of all stakeholders while preserving vital ecosystems and ensuring resilience against global change.
In this presentation, we will present data collection, the development of numerocal tools, and the evaluation of the evolution of the Seine's temperatures over 100 years. Physical models and simulations help quantify thermal fluxes, highlighting the main sources of heat input and heat losses. The use of machine learning models in projecting the Seine's temperatures in Paris by 2100 adds a predictive dimension. Future developments to achieve modeling that allows us to produce numerical simulations necessary for the integrated management of surface and groundwater in quantitative, qualitative, and thermal terms will be presented.
How to cite: Rivière, A., Killic, D., Bruel, D., Corral, D., Ducharne, A., Flipo, N., Jost, A., Gallois, N., Gourcy, L., Henriot, A., Ladet, D., Lopez, B., Peylin, P., Roy, V., and Thomas, W.: Addressing Socio-Economic and Environmental Challenges Linked to Water Temperatures in the Face of Global Change : Application at the Seine Hydrosystem, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16553, https://doi.org/10.5194/egusphere-egu25-16553, 2025.
Aquifers under urban areas are highly impacted by human activity and altered in terms of thermal, chemical, and also ecological conditions. In particular for ecological conditions, the causes and implications of changes in faunal communities for groundwater management and use are not yet fully understood. At the same time, large and dense urban clusters, such as the city of Berlin, Germany, rely on water supply from groundwater and other sources within their city limits.
The aim of the CHARMANT project is therefore to develop a groundwater management approach specifically designed for the complex, multifaceted conditions in the urban underground that incorporates assessment of groundwater ecosystems and thermal management of the subsurface. Long-term changes in the thermal subsurface conditions are evaluated based on repeated measurements of temperature-depth profiles, which show an increase in warming down to 100m. Likewise, warming near the surface (20 m below ground level) is spreading from the city centre towards the suburban areas, due to increased surface sealing, subsurface infrastructure and climate change. Frequent occurrence of groundwater fauna, i.e. stygophile and stygobiont species, is found to be limited to locations in the Berlin-Warsaw glacial valley in central Berlin or in the vicinity of surface waters (approx. 11 % of all measurement wells). At the same time, some of the regularly sampled wells exhibit rare mass events with hundreds or even thousands of fauna individuals, which are not linked to changes in abiotic groundwater parameters. Also, for the specific case of Berlin, occurrence groundwater fauna appears to be constraint mostly due to low contents of dissolved oxygen linked to natural hydrogeological conditions. Overall, these heterogeneous conditions make quantitative assessment of the ecological status based on existing approaches difficult.
The thermal state of the subsurface of Berlin is further assessed by thermo-hydraulic modelling that aims at identifying areas with similar groundwater conditions, so-called archetypes, whilst taking groundwater temperature as a proxy for overall anthropogenic impact. In the future, these groundwater archetypes will be linked to chemical conditions, e.g. presence of typical urban contaminants, as well as the ecological status, e.g. presence of specific groundwater fauna, in order to obtain groundwater use types. These use types represent 3D, spatially-resolved conceptual models, that facilitate the integration of aspects of spatial planning above the surface as well as different regulatory frameworks. Furthermore, the project aims at using the simplified representation of complex subsurface processes in these archetypes for communicating groundwater management strategies and enhancing awareness and active participation of citizen and other stakeholders with the aim of minimizing conflicts of groundwater use.
How to cite: Menberg, K., Glatting, F., Hajizadeh Javaran, M. R., Bölscher, J., Geppert, M., Hemmerle, H., Bayer, P., Pohl, L., Wittig, S., Janssen, G., Fehlenberg, V., Schweer, C., Grimmeisen, F., and Blum, P.: Integrating thermal and ecological management of urban aquifers – an example from Berlin, Germany, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11275, https://doi.org/10.5194/egusphere-egu25-11275, 2025.
Extreme weather events can have a severe impact on riverbank filtration. For example, a prolonged severe drought like the Central European summer drought of 2018 reduces river streamflow, which can quickly and negatively impact pumping performance and water quality. In addition, long dry periods in the summer months are often accompanied by increased residential water demand. Therefore, weather and climate extremes, which are projected to become increasingly dynamic and intense, lead to difficulties for public water supply and represent major challenges for public water providers.
In the German WaX-Project “TrinkXtrem” (BMBF), adaptation strategies and management models for a riverbank filtration system of Wasserversorgung Rheinhessen-Pfalz GmbH on the Rhine River were developed.
The bank filtration system comprises two primary components: groundwater and infiltrating surface water. Near the riverbank, the river water level dynamically influences both, groundwater levels and quality. Further away from the river, groundwater level responses become progressively slower and the influence of surface water diminishes.
Therefore, a carefully considered monitoring system is essential to capture the spatially variable groundwater dynamics with frequent data collection. To this end, a well-calibrated numerical groundwater model was developed, suitable for simulating the current situation and future scenarios.
Based on the model results, innovative and sustainable management concepts that integrate facility expansion with managed aquifer recharge are developed. These concepts aim to ensure public water supply during potentially extended peak water demand periods in the future, with minimal adverse effects on the environment. Additionally, these concepts seek to create added values by stabilizing landward groundwater levels to facilitate conservation of floodplain areas and forests as well as to support agriculture.
Furthermore, future scenarios that combine peak residential water demand with periods of extreme low flow are developed and numerically modelled, and the impacts of mitigation measures are evaluated.
How to cite: Ridavits, T., Stilling, M., Riedel, T., and aus der Beek, T.: From inventory analysis to numerical modelling: Preparing Riverbank Filtration for prolonged droughts – infiltration-supported riverbank water extraction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17575, https://doi.org/10.5194/egusphere-egu25-17575, 2025.
The eastern portion of the Venetian Friulian Plain (north-eastern Italy) hosts a complex aquifer system, comprising several layered confined aquifers in the southern region and a thick phreatic aquifer in the north. These aquifers are critical for meeting the freshwater demands of the population, including drinking, industrial, agricultural, and sanitary needs. Approximately 60 m³/s of water is extracted through an estimated 50,000 wells, averaging 20 wells per square kilometer. A significant portion of this water, precise estimates are unavailable, is extracted far over the actual needs through flowing wells, operating 24h per day. These extraction practices are widespread in the region and are rooted in centuries-old legislation governing water rights tied to land ownership.
Although the region is classified as low-risk for water scarcity, the protracted droughts of 2022 forced seven municipalities to rely on alternative freshwater sources after several artesian wells ceased to function due to a significant drop in the water table. Moreover, monitoring data reveals concerning trends of aquifer depletion, with rates reaching up to 10 cm per year in some areas of the northern plain. This depletion, intensified by heavy extraction near the coastline, raises serious concerns about the long-term sustainability of current practices and the growing risk of saline intrusion.
This study marks a preliminary investigation of the current status of these water resources and evaluates the impact of groundwater extraction on depletion rates. A hydrogeological model of the VFP and the surrounding regions, including the Northern Adriatic Basin, was developed and a numerical groundwater model was run to simulate water levels and flux behaviour over a 23-year period (2000–2023). The simulations included two scenarios: one with active pumping wells and one without, to assess the impact of extraction on aquifer dynamics.
The results demonstrate that aquifer depletion is significantly affected by groundwater extraction, with localized areas experiencing depletion rates up to ten times higher due to pumping. The study also reveals offshore-directed and onshore-directed fluxes along the shoreline, both of which are impacted by well pumping, raising additional concerns about the potential of saltwater intrusion while simultaneously suggesting the presence of Offshore Freshened aquifers in the Northern Adriatic basin.
Overall, these findings highlight the potentially unsustainable nature of current groundwater extraction practices and underscore the urgent need for a comprehensive review of resource management and sustainability strategies.
How to cite: Corradin, C., Camerlenghi, A., Giustiniani, M., Busetti, M., Zini, L., Foglia, L., Micallef, A., Bertoni, C., and T. Thomas, A.: Sustainability Challenges in Groundwater Management: Insights from 3D Hydrogeological Modeling in the Venetian-Friulian Plain., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16355, https://doi.org/10.5194/egusphere-egu25-16355, 2025.
The Emilia-Romagna region is located in north-eastern Italy and hosts extensive agricultural and industrial activity along with densely populated urban centers. All these elements contribute to increase the water demand, which often relies on groundwater resources, especially during droughts.
The complex regional aquifer system, consisting of multiple interconnected layers, presents a challenging yet compelling case study. Moreover, the region benefits from hydrogeological and environmental data gathered through long-term monitoring and research activities, offering a robust foundation for further detailed analysis.
In this study we estimate the potential evolution of groundwater conditions in part of the Emilia-Romagna region, considering the impacts of climate change and human activities. In particular, the goal is to evaluate the resilience of the regional multi-layered aquifer system to prolonged drought conditions, and to outline potential guidelines for long-term sustainable regional groundwater management. Two modeling techniques are employed: a numerical groundwater flow model and a random forest algorithm. This dual approach allows to compare the performance of a physics-based and a machine learning model in simulating historical and future groundwater levels within the same study area, thus investigating the potential benefits of combining both methods.
In the first phase, a groundwater model is implemented using MODFLOW 6, alongside a random forest algorithm developed in R. Input data are sourced from a MODFLOW model covering the entire Emilia-Romagna groundwater system by Arpae (Regional Agency for Prevention, Environment and Energy of Emilia-Romagna), as well as from publicly accessible datasets available through the Emilia-Romagna Region and Arpae repositories.
Next, we use the groundwater model and the random forest algorithm to analyze scenarios under different climatic and groundwater abstraction conditions. The aim is to assess the combined impacts of hypothetical drought events and changes in groundwater pumping rate regime on the groundwater heads in the regional aquifer system. Results from both approaches suggest that the aquifer system is vulnerable to potential future droughts. While increased groundwater abstraction could intensify the effects of reduced precipitation, decreasing groundwater pumping might partially alleviate the drought effects. Specific areas are also pinpointed where the impacts of reduced precipitation, changes in pumping rate, or their combination are more significant. This underscores the importance of evaluating both the overall study region and local scales to identify critical hotspots and determine the most effective strategies for mitigation and adaptation to future droughts and climate change.
The random forest algorithm offers valuable insights into the relative importance of data and variables influencing the final groundwater head distribution, enhancing the interpretation of the groundwater model results and suggesting areas for potential improvement. However, due to its lack of physical interpretability, it presents a lower generalization capability compared to a numerical model. These findings highlight the advantages of integrating physics-based and machine learning approaches to understand model outputs and improve overall performance. Combining the two methods strengthens both the calibration process and the scenario analysis, providing a significant contribution to groundwater modeling, which will play an increasingly important role in the future.
How to cite: Delfini, I., Zamrsky, D., and Montanari, A.: A comparative analysis of physics-based and machine learning methods for sustainable aquifer management in the Emilia-Romagna region (Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-660, https://doi.org/10.5194/egusphere-egu25-660, 2025.
Coastal aquifers with sloping geometry (e.g., an inclined aquifer bed or confining layer) are common worldwide, yet most analytical models for pumping-induced seawater intrusion have assumed a horizontal setting (Lu et al., 2016). Building on our previously developed steady-state analytical solution for sloping unconfined coastal aquifers (Sun et al., 2023), this study extends the approach to both unconfined and confined aquifers under a fixed-flux inland boundary condition. Specifically, single potential theory is employed for unconfined aquifers, and finite Fourier cosine transforms are used for confined coastal aquifers. The proposed analytical solutions, corrected by an empirical factor, are validated against synthetic data generated by SEAWAT-based numerical simulations, demonstrating excellent agreement.
For unconfined aquifers, a positive sloping angle (i.e., higher aquifer bed toward inland) significantly increases the maximum safe pumping rate (MSPR) compared to an aquifer with a horizontal base. For instance, a slope of 0.01 yields a 42.6% increase in MSPR, whereas a slope of -0.01 leads to a 48.4% decrease relative to the horizontal case. In confined aquifers, the MSPR is governed by the slope of the upper confining layer and the angle difference between the upper and lower confining layers. A lower slope of the upper confining layer and a smaller angle difference lead to a higher head gradient, which suppresses seawater intrusion and thus enhances MSPR. For example, for an upper sloping angle of 0.05 combined with an angle difference of -0.01, as well as for an upper sloping angle of -0.01 combined with an angle difference of 0.01, the MSPR increases by 16.3% and decreases by 29.2%, respectively, in comparison to a horizontal aquifer.
These findings highlight that neglecting aquifer sloping geometry can introduce substantial errors in estimating MSPRs. Although the presented solutions offer a rapid assessment tool for pumping-induced seawater intrusion in sloping coastal aquifers, the flow field variations arising from inclined geometry and their implications for solute transport and biogeochemical reactions warrant further investigation, underscoring the need for ongoing research in their area.
Bibliography
Lu, C., Xin, P., Kong, J., Li, L., & Luo, J. (2016). Analytical solutions of seawater intrusion in sloping confined and unconfined coastal aquifers. Water Resources Research, 52(9), 6989–7004.
Sun, J., Wu, H., Yin, J., & Lu, C. (2023). Estimating the maximum safe pumping rate in sloping unconfined coastal aquifers. Water Resources Research, 59(9), e2023WR034675.
How to cite: Sun, J., Wu, H., Yin, J., and Lu, C.: Analytical Estimation of Maximum Safe Pumping Rate in Sloping Confined and Unconfined Coastal Aquifers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8126, https://doi.org/10.5194/egusphere-egu25-8126, 2025.
Uncertainty in hydrogeological structures and properties has limited the effectiveness of traditional frameworks for aquifer characterization, groundwater monitoring and modelling in practical applications. How to properly deal with uncertainty is highly relevant for robust decision-making in sustainable management of groundwater resources, which are increasingly stressed between water use and climate change impacts for many drinking water supply sites worldwide that are strongly dependent on groundwater. Previous innovative studies, which rely strongly on the stochastic approach, are predominantly explored in synthetic and scientific cases, creating a gap in presenting how practical and efficient these frameworks can be at regional and local scales. In this work, we developed a holistic approach to better understand and manage uncertainties in hydrogeological structures and properties through groundwater flow modelling. We tested the developed approach for a local drinking water supply site in eastern Germany, which consists of a porous aquifer of glacial-fluvial unconsolidated sediments and is characterized by strong heterogeneity and anisotropy of its hydraulic properties. A large borehole dataset was analyzed to characterize the geological variability and form the basis for a detailed 3D subsurface model. Multiple subsurface structure realizations were generated using ArchPy to represent plausible hydrogeological interpretations of hydraulic conductivity and the groundwater flow dynamics were simulated using MODFLOW 6. The results highlight that hydrogeological uncertainty significantly affects simulated groundwater flow patterns and limits the reliability of deterministic models. The multi-model ensemble approach, incorporating probabilistic assessments, proved to be a robust framework for groundwater management in heterogeneous systems. More specifically, the results highlight the efficiency of the proposed approach to couple ArchPy with MODFLOW via FloPy to incorporate and acknowledge the propagated spatial uncertainty on simulated groundwater dynamics into a robust decision-making process of sustainable groundwater management. Furthermore, this research showed that a highly simplified or highly complex representation of hydraulic conductivity uncertainty almost equally leads to a less reliable and practical groundwater model. The study advances hydrogeological research by providing a practical approach to uncertainty in groundwater modelling that addresses some of the significant implications for sustainable water resource management and provides a framework that is transferable to similar systems facing challenges of aquifer variability and uncertainty.
How to cite: Moghimi Benhangi, S., Schorpp, L., Stefania Agudelo Mendieta, T., Gustav Rudolph, M., Renard, P., Franke, P., and Chen, Z.: Robust decision-making for sustainable management of groundwater resources in unconsolidated aquifers using a multi-model ensemble approach incorporating hydrogeological uncertainty, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8893, https://doi.org/10.5194/egusphere-egu25-8893, 2025.
Pressure on freshwater resources is increasing due to growing water demand for agricultural, industrial and domestic use. The effects of climate change, such as longer periods of drought, further increase water demand. In addition to pressure on water quantity, water quality is affected by pollution, including groundwater resources. Therefore, sustainable and resilient approaches for groundwater use are needed.
Managed aquifer recharge (MAR) can secure water supplies by expanding the amount of water storage available. At the same time, MAR can improve water quality through the filtering effect of soil and groundwater. However, trace organic contaminants (TOrCs) are not sufficiently attenuated by biodegradation processes during subsurface travel. Thus, an adequate pretreatment may be necessary to ensure the best possible use of the treatment effects of MAR.
As a first step, this study investigates the effects of different pretreatments on the removal of TOrCs during MAR. Columns mimicking the groundwater passage receiving differently treated wastewater qualities containing TOrCs allowed for a detailed monitoring of water quality parameters such as dissolved organic carbon (DOC) and dissolved oxygen (DO) along the depth of the columns. The microbial community that adapts to the different substrate conditions is expected to influence the potential for biodegradation of TOrCs.
The experimental setup consists of three saturated columns (1.6 m long, 0.15 m diameter) filled with technical sand. The sand has been exposed to ozonated wastewater treatment plant effluent for 2 years prior to the experiment and therefore has an existing biofilm. The columns receive three different wastewater qualities: (1) secondary effluent + cloth media filter, (2) secondary effluent + coagulation + ultrafiltration, (3) secondary effluent + cloth media filtration + ozonation + biologically activated carbon (BAC) filtration. Feed waters are continuously infiltrated at a flow rate of 9 ml/min. Water samples were taken along the columns at different depths (0.1 m, 0.3 m, 0.6 m below the sand surface). Samples were analyzed for water quality parameters such as DOC, UV absorption, 3D-excitation-emission spectra (3D-EEM), and 32 indicator TOrCs. In-situ DO measurements (DP-PSt3, PreSens GmbH, Germany) were conducted at depths of 0.1 m, 0.2 m, 0.3 m, 0.4 m, 0.6 m and 0.9 m below the sand surface.
As expected, water qualities differ as a function of pre-treatment, e.g. DOC concentrations are highest for the column receiving cloth media filtered water and lowest for the column receiving ozonated water. First results of TOrCs measurement show lowest concentrations in the influent for the column receiving ozonated water, which is expected given the high reactivity of ozone with TOrCs. TOrCs in the other two columns show differences, for example, benzotriazole and venlafaxine are more efficiently removed in the column fed with cloth media filtered water (64 % and 61 %) compared to the UF treated water (37 % and 15 %). A better understanding of biodegradation of TOrCs can help to implement customized pretreatments of MAR at larger scale.
How to cite: Linke, F., Knabl, M. A., and Drewes, J. E.: Hybrid Managed Aquifer Recharge – Effects of pretreatment on biodegradation of trace organic contaminants , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9679, https://doi.org/10.5194/egusphere-egu25-9679, 2025.
Groundwater is a vital resource supporting drinking water, agriculture, and ecosystems, which are critical in sustaining life and economic development. Groundwater contamination poses significant risks to public health, particularly for vulnerable populations such as infants, children, and adults. This study investigates the health risk assessment of groundwater contamination, focusing on key contaminants, including heavy metals contamination, irrigation indices, and hydrogeochemical characteristics in Ranipet District (RD), a region heavily influenced by agriculture and tannery industries. A total of 408 groundwater samples were collected and analysed by multivariate statistics, irrigation indices, and health risk assessment for pre-monsoon and post-monsoon during 2023 and 2024. The physicochemical parameters and heavy metals (Cr, Cd, Zn, Pb, and Cu) are considered in this analysis. The results of multivariate statistics and hydrogeochemical analysis affirm that total dissolved solids (TDS), calcium (Ca2+), magnesium (Mg2+), and potassium (K+) have controlled the hydrochemistry of the RD. Chromium (Cr), cadmium (Cd), copper (Cu), and zinc (Zn) are beyond the permissible limit and cause significant impacts on human health. Evaporation and rock-water interaction are the primary hydrochemical mechanisms controlling the hydrogeochemistry of the RD. The Piper diagram shows that CaMgHCO₃, CaMgSO₄, and NaCl are types of groundwater in the study area. The agriculture indices results confirmed that the groundwater in the RD affects crop productivity because the groundwater quality varies from very poor to unsuitable. The health risk assessment shows that infants and children are very likely to have carcinogenic and non-carcinogenic impacts due to the unauthorised industrial wastewater discharge and improper solid waste handling practices in the study area. Natural and anthropogenic activities are significantly affecting the groundwater quality in the study area. This is a pressing issue; addressing it with preventative actions to ensure the protection of groundwater sources would lead to the achievement of Goal 6 of the Sustainable Development Agenda (Clean Water and Sanitation).
How to cite: Krishnamoorthy, L. and Lakshmanan, V. R.: Seasonal assessment of groundwater quality, hydrogeochemistry, and heavy metal pollution in groundwater at Ranipet District: employing multivariate statistics, agricultural indices, and health risk evaluation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1041, https://doi.org/10.5194/egusphere-egu25-1041, 2025.
A comprehensive understanding of surface water and groundwater interaction is crucial to prevent overexploitation and contamination of groundwater. This is especially important for large rivers with installations from hydraulic engineering, such as weirs or sluices, because the interaction may be further intensified by these structures. Stable water isotopes and tritium, being part of the water molecule itself, serve as versatile natural or anthropogenic tracers, here suitable to evaluate water compartment interactions.
Since 2020 we conducted long-term monitoring of tritium and stable water isotopes at a sluice on the Moselle River in Lehmen, Germany. The study site contains several groundwater wells parallel to the river bank with one well slightly further distant to the river for reference of groundwater unaffected by surface water. The study aims to identify and quantify the surface water and groundwater interaction in a highly modified system using stable water isotope and tritium analysis of the according water compartments. The Moselle River water contains elevated tritium concentrations of up to ~400 TU induced by the French nuclear power plant Cattenom. Hence, tritium can be used as an indicator of surface water infiltration. Additionally, hydrological on-site parameters as well as water levels and further chemical parameters like major ions, trace elements and organic micropollutants were monitored to allow for a more holistic assessment of water compartments and identification of further suitable tracers for surface water and groundwater interaction.
We estimated transit times in conjunction with surface water proportions in the various groundwater wells. The transit times varied considerably when estimations were based on surface water grab samples, resulting in 1 to 12 months of travel time and low correlations coefficients (mean: 0.39). This could be attributed to the high variability of tritium concentrations in the surface water caused by random pulse emissions. With monthly composited samples for surface water transit times of 3 to 5 months and higher correlation coefficients (mean: 0.66) were calculated. Estimations using stable water isotopic composition resulted in travel times of 4 to 6 months for both grab and monthly composited surface water samples with slightly higher correlation coefficients for composite samples (grab-mean: 0.79, composite-mean: 0.86). Furthermore, the surface water proportion in the influenced groundwater wells was estimated using both tritium and stable water isotopes. Both tracers indicate a large surface water proportion in the groundwater wells, highlighting the significance of mixing processes induced by the impounded surface water of the investigated sluice site. Estimated proportions of surface water range from 66 to 74% with deuterium and 73 to 84% with tritium as the utilized tracer. As the tracers overlap at around 73 to 74% it can be assumed that both tracers deliver valid, comparable results. The observed relationship is also supported via major ion composition of the water compartments.
In conjunction with further hydrological parameters the analyses reveal elevated surface water proportions of at least 66% and travel times of 3 to 6 months. Further analysis of additional tracers may support the results gained via stable water isotope and tritium analysis.
How to cite: Landgraf, J., Beckers, L.-M., Schluesener, M., Wick, A., Duester, L., and Schmidt, A.: Evaluating surface water and groundwater interaction at a sluice system via tritium and stable water isotope analysis, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7274, https://doi.org/10.5194/egusphere-egu25-7274, 2025.
This research presents an integration of techniques such as remote sensing, field geology, geophysical profiling, hydrodynamic monitoring, and chemical analysis of groundwater, to develop the conceptual hydrogeological model of a volcanic fractured aquifer. The research area has 8000 km2, is located in South America, specifically in the southern region of Brazil, the state of Paraná, and is called Paraná 3 Hydrographic Basin (BP3). In this hydrographic basin, 83% of the public supply is by the groundwater of the Serra Geral Aquifer System. The water balance was estimated by remote sensing. The average monthly recharge between 2001 and 2022 was estimated at 61 mm/month. October (105.3 mm), February (75.8 mm), and September (75.4 mm) are the months with the highest recharge while June (16.4 mm), April (40.1 mm), and July (40.2 mm) have the lowest potential. Recharge was also observed from a network of 36 monitoring wells. There is a delay between precipitation and the arrival of this volume in the aquifer, which varies between 30 and 120 days. The results obtained with the monitoring network were compared to the results of the GRACE satellite and showed excellent correlation. During the hydrodynamic monitoring period, the reflection of an intense drought in the groundwater storage was observed. This demonstrates the influence of regional-scale climate events (for example, El Niño and La Niña) on the aquifer recharge process. Two main types of Cretaceous volcanic rocks outcrop in BP3: basalts and volcanoclastics. These rocks present discontinuities whose origin is related to the brittle tectonics, and discontinuities whose origin is associated with the cooling of the rock. In the tectonic discontinuities, a transtensive system stands out, with an E-W direction, favorable to the circulation and storage of groundwater. This same direction is observed in acoustic and heat flow metter profiles, suggesting that the E-W planes are hydraulically active. The E-W direction also proved favorable for groundwater prospecting when analyzing the relationship between the direction of structural lineaments (from digital elevation models) and the production of tubular wells. The presence of volcanic breccias, associated with the proximity of contact zones between flows, is the most important geological (non-tectonic) proxy. The horizontality of these contacts allowed us to observe interferences between wells more than 200 meters apart. Groundwater flows up to 59 meters deep present waters with calcium bicarbonate type, with higher concentrations of nitrate and other micropollutants, when compared to flows that occur between 119 and 200 meters deep, whose chemical signature is sodium bicarbonate, in which sulfate, carbonate, and TDS increase with increasing flow depth. These deeper waters reach up to 17.000 years old in C14 ages. The integration of techniques allowed the aquifer characterization and development of the aquifer hydrogeological model. This activities can be repeated in other fractured aquifers to understand the hydrogeological characteristics of the geological formations. This knowledge will reduce exploratory risk and contribute to the sustainable management of groundwater in the BP3 region.
How to cite: Barbosa Athayde, G., Garcia, L., do Amaral, B., Olivi, M., and de Vasconcelos Müller Athayde, C.: From satellite to well: integrated techniques for understanding groundwater flow in a Cretaceous volcanic aquifer of South America, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2056, https://doi.org/10.5194/egusphere-egu25-2056, 2025.
The Roussillon is a region in the south of France, bordering the Mediterranean Sea. The region is covered by an alluvial plain of about 800 km2 inland, which drains water from the eastern part of the Pyrenees. It is one of the driest regions of France with an average of 600 mm of rainfall per year over the last 20 years. It has recently suffered dry years, with a particularly low 250 mm of rainfall in 2023. The region's economy is mainly based on tourism and agriculture, both of which require water during spring and summer, which cannot be met by surface water alone and therefore relies heavily on the alluvial aquifer beneath it. This aquifer is composed of Quaternary sediments on top and thicker continental and marine Pliocene sediments below. The system has generally high permeability and has been well described by Dall'Alba (2023) using borehole data and innovative inverse methods based on multipoint statistics. If the aquifer was artesian before anthropic exploitation, the water level has dropped considerably in the last 50 years and is close to sea level near the coast. The water level oscillates during the year, with a low in summer caused by the drought period and, more importantly, by the annual distribution of pumping. This low in summer, especially in the coastal part where the aquifer water level goes below sea level, can cause irreversible saltwater intrusion, damaging the water quality. We therefore try to reproduce the observed seasonal oscillation using a Modflow model and various types of data: climatic, piezometric levels including continuous time series, boreholes, river water presence observatory, remote sensing, pumping tests. We show how important it is to understand the different boundary conditions of the aquifer to reproduce the seasonal trends, and how we can estimate the future behavior of the aquifer and better manage the resource by preventing saltwater intrusion.
How to cite: Voland, R., Renard, P., and Caballero, Y.: Managing the Roussillon aquifer by preparing for saltwater intrusion in a semi-arid coastal region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5911, https://doi.org/10.5194/egusphere-egu25-5911, 2025.
Vis is a small, remote island in the eastern Adriatic Sea predominantly composed of karstified carbonate rocks. The unique geological and hydrogeological context results in an autonomous water supply from its karst aquifer. The primary extraction site, the Korita well field in the central part of the island, benefits from natural protection against seawater intrusion via two hydrogeological barriers: (i) an impermeable volcanic-sedimentary-evaporite rock complex connected to a diapir structure to the west, and (ii) a zone of reduced permeability beneath karst poljes to the south. The current pumping capacity (up to 42 l/s) meets the local population demand. However, peak summer tourism and changes in precipitation patterns attributed to climate change impose significant stress on the groundwater resource during dry periods, leading to occasional supply reductions in the recent past. To address this issue, interdisciplinary research has been conducted over the past two decades to ensure the sustainable utilization of this primary resource under changing climatic conditions.
This research incorporates detailed aquifer and catchment characterization through a combination of methods: hydrogeological (pumping and tracer tests, continuous groundwater level, electrical conductivity, and temperature monitoring), hydrochemical (groundwater ion composition and isotope analyses), geophysical (electrical resistivity tomography, seismic refraction, and magnetotellurics), structural (fault and fracture analysis), and hydrological (water balance calculations and climate modeling). These investigations are complemented by socio-economic analyses of future water demand and the feasibility of managed aquifer recharge solutions.
Results indicate long-term stability in groundwater quality and quantity despite variable precipitation (the sole recharge source), suggesting substantial groundwater reserves and resilience to seasonal pumping peaks and periodic droughts. However, increasing water demand, climate change, and the risk of seawater intrusion pose potential threats. Ongoing and future researches aim to develop a comprehensive sustainable water management strategy, encompassing: (i) identification of potential new extraction zones and well development, (ii) an early warning system for seawater intrusion, (iii) optimized pumping rates at Korita, (iv) revitalization of rainwater harvesting for agricultural irrigation, (v) managed aquifer recharge, and/or (vi) implementation of small-scale desalination.
Acknowledgment: This research was conducted in the scope of the internal research project SIS-VIS at the Croatian Geological Survey, funded by the National Recovery and Resilience Plan 2021–2026 of the European Union – NextGenerationEU and monitored by the Ministry of Science, Education and Youth of the Republic of Croatia.
How to cite: Terzić, J., Borović, S., Patekar, M., Pola, M., Briški, M., Kosović, I., Frangen, T., and Urumović, K.: Addressing water resource challenges on Vis island, Croatia: an integrated approach to karst aquifer management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19599, https://doi.org/10.5194/egusphere-egu25-19599, 2025.
In many parts of the world, groundwater resources are under increasing pressure, with both, quantitative and qualitative causes. This can lead to various water use conflicts, especially in densely populated areas. One example of such a region is the Hessian Ried, which is part of the Upper Rhine Valley and located south of Frankfurt in Germany. The Hessian Ried covers an area of approximately 1,100 km2 and was naturally mostly marshland. To allow agricultural use, it was largely drained at the beginning of the last century. Today, mainly fruit and vegetables are grown with the extensive use of fertilizers, pesticides and groundwater irrigation. In addition, the relatively dense population in adjacent areas results in the discharge of large amounts of treated municipal wastewater into the streams of the Hessian Ried. Due to widespread influent conditions, there is substantial infiltration of these surface waters into the aquifer. However, the Hessian Ried is of enormous importance for the interregional public water supply in the Rhine-Main metropolitan area, for example, as the primary drinking water supply for the city of Frankfurt.
It is therefore important to gain an understanding of the processes by which substances are transferred from diffuse (agricultural land) and local (sewage-affected streams) sources into the groundwater and to develop reasonable countermeasures. Subsequently, monitoring tools are required that enable to examine the actual effectiveness of these measures in a timely manner. For this purpose, we have developed and implemented two types of monitoring stations at which (i) the diffuse input of nutrients and pesticides into the groundwater through the soil zone (Richard-Cerda et al., 2022, 2024) and (ii) the infiltration of pharmaceutically active compounds from a stream into the groundwater are studied. Results from the operation of these stations over a period of more than one year and additional laboratory experiments on hyporheic zone processes show initial findings on the sorption, transformation and degradation of nutrients and various organic trace substances.
References
Richard-Cerda, J.C., Bockstiegel, M., Muñoz-Vega, E., Knöller, K., Schüth, C., & Schulz, S., (2024). High-Resolution Monitoring and Redox-Potential-Based Solute Transport Modeling to Partition Denitrification Pathways at an Agricultural Site. Environmental Science & Technology Water. https://doi.org/10.1021/acsestwater.4c00540
Richard-Cerda, J.C., Giber, A., Muñoz-Vega, E., Kübeck, C., Berthold, G., Schüth, C., & Schulz, S. (2022). A high-resolution monitoring station for the in situ assessment of nitrate-related redox processes at an agricultural site. Journal of Environmental Quality 52. 188-198. https://doi.org/10.1002/jeq2.20423
How to cite: Schulz, S., Bockstiegel, M., Hillmann, S., Muñoz-Vega, E., Schüth, C., Berthold, G., Kludt, C., Knöller, K., and Richard-Cerda, J. C.: Water use conflicts and related monitoring strategies in an extensively developed groundwater system, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18667, https://doi.org/10.5194/egusphere-egu25-18667, 2025.
Recent field and modelling investigations have shown the karst vadose zone to act as an important factor in the assessment of available water resources, particularly in regions, characterised by thick unsaturated zones. In particular, in semi-arid regions of the Eastern Mediterranean, very wet years have shown to have prolonged effects of elevated groundwater discharge as well as elevated groundwater levels, compared to long-term average hydraulic conditions.
The above prolonged storage effects can generally be attributed either to delayed groundwater discharge or the sustained infiltration processes in the matrix of the vadose zone.
The research focussed on the analysis of the geohydrological processes in the field, i.e. the analysis of spring discharge and groundwater hydrograph records, both for humid-temperate as well as semi-arid conditions, the analysis of water tracers (Krypton an T/He; trace organics) as well as the coupled modelling of saturated / unsaturated flow, employing a double-continuum approach (HydroGeoSphere).
Our findings show that in less maturely karstified aquifer systems, the contribution of delayed seepage from the vadose zone can reach up to 40% of total spring discharge which is of particular importance for regions with prolonged drought periods, expected for semi-arid environments. The analysis of the tracer information allowed the discrimination of the source of the delayed discharge, in particular Krypton tracer analysis demonstrated the extended residence time of infiltrating water in the vadose zone. The quantification of the partitioning between rapid recharge and slow vadose seepage proved to be a challenge.
How to cite: Sauter, M., Maier, U., Dietrich, P., Noffz, T., Kavousi, A., Geyer, T., and Engelhardt, I.: The Karst Vadose Zone as an Important Water Storage System, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11320, https://doi.org/10.5194/egusphere-egu25-11320, 2025.
Climate change, with its rising temperatures and altered precipitation patterns, is expected to reduce soil moisture during critical phases of plant growth. This will lead to increased water stress and lower crop yields. As the frequency of low-yield years rises, farmers will become increasingly interested in irrigation as a means to stabilize crop production. This trend could accelerate if government subsidies for irrigation infrastructure increase in response to recurring low yields.
This shift towards increased irrigation may be particularly relevant for Germany, where in most regions irrigation is limited to few specialty crops. The present study focuses on the potential impact of increased irrigation in a 400 km² area south of Stuttgart, encompassing the morphological catchment of the Ammer River and part of the Neckar Valley near Tübingen. Since irrigation is not widely practiced in this region, it provides a unique opportunity to clearly demonstrate the effects of a possible transition to irrigation agriculture.
To analyze these impacts, the crop model ExpertN was used to simulate irrigation requirements for each of the region's 300 soil-weather units. The model incorporates detailed processes, such as water flow within soil layers (Richards equation) and evapotranspiration (based on the Penman-Monteith equation), to accurately describe soil moisture dynamics. Additionally, the model includes nitrogen cycling, enabling an assessment of increased irrigation to nitrate leaching.
The study highlights key outcomes, including the water demand for irrigation, additional moisture losses through evaporation, and increases in deep percolation under varying irrigation intensities. Furthermore, we evaluate the effects of irrigation on regional crop production, providing valuable insights for sustainable agricultural management under a changing climate.
How to cite: Görtz, J., Grieser, B., Weber, T. K., and Streck, T.: Impacts of Increased Agricultural Irrigation on Regional Groundwater Recharge, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18943, https://doi.org/10.5194/egusphere-egu25-18943, 2025.
Irrigation accounts for a major proportion of human water usage, exerting significant impacts on the natural environment and regional climate in inland arid basins. Groundwater overextraction and agricultural irrigation can drastically alter the water distribution in terrestrial systems, with potential impacts on hydrological processes. To better understand these risks and improve water resource regulation in inland arid basins, a land surface model was employed to investigate the impact of different groundwater overextraction ratios and irrigation efficiencies on hydrological processes in the Heihe River Basin during 2015-2020. The model integrated daily irrigation water use data that were estimated through the combination of satellite data and machine learning. The results showed a rationality of irrigation water use data between the inter-annual variation of estimated irrigation data and government reported data. When irrigation water was only withdrawn from the surface, it effectively increased evapotranspiration and soil moisture, with little impact on water table depth. However, the groundwater balance was seriously impaired when groundwater was extracted for irrigation, increasing water table depth (32.6%) and depleting groundwater storage throughout the study period.
How to cite: Xie, Z., Yang, H., and Jia, B.: Impact of groundwater overextraction and agricultural irrigation on hydrological processes in an inland arid basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2749, https://doi.org/10.5194/egusphere-egu25-2749, 2025.
Water shortage is a common challenge worldwide, and the Hungarian Great Plain is no exception. Climate change and human impacts (canal construction, afforestation, overpumping) have been causing severe water level declines in the area since the 1960’s. Water retention solutions are needed to preserve the natural vegetation and wet ecosystems and to ensure sustainable agriculture in the region. Water retention can be achieved in many ways, but consideration of the subsurface environment is inevitable. The Nature-Based MAR solution is based on the NaBa-MAR© ELTE concept that integrates MAR methods and systematic groundwater flow for comprehensive landscape-scale water replenishment. In this way, not only is the storage capacity of aquifers considered, but the governing groundwater movement is also incorporated in the design of the water retention in an area. The naturally moving groundwater transports the retained water providing benefits locally and also further away. The main objective of introducing the concept© is to match the demands and potentials in an area from a hydrogeological, social, and legal perspective. The applicability of the concept was assessed for the Danube-Tisza Interfluve area on a regional and local scale. As a first step, the available water sources were counted and the possibility of the infiltration MAR methods were investigated with MAR suitability mapping on a regional scale. Knowing this, the design of the possible MAR solutions was carried out on a local scale study area, taking into account the natural groundwater flow. Field measurements and numerical simulation helped to choose the most appropriate solution for rehabilitating a shallow lake environment. The results highlighted that local water retention solutions in regional recharge and through-flow areas have limited local effects. However, comprehensive NaBa-MAR solutions can have a landscape-scale impact in restoring the water level conditions in the area.
The work has been implemented by the National Multidisciplinary Laboratory for Climate Change (RRF-2.3.1-21-2022-00014) project within the framework of Hungary's National Recovery and Resilience Plan supported by the Recovery and Resilience Facility of the European Union. The work received funding from the European Commission and Ministry of Culture and Innovation of Hungary from National Research, Development and Innovation Fund; the Irish Enviromental Protection Agency; the Dutch Research Council and the Agencia Española de Investigación in the frame of the collaborative international consortium ClimEx-PE financed under the 2022 Joint call of the European Partnership 101060874 — Water4All. Project no. 2023-1.2.2-HE_PARTNERSÉG-2023-00005 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 2023-1.2.2-HE_PARTNERSÉG funding scheme.
How to cite: Simon, S., Czauner, B., Szijártó, M., Erhardt, I., Gyuris, F., Hoffman, I., Györfi, Á., Cazcarro, I., Lillquist, J., and Mádl-Szőnyi, J.: Nature-Based Managed Aquifer Recharge solutions for mitigating water shortage at Danube-Tisza Interfluve, Hungary, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19516, https://doi.org/10.5194/egusphere-egu25-19516, 2025.
Groundwater is a vital natural resource that supports human health, economic development, and ecological diversity. With its numerous inherent qualities, it has become immensely important for enhancing human water supply in both urban and rural regions of developed and developing countries. However, increasing population, industrialization, mismanagement, and inadequate governance have resulted in unregulated aquifer exploitation and growing contamination of water resources. Consequently, the sustainability of water resources (both surface water and groundwater) is under serious threat in the 21st century. It is advocated that only groundwater resources can ensure water security, food and nutrition security, and environmental security. Therefore, there is an urgent need to adopt a holistic approach for managing vital water resources. The groundwater resources sustainability (GRS) indicators developed by UNESCO are useful scientific tools for evaluating the availability of groundwater. These indicators aid in analyzing the extent of natural processes and the impacts of humans on groundwater systems in space and time. In this study, three GRS indicators were used to assess the condition of groundwater annually in the Yavatmal district of eastern Maharashtra, India, during the 2015-2021 period. This district is comprised of 16 blocks and encompasses an area of 13,528 km2. In this district, groundwater plays a vital role in sustaining agriculture. However, there is a threat to the sustainability of groundwater in the changing climate. The indicators used are ‘renewable groundwater resources (RGWR) per capita,’ ‘total groundwater abstraction/groundwater recharge (IA/R),’ and ‘total groundwater abstraction/exploitable groundwater resources (IA/E).’ The results of the RGWR indicator were classified into three classes, viz., low (0-3), moderate (3-6), and high (>6). It was found that in 2015, 90.65% of the study area was under the low category of RGWR per capita, 5% under moderate, and 4.32% under high. In contrast, in 2018, 67.18% of the area was under the low category, and 32.82% was under the moderate category. In 2021, 58.45% under low, and 41.55% under moderate category of RGWR per capita. The results, based on indicator IA/R, revealed that groundwater abstraction exceeds groundwater replenishment (IA/R>100%) in the four blocks (out of 16 blocks) in the year 2015, five blocks in 2018, and one block in 2021. However, the third indicator (IA/E) revealed that 15 blocks in the study area have underdeveloped groundwater resources (IA/E<90%), which suggests potential for future groundwater extraction from these blocks. In only one block, groundwater utilization is in overexploited conditions (IA/E >100%) during the study period. The findings of this study indicate that groundwater sustainability indicators are practically viable tools for formulating efficient utilization of groundwater resources. It is recommended that more groundwater sustainability indicators should be used when adequate data becomes available in the future in order to find a robust set of groundwater sustainability indicators that can help planners and water managers develop a sustainable groundwater utilization plan at a basin scale.
How to cite: Dhivar, Y. and Jha, M. K.: Assessment of Groundwater Sustainability Indicators in a Drought-Prone Region of India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14952, https://doi.org/10.5194/egusphere-egu25-14952, 2025.
The Borken region in northern Germany faces growing water challenges due to climate change and increasing water demand. Prolonged and intensified summer droughts, coupled with extreme storm events, are becoming more frequent, raising concerns about water scarcity and flood risks. These changes significantly impact stakeholders such as farmers, drinking water suppliers, and private industries, who are increasingly concerned about potential reductions in water use permits. Addressing these challenges requires a holistic water management strategy. Therefore, an integrated water balance model was developed to facilitate regional water resource planning and address ongoing challenges. Plans are underway to enhance this model into an operational system for real-time water resource monitoring and management.
Advanced modeling tools are required for capturing the complex interactions between groundwater, surface water, and the unsaturated zone. The hydrological model for Borken is based on the MIKE SHE software, which enables high-resolution temporal and spatial simulations. The integrated modelling approach offers detailed insights into the water balance of the catchment and integrates all components of the hydrological cycle.
The model incorporates a three-dimensional groundwater flow module based on a hydrogeological model, providing comprehensive insights into the subsurface hydrodynamics. The unsaturated zone, a critical component influencing aquifer recharge and the partitioning of rainfall into infiltration and runoff, is modeled with high precision, accounting for soil properties, moisture content, and evapotranspiration. This detailed representation is essential for predicting the impacts of varying climatic conditions and land-use changes on groundwater recharge rates.
In addition, overland flow processes are integrated into the model, allowing for the simulation of surface runoff during storm events. Further, the model is coupled with a 1D river model based on the MIKE+ software. The coupling ensures a seamless exchange of fluxes between the aquifer and surface water bodies, capturing the dynamic responses of the water system to weather events. The model also includes anthropogenic factors, such as groundwater extractions, irrigation, drainage systems, and hydraulic control structures.
Unlike conventional hydrological models that focus primarily on either groundwater or surface water and apply simplified boundary conditions, the integrated approach used here simulates all hydrological processes in detail. The model is calibrated against both groundwater level measurements and river discharge data, ensuring that processes such as baseflow, interflow, and direct runoff are not merely approximated but are numerically represented and calibrated.
Only through a precise representation of all processes—including the unsaturated zone, groundwater flow, and the interaction between river and groundwater—can both groundwater levels and discharge peaks be accurately modeled. In addition, the integrated model ensures a closed water balance. As a result, the use of an integrated model significantly enhances the predictive quality, offering high confidence in the models ability to forecast water behavior and outcomes.
The model has been calibrated as outlined above and is already being used to assess various retention measure scenarios. By providing this integrated model, stakeholders in the Borken Water Catchment Area are able to make informed decisions, design adaptive water management strategies, and effectively mitigate the risks posed by climate change.
How to cite: Winderl, M., Flechtner, F., Hüttner, P., and Trabak, Z.: Integrated Water Balance Modeling - Sustainable and Climate-Adapted Water Management , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20420, https://doi.org/10.5194/egusphere-egu25-20420, 2025.
Groundwater recharge is significantly influenced by anthropogenic activities, particularly changes in land use and land cover (LULC). These long-term temporal and seasonal LULC changes alter groundwater flow dynamics, necessitating their assessment for sustainable groundwater resource management. This study investigates the effects of LULC changes on groundwater recharge processes in the sub-watershed of the Nira River, Maharashtra, India. Using Google Earth Engine, LULC classifications were generated from Sentinel-2 satellite imagery acquired over a decadal period (2014–2024). A change detection algorithm was employed to decipher the long-term spatio-temporal LULC patterns, complemented by seasonal analysis using LULC maps of wet and dry months. Historical data from government agencies and private entities validated these findings, strengthening the analysis.
The results indicate a 4.6% increase in built-up areas and a 5.7% decrease in forest cover over the analysis period. Rainfall data from 2015 to 2024 was correlated with groundwater level records, revealing enhanced recharge in 2024 compared to 2014. This improvement is attributed to increased rainwater harvesting structures observed during the assessment period, contributing significantly to recharge in dug wells. Seasonal LULC variations also influenced recharge dynamics, with the dry season showing higher recharge potential compared to the wet season. These findings provide critical insights into the interplay between LULC changes, groundwater recharge processes, and sustainable water resource management in the study area.
Keywords: LULC, impact assessment, Groundwater recharge, Western Deccan Basalt, India
How to cite: Waindeshkar, P. and Umrikar, B.: Decoding the Impact of LULC Changes on Groundwater Recharge in Western India, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1029, https://doi.org/10.5194/egusphere-egu25-1029, 2025.
How to cite: Ling, Z., Shu, L., Wang, D., Lu, C., and Liu, B.: Groundwater Drought Dynamics and Vulnerability under Climate Change in the Sanjiang Plain, China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1334, https://doi.org/10.5194/egusphere-egu25-1334, 2025.
Groundwater is an essential natural resource supporting all living beings in ecological and agricultural systems, especially in the Indo-Gangetic Plains (IGP). The IGP comprises shallow aquifers densely populated with agriculturally productive regions. However, in the past few decades, the area has been under water scarcity for several reasons, including climate change and mismanagement, affecting livelihoods. For all these reasons, an accurate assessment of groundwater availability and identifying groundwater potential zones (GWPZ) are crucial. The modern techniques of GWPZ identification, including AI/ML with remote sensing, play a vital role in determining the potential zones with high accuracy. The objective of the present study is to determine the GWPZ around the Varuna River region of Uttar Pradesh, India, using remote sensing with machine learning models.
The present study tries to delineate potential areas of groundwater augmentation in the Varuna River area of Uttar Pradesh, India, by using remote sensing techniques supplemented with machine learning algorithms such as Support Vector Machine (SVM), Gradient Boosting Machines (GBM), Random Forest (RF). Satellite imagery, geospatial analysis, and predictive modeling assessed various hydrological, geological, and climatic parameters. With such state-of-the-art tools, this study tries to provide broad coverage of groundwater distribution, locating the region's possible areas, hence contributing toward sustainable water management strategies that will strengthen the communities of people depending on this precious resource.
We have classified the GWPZ into five different zones, ranging from very low, low, moderate, and high to very high zones. Compared to all models, the RF shows the highest predictive accuracy, with Area Under the Curve (AUC) values of 91%, whereas the GBM and SVM AUC curves show 88% and 84%, respectively.
How to cite: Kumar, V., Singh, S., and Kumar, A.: Harnessing Remote Sensing and AI for Groundwater Resource Mapping: A Study from the Varuna River Region, Uttar Pradesh, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1359, https://doi.org/10.5194/egusphere-egu25-1359, 2025.
The Paraná 3 Hydrographic Basin (BP3) drains its waters into the reservoir of Itaipu Binacional, the largest electricity generator in the world. It is located in southern Brazil, on basic volcanic rocks (basalts ands volcanoclastic) from the Cretaceous age. This paper presents the results of 12 analytical campaigns of the Hidrosfera project, a partnership between the Hydrogeological Research Laboratory of the Federal University of Paraná (LPH-UFPR), Itaipu Binacional and Itaipu Parquetec, where water samples are collected quarterly from 42 tubular wells that supply the 29 municipalities of BP3, among the main municipalities being Foz do Iguaçu, Cascavel, Toledo and Guaíra. Electrical conductivity, temperature, pH, STD, dissolved oxygen, ORP, alkalinity, nitrate, nitrite, ammoniacal nitrogen, phosphate, and acidity are analyzed in the field. At the LPH (Hydrogeological Research Laboratory), complementary analyses are carried out using titrators, spectrophotometry and ICP-OES. BP3 has an area of 8,000 km² and has different chemical signatures depending on the flow depth. The calcium bicarbonate chemical type predominates in flows up to 59 meters deep. In these wells, the oxygen and deuterium results are superimposed on the local meteoric line, indicating a short residence time. In this shallower flow, alteration of ferromagnesian minerals predominates. Concentrations of calcium, magnesium, nitrate, chloride, potassium, phosphate, silica, strontium, and dissolved CO2 are higher when compared to flow depths greater than 119 meters. Micropollutants such as atrazine, DEA, and nicotine also occur more frequently in shallow flows (<59 m). At this depth, the statistical correlation between nitrate (NO3-), phosphate (PO42-), and potassium (K), highlighting the possible source of “NPK fertilizers” as the origin of this contamination. The results of nitrogen isotope analyses suggest sources related to fertilizers and/or manure/sewage. The source from organic soil is also a hypothesis for some sampled wells. These sources are consistent with the land use at BP3, where agricultural use predominates, followed by pasture and urban areas. Wells with deeper water flows (>119 meters deep) have sodium bicarbonate and sodium carbonate waters. There is a tendency for pH, electrical conductivity, STD, temperature, alkalinity, sodium, arsenic, sulfate, fluorine, and vanadium to increase with increasing depth of the groundwater flow. In these deeper flows, processes related to cation exchange in the aquifer predominate, and C14 ages reach 17,000 years. Considering that BP3 has wells with excellent production (above 220 m3h-1), used for public supply, contaminants in the groundwater, even if below the guideline values, are a warning sign for local water security. Wells with contamination evidence should attempt to manage land use and occupation, seeking to delimit capture zones and regulate the land use in these areas. In areas where the aquifer has deeper circulation with more mineralized waters, strategic actions such as artificial recharge will prevent the total exploitation of the resource (unsustainable mining of the aquifer).
How to cite: de Vasconcelos Müller Athayde, C., do Amaral, B., Garcia, L., Olivi, M., and Barbosa Athayde, G.: Natural processes and human impacts on groundwater: example of a Cretaceous volcanic aquifer in southern Brazil, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2518, https://doi.org/10.5194/egusphere-egu25-2518, 2025.
The contamination of aquifers by polluted recharge from agricultural areas remains a major danger to water resources. But continuous observations are limited due to a lack of adequate monitoring systems. So far, commercial UV-Vis spectrometers have been used to continuously monitor dissolved organic carbon (DOC) and nitrate levels in surface waters and in water treatment facilities. While commercial UV-Vis spectrometers have been combined with suction cups to measure in-situ the nitrate concentration of soil water, this solution is costly and difficult to operate. Instead, we are developing a robust, compact, and user-friendly in-situ system that provides real-time data on drainage water quantity and quality like dissolved organic carbon (DOC) and nitrate concentration, electrical conductivity, and water temperature. All system components undergo rigorous laboratory testing, and initial prototypes are currently being installed and continuously operated under selected agricultural areas below the rooting zone.
In our system, we use a passive system with fiber glass wicks to quantify the amount of drainage water present. The wicks draw water from the soil at field capacity, eliminating the requirements for pumps as required by suction cups and avoiding saturation commonly found in free draining lysimeters. The extraction area and the length of the horizontal stainless-steel rod that holds the wicks provide enough coverage to average the spatial variability in typical vegetation patterns beneath agricultural fields. The quantity of drainage water is measured using a specifically developed 3D-printed tipping bucket system.
In addition to measuring drainage water quantity, our system will evaluate in-situ water quality. Parameters measured include electrical conductivity, temperature, as well as the concentration of DOC and nitrate. We have developed a fluorescence system to detect DOC concentrations in a small flow-through cuvette connected to the wicks. We are in the process of inventing an LED based optical sensor that detects nitrate absorption in the UV-C range, instead of employing costly UV/Vis spectrometers with xenon lamps to measure the complete spectrum. Preliminary tests indicate that determining nitrate concentration from groundwater samples is possible using absorbance at a wavelength of 235 nm. A calibration with standard solutions shows a linear relationship between concentration and absorption with a R2 of 0.99 for concentrations between 0 and 100 mg N/l. To adapt the system for analyzing the soil water solution, a combined sensor for nitrate, DOC and turbidity is needed to correct the nitrate absorption for interfering high concentrations of DOC and turbidity. We will discuss the overall system, its performance and preliminary results from a field deployment.
How to cite: Huebner, C., Paulsen, H., Herbstritt, B., König, F., and Weiler, M.: Developing an in-situ monitoring system for groundwater recharge flux, nitrate and DOC concentrations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3824, https://doi.org/10.5194/egusphere-egu25-3824, 2025.
Sustainable management of water resources in insular aquifers is a major challenge due to the special vulnerability of these territories to climate change. Therefore, it is very important to develop tools that help to understand the water resources of these regions. Currently, 3D geological models provide data on the geometric properties of geological bodies, allowing the inference of volumes and the availability of their water resources for exploitation. Additionally, 3D models allow the development of numerical groundwater flow models, providing valuable geoscientific information. This work has developed the first 3D geological model of the volcanic island of La Palma (Canary Islands, Spain) using the GeoModeller software. The code uses surface and subsurface geological data and then applies a geostatistical interpolation algorithm, cokriging to obtain the 3D model. ArcGIS has also been used for geographic information management. The information sources used have been the Digital Terrain Model of the island, surface geological maps, geological cross-sections, and lithological data from hydraulic works. In order to obtain a coherent 3D model, it was necessary to define the formations of the model, reclassifying and unifying the aforementioned information. The data were distributed in different geological maps and databases, encoded in different formats and transcribed in various geological classification schemes. This is relevant because the calculation by cokriging requires the coherent definition of the formations involved in it, as well as a hierarchy between them. The geological model obtained covers the entire island of La Palma, both the emerged surface and the underwater zone, down to a depth of 3km below sea level. The model includes a hydrogeological sequence of nine formations that represent the main volcanic edifices and the most important geological and hydrogeological structures of the island, including rifts, giant landslides, and perched and semi-confined aquifers. This 3D geological model will allow the development of the first hydrogeological and geothermal model of the island. This methodology can be exported to the rest of the Canary Islands, being key to improving knowledge of the island's aquifers and developing management strategies for different climate change scenarios.
How to cite: Baquedano-Estévez, C., Martínez-León, J., Marazuela, M. Á., Jiménez, J., Santamarta, J. C., and García-Gil, A.: Development of a 3D geological model of the island of La Palma (Canary Islands) to improve the management of the groundwater resources, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4461, https://doi.org/10.5194/egusphere-egu25-4461, 2025.
Groundwater recharge is a critical component of sustainable water management, especially in Ethiopia, where rain-fed agriculture supports the livelihoods of most of the population. Despite its importance, comprehensive groundwater recharge estimates for the entire country remain limited, particularly given Ethiopia’s diverse climatic, topographic, and geological conditions. This study aims to evaluate the spatial distribution of long-term groundwater recharge across Ethiopia, focusing on the relationship between precipitation and total stream runoff and baseflow. The methodology integrates hydrograph separation techniques, regression models, and GIS-based analysis. Daily flow data from 139 gauging stations (1990–2010) were analyzed using a moving minima approach to separate baseflow from streamflow. Baseflow indices (BFI) were calculated, and regression models were developed to link mean long-term precipitation averaged over the catchment area to total runoff and baseflow across different geological and hydrological settings. Spatial variability was assessed using precipitation data from satellite-derived CHIRPS datasets, calibrated with ground-based observations. Additionally, relationships between BFI, geology, and topography were explored to understand the factors influencing recharge dynamics. The results reveal significant spatial variability in groundwater recharge, with regions of high precipitation and permeable geological formations exhibiting high baseflow contributions. Conversely, arid areas with impermeable substrates show weaker recharge and lower baseflow. The analysis demonstrates a strong correlation between precipitation and baseflow in favorable regions, highlighting precipitation as the primary driver of recharge, modulated by local geological and hydrological conditions. These findings underscore the importance of tailored, localized water management strategies for Ethiopia’s diverse hydrological conditions. They provide critical insights for improving water security, supporting sustainable groundwater utilization, and enhancing resilience in climate variability, particularly for the country’s rain-fed agricultural systems.
Key Words: Baseflow Index, groundwater Recharge, Long-term Precipitation, Ethiopia
Acknowledgments: This collaborative work is a part of the development aid project by the Czech Geological Survey No. ET-2023-006-RO-43040 (to K. Verner) entitled “Improving the quality of life by ensuring availability and sustainable management of water resources in Sidama Region and Gamo and Gofa Zones (Ethiopia)” financed by the Czech Republic through the Czech Development Agency.
How to cite: Finsa, M. M. and Bruthans, J.: Estimation of Spatial Distribution of Long-term Groundwater Recharge Variability over Ethiopia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5322, https://doi.org/10.5194/egusphere-egu25-5322, 2025.
Climate change sees a shift from groundwater recharge to surface runoff caused by frequently occuring heavy precipitation events which exceed the infiltration capacity of the soil. Therefore, the impact of groundwater aquifers as buffer systems is reduced. At the same time the water demand for irrigation and cooling in agriculture is increasing. To compensate, water has to be transferred and ideally stored close to the demand to reduce costs for infrastructure. Even if water supply from major rivers which do not suffer from low water levels in dry periods is available peak demand and runoff are out of phase and peak volumes would require large water distribution systems. This is generally addressed by setting up large surface level basins with all their drawbacks (large spatial footprint, losses through evaporation, microbial contamination, stagnating waters).
One alternative adaptation strategy is to divert peak flow in surface waters and infiltrate directly into groundwaters to use them for storage during dry periods, as naturally occurring when high percolation rates are achieved. For this variant of managed aquifer recharge large aquifers with high hydraulic conductivity are required. Suitable sites have been identified using the multi-criteria decision analysis developed by [1]. Starting from the infiltration of flood peaks only, where the naturally occurring cycle of surplus water is reestablished, the concept can be extended to an active management of surface runoff while ensuring environmental sustainable flow regimes in the streams and small rivers.
Groundwater quality can be maintained using both pretreatment technologies and careful risk assessment of the catchment of the surface water. Analyses during the recent Vb weather condition in Bavaria indicate that the water quality is much better than expected and generally suitable for infiltration in phreatic aquifers.
The study site is located in Bavaria and well known for excellent soils for agriculture. Potatoes, sugar beets, and corn are the main crops grown with the potato being least resilient to increasing temperatures. Our site analysis showed a number of potential infiltration sites, and we identified several sources with enough excess water to sustain more than one dry year. The water is diverted from the river by pipelines and ditches and led to an infiltration basin surrounded by farmland. The small basin serves as a buffer for peak flow that would otherwise cause flooding. According to our hydrogeological models the infiltrated water will remain in the region and a long-term recharge of the aquifer seems possible. The favored setup will also reduce damages in downstream plots with higher groundwater levels caused by extended flooding.
The co-management of floods and low groundwater levels is applicable to streams and smaller rivers. Here, the risks in the catchment can be assessed and controlled. For water storage, natural storage in the underground is used. Based on our chemical analysis groundwater quality will benefit from the infiltration. Furthermore, the socio-economic aspects from farmers and other users are addressed and resilience for climate change is enhanced.
[1] L. Augustin and T. Baumann: Suitability mapping for subsurface floodwater storage schemes, InterPore Journal 1(2), doi://10.69631/ipj.v1i2nr20.
How to cite: Schultze, A., Augustin, L., and Baumann, T.: Co-management of floods and droughts for the adaptation of agricultural water supply to climate change, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6719, https://doi.org/10.5194/egusphere-egu25-6719, 2025.
Future drying conditions coupled with increasing water demand are intensifying the pressure on groundwater systems. Managed Aquifer Recharge (MAR) techniques in combination with water reuse could be valuable measures for mitigating water scarcity problems and promoting sustainable groundwater management. Various modelling methodologies are available to assess the effectiveness and feasibility of these measures in local to regional contexts, with distributed process-based groundwater simulation models being the most widely used for MAR assessments. However, MAR combined with water reuse lies at the interface between anthropogenic (urban) and natural water systems and must be embedded within a regional strategy on water resources management, focusing on feedbacks and interconnections within the entire system, which are crucial for identifying the propagation of effects and the investigation of trade-offs. Therefore, successful planning and implementation of these techniques in regional contexts require assessment tools that reflect this level of integration between multiple subsystems. Here we present an overview of the methodologies and modeling frameworks available for evaluating MAR combined with water reuse, with a primary focus on water quantity aspects. This includes the classification of the methodologies based on the purpose of application, phase of MAR analysis, and their characterization in terms of spatial and temporal scales and resolution, the types of processes included in the modeling frameworks, and the limitations of applicability of the methodologies, also presenting examples in literature. We further discuss the most effective methods—or combinations of methods—for modeling these interconnected systems.
How to cite: Yazdani, M., van Thienen, P., and Bartholomeus, R.: Modelling techniques for assessment of Managed Aquifer Recharge combined with water reuse, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8806, https://doi.org/10.5194/egusphere-egu25-8806, 2025.
The Friuli Venezia Giulia (FVG) region in northeastern Italy has experienced an imbalance in the hydrogeological system over the years, resulting in the lowering of groundwater levels. Reduced and erratic precipitation patterns, rising temperatures, and increased abstraction have all contributed to the decline in piezometric levels in the Friuli Plain's phreatic aquifers. These changes in the hydrogeological system have resulted in a decrease in direct infiltration and an increase in the surface run-off and evapotranspiration rate, thus affecting both the surface and groundwater resources in the region. The groundwater of the region is also polluted by nitrate content, whose concentrations in some parts of the region exceed the threshold value (50 mg/l as per Italian legislation) for potable use. To address declining water resources and improve underground storage of high-quality surface waters, three recharge sites (Carpeneto, Mereto di Tomba, and Sammardenchia), in the upper Friuli plain have been suggested for MAR practice. MAR potential in this pre-Alpine region is characterized by the availability of high-quality surface waters (primarily from rivers), a highly permeable thick aquifer system, and numerous existing structures such as pits and large-diameter wells. The present study aims to investigate the effect of MAR on groundwater levels and quality through an infiltration pond at Sammardenchia site. Modflow is applied to simulate the aquifer’s response to natural and artificial recharge through MAR by means of water from the nearby Ledra channel. The initial results show a positive effect of MAR on the groundwater levels at the local scale. The study further aims to simulate the solute transport and water quality changes resulting from the recharge operation, with the ultimate goal of predicting future hydrogeological variations in the aquifer system.
How to cite: Sufyan, M., Martelli, G., Teatini, P., and Goi, D.: Managed Aquifer Recharge (MAR) perspectives in the Friuli Venezia Giulia Region of Italy in the context of climate change trends, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-8936, https://doi.org/10.5194/egusphere-egu25-8936, 2025.
The federal state of Brandenburg is characterized by over 3,000 lakes and hundreds of kilometres of rivers and thus is one of Germany's most water-rich regions, but also ranks among the country's driest states in terms of precipitation. Climate change exacerbates this situation, with potential negative effects on groundwater resources: estimations under the RCP8.5 emission scenario predict a 10–20% reduction in total runoff for the period 2031–20601. Moreover, decadal groundwater level monitoring data from Brandenburg revealed that extremely low groundwater levels occur more often. Thus, careful management of water demand is crucial, especially given that over 90% of the region's drinking water supply relies on groundwater.
Decadal groundwater level predictions are fundamental to manage demands and allow to identify areas particularly at risk of extremely low groundwater levels. Data-driven methods, especially deep learning (DL) approaches, have recently demonstrated potential for predicting groundwater levels with high accuracy and are suitable for forecasting across larger regions where numerical flow models are not applicable.
In this study, DL models were established to generate decadal predictions for groundwater monitoring wells, based on data of Brandenburg’s broad groundwater monitoring network. After preprocessing the time series data, including aggregation to weekly resolution, the dataset comprises 650 groundwater monitoring wells with consistent records dating back to at least 1980. For these monitoring wells, DL models were implemented and trained with data from different meteorological variables data as input parameters. The predictive performance of the DL models was then systematically evaluated. Groundwater monitoring wells with high predictive accuracy (NSE > 0.7) were used to calculate decadal forecasts based on the decadal climate predictions provided by the German Weather Service.
These decadal predictions enable spatial assessments of groundwater level trends over the next decade relative to the 1991–2020 reference period. The results offer valuable insights into mid-term future groundwater level developments in Brandenburg, supporting data-driven decision-making for sustainable groundwater resource management.
1DWD (2019): Klimareport Brandenburg, 1. Auflage, Deutscher Wetterdienst, Offenbach am Main, Deutschland, 44 pp., ISBN 978-3-88148-518-0
How to cite: Broda, S., Kunz, S., Wetzel, M., Schmidt, L. K., and Hermsdorf, A.: Predicting Decadal Groundwater Levels in Brandenburg: Deep Learning Approaches for Sustainable Management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10554, https://doi.org/10.5194/egusphere-egu25-10554, 2025.
Groundwater is Germany's dominant source of drinking water; in particular near-surface groundwater resources. Long-known pressures as well as emerging stressors such as unprecedented hydrological extremes, their related water quality issues and increased use competitions challenge the assessment of these resources' sustainability. More integrated modelling along with innovative model applications that go beyond climate impact model chain experiments are needed. As part of the funding measure BMBF LURCH, the StressRes project develops a coupled modelling approach that aims to assess stress on groundwater by way of specifically designed stress test model experiments. This contribution shows how the agro-economic model PALUD, the hydrological model RoGeR and the groundwater model MODFLOW are combined towards this task. In particular, we assess the challenges encountered in the case study area which encompasses several different drinking water protection areas in southwest Germany. The challenges include the two-way coupling of RoGeR and MODFLOW in the large catchment area that drains from the fissured mountain aquifer towards the alluvial valley aquifer recharging the aquifer at the foot of hillslopes as well as through rivers. The land use of the region is highly diverse and water quantity and quality need to consider crop rotations at small scales and irregular irrigation practices may affect the water balance. The underlying agro-economic decisions made in particular for the region-specific crops may affect nitrate leaching after drought events, which is one of the issues drinking water suppliers are facing. We present a baseline model along with the stress test scenarios that will be implemented.
How to cite: Schwemmle, R., Hellwig, J., Schmit, M., Vahldiek, J., Weiler, M., Börner, J., Sponagel, C., Angenendt, E., and Stahl, K.: Integration of agricultural, hydrological and hydrogeological stressors into the modelling of groundwater used for drinking water extraction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11658, https://doi.org/10.5194/egusphere-egu25-11658, 2025.
Sustainable groundwater management is crucial in arid and semi-arid regions, such as the Mediterranean, due to high water demand, irregular rainfall patterns, and limited surface water availability. Flood-Managed Aquifer Recharge (Flood-MAR) has emerged as an effective strategy for mitigating groundwater depletion in overdrawn aquifers. This approach utilizes surplus water from high-magnitude streamflow events, reservoir releases, or excess surface water deliveries, providing a unique method of managed aquifer recharge by harnessing sporadic water sources. While Flood-MAR has demonstrated positive effects on groundwater quantity, its impacts on water quality remain underexplored. During flood events, rivers collect runoff from impermeable surfaces, such as roads and industrial areas, potentially carrying contaminants like heavy metals. These pollutants, primarily originating from vehicles, pose risks to aquifer recharge quality during flood-driven recharge operations.
In this work, we evaluated the pollution risk to an aquifer during a high-magnitude streamflow event of the Llobregat River (Barcelona, Spain). Sampling was conducted in both the Llobregat River and a nearby piezometer to ensure that temporal changes in contaminant levels could be attributed to hydrological events rather than spatial variability. Rainwater samples were also collected at the site. Water quality was intensively monitored over the rainfall period (12 hours) and the following five days, characterizing hydrochemistry (anions and cations), heavy metals, and water isotopes. Preliminary results indicate higher contamination levels in the river, particularly regarding heavy metals, especially at the onset of the rainfall event. This increase was attributed to urban runoff from roads and industrial zones in the studied area. Hydrochemistry monitoring, along with water isotopes analysis, revealed that the high-magnitude streamflow event impacted the aquifer in two distinct phases. First, during the initial hours of the rainfall, the aquifer's water quality was affected, with a general increase in the concentrations of most monitored parameters. Second, two to three days after the event, the aquifer’s hydrochemistry was influenced by the upstream rainfall's impact on the catchment area. These findings suggest that, although the aquifer quality is affected, the impact of Flood-MAR on groundwater quality is not expected to be significantly critical.
How to cite: Ferrer, N., Rodríguez-Escales, P., Pérez-Castro, C., and Fernández, D.: Evaluating the impact of Flood-MAR on Groundwater Quality, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11768, https://doi.org/10.5194/egusphere-egu25-11768, 2025.
Monitoring water security remains a significant challenge due to the complexity of the water cycle and the socio-hydrological drivers behind water consumption. Effective monitoring requires data on water use and availability, which are often difficult to obtain in large urban or semi-urban areas with limited resources and lacking hydrological instrumentation. Emerging technologies, such as Earth observation systems and indirect hydrological indicators such as energy for water pumping can help estimate water use and availability. In urban socio-hydrological systems dependent on groundwater, energy consumption for pumping provides information about water use, while water-induced land surface deformation can serve as a proxy for water availability due to its relationship to groundwater level changes. This study analyzes the trends and relationship between energy consumption for groundwater pumping and land surface deformation to characterize water security, defined as the sustainable balance between water use and availability. The study focuses on Cochabamba, Bolivia, a rapidly growing metropolis facing unique water management challenges and land deformation (i.e. subsidence in some areas and uplift in others) due to groundwater overexploitation and incomplete water infrastructure. Using Small Baseline Subset (SBAS) and Regression analysis, we estimated trends in these variables from 2018 to 2022 across an extensive network of groundwater wells. We identified four trends in pumping energy consumption (increasing, decreasing, no significant change, and no consumption) and three trends in land surface deformation (uplifting, subsidence, and no significant deformation). By combining these trends, we formulated four potential scenarios to characterize water security from wells to the regional level: Water Security, Unsustainable Water Security, Water Insecurity, and Recoverable Water Insecurity. The findings reveal a predominant domestic use and an increasing trend in pumping energy consumption across wells. Most wells exhibit a state of Water Insecurity characterized by the combination of subsidence and increasing energy consumption. The study highlights the potential of combining energy consumption and land surface deformation data as accessible and scalable tools for water security monitoring in resource-constrained regions. Understanding these trends can help to develop targeted management strategies and prevent water depletion in growing urban populations.
How to cite: Maranon-Eguivar, M., Duran, A., Rocha, R., and Jaramillo, F.: Analyzing the Relationship between Electrical Consumption by Pumping and Water Induced Land Deformation to Understand Water Security, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11930, https://doi.org/10.5194/egusphere-egu25-11930, 2025.
The average annual rainfall in Taiwan is approximately 2,502 millimeters, far exceeding the global average of 973 millimeters. However, the rainfall is unevenly distributed, with approximately 78% occurring during the wet season. Over the past decade, the average annual rainfall has been about 91.5 billion cubic meters, but more than 50 billion cubic meters flow directly into the sea. In terms of the overall water resource utilization framework in Taiwan, it is influenced by hydrological environmental factors, coupled with the impacts of global climate change and the normalization of extreme weather events, water resources are expected to be increasingly affected by droughts.
Between June 2020 and February 2021, the cumulative rainfall in the catchment areas of Taiwan's major reservoirs reached a historic low, decreasing by approximately 1,000 millimeters compared to the historical average of 1,780 millimeters for the same period. This severe drought presented significant challenges to Taiwan's water supply. Securing water availability during the drought, the government improved regional water resource allocation and evaluated suitable locations for developing emergency groundwater wells. This assessment was based on factors such as groundwater levels, geological profiles, aquifer thickness, and groundwater recharge conditions. Priority was given to gravel aquifers with higher recharge potential, aquifer thickness exceeding 50 meters, and proximity to water treatment facilities within the public water supply system. According to the factors, it selects appropriate locations to drill emergency water wells, ensuring that the extracted groundwater can be integrated directly into the public water supply system.
The government completed 195 drought relief groundwater wells with the approach in main metropolitan areas affected by water shortages. These wells provided approximately 75,000 cubic meters in totality per day, effectively assisting Taiwan in overcoming the drought crisis. The paper uses Taiwan's century drought event and methods for assessing emergency backup water sources as a case. Additionally, it compares techniques for evaluating groundwater development potential with other countries, such as utilizing remote sensing, Geographic Information Systems (GIS), and the Modified Impact Factor (MIF). Through case studies and literature reviews, the paper examines the feasibility of the proposed methods for practical application in emergencies.
Keywords: Drought; Groundwater; Emergency Backup Water Sources
How to cite: Lin, C.-F., Hung, C.-Y., and Chan, H.-C.: Assessment of Emergency Backup Water Sources: A Case of the Record-breaking Drought in Taiwan in 2021, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15010, https://doi.org/10.5194/egusphere-egu25-15010, 2025.
The management of groundwater resources will be challenged by alterations in the water cycle induced by climate change. Projections
show a global decrease in groundwater recharge, with strong regional differences. Water suppliers must adapt their management
strategies to maintain quantitative sustainability and groundwater quality, where the latter is endangered by increased microbial
contamination, rising temperatures, longer droughts, and heavy precipitation events.
A first step toward adaptation is a thorough assessment of the history, current state, and possible future scenarios of a region’s
renewable water resources. To facilitate such assessments for broad application, a suitable framework should be simple and avoid
the use of complex and regionally, often unavailable, models.
We propose a framework that assesses the renewable groundwater resources of a water-supply system relying on simple-to-apply
methods and, in most cases, openly available data. The framework consists of identifying the origin of the produced drinking water,
delineating the area of groundwater recharge, and assessing the historical and present demand and availability of water, including
the identification of the main drivers of water demand. These findings are extrapolated into the future using projections of regional
climate and changes in water demand linked to the growth of population, economy, and other water-demanding entities or their
potential establishment (e.g., introduction of irrigation agriculture in response to climate change). Known indicators, such as the
water-exploitation index, are useful to estimate the sustainability of the water supply for given conditions.
We have applied the framework to a regional water supplier in southwest Germany, the Ammertal Schönbuch Gruppe (ASG), which
provides water for about 120,000 people. Demands from industry and energy production are indistinguishable from the overall
demand. Irrigation in agriculture is not applied. Water demand is met by extraction from two different resources, a porous gravel
and a karstified limestone aquifer. Additionally, the supplier relies on a far-distance water supplier, the Bodensee Wasserversorgung
(Lake Constance water supply, BWV).
The scenario-based future developments comprise different degrees of population growth, per capita consumption, as well as
changes in groundwater recharge computed from down-scaled climate projections based on the RCP8.5 pathway. The findings of
the analysis of the historical situation are in good agreement with the reports of the water supplier. First indicators of potential
water stress appear in the years leading up to when the supply situation was reported as "tense".
The evaluation of future projections shows that the supply situation intensifies. Recharge rates are projected to drop to as low as
100 mm/a by 2060 in the 10-year average, from over 150 mm/a between 1990 and 2000 while the demand is projected to rise by up
to 30%. While meeting the average demand is feasible and complications arise only from droughts in most scenarios, contemplation
of the drier scenarios shows that severe water stress might be a permanent issue by the second half of the century.
How to cite: Höckh, F., Finkel, M., and Cirpka, O.: Combining Climate Projections, Recharge Modeling, and Statistical Forecasts to Assess the FutureState of Regional Groundwater Resources and Their Sustainable Use, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15279, https://doi.org/10.5194/egusphere-egu25-15279, 2025.
Groundwater is a critical resource in the Canary Islands, requiring a comprehensive understanding and effective management of these water resources. Hydrogeological modelling provides essential geoscientific insights for the identification, protection, and sustainable utilization of these resources. This is particularly crucial for volcanic islands like Gran Canaria, which possess unique geological formations and limited water resources. These models are instrumental in elucidating groundwater flow, recharge rates, and the overall water balance within the island's aquifers.
Climate change poses significant risks to volcanic islands, including altered precipitation patterns, increased evaporation rates, and sea-level rise, which can lead to saltwater intrusion into freshwater aquifers. These changes can severely impact water supply, agriculture, and overall sustainability. The Maspalomas Lagoon, a critical ecological site, relies on the balance of freshwater inflows from the aquifer. Understanding how climate change scenarios affect the aquifer's recharge and flow is essential for preserving the lagoon's health and the ecosystem services it provides.
By incorporating climate projections from the CMCC-ESM2 model under scenarios SSP1-2.6 and SSP5-8.5, we can assess the potential impacts of climate change on water availability in the Maspalomas Ravine aquifer. Integrating climate projections into hydrogeological models facilitates more informed planning and management of water resources. This approach provides a scientific basis for developing adaptive strategies to mitigate the adverse effects of climate change, leading to more resilient water management practices and ensuring a sustainable water supply for future generations on volcanic islands like Gran Canaria. Additionally, this methodology will elucidate the real influence of the aquifer and the sea on the lagoon.
How to cite: Martínez-León, J., Sariago, R., Baquedano, C., Marazuela, M. Á., Jiménez, J., Gasco-Cavero, S., Santamarta, J. C., and García-Gil, A.: Hydrogeological Modeling of the Maspalomas Ravine Aquifer in Gran Canaria under Climate Change Scenarios, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15690, https://doi.org/10.5194/egusphere-egu25-15690, 2025.
Coastal aquifers may be compromised by various anthropogenic impacts and saline water influences. Diverse inputs of surface and marine waters can consistently influence local hydrological, geochemical, and biological conditions, directly impacting groundwater quality, ecological status, and associated ecosystem services. The aquatic microbial community represents a fundamental component of the groundwater resident biota, playing a major role in nutrient cycling and bioremediation processes. However, the structural and functional traits of the aquatic microbial community have been poorly considered in groundwater quality assessments. This work aims to explore the microbial community responses to groundwater quality variation in a coastal aquifer subject to salinization. The sampling sites were located within the coastal area of Fiumicino (Rome, Italy). The primary physical-chemical characteristics of groundwater samples were examined, including major anions and cations, trace elements, and dissolved organic carbon. The aquatic microbial community was characterized to assess total microbial load (flow cytometry), the microbial metabolic potential (Biolog EcoPlates), and the heterotrophic respiration (Biolog MT2 MicroPlates). The phylogenetic community composition was also characterized by the 16S rRNA gene amplicon sequencing. Results indicated that distinct microbial community profiles, dominated by members of the families Sulfurimonadaceae and Comamonadaceae, were identified within two groups of water characterized by varying salinity and conductivity levels. Our findings underscored the necessity of a cross-disciplinary approach for improved management of groundwater resources, as alterations in the structural and functional dynamics of the groundwater microbial community will directly impact biogeochemical cycles and ecosystem services.
How to cite: Amalfitano, S., Melita, M., Boccanera, M., Corso, D., Cisternino, A., Valle, A., Preziosi, E., and Ghergo, S.: Groundwater microbial community and hydrogeochemical patterns in a saline-influenced coastal aquifer, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16099, https://doi.org/10.5194/egusphere-egu25-16099, 2025.
Water governance involves the political, social, economic and administrative systems set up to develop and manage water resources, and the supply of water-related services, at different levels of society (Rogers, 2003). Integrating Managed Aquifer Recharge (MAR) into water governance requires a multi-faceted approach. It must consider hydrogeological conditions, land use patterns and socio-economic factors (Ghannem et al., 2024a). “Within the AGREEMAR project”, an adaptive governance framework for MAR is proposed to address the pressing challenges of groundwater depletion and water scarcity in the mediterranean region. It is designed to guide the co-creation of sustainable, inclusive and adaptive MAR agreements. However, the success of this framework depends on collaboration among various stakeholders for effective governance leading to better water management.
The approach combines technical, social, economic, and regulatory aspects that are essential for MAR implementation (Figure 1). From a technical perspective, it focuses on identifying suitable MAR sites using feasibility maps and numerical models to assess hydrological and environmental impacts and to analyze the effects of MAR on the rest of water uses in the basin and on the quantitative evolution of the aquifers. From a social point of view, it stresses the importance of including local, regional and general stakeholders in decision-making processes. Economically, it considers cost-effectiveness, resource allocation and compensation mechanisms to equitably distribute benefits among stakeholders. Regulatory aspects focus on fulfilling existing legislation and aligning with local and international policies. This framework incorporates tools such as decision support systems “AQUATOOL” and numerical groundwater modeling “INOWAS platform” to simulate scenarios and guide informed decision-making. The approach is applied to specific case studies in Spain (Ghannem et al., 2024b). Guidelines for regional MAR agreements are proposed, which provide practical insights for implementing MAR agreements within different socio-economic, environmental, and regulatory contexts of each region.
This approach shows a participatory and systematic process to address the complexities of MAR. By integrating technical assessments, stakeholder-driven methodologies and a solid policy framework, it provides a replicable model for improving sustainable groundwater management in the mediterranean region and beyond. Details of the adaptive governance framework, that can be applicable to the Mediterranean basin, will be presented during the congress.
Fig. 1. Elements to be considered when drafting MAR agreements
References
Ghannem, S., Bergillos, R.J., Andreu, J., Paredes-Arquiola, J., Solera, A. 2024a. AGREEMAR Deliverable D3.2: General governance framework for MAR agreements. Available online at https://www.agreemar.inowas.com/deliverables.
Ghannem, S., Bergillos, R.J., Andreu, J., Solera, A., Leitão, T.E., Martins, T.N., Alpes K.G., Oliveira M.M., Horovitz M., Chkirbene A., Khemiri K., Panagiotou C.F. 2024b. AGREEMAR D3.3: Set of Regional Draft Agreements tailored to the project case studies. Available online at https://www.agreemar.inowas.com/deliverables.
Rogers, P. (2003). Effective Water Governance. Global Water Partnership Technical Committee (TEC).
How to cite: Ghannem, S., Bergillos, R., Paredes, J., Solera, A., and Andreu, J.: Adaptive Governance Framework for Managed Aquifer Recharge Agreements , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16185, https://doi.org/10.5194/egusphere-egu25-16185, 2025.
Despite adequate water availability, Germany faces a widespread need to optimize the sustainable use of groundwater due to high water utilization rates. Furthermore, being a main source for drinking water, groundwater needs profound and future-proof protection. To address these challenges, aquifer management practices must be improved for greater efficiency in order to maintain the long-term availability of good drinking water quality.
Statistical analysis of hydrogeochemical data offers valuable insights into the functioning of groundwater systems, the identification of dominant processes within aquifers, and the detection of contaminant input sources. Although long-term data is often available, the variable structure of these datasets frequently poses challenges for immediate statistical analysis. Data sparsity caused by the integration of datasets with differing parametric and temporal resolutions (e.g., data from scientific research programs versus routine monitoring programs by governmental water suppliers) poses a problem for statistical evaluation methods sensitive to data density (e.g., Principal Component Analysis). Instead of the rigorous deletion of time steps and/or parameters in cases, where data density is critical for the selected evaluation method, preprocessing by imputation can reduce the loss of valuable information.
This study demonstrates the applicability, limitations and distinctions of common script-based imputation methods for enhancing the density of long-term hydrogeochemical data. Two datasets of groundwater from two different drinking water protection areas in Germany (Düsseldorf and Dormagen, 2000–2023) and a third dataset from the Rhine River (dividing both protection areas, 1990–2023) were evaluated (provided by the Stadtwerke Düsseldorf AG within the framework of the research project iMolch, a collaborative project of the funding measure LURCH). The evaluations span conventional imputation methods to modern machine-learning approaches, while indicating an emerging new potential for the re-assessment of historical data through the utilization of recently available machine-learning algorithms. Nonetheless, data imputation must be applied cautiously, as it carries the risk of introducing non-representative data values, particularly when conducted without thorough understanding of the data structure, internal dependencies, and the imputation mechanism. Additionally, both the effectiveness of the imputation and the preservation of the data’s representativeness should be strictly verified post-application. Therefore, the results highlight methods-specific constraint differences, offering practical, Python-based recommendations for efficient hydrogeochemical data imputation.
By enhancing data density while preserving representativeness, this work contributes to addressing the broader challenge of optimizing the sustainable groundwater use and safeguarding water resources under increasing anthropogenic pressures.
How to cite: Veskov, D., Antunovic, D., Droste, B., and Schiperski, Dr. F.: Applicability of imputation methods for enhancing density of long term hydrogeochemical data — Differences and constraints of conventional and machine learning-based approaches, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-21589, https://doi.org/10.5194/egusphere-egu25-21589, 2025.
Under anoxic redox conditions dissolved nitrate in groundwater can be converted microbially into N2. However, the lack of microbial available organic and inorganic electron donors such as Fe(II) or dissolved organic carbon may lead to insufficient denitrification in aquifers and nitrate concentrations above the drinking water limit of 50 mg/L are often observed. In view of the increasing drinking-water scarcity associated with climate change and the continuously high nitrate concentrations in near-surface aquifers, it is urgently necessary and prudent to develop practicable and cost-effective methods to reduce nitrate to N2.
Faced with the persisting nitrate pollution in groundwater, we want to develop a new cost-effective in-situ remediation technology by hydrogen/methane coupled denitrification. We think that the microbial stimulation with water soluble gases may have several advantages to former artificial injection experiments using methanol and acetate as electron donors.
The first results are intended to fill the knowledge gap on the influence of methane (CH4) as electron donor on denitrification. We hypothesize that theinjection of the water soluble electron donor CH4 into groundwater may significantly enhance the rate of nitrate consumption by activation of denitrifying chemolithoautotrophic microorganisms that are already present in groundwater.
Here we show the results of a methane injection experiment into a 2D-flow tank with a length of 6 m. Isotopic and concentration measurements were performed along the flow direction and with a high depth-resolution of approximately up to 5 cm. Concentration profiles and the stable isotope composition of methane (δ13C) and nitrate (δ15N) linked with oxygen concentrations shed light on the methane coupled denitrification potential in the model aquifer. Our injection results demonstrate that methane can be sufficiently injected by the horizontal well into the model aquifer. Methane concentrations of up to 1,06 mmol/L were detected at different depths and up to a flow distance of 3 m from the injection well. Moreover, we found some isotopic evidence that nitrate is reduced to N2 or N2O with nitrite as intermediate. Nitrate concentrations decreased from around 0,89 mmol/L to 0,58 mmol/L at the outflow of the tank and decreased within the 2D-flow tank exactly there, where we observed an isotopic shift in methane to heavier (less negative) values.
How to cite: Seeholzer, A., Wunderlich, A., and Einsiedl, F.: In-situ treatment of nitrate polluted groundwater by chemoautotrophic denitrification: flow-through tank experiments with methane as electron donor, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3469, https://doi.org/10.5194/egusphere-egu25-3469, 2025.
Confined aquifers, distinguished by their large storage and long-term flow dynamics, are often overlooked in groundwater sustainability assessments and rely on frameworks developed for unconfined systems. Unlike unconfined aquifers, confined systems release water through the compressibility of the porous medium, without pore drainage. These properties lead to lower storativity and higher hydraulic diffusivity, resulting in different responses to hydraulic perturbations, such as pumping or recharge temporal variations. Addressing these differences is essential to develop tailored approaches for the sustainable management of confined aquifers, particularly in the context of balancing water supply for different competing demands with the environmental and socioeconomic impacts of abstraction.
We develop a framework for the sustainable management of confined aquifers based on numerical models over synthetic cross sections of multi-layer flow systems. We explore the fundamental differences between confined and unconfined aquifers, particularly in terms of their hydraulic behaviour, response time to hydraulic perturbations, and the interactions with surrounding hydrogeological units. This modelling study also illustrates how confined aquifers indirectly interact with unconfined systems and surface water systems, through their connection via confining layers.
A critical aspect of this work involves understanding the transient response of aquifers, which is governed by their hydraulic diffusivity and described by the concept of response time. Diffusivity governs the rate at which hydraulic disturbances propagate, and the response time describes the time required for the aquifer to reach a new equilibrium. Existing analytical formulations highlight the distinct behaviour of confined aquifers, particularly their faster response times compared to unconfined systems. However, for large-scale confined or mixed systems, response time scales may approach or even exceed those of unconfined aquifers with similar hydraulic properties and, generally, smaller extension. This underscores the importance of a proper delimitation of aquifer boundaries in the assessment of their response times.
In practice, water sustainability policies are inherently scoped within site-specific areas and timeframes. Today, these policies must address increasing pressures from population growth, climate change, surface water quality issues, and other contributing factors. Groundwater models, which support management decisions, should include these factors through accurate conceptualizations of hydrogeological systems, evaluations of their response times, and scenario analyses. Through the adaptation of sustainability concepts for confined and mixed aquifer systems, this study contributes to the development of a framework that will support groundwater management strategies for confined aquifers and highlights their role as a valuable resource for long-term adaptation, emphasizing the need to protect and optimize their use in response to environmental and societal challenges.
How to cite: Marin Rivera, C. F., Pryet, A., and Goncalves, J.: Confined aquifers: a need for an adaptation of sustainability concepts, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7027, https://doi.org/10.5194/egusphere-egu25-7027, 2025.
Confined aquifers, generally more protected from anthropogenic pressure, present potential alternative water resources of good quality to surface and subsurface water resources. However, their exploitation, potentially affecting the resource in a long-term way, requires a good understanding of their functioning to ensure their sustainable management. In order to gain some understanding of the processes involved in confined aquifers, we present here results obtained from the multilayered Beauce limestone aquifer, in the Centre region of France. This aquifer is already heavily exploited for drinking water supply and agriculture.
The developed methodology implies 1) a new interpretation of potential recharge areas from the newly acquired aquifer geometry through geological data analysis, 2) an extensive analysis of the piezometric and geochemical (major and trace elements) and isotopic groundwater database, and 3) new data obtained from groundwater sampled from a nested piezometer plateform.
The main results are synthesized below:
- Several potential recharge zone have been identified. The first one corresponds to a fault zone that could allow exchanges between the surface, the Beauce limestone and deeper aquifers. The second one is a local outcrop of the limestone caused by an anticline. The third one corresponds to local, diffuse recharge from the unconfined water table where the overlying aquitard become thinner or non-existent;
- The Beauce limestone formation comprises two main aquifer sub-units, locally separated, when existing, by a semi-permeable aquitard. The two sub-aquifers nevertheless may have distinct geochemical signatures, even though they are largely interconnected;
- Piezometric data indicate that the groundwater regionally flows from east to west, originating in an area where the aquifer does not outcrop and indicating indirect recharge from another aquifer;
- Dissolved inorganic carbon isotopes (13C, 14C) show an apparent ageing of the groundwater in the opposite direction to the flow, with more ancient groundwater upstream (up to 30 ka B.P.) and younger groundwater downstream (< 10 ka B.P.). Depleted groundwater in 2H and 18O, in agreement with the radiocarbon residence time, confirm the paleoclimatic effect recorded in the confined Beauce limestone aquifer although the confined aquifer is relatively shallow (< 150 m deep).
These results allow to better understand the hydrodynamic behaviour of this aquifer by highlighting potential recharge zones, groundwater origin as well as the possible exchanges between inter- and intra-aquifer systems. Combining all the available information (geological, hydrogeological, chemical and isotopic) is thus essential for establishing robust conceptual model of multi-layer confined systems and will provide useful information to managers for the sustainable management of the resource.
How to cite: Claveau, A., Marlin, C., Lions, J., Alus, L., Durand, V., Lasseur, E., and Briais, J.: How hydrogeological and geochemical approaches can contribute to the effective management of water resources in a confined aquifer? Example of the Beauce multilayer aquifer system (Centre region, France), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11281, https://doi.org/10.5194/egusphere-egu25-11281, 2025.
Groundwater systems play a vital role in maintaining water supply during periods of climate extremes such as droughts. However, the decreased recharge, coupled with the increased pumping rates, interferes with the natural feedback mechanism of the aquifer system, potentially pushing them beyond their resilience thresholds and causing regime shifts. Understanding and quantifying groundwater resilience is essential for evaluating how these systems maintain stability and adaptability under stress. Historically, resilience has been viewed through two lenses: engineering resilience, which emphasizes the speed of recovery to a single equilibrium, and ecological resilience, which focuses on the system’s ability to absorb disturbances before shifting to a different state. The latter approach acknowledges multiple stable states and the possibility of regime shifts. While both perspectives are essential, no existing framework has integrated them to provide a comprehensive understanding of groundwater resilience. This study presents the Endurance, Recovery, and Resilience (ERR) framework, which combines engineering and ecological resilience definitions to assess the stability and adaptability of groundwater systems. We define resilience as the ability of a system to endure disturbances and return to its original stable state, capturing both recovery and adaptability dynamics. We apply the ERR framework to seasonal groundwater levels and rainfall time series of 19 subbasins in the Ganga Basin. Using Wavelet Transform Decomposition, we isolate rainfall-induced groundwater fluctuations and calculate their magnitude of oscillation as Groundwater Sensitivity to Rainfall (GSR). This GSR time series serves as the state variable for computing the Dynamic Resilience Indicator (DRI), which reflects the groundwater system's states and resilience under different conditions. Our findings reveal that groundwater systems exhibit multiple stable states and adaptive regime shifts in response to rainfall variability. Subbasins with high resilience show better adaptability to rainfall changes, whereas low resilience subbasins display limited response, suggesting a need for more tailored management strategies. The ERR framework provides a robust methodology for assessing groundwater resilience, with broader implications for adaptive management across environmental systems. By integrating both engineering and ecological perspectives, this framework offers valuable insights for understanding and managing groundwater resources amidst the challenges posed by climate variability.
How to cite: Jnanadevan, A., Bhatnagar, I., and Dhanya, C. T.: A Dynamic Framework for Quantifying Groundwater Resilience to Rainfall Variability: Integrating Engineering and Ecological Resilience Perspectives, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11564, https://doi.org/10.5194/egusphere-egu25-11564, 2025.
Landuse and climate change alter hydrological processes and affect drinking water resources. Practical tools for understanding and quantifying these processes becomes increasingly important, for example to sustainably manage groundwater reservoirs. Analyses of the water isotopes deuterium (δ2H), oxygen (δ18O), and tritium (3H) provide useful tools, which can be applied to determine groundwater ages, assess bank filtration quantities, identify mixings of groundwater aquifers or long-term climate-induced changes. The objective of the IsoGW-project (2023-2026) is to create nation-wide interpolated isotope maps (i.e., isoscapes) of δ2H, δ18O and of 3H concentrations in German groundwaters. Aiming to provide public access to the data, an online map service and portal are set to present both the interpolated and interpreted maps as well as harmonised isotope data across the 16 German states in all relevant hydrologic compartments (groundwater, precipitation and surface waters). This work, based on an exceptional density of data points, provides new opportunities for a systematic and large-scale assessment of interactions between different compartments of the water cycle such as surface water-groundwater interactions and groundwater renewal. By establishing such a service for the first time, Germany is following its European partners, which have already published some preliminary work on the matter.
Existing data has been collected from German state offices, literature, companies and is being completed by new sampling campaigns within the project until a satisfying spacial point distribution and density is reached. Additionally, several interpolation algorithms for δ2H and δ18O, as well as different methods accounting for the 3H half-life of 12.3 years, are compared. Here, we present the latest updates regarding data research, sampling and analyses, interpolation algorithms, as well as database and web tool development. Overall, we are confident that this database and online portal will enable large-scale assessments of the water cycle and provide an important basis also for local studies. This work will be accompanied by a practice guide that will allow researchers and practitioners to use the data and tools for all these assessments.
How to cite: Gaillard, A., Wagner, A., Neuner, A., Kremer, D., Walker, B., Landgraf, J., Schmidt, A., Königer, P., Braune, S., Heidinger, M., Eisenmann, H., Schuler, P., van Geldern, R., and Barth, J. A. C.: IsoGW: groundwater isoscapes for Germany, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17726, https://doi.org/10.5194/egusphere-egu25-17726, 2025.
This study examines the pressing need for appropriate groundwater (GW) management in southern region of Delhi, due to obstacle caused by increased urbanisation and population expansion. Our objective was to identify groundwater potential zones in the study region and offer insightful information for management and decision-making by utilising Machine Learning (ML). The study utilised 15 groundwater conditioning parameters for groundwater potential zone mapping including Geology, Geomorphology, Land Use/Land Cover, Lineament density, Drainage density, Rainfall, Soil, Slope, Roughness, Topographic Wetness Index, Topographic Position Index, and Curvature. The Extreme Gradient Boosting (XGBoost) and Multi-Layer Perceptron Neural Network (MLPNN) models were utilized for evaluating groundwater suitable sites. The resulting groundwater potential zone map was classified into five categories, with different potential levels. Evidently, Both the model showed the higher accuracy, the XGBoost model showed 95% while MLPNN model showed the 96.28% accuracy. This study concluded that the south-western region has the highest groundwater potential, whereas the central and northern regions have lower potential. These models aided useful information into the influence of numerous conditioning parameters on groundwater potential and aided management decision. The study results to inform policymakers and water resource managers in southern region of Delhi about high-potential sites for sustainable groundwater management. This information optimises resource allocation to support sustainable development.
How to cite: Tanwar, D. and Sarma, K.: Application of advanced machine learning algorithms to identify sustainable groundwater potential zone in Southern Delhi Region, India , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12718, https://doi.org/10.5194/egusphere-egu25-12718, 2025.
This contribution presents the methodology and results of modeling studies conducted as part of an international research collaboration that aims to develop an innovative approach to characterize from the hydrogeological point of view water-stressed Mediterranean basins experiencing land subsidence due to excessive groundwater extraction. By integrating remote sensing-derived land subsidence rates with an iterative implementation of numerical groundwater flow and geomechanical modeling, we developed an approach to improve the estimation of hydrogeological parameters, mainly hydraulic conductivity (K) and specific storage (Ss), and obtained a flow model that can better match historical groundwater level observations. To improve the characterization of K and Ss, hydraulic head measurements from groundwater monitoring wells and displacement observations from Differential Interferometric Synthetic Aperture Radar (DInSAR) datasets were utilized. This was achieved through a novel procedure using a 3-D groundwater flow simulator (MODFLOW) and a 3D geomechanical simulator (GEPS3D) in an iterative coupled approach, with spatial variations of Ss and K described as stationary Gaussian random fields.
This approach was demonstrated in the Alaşehir-Sarıgöl alluvial aquifer located in the Gediz River watershed (Turkiye), where groundwater withdrawal for vineyard irrigation and urban water demand have led to significant land subsidence of up to 10 cm/yr. The simulated hydraulic heads from the flow model were input into the geomechanical model, allowing the calculation of the displacement time series for the subsiding areas, which were then compared with the DInSAR data. The updated distribution of the aquifer system compressibility, as obtained by fitting the simulated to the observed subsidence trends, was iteratively used in the groundwater flow simulator to update the hydrogeological parameter values, thereby improving model performance. Calibrated groundwater flow models are expected to more accurately forecast transient groundwater storage depletion/accumulation and are, therefore, more reliable for water management decision-making. In addition, the outcome of the iterative procedure highlighted considerable heterogeneity in the parameter distribution, underscoring the importance of remote sensing-based land subsidence observations for constraining the parameters of groundwater flow models.
Acknowledgments: This study was funded by the PRIMA program under grant agreement No. 1924, project RESERVOIR. The PRIMA program is supported by the European Union.
How to cite: Elci, A., Li, Y., Batkan, E. A., Bayırtepe, M. B., Zoccarato, C., and Teatini, P.: Integration of DInSAR Land Subsidence Observations with a Coupled Groundwater Flow and Geomechanical Modeling Approach, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15316, https://doi.org/10.5194/egusphere-egu25-15316, 2025.
The co-contamination of groundwater in shallow alluvial aquifers with toxic metals such as arsenic (As), mercury (Hg), lead (Pb), and chromium (Cr) has emerged as a critical global environmental health concern in the 21st century. This varies with redox conditions, and land use patterns. The present study aims to address the influence of oxidation-reduction potential, geochemical signatures, and human activities on the co-contamination of As, Hg, Pb, and Cr in groundwater and river water systems through laboratory assays and multivariate statistical analysis. Physicochemical parameters, including pH and alkalinity, were found to play a critical role in the mobility of these metals. Elevated concentrations of As and Cr in river water were attributed to industrial discharges, while Hg and Pb were more prevalent in groundwater, likely due to geogenic and anthropogenic sources. The concentration hierarchy of trace metals in groundwater followed the order Hg > Pb > Cr > As, whereas in river water, it was Cr > As > Pb > Hg. Longer residence times and evaporation processes were identified as key factors enhancing the concentration of major ions and trace metals, particularly Hg, which is predominantly of anthropogenic origin. Piper diagrams revealed the dominance of Ca²⁺-Mg²⁺-HCO₃⁻, mixed Ca²⁺-Mg²⁺-SO₄²⁻, and Na⁺-Cl⁻ water types, indicating influences of precipitation, rock weathering, and anthropogenic activities. Gibbs plots demonstrated the impact of evaporation on groundwater and rock-water interactions on river water chemistry. Probability exceedance indicated the inverse correlation between the concentration levels of contaminants and the likelihood of these concentrations surpassing the established regulatory thresholds. The R-mode clustering identifies three distinct clusters. Cluster 1 indicates halite dissolution and industrial effluents, suggesting mixed. The second cluster represents the role of the industrial contribution of the trace/heavy metals, which is also the reason why it is associated with surface or river water as could be observed from the HCA matrix. Cluster 3 represents the mobilization of important trace metalloids like As via competitive desorption due to the presence of anions like HCO3- especially in river water samples. Health risk assessment indicated significant non-carcinogenic risks associated with elevated As and Cr levels. The findings emphasize the pressing need for continuous monitoring and effective management strategies to mitigate the risks posed by toxic metal contamination in freshwater systems. This study contributes to a deeper understanding of hydrogeochemical processes and the interplay of natural and anthropogenic factors driving metal co-contamination in the region.
Keywords: arsenic, chromium, lead, mercury, redox, co-contamination
How to cite: Tripathi, S., Saxena, A., Panday, D. P., and Kumar, M.: Potential arsenic–mercury–lead–chromium co-contamination in the mid-Gangetic plains, India: Hydrogeochemical processes and health perspectives, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14046, https://doi.org/10.5194/egusphere-egu25-14046, 2025.
Posters virtual: Mon, 28 Apr, 14:00–15:45 | vPoster spot A
EGU25-543 | ECS | Posters virtual | VPS8
A more acute and continuous decline in Groundwater in Northwest IndiaMon, 28 Apr, 14:00–15:45 (CEST) | vPA.11
Groundwater is a vital resource for domestic, agricultural, and industrial purposes in many regions. However, the increasing demand and unsustainable extraction practices have raised concerns about the long-term viability and sustainability of groundwater storage (GWS), especially in areas where groundwater is the primary source of meeting various demands. Here, we focus on GWS changes in India’s Northwestern states, including Gujarat, Rajasthan, Punjab, Haryana, Uttara Pradesh, and Delhi over two decades (2002-2023). These states encompass 875,249 km2 area within the Indus and Ganges river basins, constitute approximately 59% cultivated land, and sustain 525.52 million people. Leveraging GRACE-based TWS data and GLDAS model data, our analysis reveals significant (P<0.05) declining GWS trends with a slope of −20.88 ± 0.53 mm/year, which is more acute than previously reported estimates. Some trend change points in February 2008 and June 2016 are detected that lead to segmented trends with slopes of −18.97 ± 2.45 mm/year (Jan-2002 to Feb-2008), −9.16 ± 1.96 mm/year (Feb-2008 to Jun-2016), −11.80 ± 2.51 mm/year (Jun-2016 to Dec-2023). Spatially divergent trends are found with high decreasing trends of more than 40 mm/year in Punjab, Haryana, Delhi, and some parts of Rajasthan and Uttara Pradesh. This is primarily due to anthropogenic activities like groundwater extraction for domestic and agricultural purposes. In contrast, Gujrat shows subtle positive trends, less than 10 mm/year, due to improved water management, irrigation practices, artificial recharge efforts, monsoonal rainfall, and efficient water extraction management. Multi-decadal variability and the recent depletion across these six states may foster discussions on policy actions and enhanced multilateral cooperation for a sustainable future, especially in the face of escalating groundwater extraction and a warming climate. This highlights the critical need for immediate attention to water resource challenges in the Northwestern states of India.
Keywords: Groundwater storage (GWS); GRACE; GLDAS; Anthropogenic activities; Policy interventions.
How to cite: Anjaneyulu, R. and Abhishek, A.: A more acute and continuous decline in Groundwater in Northwest India , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-543, https://doi.org/10.5194/egusphere-egu25-543, 2025.
EGU25-4752 | ECS | Posters virtual | VPS8
Hydrogeochemical Dynamics of Middle Andaman: Unraveling the Impact of Seawater Intrusion and Limestone Caves on Groundwater ChemistryMon, 28 Apr, 14:00–15:45 (CEST) | vPA.12
Title: Hydrogeochemical Dynamics of Middle Andaman: Unraveling the Impact of Seawater Intrusion and Limestone Caves on Groundwater Chemistry
Pardeep Kumar1,2#, Saumitra Mukherjee1*
*Corresponding author- saumitramukherjee3@gmail.com
#Presenting Author: Pardeepranga001@gmail.com
1School of Environmental Sciences, Jawaharlal Nehru University, New Delhi
2Quality Council of India, New Delhi
Abstract: Groundwater resources in coastal and island aquifers are increasingly threatened by seawater intrusion, exacerbated by climate change, sea level rise, erratic rainfall patterns, and over-extraction of groundwater. These challenges are particularly pronounced in Middle Andaman, where the interaction of groundwater, surface water, and seawater occurs within a complex hydrogeological framework. To assess the groundwater chemistry and its suitability for drinking and irrigation, a comprehensive study was conducted using geochemical, geospatial, and statistical methods.
Groundwater samples (n=24) and a reference seawater sample were analyzed for major ionic compositions using ICP, spectrophotometry, and flame photometry. Hydrogeochemical indices, including Chloro-Alkaline Indices (CAI), Water Quality Index (WQI), and agricultural suitability indices such as total hardness (TH), residual sodium carbonate (RSC), and magnesium adsorption ratio (MAR), were evaluated. A combination of ionic ratios—Cl/HCO₃, Ca/(HCO₃ + SO₄), (Ca + Mg)/Cl, Ca/Mg, and others—was used to characterize the influence of seawater intrusion and the dissolution of limestone minerals in the aquifers.
The results revealed that 24% of groundwater samples were unsuitable for drinking based on WQI, while 80% and 12% of samples were unsuitable for irrigation based on TH and MAR, respectively. The Durov plot and Schoeller's diagram indicated a dominance of Ca-HCO₃ and Na-HCO₃ water types in 48% and 24% of the samples, respectively, with enrichment of alkali and alkaline earth metal salts due to seawater intrusion. Chloride ion relationships suggested a reverse ion exchange process in 64% of samples, while X-ray diffraction analysis confirmed the presence of limestone minerals such as aragonite, calcite, dolomite, and magnetite.
Geospatial integration of hydrochemical data showed that 44% of the region was moderately affected, and 54% was slightly affected by salinity. Active tectonic lineaments and interconnected faults were found to facilitate seawater intrusion into the deep aquifer, highlighting the role of structural geology in the region's hydrogeochemical dynamics. This study underscores the urgent need for sustainable water resource management strategies to mitigate the adverse impacts of seawater intrusion on groundwater quality in Middle Andaman.
Keywords: Middle Andaman; Groundwater; Seawater intrusion; Water quality Index; Limestone caves
How to cite: Kumar, P. and Mukherjee, S.: Hydrogeochemical Dynamics of Middle Andaman: Unraveling the Impact of Seawater Intrusion and Limestone Caves on Groundwater Chemistry, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4752, https://doi.org/10.5194/egusphere-egu25-4752, 2025.
EGU25-16583 | Posters virtual | VPS8
Land use alters the alignment of Arsenic and Chromium co-contamination in the unconsolidated aquifer under reducing environments of the Mid-Gangetic PlainsMon, 28 Apr, 14:00–15:45 (CEST) | vPA.13
The Indo-Gangetic plain, well-known for its Alluvial landscape for human settlement, is currently facing unprecedented industrialization, and urbanization population, leading to high stress on its aquifer. On the other hand, co-contamination of arsenic (As) and chromium (Cr) in shallow aquifers has been showing an alarming global presence that varies with redox conditions, geochemical signatures, and human activities. We aim to address the influence of the suburban and urban land use on the co-contamination of As and Cr, using various geostatistical tools, models, and indices. Among twenty-six (n=26) groundwater samples, the majority of water types were found to be Mg2+-HCO3- and Na+-K+ exhibiting carbonate weathering and evaporation enrichments with saturation indices depicting the supersaturation of calcite and dolomite. The aquifer conditions in both suburban and urban settings were identified as reducing, facilitating the desorption of arsenic. Probability exceedance implied inverse correlation between contaminant concentrations and the probability of their likelihood of surpassing regulatory thresholds. Factor analysis indicates that the natural alignment of contaminants, particularly As and Cr, is maintained under suburban land use but significantly altered in urban settings. The influences of oxidation-reduction potential (ORP), dissolved oxygen (DO), pH, and iron (Fe) concentration on As and Cr co-contamination are effective in suburban environments, while urban aquifers face additional confounding factors, including artificial sources from industries and subsurface leaching. An integrated cluster heatmap has identified a trifecta of As, Cr, and lead (Pb), closely linked to pH, DO, and K+, highlighting the effects of increased anthropogenic activities in alluvial floodplains. Finally, a conceptual model was developed to clarify the common processes in these environments, facilitating the creation of universal management strategies for aquifers impacted by As and Cr co-contamination.
Keywords: arsenic; chromium; redox; mid-Gangetic plains; co-contamination
How to cite: Saxena, A., Kumar, M., and Bahukhandi, K. D.: Land use alters the alignment of Arsenic and Chromium co-contamination in the unconsolidated aquifer under reducing environments of the Mid-Gangetic Plains, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-16583, https://doi.org/10.5194/egusphere-egu25-16583, 2025.
