Orals: Mon, 28 Apr | Room B
Groundwater extraction is a major driver of land subsidence, posing significant challenges in many regions. This study focuses on developing mitigation strategies through field experiments and numerical modeling, with severe subsidence areas in Taiwan selected as test sites for cyclic and reduced pumping trials. The analysis revealed a strong positive correlation between groundwater level changes and soil compression, as well as between groundwater level fluctuations and power consumption. Monitoring data from 24 wells indicated that groundwater extraction predominantly occurs during peak hours from 8:00 AM to 4:00 PM, while non-peak extraction spans 4:00 PM to 8:00 AM. Field experiments involving four wells under three scenarios—current conditions, cyclic pumping, and reduced pumping—demonstrated that cyclic pumping significantly reduced groundwater level drawdowns and soil compression compared to current practices. A three-dimensional numerical groundwater model was developed and calibrated to simulate these scenarios. Results showed that both cyclic and reduced pumping scenarios outperformed current conditions in minimizing drawdowns, with the optimal strategy being group-based cyclic pumping combined with a 50% reduction in extraction. These findings underscore the potential of targeted groundwater management practices in mitigating land subsidence effectively.
How to cite: Ku, C.-Y. and Liu, C.-Y.: Advancing Groundwater Management Strategies to Mitigate Land Subsidence, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2070, https://doi.org/10.5194/egusphere-egu25-2070, 2025.
The Choshui Delta in Taiwan is experiencing accelerated land subsidence due to excessive groundwater extraction and the impacts of climate change. Addressing this challenge requires advanced predictive tools to monitor and forecast subsidence over time. This study proposes a novel artificial intelligence (AI) framework combining Deep Neural Networks (DNNs) with Principal Component Analysis (PCA) for time-series land subsidence prediction. PCA is utilized to analyze eight critical factors influencing subsidence, reducing their complexity by extracting principal components. These components are then used as input features for the DNN model, enabling it to effectively capture the intricate, multi-factorial dynamics of subsidence. Validation of the model was conducted by comparing reconstructed groundwater level data with historical measurements, demonstrating high reliability and accuracy. The integration of DNN and PCA delivers precise predictions of subsidence patterns, offering a robust and scalable solution for managing subsidence risks in rapidly sinking regions like the Choshui Delta. This AI approach provides valuable insights for sustainable groundwater management and infrastructure protection in vulnerable areas.
How to cite: Liu, C.-Y. and Ku, C.-Y.: Innovative AI Strategies for Groundwater and Subsidence Management in Taiwan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2075, https://doi.org/10.5194/egusphere-egu25-2075, 2025.
Characterizing the degree of aquifer confinement with passive aquifer tests can partly replace aquifer pumping tests for reliable evaluations of sustainable yields for groundwater management. Where there is insufficient data for modelling in groundwater management units (GMUs), sustainable volumes for pumping allocations are currently defined by several different methods, depending on the degree of aquifer confinement.
We present methods, results and limitations of using passive aquifer tests to characterize confinement. These are demonstrated across south-west Victoria, Australia where a state-wide program of sustainable yield assessment is in progress. Research methods included high resolution pore pressure sensors and tidal subsurface analysis (TSA) of responses to earth tide and barometric effects, with several quantitative diagnostic criteria. Results at 38 monitoring bores across seven GMUs were mapped in this part of the research. An example is presented for TSA results of both unconfined and confined conditions in a GMU that would require more detailed studies prior to large scale groundwater pumping. However, in another example, TSA analysis verified confined conditions with high confidence for a GMU where confined sustainable yield assessment methods applied. Therefore, utilising a confined aquifer to augment town water supply during drought could be an appropriate management strategy to avoid unacceptable long-term groundwater drawdown.
It is recommended that passive test methods are better utilized as a routine step for assessment of sustainable yield, particularly for GMUs at high risk of unacceptable drawdown and environmental impacts. The possibility that confined aquifer systems become semi-confined over-time could be readily monitored using these passive test methods. These relatively low cost of passive TSA methods could use existing data, where suitable. Passive test diagnostics can better characterize groundwater systems and improve sustainable water management.
How to cite: Timms, W. and Chowdhury, F.: Passive test diagnostics of confined to unconfined groundwater systems for sustainable water allocations, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7773, https://doi.org/10.5194/egusphere-egu25-7773, 2025.
Groundwater contamination is considered worldwide an emerging challenge due to the industrial and human activities. It has been demonstrated that a cost-effective remediation is increasingly dependent on high-resolution site characterization (HRSC), which is supposed to be necessary prior to the interventions. In this framework, groundwater sampling and monitoring strategy have become key factors in interpreting results and subsequently modelling contamination phenomena. Nowadays, low-flow purging and sampling (LFPS) is a consolidated methodology in groundwater monitoring, consisting of pumping water at low flowrates (in fine-grained soils from 0.1 to 1 L/min) prior to the sampling, until the stabilization of measured chemical physical parameters has been obtained. This is mainly due to minimize the induced stabilized drawdown in the well and, consequently, the aquifer stress too.
Recent outcomes focused on the great potential of a new low flow sampling method (the high-stress low-flow sampling) and the use of collected water level data to estimate hydraulic conductivity (He et al., 2022; De Filippi et al., 2023). The high-stress low-flow (HSLF) approach is characterized by an initial high pumping rate followed by low-flow and it is particularly effective in systems limited by long aquifer-responding time scales, typically low-yield aquifers. Preventing downward movement of the well casing water is the main goal and groundwater sampling duration can be significantly shortened. The second one, taking advantage of monitoring operations on groundwater quality, allows to provide to the stakeholders a very large amount of quantitative data on the aquifer over time, reducing time and costs for site characterization in case of future contamination. This new quali-quantitative approach can provide much more information and knowledge about the site, reducing time and costs of further activities. In addition to that, as the monitoring continues and new quantitative values are estimated, this approach allows also to track changes in aquifer hydrodynamic properties after the application of remediation techniques due to a possible contaminant release. Modelling the groundwater flow to the intake helps to get some precautions and be prepared to local hydrogeological conditions prior to the field work. In this way, the LFPS procedure could lead to obtain more representative groundwater samples in a shorter time and provide hydrogeological parameters.
How to cite: De Filippi, F. M., He, Y., and Sappa, G.: Low-Flow Sampling: practical guidelines, modelling and new approaches for boosting the representativeness of groundwater samples and aquifer knowledge., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-19211, https://doi.org/10.5194/egusphere-egu25-19211, 2025.
Groundwater is the primary water source for urban and industrial use in the lower Spree catchment, southeast of Berlin, Germany, and supports critical groundwater-dependent ecosystems, including lakes, wetlands, streams, and springs. Recent droughts and groundwater overexploitation have caused declines in groundwater levels, lake water levels, and river flows. The region's complex hydrogeology, coupled with extensive human interventions in the hydrological cycle, highlights the pressing need for a comprehensive understanding of groundwater dynamics and aquifer-surface water interactions to ensure effective and sustainable water resource management. This study develops a high-resolution hydrogeological conceptual model for a complex multi-aquifer system, providing insights into groundwater recharge, flow mechanisms, and lake-aquifer interactions. A 3D geological model was constructed to represent aquifer lithology and structural heterogeneity, forming the foundation of the conceptual framework. Hydrogeological, hydrochemical, and isotopic analyses—employing tracers such as Tritium, Oxygen-18, and deuterium—revealed groundwater flow paths, recharge sources, and the aquifers connectivity. The study highlights dynamic lake-aquifer interactions, driven by meteorology, hydrogeological conditions, and human activities such as groundwater abstraction. A comparative water balance study between the two decades revealed significant variations driven by both natural and anthropogenic factors, with minimal groundwater level drawdown during 2000–2009, compared to noticeable drawdown during 2010–2019. During the second decade, groundwater extraction increased by an additional 20.7 million cubic meters (MCM), rising from 196 MCM to 216.7 MCM. At the same time, aquifer recharge decreased by 67.8 MCM, dropping from 643.4 MCM to 575.6 MCM. This imbalance underscores the urgent need for sustainable groundwater management. The conceptual model revealed confined conditions in large parts of the aquifer system due to fine glacial sediments, making subsurface Managed Aquifer Recharge (MAR) methods such as Aquifer Storage and Recovery (ASR) and Aquifer Storage Transfer and Recovery (ASTR) essential. Based on evaluation criteria, including the presence of a high-yield deep aquifer, continuous aquifer thickness (i.e., absence of clay lenses), proximity to the source water, and distance from existing extraction wells, potential MAR sites were identified. Moreover, using historical streamflow data and thresholds such as hydro-ecological limits, median daily flow, channel maintenance flows, the available surface water for injection into MAR projects was estimated for six locations across the study area. The yearly available surface water for MAR was found to range between 0.5 and 3.2 MCM per location, with a total of 7.4 MCM across all sites. These findings provide critical insights for sustainable groundwater management, ensuring water supply security, and protecting ecosystems in the Berlin-Brandenburg region.
How to cite: Joodavi, A., Abdelrahman, A. A. A., Saft, M., Craven, J., and Engelhardt, I.: Advancing Sustainable Water Resource Management Through a Hydrogeological Conceptual Model of a Complex Multi-Aquifer System: A Case Study from the Spree River Basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3742, https://doi.org/10.5194/egusphere-egu25-3742, 2025.
The enhancement of stream flow has not been considered an objective in Managed Aquifer Recharge (MAR) projects due to the absence of a framework for quantifying River-Aquifer Exchange improvements. This work employs a numerical approach to assess the baseflow enhancement potential of a site. A novel metric, called the Baseflow Restoration Index (BFRI), has been developed to calculate the percentage increase in baseflow resulting from a unit rate of water injection.
Additionally, the capacity of the aquifer to be recharged has been quantified using a proposed metric known as the Permissible Aquifer Recharge Capacity (PARC). The PARC is defined as the maximum allowable rate of water injection at a site, taking into account the constraints of injection duration and permissible water head. By combining these two metrics, it is possible to determine the maximum potential baseflow enhancement achievable through the use of an injection well at a specific site.
The proposed metrics were applied in the Varuna River Basin, India, to evaluate the baseflow restoration potential of MAR projects. A straightforward TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) method was utilized with the calculated metrics to rank the sites based on baseflow enhancement, groundwater storage improvement, and overall project cost. This framework employs a 3D-integrated numerical model of surface water and groundwater in the Varuna River Basin to determine the proposed metrics.
How to cite: Kumar, R., Gaur, S., and Ohri, A.: Parametrization of River Aquifer Exchanges Enhancements in Managed Aquifer Recharge for Baseflow Restoration, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2748, https://doi.org/10.5194/egusphere-egu25-2748, 2025.
Artificial recharge of groundwater is a sustainable approach to mitigate water scarcity, particularly in arid and semi-arid regions. This study explores the utilization of wells for artificial groundwater recharge in dam reservoirs to enhance water storage, using remote sensing technology, geographical information systems, and groundwater surveys as well as meteorological data. The findings reveal that artificial recharge rates surpass natural recharge from rainfall, significantly enhancing groundwater storage. In addition, recharge wells effectively reduced evaporation losses from reservoirs and contributed to supplying groundwater aquifer. The study recommends the establishment of strategic water storage projects using artificial recharge wells, an increase in monitoring wells around dams, and the monitoring of hydrochemical changes in groundwater pre- and post-recharge. This research underscores the importance of integrating advanced technologies and strategic planning to optimize artificial recharge, reduce evaporation, and sustainably manage groundwater resources in arid regions.
How to cite: Alrehaili, A.: Enhancing Groundwater Storage Through Artificial Recharge in Arid region, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15974, https://doi.org/10.5194/egusphere-egu25-15974, 2025.
The use of Managed Aquifer Recharge (MAR) has been increasing in recent years as a climate change adaptation measure to increase water availability in dry seasons, reduce the impact of subsidence, contrast the seawater intrusion, etc.
The SeTe project, funded by the EU programme Interreg ALCOTRA, involves the feasibility study and demonstration of MAR in the Cuneo plain, a large shallow alluvial aquifer at the south-western edge of the Po Plain. In this area, the availability of water for irrigation during summer has dramatically diminished in recent years, such as in 2017, 2021, and 2022, and these droughts have sparked the initiative for testing MAR as a low-cost countermeasure.
The three project pilot sites identified in the project - Beinette, Tetti Pesio-Morozzo and Tarantasca-Centallo - are characterized by the presence of “fontanili”, i.e. drainage trenches dug since the Middle Ages to reclaim marshy land by lowering the groundwater level, sometimes integrated by shallow free-flowing wells called “Calandra pipes”. The water extracted, with flow rates ranging from a few tens of L/s to values exceeding 1000 L/s, is channelled and used in fields located further downstream. Unlike wells, where the flow is determined by the activation of a pump, the flow rate of the springs depends on nearby groundwater levels and, during the aforementioned summer droughts, the groundwater level decline led to a substantial reduction or even the cessation of spring flows.
The project, started in October 2023, will last for three years to study MAR solutions to increase spring flow during the irrigation season.
Historical meteorological, geological, and hydrogeological data have been collected to reconstruct the climate impacts on water resources, to characterize the aquifer and understand the correlations between climatic variables and spring yields.
A groundwater level monitoring network has then been developed exploiting existing wells, the fontanili wells known as Calandra pipes, and nine newly drilled monitoring wells (three per site).
Three infiltration structures are now being designed and installed, testing two configurations (shallow trench and vadose zone well) to infiltrate water available in channels out of the irrigation season. To this purpose, core sampling and shallow excavations were performed, collecting samples to study the shallow stratigraphy and characterize the hydraulic conductivity of the shallow subsurface through Lefranc tests and grain size distribution analyses. As these structures will be built, the project will proceed with the monitoring and modelling of infiltration in the three sites, also from the point of view of water quality, and results will be analysed to assess the large-scale applicability of MAR in the Cuneo plain.
How to cite: Taramasso, M. A., Secco, E., Tavernelli, G., Casasso, A., Gandolfo, M., Vigna, B., Fiorucci, A., Tosco, T., Sethi, R., and Algarotti, P.: The SeTe-ALCOTRA project to study the feasibility and the beneficial effects of Managed Aquifer Recharge (MAR) in the Cuneo plain , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-930, https://doi.org/10.5194/egusphere-egu25-930, 2025.
The Upper Godavari (UG) catchment, India, faces critical water quantity and quality challenges driven by high evaporation rates and spatially variable rainfall, which significantly affects the catchment's hydrodynamics and threatens agriculture-based livelihoods. Understanding groundwater recharge processes and the impact of contaminants is essential for effective groundwater management. This study employs stable isotopes and tritium, alongside major ion geochemistry, to investigate hydrological processes in the riverine belt of the Western Ghats, characterized by Deccan basaltic terrain. Groundwater, surface water, and precipitation samples were collected in pre- and post-monsoon seasons (2022-2023). Post-monsoon stable isotope signatures indicate recharge predominantly from Indian monsoonal precipitation, while pre-monsoon stable isotopes reflect evaporation. The stable isotope signatures of the shallow aquifers imply rapid recharge and higher vulnerability to evaporation and contamination from agricultural runoff. In contrast, the stable isotope signatures of the deeper aquifers suggest older, more distant recharge sources with minimal recent contribution. Surface water closely resembles isotopically lighter monsoonal precipitation, and this plays a key role in recharging shallow aquifers. Tritium (³H) concentrations in groundwater (0.64 to 7.6 TU) locally exceed the annual average tritium concentration in modern rainfall (~7 TU), and locally higher values are observed post-monsoon and lower values pre-monsoon. This implies that most of the water in the subsurface is derived from recent rainfall with low transit times. Lumped parameter models (LPM) were used to estimate the mean transit times (MTTs) of groundwater, which ranged from <2 to 40 years. Older MTTs (25-40 years) were observed during the pre-monsoon season, reflecting slower recharge dynamics than the post-monsoon period (1.5 – 20 years). A mass-balance mixing model determined the contribution of each NO3 source to the UG catchment. Results from the mixing model indicated that NO3 from the irrigation return flow contributed 90%, and the other NO3 sources contributed 8% in groundwater. These findings demonstrate the value of a multi-tracer approach in unraveling the hydrological complexities of the Upper Godavari catchment. The relatively young groundwater indicates high recharge rates, underscoring the catchment's resilience in sustaining water resources. However, this also highlights its vulnerability to decadal climatic variations and contamination risks. By elucidating recharge mechanisms, contamination pathways, and groundwater depletion patterns, this study provides insights to support sustainable water management strategies tailored to the dynamic hydrogeological conditions of the region.
How to cite: Prasad, G., Cartwright, I., and Chinnasamy, P.: Investigating Hydrological Processes and Groundwater Dynamics in the Upper Godavari Catchment, India, Using Environmental Tracers , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-274, https://doi.org/10.5194/egusphere-egu25-274, 2025.
The aim of this study is to emphasize the growing importance of localized hydrogeological investigations when putting forward sustainable water resource management strategies at a regional scale. Accordingly, this research focuses on the hydrogeological and hydrogeochemical dynamics near the Kesikköprü Dam area, a vital water reservoir for Ankara, the capital city of the Republic of Türkiye. The region is notable for hosting Türkiye’s richest iron ore deposits, intensive agricultural activities, and mining operations. It was previously characterized by semi-permeable and impermeable units with limited groundwater potential. As part of this investigation, hydrogeochemical and isotopic characterization studies of groundwater in the area were conducted. To this end, 21 groundwater sampling locations (wells, springs, fountains, and open-pit mine lakes) were selected in the field, and five distinct hydrogeochemical facies were identified: CaHCO₃, NaMgHCO₃SO₄, CaMgHCO₃, CaNaHCO₃, and NaCaSO₄. The groundwater chemistry in the area is predominantly shaped by water-rock interactions and salinization through cation exchange. Some samples contained dissolved arsenic (up to 120 µg/L) and nitrate (maximum concentration 374 mg/L). Stable isotope analyses were performed on selected samples to examine the relationship between δ¹⁸O and δD. The results revealed that certain samples, particularly those collected from mining lakes and Kesikköprü Dam Lake, were influenced by evaporation. The slope of the evaporation line was found to align with the average relative humidity recorded at meteorological stations near the study area (Bala, Çelebi, and Kaman). In addition to field and hydrochemical investigations, remote sensing studies using satellite images and the identification of open-pit mine lakes provided solid evidence of groundwater presence. An investigation of recharge and discharge dynamics using satellite data from 2016 for one of the selected pit lakes showed that the lake was recharged by groundwater during the dry season, while the groundwater system was recharged by the pit lake during the wet season. Contrary to previous studies conducted at a catchment scale in the Kızılırmak Basin, the findings of this study suggest the possibility of interconnected shallow and deep groundwater systems in the region.
How to cite: Yurttaş, O. and Arslan, Ş.: Unlocking Hydrogeological Secrets on a Small Scale: A Case Study in the Kesikkopru Dam Region, Ankara, Republic of Turkiye, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-494, https://doi.org/10.5194/egusphere-egu25-494, 2025.
Groundwater plays a crucial role in the global water cycle. Unlike surface water, which exhibits immediate and observable reactions to environmental changes, groundwater is stored in aquifers beneath the Earth’s surface and demonstrates a more gradual response to external influences. The impact of environmental changes on the driving factors and interaction mechanisms of the water cycle introduces uncertainties regarding the renewal and response status of groundwater. This study aims to establish a comprehensive evaluation system to scientifically assess groundwater renewal capacity (GRC) and systematically elucidate the interaction processes between groundwater and various water sources during the recharge phase.
To meet urban water supply demands and mitigate the impacts of prolonged drought periods, Beijing has extensively relied on groundwater since the 1980s. However, since 2015, groundwater levels have exhibited an upward trend due to the implementation of the South-to-North Water Diversion Project, ecological replenishment initiatives, and several significant rainfall events. This region, which has undergone natural fluctuations characterized by periods of decline followed by recovery, serves as a pertinent case study for examining the responses of groundwater to both climatic influences and human activities.
The study elucidates the concept of GRC and identifies essential interaction and evaluation indicators between groundwater and external hydrological cycles. By considering factors such as groundwater sources, age, ion sensitivity, flow dynamics, and variations in burial depth, we evaluate GRC from multiple perspectives. Furthermore, we examine the responsiveness and adaptability of groundwater to external drivers, as well as the characteristics of recharge areas, pathways, and the overall mobility and openness of the system.
The following results are observed: (1) the system exhibits a high degree of openness and rapid responsiveness, characterized by swift infiltration and mixing processes, as well as a strong correlation between groundwater levels and precipitation. The heavy rainfall experienced in 2023 resulted in significant replenishment and mixing, leading to a reduction in burial depth from 16.97m to 15.22m. Following the flood season, the young water fraction of groundwater in the Chaobai River and Yongding River basins was 11.2% and 30.7%, respectively. (2) In recent years, GRC have undergone significant changes due to intensive environmental events, which are reflected in variations in sources, age, water levels. While precipitation remains the primary source of replenishment, the proportion of direct precipitation infiltration has decreased. Conversely, river water recharge, particularly following flooding events, has emerged as a significant contributor near the river channel, accounting for 25%. (3) Spatial variations in GRC have been identified, and areas with high potential for utilization, as well as groundwater circulation depths, have been preliminarily determined. The hydraulic gradient and runoff velocity exhibit a gradual decrease from the top of the alluvial fan to the middle aquifer, which corresponds with a decline in GRC. Furthermore, as aquifer depth increases in the plain area, GRC also diminishes.
This study elucidates the dynamics of groundwater circulation and renewal within the context of changing hydrological conditions, thereby contributing to a better understanding and management of groundwater resources.
How to cite: Xu, J. and Wei, J.: Human Activities and Extreme Precipitation Boost Groundwater Renewal Capacity in the Beijing Plain, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-3934, https://doi.org/10.5194/egusphere-egu25-3934, 2025.
Coastal groundwater resources can be complex to study, due to temporally variable saline water intrusion associated with sea level variation. In the current climate change context, the challenge of rising sea level in West Africa is compounded by the pressures of a growing coastal population. In the densely coastal African cities, groundwater resources are therefore subject to major impacts on their quantity and quality by both sea-water intrusion, enhanced by aquifer over-exploitation, and pollution due to the lack of sanitation facilities, while freshwater needs are growing.
The aim of this work is to propose an integrated approach by combining hydrodynamic and geochemical studies in order to develop sustainable management strategies of the main coastal aquifer of the Greater Abidjan in Côte d’Ivoire. This area accounts for 36% of the national population and whose main source of drinking water is the Continental Terminal (CT) aquifer.
In 2024, a field campaign conducted on a set of 28 piezometers, reaching depths of up to 300 meters, enabled a 3D analysis of the aquifer. Current piezometric data align with the topography, but temporal data show a continuous decline in water levels. From a geochemical point of view, groundwater has generally a very low to moderate mineralization, with electrical conductivity values ranging from 21 to 2830 µS/cm (average of 288 µS/cm). However, groundwater tends to be more mineralized at greater depths in urbanized areas, where nitrate concentrations are higher. The waters of the CT aquifer are characterized by high acidity, with an average pH value of 5.1, reflecting the silicate nature of the aquifer, amplified by sulfide oxidation and dissolution of high amounts of soil CO2. Furthermore, some piezometers show relatively high chloride concentrations (600-756 mg/l), combined with isotopic ratios 18O and 2H similar to those of seawater. These observations suggest the presence of saline intrusion in some coastal deep wells, as well as recharge by ancient waters, particularly in areas covered by Quaternary deposits.
How to cite: Durand, A. D., Marlin, C., Durand, V., Adiaffi, B., Gibert-Brunet, E., and Oga, Y. M.-S.: Aquifers quantity and quality evolution within urbanized coastal areas: insights from piezometric and geochemical analyses of the Deep Continental Terminal Aquifer in Côte d’Ivoire, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11585, https://doi.org/10.5194/egusphere-egu25-11585, 2025.
This study is aimed to delineate and determine its hydraulic properties in Wama catchment with drainage area of 3,390 km2, in the Upper Blue Nile basin, Western Oromia, Ethiopia. The tertiary volcanic rocks are the predominant geologic units, which make up 83.36% of the region. The main tools utilized for data processing and interpretation include ArcGIS 10.4, Global mapper 23.0, Surfer 20, Strater 5, AQTEVSOLV Pro.4.5, and Microsoft Excell. Aquifers’ structures were manually delineated with Surfer via 19 boreholes and 13 shallow wells using lithologic units whereas hydraulic properties were estimated from constant pumping test data of 1 shallow well and 17 boreholes using AQTEVSOLV Pro based on a single well test approach by clustering into western, northern, north eastern, central and southern regions. Due to variations in the deposition of geologic units, the study area's aquifer structure's thickness varies both vertically and laterally. Materials like sand, gravel, scoria, and fractured and weathered volcanic rocks were considered as good aquifer whereas clay, pyroclastics, and massive basalts are aquitards. Semi-confined aquifer type dominates majority of the catchment except the central region which is confined aquifer based on available lithologic units, position of water level and pumping test data using AQTEVSOLV Pro. Transmissivity (T) of western, north eastern and central region varies from 0.94-64 m²/d, 22.4-60 m²/d and 23.4-30 m2/d respectively, indicating intermediate aquifer potential for extraction of local water supply (dominant). In northern region, transmissivity (T) varies from 12.3-827 m2/d, implying high aquifer potential for withdrawal of regional importance. Specific capacity (SC) of western, northern, north eastern and central regions ranges from 1.15-157 m²/d, 16-632 m²/d, 41-78 m²/d, and 4 - 43 m2/d respectively. Transmissivity of southern part is 10.4 m2/d (potential for local water supply). In this study, the correlation of T and SC is about 97% indicates direct relationship. Therefore, the higher transmissivity value shows the aquifer is supplying adequate water towards the well across aquifer thickness and the higher specific capacity shows the well has good efficiency for water extraction.
Key words: Aquifer structure; hydraulic properties; Wama catchment; volcanic rocks.
How to cite: Debela, S. K., Feyessa, F. F., and Walraevens, K.: Identifying the structure of a volcanic aquifer and estimating its hydraulic properties: A case of Wama catchment in the Upper Blue Nile Basin, Western Oromia, Ethiopia, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15054, https://doi.org/10.5194/egusphere-egu25-15054, 2025.
Understanding hydrogeological conditions is crucial for selecting and assessing the long-term safety performance of a high-level radioactive waste (HLW) disposal repository. Utilizing environmental isotopes as effective markers for analysing groundwater movement, this study investigates groundwater recharge sources, age, and renewal rates using multiple isotopes in China’s potential HLW repository site, the Beishan area. The results indicated deep bedrock groundwater primarily derives from ancient precipitation infiltration under cold climatic conditions. A noteworthy distinction is that loose sedimentary groundwater exhibits higher tritium content (>10 TU) compared to bedrock groundwater (<3.2 TU). Groundwater within the recharge area, especially within gullies and piedmont slope deposits, is relatively youthful, with an age of less than 30 years and an annual renewal rate exceeding 5 %. In contrast, the shallow groundwater age in the intermountain basins and depressions of the discharge area generally exceeds 50 years, with an annual renewal rate often falling below 0.5 %. At the Beishan underground research laboratory site, deep groundwater at the disposal repository depth displays a corrected 14C age exceeding 8,000 years, indicating an extremely slow movement and alteration rate. As a result, the hydrogeological conditions in the Beishan area are expected to be relatively beneficial for ensuring the safety of HLW repository.
How to cite: Li, J., Zhou, Z., and Liang, X.: Using multiple isotopes to determine groundwater source, age, and renewalrate in the Beishan preselected area for geological disposal of high-levelradioactive waste in China, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20425, https://doi.org/10.5194/egusphere-egu25-20425, 2025.
Gold mining activities can have long-lasting impacts on the environment. These impacts include soil and water contamination due to the generation of acidic drainage (AMD) and the release of potentially toxic elements (PTEs) including metals and metalloids as well as other chemical residues derived from ore processing.
In the Anzasca Valley (NW Italy), the Pestarena and Crocette gold mines were exploited from the Middle Ages until their final closure in 1961. The study area is an alpine valley where paragneiss, mycascists and orthogneiss outcrop. The metamorphic rocks at the valley floor are covered by alluvial deposits that host a phreatic aquifer connected to surface water bodies.
The gold mineralisation is associated with sulphides (pyrite and arsenopyrite) that were initially processed by mercury amalgamation, followed by cyanidation. Waste from ore processing was abandoned in the large area near the processing plants and deposited in waste dumps. The mobilization of PTEs due to the leaching of mining waste and the drainage of mine waters has led to significant soil and water contamination.
Previous studies of soils in the area indicate acidic conditions, with pH values ranging from 3.8 to 6.2, and concentrations of PTEs exceeding Italian legislative threshold, including antimony (up to 40 mg/kg), lead (up to 2360 mg/kg), mercury (up to 470 mg/kg) and in particular arsenic (up to 25800 mg/kg). Furthermore, surface water (SW) found arsenic concentrations peaking at 280 µg/l. However, until now, no studies have evaluated the quality of groundwater (GW) in these areas.
The current study aims to assess the level of water contamination in Pestarena and Crocette. Analyses were carried out during three water sampling campaigns in May, July and September 2024, to highlight possible chemical variations over time in GW and SW. In Crocette, 11 samples were collected, including 2 GW samples and 9 SW samples. At Pestarena, 18 samples were collected, equally divided between GW and SW. pH varied slightly but remained neutral or sub-acid, while electrical conductivity (EC) and total dissolved solids (TDS) increased during the summer months, with particularly high levels observed in GW near the waste dumps in Pestarena. Arsenic levels exceeded the Italian limit (70 µg/l) in 83% of the GW and SW samples. While other metals remained at low concentrations in SW, elevated levels were found in GW at Pestarena downstream of the mining waste, including aluminium (up to 7266 µg/l), iron (up to 1785 µg/l), lead (up to 25 µg/l), manganese (up to 276 µg/l) and nickel (up to 86 µg/l). Cyanide and mercury analyses are currently underway.
These preliminary results confirm that GW also is affected by past mining activities and emphasise the need for long-term monitoring to assess contamination levels and future remediation activities. Further studies are needed to fully understand how factors such as precipitation, snowmelt and soil characteristics influence these parameters, as well as the mobility and concentration of PTEs throughout the seasons.
How to cite: zaniboni, L., Lasagna, M., Dino, G. A., and De Luca, D. A.: Water contamination in the Anzasca valley (NW Italy): the long-term effects of historical Au-mine activities, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17065, https://doi.org/10.5194/egusphere-egu25-17065, 2025.
The presence of tides and subsurface dams adds complexity to the migration and mixing processes of land-sourced contaminant in coastal aquifers. While prior studies have explored the individual effect of tides and subsurface dams, their combined impact on the transport characteristics of land-sourced contaminant remains unclear. This study conducted laboratory experiments and numerical simulations to thoroughly investigate the migration and discharge behaviors of land-sourced contaminant in an unconfined coastal aquifer. The spatiotemporal variation, transport pathways, spreading, residence time and mass fluxes were analyzed in detail. Results demonstrate that a large low-velocity zone forms near the bottom corner upstream of the subsurface dam, and the mixing of the contaminant with residual saltwater in this zone substantially delays its discharge to the ocean. Compared to the nontidal condition, the addition of tides enhances seawater circulation within the saltwater wedge downstream of the subsurface dam while slowing particle transport in the freshwater zone. Moreover, increased tidal amplitude induces a time lag in the peak efflux of contaminant. The residence time of the contaminant is jointly affected by the subsurface dam, saltwater wedge and tidal forces. Sensitivity analysis indicates that a greater aquifer permeability and lower contaminant dispersiviy reduce the maximum spreading area while significantly promoting the maximum daily contaminant efflux. However, the residence time exhibits non‐monotonic relationships with respect to dam locations and aquifer permeabilities. The findings highlight the complexity of nearshore subsurface systems subjected to both natural and human factors, and have valuable insights for developing effective strategies to safeguard coastal environments.
How to cite: Yin, J. and Wu, Y.: Effects of Tides and Subsurface Dams on the Land-sourced Contaminant Transport, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-5043, https://doi.org/10.5194/egusphere-egu25-5043, 2025.
Groundwater resources in Kabul City, Afghanistan, are experiencing critical stress due to overexploitation driven by rapid urbanization, population growth, and inadequate water management systems. This study highlights a rigorous and comprehensive assessment of groundwater overexploitation in the region, focusing on its causes, impacts, and long-term implications. Key challenges, including a dramatic decline in water tables (from 2014 to 2023 annually about -1.8 m/year on average, and a drop of 70 m in some areas), rapid urbanization (increased 42% from 1985 to 2023), deteriorating water quality (NO3ˉas dominant contaminants), the associated land subsidence phenomena (-5.3 cm annual from 2014 to 2019), the exacerbating effects of climate change (1 to 1.5 °C increase over recent decades) and weak governance frameworks are examined in depth. The analysis underscores the significant socioeconomic and environmental consequences of unsustainable groundwater use and highlights the urgent need for coordinated interventions.
An integrated framework for sustainable groundwater management is proposed to address these challenges. The framework encompasses technical measures such as artificial aquifer recharge, treatment and enhancement of surface water usage, climate-adaptive water-use strategies, and advanced groundwater monitoring technologies. These are complemented by institutional reforms, policy development, and active stakeholder participation to enhance governance and accountability. By integrating multidisciplinary approaches with community engagement, the framework aims to promote equitable, efficient, and resilient groundwater management practices that mitigate the impacts of over-extraction and climate change.
This research contributes to advancing the understanding of groundwater management in arid and semi-arid regions and offers practical insights for policymakers and water resource managers. The findings provide actionable strategies to address the dual crises of groundwater overexploitation and climate change in Kabul City and other vulnerable regions worldwide.
How to cite: Farahmand, A., Abrunhosa, M., and Nab, A. W.: Assessing Groundwater Overexploitation in Kabul City, Afghanistan: Challenges, Impacts, and the Path Toward Sustainable Management Through an Integrated Framework, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-1682, https://doi.org/10.5194/egusphere-egu25-1682, 2025.
In the Gironde department (France), which relies on deep aquifers for 97% of its drinking water supply, groundwater management is critical to meet human needs while preserving ecosystems dependent on these resources. With a population of 1.7 million, including Bordeaux Métropole, and a history of overexploited aquifers identified as early as the 1990s, local stakeholders have adopted innovative approaches to ensure long-term resource sustainability.
Groundwater management in Gironde combines global and local strategies. At the global level, the SMEGREG (a public entity dedicated to deep aquifers) developed a trial-and-error methodology to determine extractable volumes, incorporating extraction scenarios, regional flow model simulations, and expert validation. A panel of hydrogeological experts - currently unique in France - examines variations in groundwater reserves and evaluates their acceptability. Adherence to these extractable volumes is now central to the region’s water management strategy.
However, meeting human water needs is not the only concern of local stakeholders. Locally, the focus shifts to preserving groundwater-dependent systems (wetlands, rivers, springs, etc.) by identifying these areas and maintaining critical piezometric levels. An atlas of groundwater-dependent systems is currently being developed. This atlas is designed to facilitate the management of interface environments and to provide a shared foundation for establishing operational management rules.
Additionally, a strong emphasis on public awareness and demand management has been pivotal. Programs such as "Espaces Info Économie d'Eau" (information booths on water resources and consumption management) and "L'eau un enjeu majeur" (school-based awareness programs) engage the public and students, while technical guides and communication campaigns encourage water-saving behaviors. These efforts have allowed the region to accommodate 300,000 new residents without increasing water extractions, demonstrating the effectiveness of managing demand to complement supply-side strategies.
By adopting this dual-scale approach, combined with a water-saving strategy, the Gironde department exemplifies how sustainable groundwater management can effectively balance the needs of human populations and fragile ecosystems. However, with the increasing population driving higher water demand despite the ongoing conservation efforts, and the significant influence of recharge modifications on these inertial hydrosystems, the ongoing revision of the Water Management Plan (SAGE) will provide an opportunity to collectively adapt our water management strategy to ensure long-term sustainability.
How to cite: Erostate, M. and de Grissac, B.: The role of deep groundwater management strategies in ensuring sustainable resource management and preserving dependent ecosystems Case study of the Gironde department, France, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6976, https://doi.org/10.5194/egusphere-egu25-6976, 2025.
The groundwater quality assessments are challenging in complex hydrogeological settings and highly anthropized areas where geogenic and anthropogenic pollution may coexist. The objective of this study was to elucidate groundwater quality patterns beneath an inactive landfill in a coastal region of central Italy by integrating chemical-physical and geochemical parameters with isotopic and microbiological analyses. The groundwater under the landfill, predating the EU Landfill Directive (1999/31/EC), is under pump-and-treat remediation. The site features a complex stratigraphy of fluvio-palustrine sediments, eolian sands, and volcanic deposits of Pleistocene age, with a water table aquifer overlying Pliocene clays. Sampling was performed from 13 piezometers within the landfill and two surface water sites between March and July 2024. Laboratory analyses were conducted to measure the concentrations of major, minor, and trace cations and anions (with a specific focus on Fe, Mn, and As), dissolved organic carbon (DOC), and isotopes (δ18O, δ2H, δ13C, tritium and 87Sr/86Sr). Microbiological analysis were performed by flow cytometry (microbial cell abundance) and spectrofluorimetry (microbial respiration rates).
Upgradient of the landfill, the aquifer exhibits oxidizing conditions, with low concentrations of metals and bicarbonates. Electrical conductivity (EC, μS/cm) is higher near the most upstream piezometers, where chloride concentrations exceed 800 mg/L. In the downgradient zone, high concentrations of Fe (4.2 mg/L) and Mn (1.1 mg/L) – occasionally exceeding the legal limits for groundwater – are associated with the strongly reducing conditions of the aquifer, driven by the presence of fluvio-palustrine deposits rich in peat, as identified through available borehole logs. The presence of As (1.3-15.4 μg/L) was likely due to interaction of groundwater with the volcanic deposits in the area. The leachate-tracer tritium showed generally lower activity (0.4-5.5 U.T.) than previous measurements, implying that historical contamination is currently declining. DOC concentration has a range from 0.5 to 7.4 mg/L, higher downgradient. Surface water sampled in two sections in the nearby river is highly oxygenated and rich in organic matter. Microbial cell abundance ranged from 104 – 105 cells/mL in most of groundwater samples, with higher values downgradient (106 cells/mL). Microbial respiration showed an inverse relationship with DOC exclusively in downgradient piezometers.
These data indicated a highly specific hydrogeological and geolithological context, further complicated by anthropogenic activities throughout the region. As suggested by the Na/Cl ratio and the 87Sr/86Sr ratio, high chloride seems linked to mixing with fossil seawater, likely associated with a geological history marked by marine incursions following the end of the last glaciation (Würm). Elevated metal levels were connected to anoxic conditions promoted by the occurrence of fluvio-palustrine sediments, where heterotrophic microbial communities consume oxygen for organic matter degradation.
Our findings highlight the critical need for tailored monitoring strategies that consider the unique hydrogeological and geolithological characteristics of the site, ensuring effective long-term management and protection of groundwater resources in similarly complex environmental settings.
How to cite: Cisternino, A., Casentini, B., Amalfitano, S., Melita, M., Gatta, R., and Preziosi, E.: A multidisciplinary approach for groundwater quality assessments in complex hydrogeological settings, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11025, https://doi.org/10.5194/egusphere-egu25-11025, 2025.
Demand for groundwater resources as drinking water is highly increasing worldwide. Groundwater accounts to 92% of drinking water sources also in Hungary. Through rock-water interactions, different elements can be enriched in groundwater including naturally occurring radioactive elements, which may have considerable health risk. Due to the hierarchically organized movement of groundwater, the spatial distribution of dissolved solid content, and associated physical, chemical and kinetic processes are also systematized. Areas of different hydraulic regimes even within the same aquifer are characterized by different geochemical environments, which is decisive in case of the mobility of redox-sensitive elements, such as uranium and radium. The groundwater flow system approach, therefore, helps to understand the origin of the different physicochemical characteristics and components of groundwater. Moreover, the vulnerability to any changes depends also on both the type of the hydraulic regime and the order of the hierarchically nested flow system.
This study aimed to identify the cause of gross alpha activity exceeding the parametric value of 0.1 Bq/L in groundwater-derived drinking water in northwestern part of Hungary using a regional groundwater flow system approach. Sampling of springs, drinking water and thermal wells was performed in 2021 and in 2024. In-situ water quality parameters were recorded on the field. The concentrations of major ions and trace elements, oxygen and hydrogen isotopic ratios and activity concentration of radioactive isotopes (uranium, radium, radon) were determined by laboratory measurements. Local groundwater flow conditions were characterized by pressure-elevation profiles. In drinking water samples total U activity concentration up to 540 mBq/L was measured that can be connected to local geogenic sources related to the metamorphic outcrop of Sopron Mountains and to the Pannonian sediments in its surroundings. The radionuclide-specific measurements explained that the elevated gross alpha activity identified in several drinking water wells is a result of dissolved uranium favored by the prevailing oxidizing environment of local flow systems and/or recharge areas. Low activity concentrations of 226Ra and 222Rn were measured in all samples except one sample, where 301 mBq/L of 226Ra and 219 Bq/L of 222Rn activity concentration was found. The presence of radium could be attributed to regional flow systems; however, the high concentration of radon activity cannot be accounted for solely by the decay of radium calling for further detailed investigation. The results highlight also that climate change induced groundwater level decline will enhance the problem with uranium. This 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. Furthermore, some radioactivity measurements were supported by the open-access scheme of the European Commission’s Joint Research Centre (JRC) (Research Infrastructure Access Agreement No. 36227-1).
How to cite: Erőss, A., Garcia, R. D. U., Hegedűs-Csondor, K., Baják, P., Jobbágy, V., Izsák, B., Horváth, Á., Kohuth-Ötvös, V., and Vargha, M.: Understanding the behaviour of naturally occurring radioactive isotopes in groundwater towards sustainable drinking water resource management , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13188, https://doi.org/10.5194/egusphere-egu25-13188, 2025.
Groundwater sustains about 75% of Uganda’s population, especially in rural and peri-urban areas [1,2]. While recent progress has been made to understand groundwater quality at the time of drilling [3], the baseline hydrogeochemical characteristics of operational community drinking water sources remain poorly understood, further complicated by potential surface-groundwater interactions [4]. This study assesses the variations in major groundwater chemistry and geochemical controls across five distinct hydrogeological settings in Uganda: Precambrian metasedimentary (MS; n=30), granulitic-gneissic complex (GG; n=21), unconsolidated sedimentary (SDM; n=10), volcanic (VO; n=7), and metavolcanic (MV; n=6), as well as surface water (SW; n=8). Hydrochemical facies are predominantly CaHCO3, with HCO3- as the dominant anion, reflecting limited geochemical evolution in shallow, discontinuous aquifers. However, NaHCO3 and NaCl facies dominate in MV and SDM settings, respectively, indicating cation exchange processes and more advanced geochemical evolution. The mean (Ca2++Mg2+)/(Na++K+) ratios were generally >1, except in SDM, suggesting reverse cation exchange, further supported by the ion balance plot (slope = –1; R² = 0.6). A mean (Ca2++Mg2+)/HCO3– ratio of ~1 across all settings suggests a dominant influence of carbonate dissolution. The (Ca2++Mg2+)/SO42– ratio was consistently high (>1), with a maximum of 74 for VO, indicating limited gypsum dissolution. Similarly, (Na++K+)/Cl– ratio was high (>1) across all hydrogeologies, with a maximum (17) in MV and a minimum (2.3) in SDM, suggesting minimal evaporative concentration and dominant meteoric recharge. The HCO3–/Na+ ratio [5] was low (1–4) across all settings, with the highest in VO and lowest in SDM, reflecting the influence of silicate weathering. Interestingly, mineral stability diagrams based on ion activity ratios suggest kaolinite as a stable secondary mineral in VO, in contrast to clinoptilolite in other settings. This likely reflects active monosiallitisation in volcanics, where rapid water flow, good drainage, and low silica favour kaolinite stabilisation. Geochemical modelling predicts undersaturation in calcite, dolomite, gypsum, and anorthite across all settings, while feldspars like K-feldspar and albite are supersaturated, with albite undersaturation mainly in VO settings. These findings reveal diverse geochemical processes shaping Uganda's groundwater chemistry, emphasizing the need for hydrogeologically-tailored groundwater monitoring and management.
Acknowledgements
We acknowledge the University of Manchester Faculty of Science and Engineering Dean’s Doctoral Scholarship (to DM), the Dame Kathleen Ollerenshaw Fellowship (to LAR), the International Science Partnership Fund – England project (ODA), and UKRI Future Leaders Fellowship (MR/Y016327/1 to LAR). Thanks to the Ministry of Water and Environment, Uganda for permissions, Jonny Huck for discussions, and the MAGU analytical team for lab support.
References:
[1]MWE, 2024. Water Supply Atlas: National Report.
[2]Nsubuga et al. 2014. Water Resources of Uganda: An Assessment and Review. J. Water Resour. Prot. 06, 1297–1315. https://doi.org/10.4236/jwarp.2014.614120
[3]Owor et al. 2021. Hydrogeochemical processes in groundwater in Uganda: a national-scale analysis. J. Afr. Earth Sci. 175, 104113
[4]Wilson et al., 2024. Surface-derived groundwater contamination in Gulu District, Uganda: Chemical and microbial tracers. Sci. Total Environ. 177118.
[5]Gaillardet et al., 1999. Global silicate weathering and CO2 consumption rates deduced from the chemistry of large rivers. Chem. Geol. 159, 3–30.
How to cite: Muloogi, D., Wilson, G. J., Ahmed, F. T., Polya, D. A., and Richards, L. A.: Major Groundwater Chemistry of Contrasting Hydrogeological Settings in Uganda, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-662, https://doi.org/10.5194/egusphere-egu25-662, 2025.
Although overlooked, groundwater is crucial to sustain life itself and consequentially also human life and its activities. Groundwater sustainability relies on a delicate balance between recharge and discharge, in which both human uses and behavior play an important role. If not adequately managed and planned, pumping rates for human consumptions, as well as changes in irrigation practices, can alter the balance between inputs and outputs, potentially damaging groundwater-dependent ecosystems. This is the case of lowland springs in Northern Italy, called “fontanili”: man-made-pits and canals dug from the XIV century to reclaim large zones of the Po plain, which have been used since to irrigate fields while generating biodiversity hotspots right in the middle of one of the most polluted and urbanized areas in the European Union.
The role of these groundwater-dependent ecosystems has been studied in the past, but their relationship with groundwater still holds some uncertainties: How does this type of lowland spring interact with the aquifer along its course? How much do they influence the surrounding groundwater system?
To answer these questions, this work presents numerical models in MODFLOW that, with increasing complexity, reproduce a single fontanile’s behavior based on in-situ observations and literature. The pros and cons of the different methods are explored, also considering their applicability at larger scale and increased number. Results bring more light to these unique systems’ behavior and show concrete and successful possibilities of representing them inside a well-known and broadly utilized software, aiming to foster their consideration in management plans to prevent their depletion. This research has been developed in the context of MAURICE project (CE0100184).
How to cite: Colombo, P., Pirovano, M., Medina Montecinos, C., Mazzon, P., and Alberti, L.: Modeling groundwater-dependent ecosystems under increased complexity: the case of Northern-Italy lowland springs, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13305, https://doi.org/10.5194/egusphere-egu25-13305, 2025.
Undercover karst are characterized by limestone formations underneath a variability thick, low-permeability cover. Karst landforms such as sinkholes or swallow holes are thus not very frequent in these environments. This leads to a high inertia of the environment. This makes it complex to use the tools and methods usually employed to characterize a system and complexify in the interpretation of usual chemical methods to understand the role of the cover karst system.
The covered karst system of the Moulineaux spring is a key resource for the urban area of Perigueux (France) by ensuring the supply of drinking water to more than 60,000 inhabitants. It’s average flow rate is 820 L.s-1 and can range between 118 L.s-1 and 4 000 L.s-1. The karstic system is mostly covered by a thick semi-permeable layer of alternating marly limestone, alterite rocks and sediments dating from the Campanian period (Upper Cretaceous). Its sizeable catchment area spans more than 80 km² more than 50% of which is occupied by agricultural activities.
A year-long monitoring campaign of physical-chemical parameters has been conducted at the spring, complemented by periodic analyses of major chemical elements at several locations within the study area. A combined approach was used to analyze long-residence-time tracers such as magnesium and silica, natural markers of anthropogenic pollution such as nitrates, potassium, sulfates, pesticides, and short-residence-time tracers, including artificial tracers, dissolved organic carbon (DOC) measurements, physico-chemical parameters, and pCO2. The results were integrated into a conceptual model of the karst spring, highlighting the significant role of the semi-permeable cover in influencing groundwater quantity and quality. While this cover acts as a natural buffer and filter, anthropogenic markers revealed significant variations in water quality linked to the hydrological cycle.
How to cite: Jolly, M., Lorette, G., Peyraube, N., Lastennet, R., and Denis, A.: Assessing the impact of semi-permeable cover on karst with natural tracer and physico-chemical monitoring. Example of the Moulineaux spring (Dordogne, France), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17605, https://doi.org/10.5194/egusphere-egu25-17605, 2025.
Fontanili are peculiar lowland springs that occur in Northern Italy along the transition zone between the higher and lower Po plain (called the ‘‘fontanili line’’), where the phreatic table of alluvial shallow aquifer spontaneously or anthropically reaches the soil surface. These springs provide a variety of ecological benefits such as self-cleansing of water, stable water temperature and unique ecosystems. They are extremely important from an ecological and hydrogeological point of view, as well key indicators for the effects of climate change and anthropic influence on the shallow aquifer which directly supplies their discharge. Unfortunately, fontanili appear to be deteriorating or completely disappearing over time, so it’s important to determine the danger they are facing in order to enable authorities to monitor and manage them properly and observe relevant data that is certainly connected to climate change. Consequently, an assessment of the hydrogeological features of these springs and the shallow aquifer is also important.
This study is focused on a sector of the southern Turin Po Plain, in Piedmont (Italy) with data being collected during the year 2022, a record-breaking year for drought and heat in the area. Fontanili were mapped during the summer and autumn of 2022, revealing a total of 92 springs, most of which were revealed to be inactive and lacking water, with only 26 being active and only in autumn. The spring heads were grouped into 21 systems based on the primary canal that collected their waters. To analyse the features of the shallow aquifer, piezometric and hydrochemical studies were also conducted.
Piezometric level of the shallow aquifer appeared to have decreased in time and didn’t reach the surface. This situation created the conditions for the fontanili’s disappearance. From a hydrochemical point of view, groundwater samples belong to the calcium bicarbonate facies, while surface water samples belong to the calcium sulphide facies. Fontanili samples mostly appeared to have the same characteristics of well samples, confirming the springs are supplied by the shallow aquifer. Hydrochemical data appeared to be consistent with the previous literature with only four samples showing concentrations of nitrate or nitrite unsuitable for human consumption: this is connected to land use and agricultural practices, as these concentrations are higher in wells in the northern sector of the area, where activities are more intense. However, all the samples have excellent quality for agricultural when compared to the Sodium Adsorption Ratio Wilcox diagram.
The study shows that fontanili in the southern Turin Plain faced a critical situation in 2022 due to the decrease in piezometric level caused by climate change, alongside lack of maintenance and agricultural practices that contributed both to the overexploitation of the shallow aquifer and to the pollution of the water.
This study also aims to highlight how important preserving these precious resources is and how observing their evolution in time can help to mark the impact of climate phenomena that are being observed on a global scale.
How to cite: Franco, F. E., Lasagna, M., De Luca, D. A., Cocca, D., Egidio, E., and Minciardi, M. R.: Influence of Climate Change and Human Activity on Fontanili (Lowland Springs) and Shallow Aquifers in the Southern Turin Po Plain (Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-17879, https://doi.org/10.5194/egusphere-egu25-17879, 2025.
Water management must be defined within a coherent territorial unit. Marismas Nacionales, internationally recognized as a RAMSAR site, harbors one of the biosphere's most extensive mangrove systems. This region constitutes a regional discharge zone of Regional Groundwater Flow Systems, which provide the primary source of continental water sustaining the development of mangroves and their subsequent ecosystems and strategic environmental services.
However, the current polygon of the protected natural area excludes the recharge zones that generate the Regional Groundwater Flow Systems, essential for the subsistence of these internationally significant ecosystems. The proper understanding and development of Tóthian Theory is key to integrating the uniqueness and ubiquity of the hydrological cycle and its environmental dynamics, which, together with the mapping of Regional Groundwater Flow Systems and territorial management units, enables the identification of critical points in the water-territory unit. This information and knowledge are essential for developing Environmental Impact Assessment processes to: i) strengthen the identification of current and future relevant consequences and impacts; ii) adjust the polygon, or polygons, of the protected natural area; and iii) redesign conservation measures both within and outside its territorial boundaries, ensuring robust hydro(geo)logical environmental characterization and evaluation that poses the correct questions to the answers manifested in the landscape. Therefore, mapping Regional Groundwater Flow System zones is essential for redesigning the legal-administrative framework and directly implementing integrated water management in the territory that safeguards the regenerative capacity of water as a system.
How to cite: Kachadourian, A. and Carmona Lara, M. C.: "Convergence between Regional Groundwater Flow Systems and Territorial Units: Towards Integrated Water Management", EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7780, https://doi.org/10.5194/egusphere-egu25-7780, 2025.
Subsidence has become a critical issue in Mexico due to the intensive exploitation of groundwater resources. Understanding subsidence in the context of groundwater flow systems is vital for addressing the interaction between water flow patterns and land deformation, thereby improving resource management and preventing damage.
This study analyzed subsidence at a national level using tools such as satellite imagery and GNSS station data to identify and correlate the most affected areas. The evaluation incorporated groundwater flow systems, geological conditions (e.g., soil type, faults, and fractures), and hydrological factors (e.g., over-extraction and limited water availability) that accelerate subsidence.
The results include detailed maps prioritizing the most impacted areas, demonstrating a strong link between subsidence patterns and groundwater extraction. Twelve critical hydrogeological systems were identified, highlighting how local geological conditions and aquifer overexploitation exacerbate sinkholes, impacting ecosystems and infrastructure.
Additionally, predictive models were developed to simulate future subsidence scenarios based on current extraction trends and potential sustainable management strategies. These models provide valuable insights for optimizing water use and mitigating risks associated with subsidence and water stress.
This approach underscores the importance of integrating groundwater flow systems into water management policies to ensure sustainable resource use and minimize the adverse effects of subsidence.
How to cite: Jiménez, L., Escolero Fuentes, O., Olea Olea, S., and Medina Ortega, P.: Subsidence and sinkholes in Mexico's flow systems caused by intensive groundwater extraction, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2922, https://doi.org/10.5194/egusphere-egu25-2922, 2025.
The Yucatan Peninsula, situated in the Gulf of Mexico, is characterized by a unique karst topography that sustains groundwater-dependent ecosystems and holds significant archaeological sites of the Maya civilization. Despite its environmental and cultural importance, the region faces considerable challenges related to water quality. The karst landscape allows for easy infiltration of contaminants, while an extensive seawater wedge beneath the aquifer and the dissolution of gypsum from the Paleocene formations in the southern peninsula further limit the availability of freshwater. These factors complicate the provision of potable water, particularly in an area with insufficient sanitation infrastructure and a limited understanding of the aquifer system. This study offers the first detailed analysis of regional water quality trends in the Yucatan Peninsula, based on 1528 water quality samples collected from 1998 to 2022. Using pattern recognition of major ions along with dimensional reduction, network clustering, and traditional hydrogeochemical techniques, the study identifies key factors driving salinization across the region. Fourteen clusters were identified, linked to seawater intrusion, gypsum dissolution, widespread carbonate dissolution, and nitrate leaching. Approximately 23% of water samples from human-use sources exceeded acceptable sulfate and nitrate levels. The findings emphasize the critical need for ongoing water quality monitoring to inform future management strategies, particularly in the face of population growth, tourism, and climate change.
How to cite: Narvaez-Montoya, C., Mondragon-Bonilla, R., Goldscheider, N., and Mahlknecht, J.: Patterns of Groundwater Salinization in the Yucatan Peninsula: Insights into the Ancient Karstic Maya Aquifer, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-7622, https://doi.org/10.5194/egusphere-egu25-7622, 2025.
In the North German Basin, highly mineralised saline groundwaters are common below the Lower Oligocene Rupelian clay. The Rupelian Clay separates the Quaternary and Tertiary freshwater aquifer complex from the underlying saline aquifer complex and is of great importance for groundwater management. However, brackish groundwater influenced by deep saline water is found in the freshwater aquifer complex where the Rupelian Clay has been eroded. This is often the case above salt structures and along Pleistocene channels deeply cut into the underlying strata. As a result of this groundwater salinisation, various water utilities in the Berlin-Brandenburg region, including the Berlin water utility (Berliner Wasserbetriebe), were forced to reduce groundwater extraction volumes at certain locations or to abandon drinking water wells.
This study analyses the spatial and temporal variations of environmental isotopes (δ¹⁸O, δ²H, 14C and δ13C) and hydrochemistry (Cl-, Br-, HCO3- and DOC) in combination with a 3D geological model of stratigraphic units in the freshwater aquifer complex focusing on a waterworks with elevated saltwater intrusion risk in Berlin (Germany). Issues on the genesis and temporal dynamics of geogenic groundwater salinisation were addressed in the study.
A graphical method was employed to identify dominant geochemical processes and to produce a qualitative estimate of radiocarbon age using measured 14C and δ 13C and dissolved inorganic carbon (as hydrogen carbonate). The analyses indicate additional carbon input from ancient organic matter, which is more depleted in 13C than recent soil CO2. Radiocarbon dating revealed time scales of thousands to tens of thousands of years, depending on depth and geological conditions. The local meteoric water line (LMWL) and isotopic signatures (δ¹⁸O, δ²H) of hydrological half-years (winter/summer) were calculated using volume-weighted least squares from the local Global Network of Isotopes in Precipitation (GNIP) data station. The calculation of the hydrological half-year signatures proved to be particularly useful for the interpretation of regional flow and mixing processes. The half-year signatures allowed differentiation between samples influenced by bank filtrate and natural groundwater recharge. Stable isotopes in deep groundwater (>50 m below surface) samples showed light isotopic signatures indicating cold recharge conditions, e.g. during the Weichselian glacial period. Analysis of Cl/Br and DOC content revealed the geological units in which saltwater migration is dominant and where DOC dissolution occurs along the flow path. Together with isotopic measurements, literature research, numerical modelling and hydrochemical monitoring, an improved understanding of deep groundwater circulation and its implications for groundwater management in the freshwater aquifer complex has been developed. Although the spatial variability of elevated Cl concentrations due to saline upwelling in a well field is high, recommendations for the sustainable operation of saltwater-influenced well galleries were developed.
How to cite: Sprenger, C., Lorenzen, G., Baldwin, D., Sperlich, A., and Haacke, N.: Isotopic and Hydrochemical Analysis of Groundwater Salinization in Berlin: Implications for the management of salinity prone well fields, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-20099, https://doi.org/10.5194/egusphere-egu25-20099, 2025.
Submarine groundwater discharge (SGD) plays a crucial role in coastal ecosystems by influencing nutrient cycling, water quality, and biological productivity, while also serving as a vital freshwater resource for coastal populations. Hydrogeochemical assessments, particularly isotope tracers, are pivotal in identifying water sources and understanding hydrological processes. However, the applicability of radioactive isotopes is often limited due to their decay over time. Thus, stable isotopes of oxygen (δ18O) and hydrogen (δ2H) seem promising tracers for identifying and characterizing SGD in coastal regions. Leveraging these stable isotopes, this study focuses on investigating SGD along the Eastern Arabian Sea coastline for effective water management. Groundwater discharge through the coastline was assessed by analyzing groundwater, porewater, and seawater samples for their stable isotopic compositions. In situ measurements of electrical conductivity (EC) were also conducted to differentiate between fresh, brackish, and saline SGD. Results indicate that δ18O values range from -3.23 to -2.67 ‰ in groundwater and -1.99 to -0.01 ‰ in porewater, while δ2H ranges from -20.21 to -11.36 ‰ and -16.31 to -1.12 ‰, respectively. The analysis confirms the presence of SGD at multiple sites, while few locations exhibit isotopic signatures and EC consistent with sea water (δ18O: 0.15‰, δ2H: 1.07‰, 43.80 ms/cm), likely influenced by tidal or wave-induced pumping. The SGD zones identified by hydrogeochemical analysis were further validated by sea surface temperature anomalies detected through thermal infrared data along the coastline. The findings of this study will be useful in coastal zone management, coastal urban planning, and mitigating saltwater intrusion risks in coastal aquifers.
Keywords: Stable isotopes, Submarine groundwater discharge, Eastern Arabian Sea
How to cite: Keshariya, A. and Yadav, B. K.: Investigating submarine groundwater discharge (SGD) along the Eastern Arabian Sea coast using stable isotope tracers , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-868, https://doi.org/10.5194/egusphere-egu25-868, 2025.
Climate change can significantly impact on water resource, in terms of quality and quantity. In a changing world the climate can intensify the vulnerability of hydrogeological systems such as karst aquifers. The combination of long dry summers with the change in the trend of precipitation (characterized by few but very intense events) is expected to influence the storage of water that could intensely decrease with important consequences on potable water in mountain area. Also, the quality of water may change, water turbidity and water pollutants can increase.
The aim of this work is to better understand the behavior of a karst spring (Praondè) located in the province of Lecco, in the town of Civate. The purpose is to understand the behavior of the spring under different climate conditions for a better management of water resource. In the beginning, precipitation and temperature data, extrapolated from ARPA Lombardia, were analyzed to identify a specific climate trend in this area. Then, thanks to the collaboration with Lario Reti Holding S.p.A, discharge data of the spring were analyzed and paired with precipitation and temperature data.
From September 2023 different samples were collected at the spring and since the end of 2024 we started collecting precipitation samples. All the samples were collected to define the ratio of oxygen and deuterium isotopes. To describe the behavior of the spring, several parameters were detected. These parameters provide us with information on how fast the aquifer is draining and the level of vulnerability of the spring. The most important parameter detected is the depletion coefficient α (Maillet, 1905). The outcome of this analysis is important for trying to predict the possible behavior of the spring in extreme drought conditions.
The primary objective of this study is to enhance data quality by improving monitoring systems, thereby enabling more precise and effective management of water resources
How to cite: Rinaldi, N., Rossi Ronca, R., Ronchetti, F., Papini, M., and Longoni, L.: How climate change affect spring discharge and what we can do to improve water management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12418, https://doi.org/10.5194/egusphere-egu25-12418, 2025.
Mountain hydrology and hydrogeology in the European Alps have been impacted by climate change, land use modifications, and evolving water consumption patterns. These factors have affected drought and flood dynamics, evapotranspiration, snow-to-rainfall ratios, and spring recharge mechanisms, introducing new rainfall patterns linked to increased average air temperatures. Consequently, understanding balance fluctuations in alpine aquifers is critical for predicting future water availability in mountain regions.
This study investigates hydrogeological dynamics at the catchment scale through the analysis of selected mountain springs in the Aosta Valley Region (northwestern Italy), specifically Promise Spring (1580 m a.s.l.), and Entrebin Spring (981 m a.s.l.). Given the complexity of contextualizing spring behavior within a rapidly changing climatic framework, innovative methodologies are required for a more detailed characterization of the inputs feeding the aquifers. Fast Fourier Transform (FFT) analysis of hydrograph signals was applied to decompose environmental variables, enabling the identification of physical relationships between flow rate, temperature, and precipitation signals. Additionally, isotopic analyses of water samples, conducted according to V-SMOW2 standards, provided valuable insights into the origin and flow paths of groundwater recharge, leveraging the utility of Oxygen-18 and Deuterium for hydrogeological applications. The altitude of rainfall or snowfall deposition was subsequently determined using empirical relationships derived from the literature.
The integration of these two independent analysis techniques facilitated a comprehensive understanding of the nature and origin of water inputs feeding the springs. Moreover, the study elucidates the influence of climate change on the variability of spring discharge over both short- and long-term timescales. The findings contribute to a more detailed understanding of aquifer recharge dynamics and provide critical insights for the sustainable management of water resources in alpine regions. Their application to drinking water sources holds significant social implications, fostering more effective resource management strategies in the face of climate-sensitive variations.
How to cite: Gizzi, M. and Biamino, L.: Characterizing Recharge Dynamics of Mountain Springs in Aosta Valley (NW Italy): A Combined Harmonic and Isotopic Investigation, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6491, https://doi.org/10.5194/egusphere-egu25-6491, 2025.
Stable water isotopes are valuable tools to determine the flow pathways, and, when combined with other analyses, can provide insights into the hydrogeology in complex settings.
This study aims at determining the recharge and flow pathways processes of groundwater in an alpine stream basin, focusing on a spring characterized by exceptionally high discharge.
Montellina Spring is one of the drinkable water springs with the highest discharge in the Turin Province (Piedmont, NW Italy); its discharge varies between 50 and 180 L/s. It feeds the local water supply system and it is therefore necessary to identify and safeguard the recharge area. The spring is located at 380 m above sea level at the base of the Renanchio Stream Basin, on the low alpine Dora Baltea Valley. The peaks forming the watershed are at an altitude of 2000 m a.s.l., approximately. The aquifer feeding the spring consists of an eclogitic bedrock with limited layers of dolomitic marble, fissured due to deep-seated gravitational slope deformations (DSGSD), and is covered by thick layers of glacial sediments.
Surface water, groundwater and precipitation were sampled at several sites along the Renanchio Stream Basin (altitude of the sites: 380 to 1460 m a. s.l.), in different seasons during three sampling campaigns (autumn 2017, winter 2017-2018 and spring 2018). Chemical analyses of major ions and water stable isotopes (δ18O and δ2H) were evaluated, showing a bicarbonate alkaline-earth facies. Furthermore, waters referred to Montellina Springs are mostly enriched in major ions and in term of isotopic contents, similars to the Renanchio Stream, latter sampled at altitudes of up to at 1460 m a.s.l.
The similar isotopic content and the higher major ions content (especially Mg++, Ca++ and HCO3- due to the dissolution of bicarbonate minerals) indicate an important aquifer and a significant circulation in the bedrock interested by DSGSD and glacial sediments. Lastly, chemical and isotopic data suggested that the spring’s recharge area is located at elevations above 1500 m a.s.l., that the spring is partly feed by precipitation and inflow from the Renanchio Stream and that the DSGSD and glacial sediments play a fundamental role in the recharge of Montellina Spring.
The present work seeks to better highlight the hydrogeological context of the Renanchio Stream Basin and provide a new perspective on water resource research and safeguard in an alpine environment.
How to cite: Pigozzi, G., Lasagna, M., and De Luca, D. A.: Study of recharging dynamics of a spring in an alpine valley through isotopic and hydrogeochemical approaches: the Montellina Spring case study (NW Italy), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18073, https://doi.org/10.5194/egusphere-egu25-18073, 2025.
Surface water (SW) and groundwater (GW) are deeply interconnected and can vary according to different hydrologic conditions, including physical, chemical and biological variations. Understanding the nature and extent of involvement between SW and GW is particularly important under global change, where the alteration of freshwater cycles and transformation of natural landscapes has led to widespread ecosystem degradation, as well as issues regarding availability and quality of water resources.
Therefore, the present work aims to identify relevant hydrological pathways at a regional scale using a combined approach to study GW-SW interaction in western Mexico, considering hydrochemistry, stable isotopes of oxygen (18O) and hydrogen (2H), and statistical analysis.
Stable isotopes data showed SW undergoing evaporation and becoming enriched in heavy isotopes. Widespread drought showed lake water (LW) isotopes enriched beyond the isotopic range observed in precipitation samples. Spatial differences of LW δ2H and δ18O suggest precipitation and GW as sources for only one of the lakes. Lake samples also exhibited the largest variability, as well as the lowest d-excess values reported for SW samples. Among GW samples, wells showed the most variability and hot springs the least. Major ions data showed strong thermal influence on groundwater processes, related to both tectonic and volcanic processes developed in the region.
Environmental tracers, such as stable isotopes can help us understand complex SW-GW interactions at a broader scale. This is particularly true for arid and semi-arid areas were interactions are becoming more complex under the effects of human activity.
How to cite: Ramírez González, L., Olea Olea, S., Sánchez-Murillo, R., and Villanueva Estrada, R. E.: Understanding hydrologic connectivity of groundwater and surface water in western Mexico using chemistry and stable isotopes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2910, https://doi.org/10.5194/egusphere-egu25-2910, 2025.
The Cuitzeo Groundwater Flow System, located in central Mexico within a volcanic rock region, encompasses two of the largest lakes in the country, Lake Cuitzeo and Lake Pátzcuaro. These lakes are sustained by both surface water and groundwater discharges, playing a critical role in local ecosystems and the surrounding population.
Groundwater is particularly important for maintaining the lakes' existence. However, the behavior of the groundwater flow system in this region has not been described before.
This study compiles data from 170 groundwater sites within the system, collected during the years 1983, 1990, 1997, 1999, 2001, 2002, 2003, 2006, 2007, 2014, and 2015. The compiled parameters include temperature (T°C), pH, Total Dissolved Solids (TDS), and major ions (Ca2+, Mg2+, Na+, K+, SO42-, Cl-, HCO3-, CO32-, and NO3-). The compiled data were analyzed to study the historical behavior of the system, identify recharge and discharge zones, assess water-rock interaction processes, and trace the evolution of groundwater using hydrochemical diagrams such as Piper, Gibbs, and scatter plots.
The results highlight distinct chemical behaviors across the different zones of the study
area, with the most notable being ion exchange consistent with the weathering of volcanic silicates and interaction with lacustrine sediments. A key finding is the identification of a base-level discharge zone near Lake Cuitzeo. Water-rock interactions are the dominant process within the flow system, though some sites are influenced by precipitation and evaporation, and have a relation to the increased Lake Cuitzeo salinity that suggests a natural process of groundwater evolution within endorheic conditions.
This study is crucial as it offers valuable insights into the historical state of the groundwater flow system and highlights areas where additional data is needed to better understand its dynamics. For instance, the lack of data near Lake Pátzcuaro emphasizes the significance of this data compilation and underscores the need for further research in the region.
How to cite: Llanos Solis, A. G. and Olea Olea, S.: Hydrogeochemical characterization from historical data of the groundwater flow system in the center of Mexico, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-2925, https://doi.org/10.5194/egusphere-egu25-2925, 2025.
The transboundary water resources of the Lower Colorado River Basin necessitate robust and collaborative governance frameworks to address pressing challenges associated with drought conditions and escalating water demands in both the United States and Mexico. Recent Minutes (319, 323, and 330) under the 1944 Water Treaty between the United States and Mexico highlight the critical challenges related to water allocation from the Colorado River, exacerbated by prolonged droughts that have significantly impacted the Upper Basin in recent years. However, few of these Minutes integrate surface water and groundwater management as a core strategy for achieving sustainable resource use, despite the increasing strategic importance of groundwater as a vital supply source for various user groups and economic sectors. This study employs Gravity-Driven Groundwater Flow Systems Theory to analyze publicly available geospatial and environmental data, offering an indirect characterization of regional groundwater flow components. The approach leverages natural features and groundwater data to identify surface manifestations of regional groundwater systems, including recharge and discharge dynamics. The results include cartographic evidence that underscores the critical systemic interrelationship between groundwater and the natural environment, particularly in the context of anthropogenic impacts such as groundwater abstraction and land-use changes. Through environmental interpretation of hydrogeological indicators—including groundwater depth in wells, perennial surface water features, topographic relief, vegetation patterns, and soil characteristics—this study identifies regional recharge and discharge zones shared by Mexico and the United States. These zones illustrate the interconnected nature of transboundary groundwater and its reliance on cross-border collaboration for sustainable management. However, significant data gaps persist between the two nations, particularly in the standardization of methodologies for data collection, interpretation, and spatial coverage. The absence of a consistent and comprehensive framework for studying regional groundwater flows shared across the border underscores the need for enhanced binational coordination. This research emphasizes the necessity of integrating hydrological data and harmonizing policies to ensure equitable and sustainable water resource management in the Lower Colorado River Basin. Addressing these challenges through cooperative mechanisms will be critical for mitigating the impacts of superficial water scarcity and securing the long-term sustainability of shared transboundary water resources.
How to cite: Abud Russell, Y. and Hatch Kuri, G.: Surface manifestations of regional groundwater flow systems in the Lower Colorado River Basin. Environmental understanding and management opportunities for a transboundary basin., EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11814, https://doi.org/10.5194/egusphere-egu25-11814, 2025.
Posters on site: Tue, 29 Apr, 08:30–10:15 | Hall A
The Mediterranean basin is particularly vulnerable to climate change. These changes lead to disruptions in the hydrological cycle, potentially impacting groundwater resources and recharge. The hydrogeological catchment of the Lez karst Spring, located south of France north of Montpellier city is actively used to supply Montpellier Mediterranée Métropole (MMM), with drinking water. This study aims to assess the long-term hydroclimatic changes over the hydrogeological basin of the Lez Spring with an approach combining climatic and hydrological analyses. The main objective of this research is to assess eventual long-term trends in the climatic (rainfall, temperature, potential evapotranspiration, soil moisture) and hydrological variables (piezometric levels, spring and river flows); a focus on the interrelationship between these different parameters is also performed to understand the hydroclimatic trend and temporal evolution of this highly anthropized aquifer. The analysis combines measurements of local soil and hydrogeological variables, with longer time series of meteorological observations and the French climate reanalysis SAFRAN since 1960, and the high-resolution COMEPHORE radar rainfall product since 2000 providing hourly rainfall intensities at the kilometric scale to investigate the spatial dynamics of rainfall. The trend analysis results indicated a strong increase of temperature but no significant changes in precipitation totals from the different datasets. However, a positive trend in annual maximum hourly rainfall intensities was detected, associated with an increased spatial variability of rainfall fields and flashiness characteristics. There is a sharp increase of potential evapotranspiration, associated with a decline in soil water content throughout the year. The piezometric levels do not exhibit significant trends since 2007, similarly to the water uptake for the consumption of the city of Montpellier. The combination of the different high-resolution datasets allows a deepened analysis of the relative effects of the contribution of extreme rainfall events and the spatiotemporal variability of rainfall patterns on the recharge processes of the aquifer. This study will ultimately provide the keys to more sustainable management of the karst water resource for drinking water supply in the face of climate change, through a better understanding of the functioning of the Lez spring Hydrogeological catchment.
How to cite: Fabre, E., Jourde, H., Tramblay, Y., Brunet, P., Madziarski, A., Bottet, F., and Kong A Siou, L.: Long term changes in hydrometeorological controls on water recharge in a karstic Mediterranean basin, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-6591, https://doi.org/10.5194/egusphere-egu25-6591, 2025.
In February 2022, the siderite mine in Nižná Slaná (Slovakia) was flooded. Because of this accident, mine water with an enormously high content of iron, manganese, arsenic, nickel and sulfates began to flow into the Slaná River and ferrous ocher with a high content of arsenic was precipitated. It caused intense turbidity of water and deterioration of the ecological status of the Slaná River.
For representative assessment of the impact of this accident on groundwater quality, the results of groundwater quality monitoring in 18 sampling sites (groundwater wells) of the State Hydrological Network were assessed for selected determinants (iron, manganese, arsenic, antimony and nickel), which could have impact on the deterioration of the groundwater status in the interested area. The area where the contamination impact was investigated was the area from the Nižná Slaná River to the state border with Hungary.
The assessment was based on long-term results of groundwater quality monitoring since 2000. We focused mainly on assessment of quality change in 9 sampling sites located directly in alluvial sediments of the Slaná River.
From the total number of 7,587 measurements since 2000, the worst groundwater quality was in Betliar, where the highest concentrations of manganese, iron and arsenic were measured. However, we should note, that in comparison with the previous monitoring period of sites in alluvial sediments of the Slaná River, above – limit concentrations were repeatedly determined even in the period before the accident of the siderite mine in Nižná Slaná.
Despite the results of the monitoring so far, there is still a risk of pollution caused by the flooding of the former siderite mine, and it is therefore necessary to continue to pay increased attention to this area and further monitoring of the impact of pollution of the Slaná River on groundwater quality.
How to cite: Molnárová, A., Ľuptáková, A., and Urbancová, J.: Assessment of the Slaná River contamination impact on groundwater quality, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9448, https://doi.org/10.5194/egusphere-egu25-9448, 2025.
Deep groundwater aquifers offer a high-quality drinking water supply and serve as a vital reserve in emergencies because no prior treatment is required. However, considering its slow replenishment, deep groundwater in its original hydrochemical composition, and age structure has to be considered as a finite resource. At the same time its extraction alters both the hydraulic and hydrochemical dynamics of the aquifer. Ensuring the long-term availability and protection of mineral water necessitates sustainable management practices to prevent depletion of the reservoir or "mineral water mining".
This study aims to develop concepts determining the sustainable yield of mineral water, using time-series of the hydrochemical signature and persistent organic trace substances. Together with production data this concept elucidates the flow paths in the deeper aquifer and the availability of the mineral water resource. The different approaches are discussed and illustrated using a deep groundwater aquifer that has been used for bottled water production since the early 1900s. Following the stop of the production in 2020 we observed a rather rapid increase of the hydraulic potential and a slower decrease of persistant trace chemicals. The concentration of dissolves solids recovered faster for the deeper wells compared to the more shallow wells. The hydrochemical signature reveals a change in the ion ratios which can be attributed to changing mixing ratios in the groundwater wells.
The unique data collected before and after the shut-down of the operation suggests that the mineral water, in its original composition has been depleted in the shallow parts of the stratified fracture aquifer. The concepts developed in this study would have suggested a lower limit to the extraction rates and volumes to sustain the operation.
How to cite: Hegels, M. and Baumann, T.: Safe yield of deep groundwater aquifers - a case study from mineral water production, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-9760, https://doi.org/10.5194/egusphere-egu25-9760, 2025.
The preservation of good chemical and quantitative status of a groundwater resource requires a detailed management plan that needs to account for the site-specific hydrological and hydrogeological settings and the utilization of the groundwater resource. Management plans are particularly crucial in areas with a complex surface water-groundwater interaction or an unevenly distributed exploitation of the resource.
This research aims to reconstruct the hydrogeological setting of the Baranja region (NE Croatia; area of 1,172 km2) extending between the Drava River to the S and W and the Danube River to the E. Effective water resource management is crucial in Baranja. The steady growth of tourism capacities (33% increase in last 5 years), particularly in rural tourism and the Nature Park Kopački rit, drives increasing demand for water. The Nature Park Kopački rit holds particular natural and touristic value since it hosts a rich swamp ecosystem along the backwaters and ponds of the Danube and Drava rivers that strictly depend on the surface water-groundwater interaction. In addition, the agriculture industry in the region is well developed with several farms feeding one of the biggest food industry in Croatia. Despite the natural and economic appeal, the population density in Baranja is low with the inhabitants concentrated in a few settlements. The water supply system is fed by 3 well fields with a few active wells reaching a depth of 40-60 m and providing a total of 40-50 L/s. Farms and many small activities use local wells that provide water for different industrial uses. Surface water flow of rivers and main canals is regulated by several pumping stations. These conditions result in an unevenly distributed anthropic pressure on the surface water-groundwater system that could cause localized overexploitation or pollution.
Hydrogeological investigations in Baranja have been mostly conducted in the main well fields. This research includes the regional hydrogeological mapping of the aquifer system and the continuous monitoring of the groundwater level and its physico-chemical parameters. Currently, stratigraphic logs from different sources and results of well testings have been collected and digitalized in a geodatabase that contains approximately 200 wells and exploration boreholes. These data will permit to develop a 3D reconstruction of the hydrogeological setting and to plan both a continuous monitoring of the water level and a periodic sampling of the groundwater. The obtained results will represent key inputs for a comprehensive understanding of the surface water and groundwater interaction and their utilization, the reconstruction of the main geochemical processes in the aquifer, and a sustainable groundwater management.
Acknowledgment: This research was conducted in the scope of the internal research project BAKA 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, and the and the PACT-VIRA project of the Croatian Science Foundation, grant number IP-2024-05-9190.
How to cite: Urumović, K., Pola, M., Copić, M., Patekar, M., Karlović, I., Borović, S., Terzić, J., Kordić, B., and Marković Vukadin, I.: Hydrogeological reconstruction of Baranja region (NE Croatia) as a key input for sustainable water management, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10074, https://doi.org/10.5194/egusphere-egu25-10074, 2025.
Groundwater resources are fully allocated in many coastal aquifers in New Zealand. External forces such as a reduction in recharge and climate change add additional pressure for a sustainable management of the resource. Groundwater levels in the unconfined Wairau Aquifer (Marlborough, New Zealand) have been declining for decades due to both natural and human-made reasons and are superimposed by strong seasonal variability and increasingly also climate-change effects. Groundwater is abstracted mainly for irrigation (viticulture) but also for municipal and industrial uses. There are growing concerns that current management limits and thresholds in the regional water plan are not sustainable.
A detailed 3D surface water-groundwater flow model (MODFLOW) is used to investigate the effect of different groundwater allocation scenarios on groundwater storage and the flow of low-land springs which possess high cultural and recreational values for the community. An earlier version of the model (Wöhling et al. 2018, Groundwater, doi:10.1111/gwat.12625) has been recently extended and updated with an improved conceptualization. The regional-scale model was calibrated using 2.5 years of data and evaluated on more than 20 years which include two major flood events (18/07/2021 & 21/8/2022) that rank among the highest on record. Uncertainty of model simulations are estimated using Null-Space Monte Carlo simulations. The regional-scale model performs well with respect to observed groundwater heads, spring flows and river-groundwater exchange flows and generally agrees well to the data, even for the flood events in 2021 and 2022.
Current groundwater management regulations are cut-off limits at four goundwater observation wells and at a major spring as well as a total abstraction volume of 73 million m³ per year. Under current conditions, groundwater abstraction for irrigation can vary widely between years, while industrial and municipal water demands remain relatively constant. The actual groundwater abstraction is on average only 30% of the permitted annual allocation limit. However, the cut-off limits for groundwater levels and spring flows have been approached and exceeded frequently in recent years. This occurs in the summer months, when irrigation demand is high and river recharge and groundwater storage are on a seasonal low.
The simulations show a strong impact of irrigation water takes on groundwater depletion in summer. Compared to current conditions, a scenario with the full permitted annual abstration leads to significantly lower groundwater levels, aquifer storage and spring flows which would lead to continuous cut-offs given current regulations in the regional management plan. Under past climatic conditions, a strong increase in carry-over effects of storage depletion to consecutive years is not evident. But it has been shown previously that prolonged summer low-flow periods lead to low groundwater storage that may take several wet years to recover.
The scenario simulations suggest that the hard cut-off levels in the current management plan are not suitable for the future groundwater mangement of the Wairau Aquifer. A lowering of the annual allocation limit for irrigation to 20-25 M m³/a seems appropriate for the near-future and would not impose severe restrictions on farmers under current land-use practice.
How to cite: Wöhling, T., Kraft, M., and Davidson, P.: Groundwater management under instationarity: scenario simulations for the Wairau Aquifer, New Zealand, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-10996, https://doi.org/10.5194/egusphere-egu25-10996, 2025.
Understanding geochemical dynamics and salinity patterns in aquifer systems of endorheic basins is crucial for water resource management in arid and semi-arid climates. These environments, often characterized by intense agriculture and limited water availability, face significant challenges due to water scarcity and elevated groundwater salinity. This study investigates the geochemical processes shaping salinity patterns in interconnected shallow and deep aquifers within a structurally complex endorheic basin. A comprehensive dataset of groundwater samples from 213 wells across two aquifer systems in Bahira, central Morocco, was analysed for major ions and stable isotopes. Known for agriculture, Bahira faces notable issues of water scarcity and high groundwater salinity. The results highlight contrasting salinity levels, with the shallow aquifer exhibiting extreme salinity (EC up to 60,000 µS/cm) due to enhanced evaporation and soil leaching, whereas the deep aquifer maintains relatively lower EC values (500 to 3,000 μS/cm). Spatial analysis reveals a west-to-east salinity gradient driven by recharge variability and hydrogeological connectivity. Geochemical data underline the critical role of water-rock interactions, gypsum dissolution, and ion exchange in controlling salinity. Stable isotope analyses corroborate these findings, demonstrating evaporative enrichment and distinguishing between local recharge sources for the shallow aquifer and regional contributions from high-altitude precipitation in the deep aquifer. These insights enhance understanding of the hydrogeochemical dynamics in endorheic basins, emphasizing the interplay of climatic, geological, and anthropogenic factors in shaping groundwater quality. The findings offer broader implications for sustainable water management in similar arid environments worldwide.
How to cite: El-Azhari, A., Ait Brahim, Y., Barbecot, F., Hssaisoune, M., Berrouch, H., Hadri, A., Laamrani, A., Brouziyne, Y., and Bouchaou, L.: Contrasting Salinity Patterns and Spatiotemporal Groundwater Dynamics in Complex Endorheic Aquifer Systems: Insights from Chemical and Isotopic Tracers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11089, https://doi.org/10.5194/egusphere-egu25-11089, 2025.
The global water crisis, amplified by climate change, illustrates the pressing need for sustainable groundwater management, especially in semi-arid regions where water resources are under severe depletion.
In Zaghouan region of northern Tunisia, groundwater overexploitation, degradation of water quality (notably due to nitrate pollution and salinization), and the effects of climatic change are all threats to human livelihoods and ecosystems. Groundwater is the region's main source of water, provide drinking water, they are also essential for agricultural and socioeconomic development. However, insufficient surface water supply, harsh weather conditions, and high evaporation rates are all factors that compromise its long-term sustainability.
This study relies on a multidisciplinary approach, integrating geology, lithostratigraphy, hydrology, hydrogeology, and environmental tracers (major ions, noble gases, and isotopes: δ¹⁸O, δ²H, ³H, ¹⁴C, δ¹³C, δ¹⁸O-NO₃, and δ¹⁵N-NO₃) to investigate the dynamics of three key aquifers: the Jurassic limestones of Djebel Zaghouan and the Mio-Plio-Quaternary aquifers of the Sminja and Oued Rmel plains.
Groundwater samples were taken during three major campaigns: (1) October-November 2023, concentrating on major ions, stable isotopes, and tritium; (2) February-June 2024, targeting noble gases and radiocarbon (¹⁴C/¹³C); and (3) November 2024, assessing major ions, organic contaminants and nitrate isotopes. Preliminary findings shows that waters are classified into three types based on their chemical facies (sodium chloride, calcium sulfate chloride, and a mix between these two endmembers). Some of the samples exhibit chloride concentrations up to 8 g/l and sulfate concentrations up to 5 g/l. Furthermore, nitrate contamination is present in 25% of samples, and five samples exceed 100 mg/l.).
Occurrence of organic contaminants testifies to the general degradation of water resources quality caused by wastewater and the use of pesticides in the agricultural sector.
Stable isotope analysis identifies two different groundwater groups. The first group is isotopically aligned with local precipitation, indicating direct recharge processes. It is found mostly in deep and shallow wells in all aquifers. The second group shows isotopic signatures indicative of evaporation. It is found in shallow wells (depth < 20m). Most samples have tritium values above 0.5 TU, indicating that the aquifers have been recently recharged. Ongoing noble gas analyses will refine recharge estimates, including the determination of groundwater age using T-He.
This research advances our knowledge of semi-arid groundwater flow patterns and offers practical advice for integrated groundwater management. The case study of the Zaghouan region offers valuable insights that can effectively address the challenges posed by climate change and human impact.
How to cite: Jarraya, A.: A multidisciplinary approach for sustainable groundwater management in a semi-arid region: A case study in Zaghouan region (northern Tunisia), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11596, https://doi.org/10.5194/egusphere-egu25-11596, 2025.
Groundwater resources on volcanic islands are vital for societal and economic development, especially due to their scarcity and reliance on agriculture and tourism. This study examines the hydrogeological and hydrochemical processes shaping groundwater quality in volcanic islands, focusing on El Hierro Island (Canary Islands, Spain). The findings reveal that volcanic dykes play a critical role in controlling groundwater flow, creating freshwater reservoirs, and influencing flow paths. Four primary processes affecting groundwater quality are identified: seawater intrusion, volcanic CO₂ emissions, nitrate contamination from fertilizers, and CO₂-driven water-rock interactions. A 3D groundwater flow model shows that the anisotropy in hydraulic conductivity induced by volcanic dykes reduces seawater intrusion in specific areas, thereby enhancing groundwater quality. Volcanic CO₂ emissions are found to lower pH, increasing acidity and altering groundwater chemistry. CO₂-driven water-rock interactions result in the dissolution of basaltic minerals, raising concentrations of key rock-forming elements such as sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), and silica (SiO₂) in groundwater. Additionally, nitrate pollution is linked to fertilizer use, particularly in agricultural regions. These insights highlight the need for sustainable water management to address the challenges posed by salinization, pollution, and volcanic activity. This research not only advances understanding of El Hierro's groundwater system but also offers a framework applicable to other volcanic islands with similar hydrogeological conditions, supporting improved management strategies for freshwater resources.
How to cite: Marazuela, M. A., Jiménez, J., Baquedano, C., Martínez-León, J., Gasco-Cavero, S., Cruz-Pérez, N., Santamarta, J. C., and García-Gil, A.: Exploring Groundwater Quality in Volcanic Islands: Lessons from El Hierro (Canary Islands, Spain), EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-12959, https://doi.org/10.5194/egusphere-egu25-12959, 2025.
Keywords: Karst aquifer, drought, Tanour and Rasoun springs, Jordan
Due to limited precipitation and water resources, Jordan mainly depends on groundwater resources to address water scarcity challenges. This puts tremendous pressure on groundwater resources that increased due to population growth, droughts, and the effects of climate change. In Jordan, there are more than 800 springs. The most important springs emerge from karst aquifers, where some larger share of recharge is facilitated via inflow into karst surface features, concomitant with a generally higher risk to pollution due to mobilization of pollutants in the course of extreme events.
Tanour and Rasoun karst springs are among the most important karst springs in Jordan. The springs that discharge from upper Cretaceous limestones, are located in the northern part of Jordan and served as the main local water supply for surrounding villages.
The main challenge in developing a drought early warning system for karst springs is the application to sparsely gauged karst aquifer catchments, such as Tanour and Rasoun Springs. To meet this challenge we performed further measurements on spring-water hydrological and physico-chemical variables, along with projection of drought indicators recently employed for an adjacent karst aquifers with higher data availability.
Records for different parameters in Tanour Spring were monitored, on an hourly basis, since 2014 (i.e. Water temperature (c°), Conductivity (ms/cm), Salinity (sal), TDS (g/l), Density (g/l), pH, Oxygen content (mg/l), Oxygen saturation (%), Turbidity (NTU), TSS (g/l), and Flow (m3/h) (the flow pressure probe has discontinuity in measurements due to some physical problems in the probe). Moreover, offline probes were installed in the Rasoun Spring to monitor water temperature and electrical conductivity.
The long-term monitored data is used to develop an integrated method to determine groundwater recharge and predict droughts in the karst aquifers to support water management in this semi-arid region.
How to cite: Hamdan, I., Kavousi, A., and Sauter, M.: Development of a process-based method to predict droughts in karst aquifers- A case study of Tanour and Rasoun springs, North of Jordan, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-13967, https://doi.org/10.5194/egusphere-egu25-13967, 2025.
Eutrophic shallow lakes are hotspots of carbon (C) and nitrogen (N) accumulation and transformation, and are increasingly recognized as important sources of greenhouse gases (GHGs: CO2, CH4 and N2O). Lacustrine groundwater discharge (LGD) is a crucial component of the water budget and terrestrial material delivery for lakes, but its interplays with intrinsic C-N biogeochemical processes remain less tackled. In this study, C and N ingredients and multiple stable isotopes (δ2H, δ18O, δ13C, and δ15N) were measured seasonally in groundwater, river water and lake water of a large eutrophic shallow lake in eastern China. The results revealed that groundwater is enriched with various forms of C and N that have similar sources and pathways as surface water in lake and rivers. The isotope balance model also indicated that LGD-derived C and N contribute significantly to lake inventories in addition to river runoff. These allochthonous C and N provide extra substrates for related biogeochemical processes, such as algae proliferation, organic matter degradation, methanogenesis and denitrification. Simultaneously, the excess oxygen consumption leads to depletion and hypoxia in the lake, further facilitating the processes of methanogenesis and denitrification. LGD functions not only as an external source of C and N that directly increases GHG saturations, but also as a mediator of internal C-N pathways, which significantly affect hypoxia formation, GHG productions and emissions in the eutrophic lake. This study highlights the unrevealed potential regulation of LGD on biogeochemical processes in the eutrophic lake, and underscores the need for its consideration in environmental and ecological studies of lakes both regionally and globally.
How to cite: Shi, X., Luo, X., Jiao, J. J., Zuo, J., Kuang, X., and Zhou, J.: Regulatory effects of lacustrine groundwater discharge-derived carbon and nitrogen on biogeochemical processes in a large shallow eutrophic lake, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-14467, https://doi.org/10.5194/egusphere-egu25-14467, 2025.
Water tunnels play a crucial role in managing groundwater resources on volcanic islands, where freshwater availability is limited and highly sensitive to climate change impacts. However, hydraulic interferences between water tunnels and surrounding aquifers often lead to unintended drawdowns, reduced efficiency in water resource utilization, and ecological disturbances. Addressing these challenges is essential to enhance the resilience of critical water infrastructure, particularly in regions like the Macaronesian islands, which are the focus of the GENESIS project.
This study explores the strategic installation of artificial bulkheads within water tunnels, restoring existing geological hydraulic barriers to mitigate three-dimensional hydraulic interferences. By integrating these engineered solutions with nature-based approaches, it is possible to regulate groundwater flow, minimize hydraulic connectivity, and protect aquifers from saltwater intrusion. Hydrogeological modeling and geotechnical analysis were employed to assess the performance of this approach under various operational and climatic scenarios.
The results demonstrate that the implementation of these devices significantly reduces hydraulic interferences, stabilizes aquifer drawdowns, and improves the efficiency of water capture and storage. Furthermore, these solutions enhance the resilience of groundwater systems to external stressors, including over-extraction, seasonal variability, and the impacts of extreme climatic events such as droughts and floods.
This work aligns with the GENESIS project's mission to develop geologically enhanced nature-based solutions (NbS) for climate-resilient water management in the Macaronesian biogeographical region. By harmonizing engineering and natural systems, this methodology provides a replicable framework for securing freshwater resources on volcanic islands and other vulnerable regions in the EU, ensuring sustainable socio-economic and ecological development in the face of climate change.
How to cite: García-Gil, A., Martínez-León, J., Sariago, R., Baquedano, C., Jimenez, J., Gasco, S. G., Meixueiro Ríos, G., Marazuela, M. Á., Hernández Ríos, I., Coello Bravo, J. J., and Santamarta, J. C.: Reducing 3D Hydraulic Interferences in Water Tunnels through the Strategic Installation of Artificial Bulkheads in Geological Hydraulic Barriers, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15289, https://doi.org/10.5194/egusphere-egu25-15289, 2025.
Seawater intrusion (SWI) poses a significant threat to groundwater preservation in coastal aquifers. Understanding the mechanisms driving SWI and determining key hydrogeological parameters are essential for developing effective preservation and mitigation strategies. Tidal Methods provide a validated technique for determining these parameters when variations in sea level and aquifer piezometric head are available.
Despite the widespread application of Tidal Methods and the availability of various solutions based on aquifer conceptual models, significant gaps remain. Key challenges include reliably extracting tidal oscillations from raw monitoring signals and determining the optimal duration of data series for analysis.
This study examines the Neretva Valley in southeastern Croatia, a significant agricultural area near the Adriatic Sea, as a case study for the application of Tidal Methods. A monitoring system has been set up to capture the transient dynamics of SWI in situ.
This research expands upon prior studies in the Neretva Valley by examining tidal oscillations during dry and rainy periods—characterized by substantial precipitation and discharge—and investigating the influence of time series duration on the determination of hydrogeological parameters.
Key findings indicate that the diffusivity values of the deep restricted aquifer exhibit considerable variation between dry and rainy periods when determined using same methodology. The duration of the investigated time series strongly impacts the accuracy of hydrogeological parameter determinations. The hydrogeological values acquired during dry periods via Tidal Methods nearly correspond with those determined with geophysical investigation. These findings enhance comprehension of SWI processes and offer significant insights to improve Tidal Method applications in aquifer management.
How to cite: Lovrinovic, I.: Optimizing Tidal Methods for Determination of Hydrogeological Parameters: Lessons from the Neretva Valley, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18714, https://doi.org/10.5194/egusphere-egu25-18714, 2025.
Effective decision-making in urban water management requires integrating outputs from specialized models. Berlin’s drinking water supply relies on induced bank filtration and managed aquifer recharge from the Spree and Havel rivers. However, river inflows into Berlin are declining -e.g., in summer 2019, the Spree’s inflow was half that of an average dry summer year- and are expected to decrease further over the next decade due to the ending of coal sump water discharge into the Spree. Long-term impacts from climate change are anticipated to exacerbate this trend. Additionally, an analysis of streamflow data and bank filtrate rate-corrected groundwater extraction has identified regions where maximum monthly extractions from drinking water wells already exceed the lowest monthly river flows in Berlin. This imbalance, combined with increasing water demand driven by population growth, leads to a higher proportion of treated wastewater in Berlin’s streams. As a result, risks to drinking water quality intensify, and the complexity and costs of water and wastewater treatment escalate. Furthermore, higher extraction levels are associated with increased bank filtrate fractions, amplifying system stress and emphasizing the need for sustainable water management practices.
In collaboration with the Belin Waterworks (Berliner Wasserbetriebe), we applied a well-calibrated FEFLOW© model of the Berlin-Friedrichshagen waterworks to simulate bank filtrate rates under various recharge and groundwater extraction scenarios. The model was run under three historical well configurations (2010, 2015, and 2019) and then well pumping rates were adjusted in the same relative configuration under three groundwater recharge scenarios. A review of prior investigations revealed groups of well galleries exhibiting similar changes in bank filtrate fractions in response to extraction levels; our results complement these former investigations.
Bank filtrate behavior across well galleries was found to depend on several factors, including well depth, distance to the riverbanks, the presence of opposing riverbanks, and regional groundwater heads. Relating bank filtrate change groups to site characteristics and bank filtrate fractions in other Berlin develops a city-wide understanding of changes in bank filtrate. Future FEFLOW© modeling scenarios, including commissioning and decommissioning of well galleries, and implementing managed aquifer recharge will be essential to address remaining uncertainties.
Outputs from this modeling effort contribute to regional dynamic water balance modeling for Berlin’s semi-closed water cycle in order to support sustainable water management decision-making amid evolving climatic and regulatory challenges.
How to cite: Baldwin, D., Haacke, N., Sprenger, C., Wicke, D., Monninkhoff, B., and Gnirss, R.: Simulating Bank Filtrate Dynamics in Berlin: Decision Support Under Climate and Water Use Changes, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18738, https://doi.org/10.5194/egusphere-egu25-18738, 2025.
Nitrates are naturally occurring molecules in the environment, but their concentrations have become increasingly concerning due to agricultural activities. This is partially due to the widespread use of nitrogen fertilizers and manure, which convert to nitrates, significantly decreasing groundwater quality. This issue prompted the European Union to introduce the “European Nitrate Directive” in 1991, setting a nitrate concentration limit of 50 mg/L in groundwater. Spatial and temporal data on annual nitrate concentrations were collected across the Veneto region by the Regional Environmental Agency over a 20-year period (2003-2023). Understanding groundwater hydrology and retention times is essential to evaluate whether the measures implemented by EU member states are improving water quality. This study focused on the sub-region of Veneto plain to the east of the Brenta river extending from the pre-Alpine foothills to the Venice Lagoon characterized by unconfined aquifers and a multi-aquifer system. For the multi-aquifer system, accurately defining the depth and extent of each layer was crucial to constructing an accurate model to describe the fate of nitrates in groundwater. In the study area, data from more approximately 800 boreholes were analyzed to define the subsoil stratigraphy accurately. However, data discrepancies were occasionally observed, making a detailed analysis and reorganization of the dataset essential to achieve representative results. To further investigare subsurface dynamics, isotope analyses provided insights into water retention times and groundwater flow. Isotopes such as 18O, 3H, 3He/4He, Ne, 14C , 13C and 87Sr/86Sr quantified in the 1970s and 2000s proved particularly valuable in the understanding the hydrodynamics of the subsurface domain of interest.
How to cite: Fabrello, L., Lewis, E., Lazzaro, B., Teatini, P., and Morari, F.: Assessing Nitrate Concentration and Groundwater Hydrodynamics in Veneto Region : A Multi-Decade Analysis Using Spatial, Stratigraphic, and Isotopic Approaches , EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-18787, https://doi.org/10.5194/egusphere-egu25-18787, 2025.
Posters virtual: Mon, 28 Apr, 14:00–15:45 | vPoster spot A
EGU25-4251 | ECS | Posters virtual | VPS8
Optimization of groundwater pumping rates using meshless simulation-based optimization modelMon, 28 Apr, 14:00–15:45 (CEST) | vPA.9
Recent water demands have created immense stress on groundwater, especially in the region facing water scarcity. Hence, optimizing groundwater pumping and developing sustainable water management strategies becomes important for such areas. The traditional mesh-based methods, such as finite difference (FDM) and finite element methods (FEM) for groundwater modelling requires high-quality mesh generation. In these methods, generating a high-quality mesh for complex aquifers is a time-consuming task. Therefore, meshless methods that work with scattered field nodes and avoid mesh generation are more suitable for complex groundwater problems. The present study uses the meshless generalized finite difference method (GFDM) for modelling the groundwater flow and integrating it with particle swarm optimization (PSO) to determine the optimal pumping rates for a hypothetical aquifer system. In this work, optimal pumping rates for different groundwater withdrawal scenarios are obtained through the proposed meshless simulation-based optimization model (GFDM-PSO), indicating its application to real-world problems.
How to cite: Singh, K. G. and Pathania, T.: Optimization of groundwater pumping rates using meshless simulation-based optimization model, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-4251, https://doi.org/10.5194/egusphere-egu25-4251, 2025.
EGU25-15495 | ECS | Posters virtual | VPS8
Are baseflow separation methods suitable for assessing shallow alluvial aquifers’ contribution to streamflow?Mon, 28 Apr, 14:00–15:45 (CEST) | vPA.10
Currently, climate change and increasing water demand pose a growing threat to the future availability of water for human societies and ecosystems that depend on it. At the same time, growing evidence suggests that groundwater is playing an increasingly active role in the global water cycle, particularly in sustaining river flows worldwide (Xie et al., 2024). In this context, quantifying the water exchange between these two components of the hydrological cycle becomes essential for an integrated assessment of water availability. For this purpose, baseflow separation methods are valuable tools, though their limitations remain a subject of debate.
Several authors have suggested that commonly used baseflow separation methods should be applied with caution, since these methods often produce large estimation errors, when they are compared with results obtained using three-dimensional flow numerical models (hereafter referred to as 3D models), thereby limiting their applicability. Nevertheless, these methods remain a widely used alternative due to their lower data and resource requirements compared to 3D models. To address these limitations, we proposed a novel methodology based on baseflow separation methods for analysing the interactions between a shallow alluvial aquifer system and the overlying river network. Subsequently, we tested its performance against a 3D model.
The study area is the alluvial aquifer system located at the confluence of the Tarn, Aveyron and Garonne rivers. A 3D model was developed using the BRGM’s MARTHE software. The study area was divided into sub-zones that meet the same isolation conditions for the river network delimited for the analysis of the results to ensure a more robust validation. Time series of flow and cumulative volume for components of the water balance in the river network, as well as flow at gauging points, were analysed. Additionally, different integration periods (quarterly, half-yearly, annual, and biannual) were examined. Several baseflow separation methods were tested, including both digital filtering and graphical methods.
The results showed that the methods proposed by Chapman (1991) and Chapman and Maxwell (1996) consistently outperformed all others across the entire study area and for all integration periods. R² coefficients of determination greater than 0.8 were obtained in both cases for integration periods exceeding six months. Notably, shorter integration periods better captured the temporal variation of water exchange between the aquifer and the river network. However, longer integration periods produced more accurate overall results, likely because the filters struggled to capture flow reversals between the aquifer and river network during flood events.
Acknowledgments: Authors acknowledge the funding provided by project WaMA-WaDiT (PCI2024-153483) funded by MICIU /AEI /10.13039/501100011033/ UE
References
Chapman, T. G. (1991). Evaluation of automated techniques for base flow and recession analyses. Water Resources Research, 27(7), 1783–1784. https://doi.org/10.1029/91WR01007
Chapman, T. G., & Maxwell, A. I. (1996). Baseflow separation: Comparison of numerical methods with tracer experiments. Paper presented at the Hydrology and Water Resources Symposium: Water and the Environment, Institution of Engineers, Australia.
Xie, J., Liu, X., Jasechko, S., et al. (2024). Majority of global river flow sustained by groundwater. Nature Geoscience, 17, 770–777. https://doi.org/10.1038/s41561-024-01483-5
How to cite: García Montealegre, J. P., Caballero, Y., and Del Jesus Peñil, M.: Are baseflow separation methods suitable for assessing shallow alluvial aquifers’ contribution to streamflow?, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-15495, https://doi.org/10.5194/egusphere-egu25-15495, 2025.
