HS8.2.3 | The role of groundwater flow systems in solving water management and environmental problems
EDI
The role of groundwater flow systems in solving water management and environmental problems
Convener: Judit Mádl-Szőnyi | Co-conveners: Manuela Lasagna, Jim LaMoreaux, Daniela Ducci, John Molson
Orals
| Fri, 28 Apr, 10:45–12:30 (CEST), 14:00–15:30 (CEST)
 
Room 2.15
Posters on site
| Attendance Fri, 28 Apr, 08:30–10:15 (CEST)
 
Hall A
Posters virtual
| Attendance Fri, 28 Apr, 08:30–10:15 (CEST)
 
vHall HS
Orals |
Fri, 10:45
Fri, 08:30
Fri, 08:30
The session aims to bring together scientists studying various aspects related to groundwater flow systems, and their role in solving water management and environmental problems.
Understanding groundwater flow systems requires knowledge of the governing processes and conditions from the local to regional and basin-scales, including porous and fractured porous media. Moreover, problems connected to groundwater management underline the importance of sustainable development and protection of groundwater resources.
In this context of groundwater flow understanding, the session intends to analyze issues connected to groundwater management and its protection from degradation with respect to quantity and quality (e.g. due to over-exploitation, conflicts in use, climate change, resource development or contamination). Papers related to methods of characterizing groundwater flow systems, and preventing, controlling and mitigating harmful environmental impacts related to groundwater, including those in developing countries, are also welcome.
The session is sponsored by RGFC-IAH. We are pleased to announce that we have launched a Special Issue entitled "The role of groundwater flow systems in solving water management and environmental problems" in the journal "Italian Journal of Groundwater" (https://www.acquesotterranee.net/acque) and in Water MDPI with the title of "Regional Groundwater Flow
Concept and Its Potential for Interdisciplinary Application"(https://www.mdpi.com/journal/water/special_issues/H4I7230H76),

Orals: Fri, 28 Apr | Room 2.15

Chairpersons: John Molson, Judit Mádl-Szőnyi, Daniela Ducci
10:45–10:50
Process understanding:
10:50–11:00
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EGU23-12238
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On-site presentation
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Anita Erőss, Petra Baják, Bence Molnár, Katalin Hegedűs-Csondor, Mia Tiljander, Bálint Izsák, Márta Vargha, Ákos Horváth, Viktor Jobbágy, Mikael Hult, Krzysztof Pelczar, Péter Völgyesi, Csaba Tóbi, Mihály Óvári, Emese Csipa, and Viktória Kohuth-Ötvös

Our study aimed to understand the origin of elevated (>100 mBqL–1) gross alpha activity measured in groundwater-derived drinking water in the vicinity of the Sopron Mountains and Lake Fertő (Neusiedl). Water samples from 10 springs and 7 water wells were analyzed for major ions and trace elements. Total U and 226Ra activity concentrations were determined by alpha spectrometry using Nucfilm discs, and 222Rn activity was measured by liquid scintillation counting. 234U/238U ratio was determined by ICP-MS and alpha spectrometry. Additionally, δ2H and δ18O measurements were performed. To get an insight into the dynamics of the groundwater flow system and to better understand the radionuclide mobilization and transport processes, the geochemical results were evaluated in the groundwater flow system context.

Uranium activity was measured up to 540 mBqL–1, thus it can be concluded that dissolved uranium causes the previously measured elevated gross alpha values, though no health risk arises from drinking water consumption. The occurrence of dissolved uranium can be explained by oxidizing conditions that are prevalent along local flow systems and in recharge areas. The relatively short residence time of water, thus the presence of local flow systems is indicated by δ18O (-11.96 to -7.17‰) and δ2H values (-83.4 to -52.6‰). Spring samples have lower uranium activity (up to 93 mBqL–1) than groundwater samples (up to 540 mBqL–1) which can be explained by the longer residence time of water. Uranium is transported along flow paths under oxidizing conditions and the longer the flow route the higher the uranium concentration.

This topic is part of a project that has received funding from the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement No. 810980. Besides, the research was funded by the National Multidisciplinary Laboratory for Climate Change, RRF-2.3.1-21-2022-00014 project project. Some radioactivity measurements were supported by the European Commission’s Joint Research Centre (JRC) – Research Infrastructure Access Agreement No. 36227-1/2021-1-RD-EUFRAT-RADMET.

How to cite: Erőss, A., Baják, P., Molnár, B., Hegedűs-Csondor, K., Tiljander, M., Izsák, B., Vargha, M., Horváth, Á., Jobbágy, V., Hult, M., Pelczar, K., Völgyesi, P., Tóbi, C., Óvári, M., Csipa, E., and Kohuth-Ötvös, V.: Natural radioactivity in drinking water in the surroundings of a metamorphic outcrop in Hungary: interpretation of practical problems in groundwater flow system context, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12238, https://doi.org/10.5194/egusphere-egu23-12238, 2023.

11:00–11:10
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EGU23-12255
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ECS
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On-site presentation
Luis Miguel Santillan Quiroga, Daniele Cocca, Chiara Marchina, Manuela Lasagna, Enrico Destefanis, Giacomo Vescovo, Davide Bolognini, and Domenico Antonio De Luca

The Perrot spring (1305 m a.s.l.), located on the right side of the Chalamy Stream, inside the Monte Avic Natural Park (Aosta Valley, NW Italy), is an important source of drinking water for Champdepraz municipality.

The spring is placed on a large slope characterized by the presence of debris covers of various origin (glacial, fluvial and landslide) above the bedrock (serpentinised peridotites and metabasites of the Zermatt-Saas Zone, Penninic Domain) which crops out only in the upper part of the basin.

The water source is fed by rainwater infiltrating and flowing into the shallow deposits, with a permeability by porosity, and into the most fractured portion of the substrate. The water emerges at the contact between the topographic surface and impermeable or semi-permeable basal lithologies (unfractured crystalline rocks and glacio-lacustrine deposits).

The aim of this study is to delineate the recharge processes of the spring and the definition of the recharge area extension that is very important for its conservation.

In this view, an analysis of groundwater spring parameters (e.g. daily discharge, temperature and electrical conductivity) were conducted for the years 2018-2020.

The flow rate ranges between 22 and 47 L/s with two maxima, one in spring and one in autumn; the electrolytic conductivity varies between 60 and 75 S/cm. The variation of groundwater temperature is very low, between 4.9°C and 5.5°C.  The low discharge and temperature variations suggest a relatively high average share of the supply area and a sufficiently deep flow circuit.

The analysis of these data shows the presence of two contributions to the spring supply: a spring contribution from snowmelt, characterized by a low INCREASE in flow rate, and an autumn contribution from rainwater infiltration.

Moreover, sampling campaigns were also carried out in the entire Chalamy stream basin in August 2021 and January, July, September 2022. In particular, water from lakes, rivers, spring and rainwater was sampled.

During the field campaigns, pH, electrical conductivity and temperature were measured in situ. Chemical analysis of major ions and stable isotopes (δ2H and δ18O) were then conducted on water samples.

The chemical analyses show a groundwater chemistry coherent with the regional geology: the hydrochemical facies is bicarbonate-sodium, the main cations are Ca2+ and Mg2+ and the anions HCO3-.  Finally, isotopic analyses of precipitation and spring water suggest a recharge elevation of around 2,500 m a.s.l.

How to cite: Santillan Quiroga, L. M., Cocca, D., Marchina, C., Lasagna, M., Destefanis, E., Vescovo, G., Bolognini, D., and De Luca, D. A.: Analysis of the recharge process of Alpine Spring through an integrated approach: the case of Perrot spring (Aosta Valley, Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12255, https://doi.org/10.5194/egusphere-egu23-12255, 2023.

11:10–11:20
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EGU23-6980
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ECS
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On-site presentation
Elena Egidio, Susanna Mancini, Domenico Antonio De Luca, and Manuela Lasagna

This study represents the first regional-scale investigation in the Piedmont Po plain about the relationship between groundwater temperature in the shallow aquifer (GWT) and climate variability.
The aim of this investigation is to study and compare time trends in air temperature (AT) and GWT over a 10-year time period (between 2010 and 2019), and to evaluate possible relationships between the two parameters. For doing so we had used daily measures taken from 41 monitoring wells located in the shallow aquifer and 20 weather stations throughout the Piedmont Po plain area.

Both AT and GWT showed an increase over the observed period with a more pronounced growth of the AT. With regard to AT all the weather stations had shown an increasing trend with a variation in the annual mean 1.7 and 2.2 C/10 years; moreover, GWT annual mean generally shows a variation between −0.3 and 2.1 C/10 years. This result allows to state that GWT is more resilient to climate change than AT. However, some monitoring wells in the study area showed a behaviour that partially deviated from the standard trend observed for the majority of the region: these wells were influenced by particular anthropic factors (for example the paddy fields) or natural elements (as the monitoring wells located downstream of melting glaciers, or the wells located close to Rivers). Further investigations will be conducted in future in Piedmont plain areas with different behaviour, in order to better understand their dynamics and the factors that may influence GWT and how they are affected by climate change.

Moreover, this study wanted to stress the importance of the knowledge of the localization in wells of the instruments for the GWT measurement, to have the most accurate and comparable data. As already state in literature the GWT fluctuation in the bottom part of the aquifer was milder than the fluctuation observed in the most superficial part. Therefore, it has been possible to observe that in the study area when the depth of the instrument increased, the maximum and minimum peaks of the GWT shifted in time respect to the maximum and minimum peaks of the AT.

Lastly, we are conducting a groundwater and heat flow simulation of the shallow aquifer of the Turin Plain area using a numerical model with Smoker Heatflow code. The calibration performed with the available hydrogeological setting information of the area and the GWT and AT data will allow us to model the future spatial distribution of GWT in the study area, according to the IPCC forecast scenarios.

How to cite: Egidio, E., Mancini, S., De Luca, D. A., and Lasagna, M.: How Climate Change influence groundwater temperature? A case study in the Piedmont Po Plain (NW Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6980, https://doi.org/10.5194/egusphere-egu23-6980, 2023.

11:20–11:30
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EGU23-11700
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ECS
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Virtual presentation
Selene Olea Olea, Eugenio Gómez Reyes, Oscar Escolero, and Felipe de Jesús Armas Vargas

The Mexico City region is a densely populated region in the world and has problems in guaranteeing the supply of drinking water to its inhabitants. Its groundwater flow system is subject to intensive exploitation. The water in the city is coming from a lot of sources as wells located in the city and springs in the ranges. The geology in the basin is mainly in lacustrine sediments; volcanic rocks shallow and deep and carbonate rocks in the depths.

We collected water table values, major ions, and trace elements compositions from other research: wells (1999) and springs (2015) to investigate hydrogeochemical processes as well as to understand the hydrodynamics of groundwater and their chemical differences between ranges and plains. The groundwater chemical composition is related to the water-rock interaction processes.

We applied two inverse model sections (PHREEQC code) in springs and wells. The inverse model section in the springs showed the dissolution of gypsum, biotite, SiO2 (aqueous), volcanic glass, labradorite, chloride, and precipitation of amphibole, kaolinite, and H2O (gaseous). Whereas the inverse section model in wells presents the dissolution of CO2 (gaseous), gypsum, biotite, volcanic glass, halite, plagioclase, olivine, and precipitation of kaolinite and pyroxene.

Understanding the hydrochemical mechanisms of water-rock interactions eventually leads to the development of appropriate strategies for sustainable groundwater management.

How to cite: Olea Olea, S., Gómez Reyes, E., Escolero, O., and Armas Vargas, F. D. J.: Water-rock interaction processes in springs and wells of the Mexico City groundwater flow system, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11700, https://doi.org/10.5194/egusphere-egu23-11700, 2023.

11:30–11:40
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EGU23-2088
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ECS
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On-site presentation
Daniele Cocca, Manuela Lasagna, Chiara Marchina, Luis Miguel Santillan Quiroga, and Domenico Antonio De Luca

The precipitation constitutes one of the main sources of the groundwater resources. The chemical composition of precipitation is influenced both by natural and anthropic sources. For this reason, it is essential to monitor rainfall potentially able to influence groundwater quality. The Po Plain sector (NW Italy) is one of the most urbanized, industrialized and air polluted area in Europe but few studies have been conducted in this area, particularly in the Piedmont Region.

The main purpose of this study was: I) to provide a preliminary assessment of quality and isotopic composition of rainwater in the western Po Plain, II) to show the spatial and temporal differences of rain chemical composition between the monitoring points, and III) to define the influence of rain to groundwater chemistry.

A long-term trends on the groundwater concentration of NO3 and SO42– in the shallow aquifer on 227 monitoring points of the Regional Monitoring network database were conducted (2000-2020 period).

In the last decades, in Europe a large effort was carried out to reduce sulphur and nitrogen emission in the atmosphere. This resulted in a sharp decrease in the deposition of SO42– and nitrogen compounds.

The rain analysis of long-term trends in near regions, revealed a large proportion of significant decreasing trends in the concentration of both sulphate and nitrogen compounds.

Actually also the analysis of groundwater long-term trends revealed a significant decreasing trends in the concentration of NO3 and SO42– in the shallow aquifer.

A sampling campaigns was carried out during one year (September 2021 – September 2022) in 4 monitoring points located in the western Po Plain. Rainfall collection occurred every 2 months, for a total of 20 samples. Physical-chemical analyzes of the main ions and isotopic analyzes (δ18O, δ2H) were conducted for all samples.

The period  September 2021 – September 2022 was characterized by a rainfall deficit in the winter period in the NW Italy, recording a 62% reduction in rainfall (compared to the climatic average of the thirty year period 1981-2010).

The processing of rainfall chemical data has shown different concentrations between the monitoring points and a temporal variability. High NO3 and SO42– concentrations were observed.

Rainfalls sampled after the winter dry period (March-April samples) show higher ions concentrations (NO3 13 mg/L, SO42– 4 mg/L) respect to other periods. Differences in rainfall samples depend on the location of the monitoring point (urban or rural areas).

Isotopic data has shown different spatial and temporal isotopic signals, linked to the location and elevation of the monitoring points. In the δ18O/δ2H diagram all isotopic signals are not placed on the Local Meteoric World Line, potentially linked to climate change.

The isotopic signals are within the ranges of previous studies (δ18O: -12,6/-6,2; δ2H: -82,15/-35,1 ‰ (min/max)).

In conclusion, the rain ions concentrations are influenced by anthropic pollution, they are affected by dry periods and they appears to influence the concentration in groundwater.

How to cite: Cocca, D., Lasagna, M., Marchina, C., Santillan Quiroga, L. M., and De Luca, D. A.: Chemical and isotopic composition of precipitation in the Piedmont Po Plain (NW Italy): preliminary evaluation of impacts on the groundwater quality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2088, https://doi.org/10.5194/egusphere-egu23-2088, 2023.

Modelling applications for groundwater management:
11:40–11:50
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EGU23-10325
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Virtual presentation
Coupled analysis of the groundwater flow system, heat and solute transport, and the potential effect of hydraulically conductive faults for sustainable water management.
(withdrawn)
Adrian Ortega-Guerrero
11:50–12:00
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EGU23-12278
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ECS
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On-site presentation
Petra Baják, Katalin Hegedűs-Csondor, András Csepregi, Máté Chappon, Katalin Bene, and Anita Erőss

Lake Velence is a shallow soda lake in Hungary, which has a diverse ecosystem and is a popular tourist destination. Because of that, the lake is the focus of continuous interest and is constantly examined in terms of water quality and quantity. In recent years, it has been observed that the lake's water and nutrient budget is negatively affected by climate change. Since the very existence of the lake is threatened, it has become important to assess the quantity of water flowing into and out of the lake. In our research, the emphasis is on the investigation of the groundwater component, since groundwater can represent a significant buffer in the lake's water balance against climate change, and since in water management practice, neither inflow nor outflow of groundwater is currently considered in the lake’s water budget. Therefore, we wanted to understand the nature of the relationship between the lake and the groundwater and quantify the amount of inflowing and outflowing groundwater.

To achieve our aim, we created a regional-scale transient 3D numerical groundwater flow model for the lake's catchment area using Visual MODFLOW. The time series of weather parameters (i. e. amount of precipitation, evaporation, temperature), the discharge rate of surface water courses, and groundwater extraction data from 1990-2020 have been incorporated into the model. To calibrate the model, we used the time series of monitoring wells of unconfined and confined aquifers. The mentioned time series were also analyzed using statistical methods such as the relationship between rainfall, the groundwater level measured in wells, and the lake level.

Our results complemented the previous studies on the lake's catchment area: there is a not insignificant connection between the lake and groundwater, and the lake is fed by local flow systems with shallow penetration depth and relatively short residence time, which are known to be more sensitive to climate change. Finally, we used the calibrated model to test different scenarios, e. g. we have reduced rainfall or increased water withdrawals to highlight the lake's vulnerability to future changes.

The research was supported by the ÚNKP-22-3 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund. Part of the research was funded by the National Multidisciplinary Laboratory for Climate Change, RRF-2.3.1-21-2022-00014 project.

How to cite: Baják, P., Hegedűs-Csondor, K., Csepregi, A., Chappon, M., Bene, K., and Erőss, A.: Numerical modeling and time series analysis to quantify the neglected groundwater component in Lake Velence’s water budget – a case study from Hungary, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12278, https://doi.org/10.5194/egusphere-egu23-12278, 2023.

12:00–12:10
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EGU23-13692
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ECS
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On-site presentation
Claudio Arras, Francesca Lotti, Maria Chiara Porru, Fabrizio Antonio Piscedda, and Stefania Da pelo

The alluvial aquifer of the Flumendosa delta plain, in south-eastern Sardinia (Italy), is overexploited for drinking and agriculture purposes and it is subjected to ongoing sea water intrusion phenomena. In a context of progressive quali-quantitative deterioration of groundwater resources, development of a sustainable management plan and, eventually, effective remediation actions require a deep understanding of the investigated system. A systematic review of dataset collected from literature, integrated with new field hydrogeological and geochemical data, is performed to improve the knowledge of the aquifer system. Despite the large amount of processed data, many aspects require further investigations. In this frame, a fast-running steady state groundwater flow numerical model is developed as a tool for testing the preliminary assumptions, to address the main uncertainties, and to optimize the acquisition of new field data. The adopted approach follows the methodology proposed by Lotti et al. (2021) for the development of a Numerically Enhanced Conceptual Model (NECoM).

Geometrical discretization of the numerical model is based on results of the 3D hydrogeological reconstruction of the plain area (Arras et al. 2019); simulation of main inflows and outflows, water exchange between surface water bodies and groundwater, irrigation and drinking water withdrawals is performed through the implementation of general head boundaries (GHB), river (RIV), and well (WEL) packages, respectively. Results from the application of the Soil Water Balance code (Porru et al. 2020) are used as input for simulating the average recharge from precipitation. Lateral recharge from the Paleozoic basement is also simulated. More than 4000 heads observations from about 350 wells and piezometers are used as targets in the calibration process; weights are assigned to deal with the high heterogeneity of the dataset quality. RIV and GHB conductance, irrigation well yields, direct and lateral recharge, and hydraulic conductivity are set as parameters in the calibration process. Due to the high sensitivity of some parameters, different calibration cycles are performed; hydraulic conductivities and lateral recharge are then calibrated in the last cycle.

Model results show that the hydrogeological conceptualization used for implementing the numerical model can reproduce the main general features of the piezometric head field. According to field observations, the Flumendosa river shows losing conditions in the western part of the plain and next to the river mouth, while gaining conditions occur in its central part; gaining conditions are also observed along the abandoned branches of the Flumendosa river, also known as foxi. Moreover, mass balance analysis show that the Flumendosa river represents the main recharge input of the whole groundwater system, providing an average inflow of about 4.3 Mm3/year. Nevertheless, several local incongruencies with the observed data were precious to highlight the effects of unknown variables such as agricultural extraction wells, the hydrogeological role of the bedrock or the water exchange between surface and groundwater bodies. The discrepancies, rather than the agreements, provided useful direction for the detection of new data to be collected to capture the salient information needed for a proper water resource management.

How to cite: Arras, C., Lotti, F., Porru, M. C., Piscedda, F. A., and Da pelo, S.: Numerically Enhanced Conceptual Modelling (NECoM) applied to the Flumendosa Plain groundwater system (SE Sardinia, Italy), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13692, https://doi.org/10.5194/egusphere-egu23-13692, 2023.

12:10–12:20
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EGU23-15653
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ECS
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On-site presentation
Linda Franceschi, Matia Menichini, Brunella Raco, and Marco Doveri

 In most regions worldwide, the groundwater usage is increasingly common due to the progressive decreasing
of the effective availability of surface water for both quantity regime and quality issues, as a consequence of
global population increasing, global climate change and growing water pollution. Therefore, groundwater is
the most important and safest source for water supply being less affected by pollution and climate changes.
For example, in European Union countries, groundwater provides nearly 70% of the piped water supply and
80% of the drinking water. However, the overexploitation of groundwater may sometimes exceed recharge
over long periods and over extensive areas and the subsequent decline in water table level may affect natural
groundwater discharge and quality, which in turn may have harmful impacts on groundwater dependent
streams, wetlands and ecosystems. For these reasons a correct management of the groundwater resources
is of paramount importance. In this scenario, groundwater modelling, both conceptual and numerical, is
particularly crucial for the sustainable and efficient management of groundwater resources, even more in
the context of expected climate change.
The middle-high Brenta river plain (NW of Veneto, Italy) is characterized by the existence of an important
unconfined to semi-confined foothill aquifer system, that is made of a very thick single-layer of gravellypebbly alluvial deposits, in the northernmost part, whereas in the southern part the aquifer becomes a
multilayer composed of gravelly deposits and levels of silt and clay. The existence of an important aquifer
system is tied to the high annual rainfall amount, about 1200 - 1500 mm/year, however the main
groundwater recharge component of the aquifer is related to the water dispersion from the Brenta river.
Groundwater hosted in the aquifer represents an important resource for drinkable supply, industrial and
agricultural usages. However, over the last decades, the exploitation of groundwater resource and the
meteo-climate regime caused a decrement of the piezometric level alerting the local authorities. Thanks to
the existence of a consistent and continuous monitoring network made up of several meteoric, hydrometric
and piezometric stations, very long time-series of data are available. The availability of a long time-series
allowed to develop Data-Driven models, specifically Multiple Linear Regression Models, of the Brenta river
hydrometric level (using rainfall, snowfall and atmospheric temperature as independent variables) and of the
piezometric level of groundwater in the middle-high plain (using atmospheric temperature, the local rainfall
and the model of Brenta river as independent variables). The regression models were used to make
predictions on the development of the hydrometric level of Brenta river and consequently of the
groundwater level under extreme weather and climate conditions as those of the last years, thus providing
useful information for steering the best water management practices in a zone where strategic groundwater
exploitation systems are located.

How to cite: Franceschi, L., Menichini, M., Raco, B., and Doveri, M.: Data-Driven models for groundwater level forecasting and improvement of waterresource management: example of the Foot-hill aquifer system in the Brenta riverplain (Veneto, Italy) , EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15653, https://doi.org/10.5194/egusphere-egu23-15653, 2023.

12:20–12:30
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EGU23-16604
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Highlight
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On-site presentation
Assessment of multiple pressures on regional groundwater resources under historical and future climate conditions
(withdrawn)
René Lefebvre, Jean-Marc Ballard, and François Huchet
Lunch break
Chairpersons: Jim LaMoreaux, Manuela Lasagna, Judit Mádl-Szőnyi
14:00–14:10
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EGU23-6876
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ECS
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On-site presentation
Pierre L'hermite, Valérie Plagnes, Anne Jost, Benoît Reile, Isabelle Blanc-Potard, Damien Regnier, and Michael Descostes

Water flow is an essential component of the long-term environmental management of former mine sites. Flow through tailings storage facilities (TSF) often generates chemical reactions and releases acidic water. In the case of static leaching, this acidification can last for multiple decades depending on the acid remaining in the tailings. This mining water is then collected and treated in treatment plants before it is released in the environment in compliance with environmental standards. The understanding of the current hydrogeological functioning of the TSF is essential to properly adapt water management today. Given the potential impact of climate change, simulation of future hydrogeological behaviour is also required to ensure sustainable water management over this century.

We developed a daily time step model with HYDRUS 2D to represent the unsaturated hydrogeological functioning of a tailings pile of the former mine of Le Cellier (France). A granulometric analysis over the pile height provided reliable hydraulic properties and showed that the pile heterogeneity can be distributed into three layers. The historical monthly monitoring and the new daily hydrogeological monitoring implemented in 2021 measured the rainfall and discharges from the various drains that collect the water from the pile. As cross-correlations confirmed the fast reaction of drains discharges to rainfall (1 day), we simulated the water flow with the dual porosity package of HYDRUS. We also implemented the vegetation transpiration due to the presence of bushes and coniferous trees over the pile.

The model performance was evaluated by comparing the observed (monthly and daily) discharges and the simulated one. The calibrated model reproduces correctly the annual discharges for the period 2014-2022 as well as the pile fast reaction to rainfall. To evaluate the climate change impacts on the hydrogeological functioning of the pile, we used as input of our calibrated model the daily precipitations and temperatures of the Coupled Model Intercomparison Project (CMIP5) for three climatic scenarios (RCP2.6, RCP4.5 and RCP8.5). The calculation of the Mann-Kendall trend test on the predicted water balance components leads to the conclusion that the effective rainfall should remain stable over the next 100 years. At the end of the century, the frequency of extreme events could increase by 50% and their intensity could rise by 9%. With the calibrated model, we simulated the discharges at the pile outlet and studied their annual changes as well as the pile response to extreme events under climate change. These simulations are essential to ensure an accurate water management for this century.

How to cite: L'hermite, P., Plagnes, V., Jost, A., Reile, B., Blanc-Potard, I., Regnier, D., and Descostes, M.: Present and future flow simulation in a tailings pile at a former mine in France, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6876, https://doi.org/10.5194/egusphere-egu23-6876, 2023.

14:10–14:20
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EGU23-7742
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ECS
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On-site presentation
Mohammadali Geranmehr, Domenico Baù, Alex S. Mayer, Lauren Mancewicz, and Weijiang Yu

The simulation of seawater intrusion (SWI) in coastal aquifers under complex hydrogeological conditions typically requires using "variable-density" models, which simulate the groundwater flow and the transport of salt dissolved in water. When combined with optimization algorithms, variable-density models constitute powerful tools to support the management of groundwater resources in coastal systems vulnerable to SWI, sea-level rise and unstainable groundwater abstraction. However, the application of simulation-optimization (SO) to SWI problems has so far been limited by the prohibitive computational effort required by full-scale variable-density models that simulate the aquifer response to proposed groundwater abstraction strategies. A viable solution is thus to develop “surrogate” models that emulate full-scale model responses at a fraction of their computational cost. In this study, a surrogate model of SEAWAT, a popular variable-density groundwater flow model, will be presented. This surrogate is based on the proper orthogonal decomposition (POD) method, which is a projection-based approach where the coefficient matrices and the right-hand side vectors derived through finite-difference discretization of the coupled flow and transport equations, are mapped onto a space of size significantly smaller than the model grid. Preliminary results show that the POD-based surrogate model is remarkably faster than the full-scale model, and provides results of comparable, and thus acceptable, accuracy. These features make the surrogate ideally suited for substituting the full-scale variable-density model within the SO framework adopted to support the management of coastal aquifers.

How to cite: Geranmehr, M., Baù, D., Mayer, A. S., Mancewicz, L., and Yu, W.: Sustainable Management of Coastal Aquifers subject to Seawater Intrusion using Reduced-Order Groundwater Flow Models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7742, https://doi.org/10.5194/egusphere-egu23-7742, 2023.

Management issues and approaches:
14:20–14:30
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EGU23-699
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ECS
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Virtual presentation
Exploring the Sensitivity of Groundwater Stress Regimes to Water Resources Management Practices in the Ganga basin, India
(withdrawn)
Ishita Bhatnagar, Chandrika Thulaseedharan Dhanya, Harrie-Jan Hendricks Franssen, and Bhagu Ram Chahar
14:30–14:40
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EGU23-1517
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ECS
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Highlight
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On-site presentation
J.A. (Janine) de Wit, M.H.J. (Marjolein) van Huijgevoort, J.C. (Jos) van Dam, G.A.P.H. (Gé) van den Eertwegh, D. (Dion) van Deijl, and R.P. (Ruud) Bartholomeus

Sufficient freshwater is needed for several water dependent sectors. However, e.g. climate change, weather extremes, economic growth, urbanization and increased food production make it more complex to guarantee sufficient freshwater for all sectors, even in temperate climates like the Netherlands. The range of weather extremes from extremely dry to extremely wet is expected to increase and to occur more frequently. However, the current Dutch water management system is not designed to anticipate both weather extremes.

Controlled drainage with subirrigation could be a viable measure to i) discharge water only when needed, ii) retain water and iii) recharge water using an external source. This system thus has the potential to 1) improve growing conditions for crops at field scale, 2) reduce peak discharges at regional scale, and 3) increase groundwater recharge on regional scale. Consequently, this system could anticipate both dry and wet extremes. However, the implementation of controlled drainage with subirrigation could significantly alter different water balance components.

We show data and model output of five experimental sites where controlled drainage with subirrigation is applied. Field data were collected over the years 2017-2022, like external water supply, groundwater table and soil moisture content. Other water balance components, crop yield and configuration of the management of the system were modelled with SWAP (Soil-Water-Atmosphere-Plant model), using observations for calibration purposes.

Results show that by subirrigation, water can be applied to the soil and will lead to increased water storage and higher groundwater tables. Groundwater tables were up to 0.7 m higher during the growing season, leading to both increased crop yields and larger groundwater recharge. Drought vulnerability decreased at the test sites. However, the water supply for subirrigation can be high (500 mm per year, on average). Additionally, effects of subirrigation on the water balance components are strongly site-dependent. For example, a resistant layer below the drainage/infiltration pipes is needed to ensure enough resistance to limit downward seepage and to raise the phreatic groundwater level. Furthermore, ditch levels surrounding agricultural fields need to be adjusted to the raised groundwater levels, as too deep ditch water levels result in (unfavorable) drainage and loss of water. Field experiments also show that proper management is important to prevent clogging of the drainage systems.

Construction, topographical location, external water source and proper management are important for subirrigation to be successful. Responsible implementation of subirrigation in terms of the water balance at the regional scale is needed; freshwater availability to apply subirrigation is an issue. When these boundary conditions are met, controlled drainage with subirrigation could raise the groundwater level and improve the soil moisture availability for crops, while still having the option to discharge water when needed.

How to cite: de Wit, J. A. (., van Huijgevoort, M. H. J. (., van Dam, J. C. (., van den Eertwegh, G. A. P. H. (., van Deijl, D. (., and Bartholomeus, R. P. (.: Hydrological consequences of controlled drainage with subirrigation, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1517, https://doi.org/10.5194/egusphere-egu23-1517, 2023.

14:40–14:50
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EGU23-13570
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On-site presentation
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Staša Borović, Matko Patekar, Marco Pola, Josip Terzić, and Maja Briški

The assessment of groundwater resources quality and quantity in arid or semi-arid climates is crucial for achieving long-term sustainable management due to their limited volume and scarce replenishment. The relevance of this topic is enhanced by their vulnerability to climate change. The Mediterranean region is considered to be a hot spot for climate change with a generally arid climate. Its groundwater resources are under increasing stress due to: growing population, agricultural and industrial development, seawater intrusion, and changing climate. Groundwater resources in islands are particularly stressed since they have small aquifer volumes and a limited extent of the recharge area. The island of Vis (Croatia) in the Adriatic Sea is a representative case study for stressed island groundwater resources. Vis is located 40 km from the mainland and depends exclusively on its local karst aquifer for public water supply. This groundwater resource is affected by a concomitant decrease of recharge, an increase of evapotranspiration, and a progressive anthropic impact due to tourism. Geochemical and hydrogeological monitoring were conducted from September 2019 to December 2022 in deep wells and coastal springs to assess the hydrochemical characteristics and the regime of the Vis groundwater resource. Although the monitoring period was characterised by low rainfall resulting in the decline in groundwater levels, the principal ion composition showed relative stability. The groundwater in wells generally showed predominant Ca-HCO3 hydrochemical facies, while coastal springs or wells nearby the sea showed both Na-Cl and mixed Ca-Mg-Cl-SO4 facies. Time series of in-situ measurements of groundwater temperature, pH value, and electrical conductivity have shown low variability, notwithstanding the low precipitation during the observed period. Groundwater temperature between 16°C and 18°C varied throughout the year following the air temperature variations. The groundwater pH was neutral to mildly alkaline with low annual variability. EC values were variable depending on the interaction between groundwater and seawater. However, all objects displayed relatively stable EC values despite the prolonged drought and the intensive exploitation during the summer period. These results evidenced the resilience of the aquifer, which owes to its favourable geological structure. Due to increasing natural and anthropic pressures on the resource, continuous monitoring and the establishment of an early warning system should be foreseen in the coming years.

Acknowledgments: This research was carried out within the framework of the INTERREG-CE project DEEPWATER-CE, funded by the European Regional Development Fund (ERDF).

How to cite: Borović, S., Patekar, M., Pola, M., Terzić, J., and Briški, M.: Monitoring of a small karst island aquifer as a prerequisite for its sustainable management (Vis island, Croatia), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13570, https://doi.org/10.5194/egusphere-egu23-13570, 2023.

14:50–15:00
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EGU23-6268
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ECS
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On-site presentation
Magdaleena Männik, Enn Karro, Andres Marandi, and Alar Rosentau

Groundwater is the most crucial drinking water resource in many areas of the world. In spite of its overall abundance, the resource remains vulnerable to pollution, as groundwater quality may be severely affected by urbanization and growth in industrial activities and agriculture. The most sustainable approach to managing groundwater quality is to ensure its protection, thus avoiding contamination. Therefore, accurate groundwater vulnerability assessment methods are necessary tools for groundwater management and protection.

The DRASTIC method is one of the most widely used groundwater vulnerability assessment methods. However, in areas where the main useful aquifers are covered with an extra layer of diverse Quaternary sediments, the original DRASTIC method overestimates the vulnerability of groundwater in overflow areas and in regions where groundwater is occasionally confined. Therefore, the DRASTIC method needs to be modified to increase the accuracy of vulnerability maps in areas with a highly variable Quaternary layer, which remarkably influences the nature of the infiltration conditions.

For this, in this study, the depth to water, soil properties, and impact of the vadose zone parameters of the DRASTIC methodology were modified to be suitable in areas with glacial sediments. Originally, the depth to water parameter (D) allows assessing the distance from the ground surface to the aquifer: the deeper the water table, the lower the contamination risk. In the modified DRASTIC method, the water table is as an alternative compared to the bedrock surface beneath the Quaternary sediments layer. When the piezometric head is above the bedrock surface, the aquifer acts as confined, and the movement of the pollutant to the aquifer is hindered. Therefore, the groundwater vulnerability considering the D-parameter is lower in areas where the piezometric head is above the bedrock surface and higher in areas where it is below the bedrock surface.

Both the original and the modified DRASTIC methodology were applied in an area with glacial sediments located in Central Estonia. The modified DRASTIC method showed significantly better results than the original DRASTIC method. Furthermore, comparing the maps generated using the modified DRASTIC with a former local groundwater vulnerability assessment method showed considerably more similarities than this by the original DRASTIC method. Thus, the modified DRASTIC method is successfully applicable in areas with an extra layer of diverse Quaternary sediments.

The study has been funded by Iceland, Liechtenstein and Norway through the EEA and Norway Grants Fund for Regional Cooperation project No.2018-1-0137 “EU-WATERRES: EU-integrated management system of cross-border groundwater resources and anthropogenic hazards

How to cite: Männik, M., Karro, E., Marandi, A., and Rosentau, A.: Groundwater vulnerability assessment in areas with diverse Quaternary deposits, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6268, https://doi.org/10.5194/egusphere-egu23-6268, 2023.

15:00–15:10
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EGU23-10500
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ECS
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Virtual presentation
Environmental and educational challenges of a conceptual model proposal for transboundary groundwater flow systems: Southern Mexican Borders.
(withdrawn)
Yussef Abud Russell, Samira Ouysse, Gonzalo Hatch Kuri, and Joel Carrillo Rivera
15:10–15:20
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EGU23-15998
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ECS
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Virtual presentation
Groundwater conceptual model built for general public access and contribution: A case study from Australia
(withdrawn)
Quanyi Ye, Michaela Beardsell, and Ifeanyi Emmanuel Anyanwu
15:20–15:30

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

Chairpersons: John Molson, Jim LaMoreaux, Manuela Lasagna
A.142
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EGU23-1280
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ECS
Cyril Aumar, Pierre Nevers, Hélène Celle, Gilles Mailhot, Frédéric Huneau, Virginie Vergnaud, Barbara Yvard, and Marie-Laure Clauzet

Clermont Auvergne Métropole is an agglomeration of 300,000 inhabitants. Two types of aquifers are exploited for the drinking water supply of this population: the alluvial aquifer of Allier River (70%) and three volcanic water basins located in the Chaîne des Puys (30%). Recent studies have shown that the quantity of water in the Allier alluvial aquifer decreases drastically during drought periods and that this decrease will amplified in the future due to climate changes (2022 for example). Water managers of Clermont Auvergne Metropole are thus interested in identifying the potential of their volcanic resources to secure the water supply of the population. In this purpose, a multidisciplinary study, using existing data and providing new ones has been projected. This study includes: 1) the use of the geological model previously established by Aumar (2022) at the Chaîne des Puys scale, that allows to constrain the geometry of aquifers; 2) the acquisition of hydrochemical data that help to better define the functioning of the volcanic watersheds; 3) the measurement of hydrodynamic and meteorological data to better define the terms of the hydrological balance. Natural tracers such as stable water isotopes (18O and 2H) or major and trace elements give information on the origin of those groundwaters (local or remote) and in particular their infiltration zone (average altitudes), their flow paths or the impact of various external processes (environmental or anthropic). Groundwater dating methods (CFC, Tritium) brings a constraint on the residence time of water within the aquifer. Yet, groundwater ages are still unknown in all watersheds of the Chaîne des Puys, but it remains essential to understand groundwater flow and storage. The coupling between hydrodynamic monitoring, a large panel of hydrochemical tracers and groundwater residence time data associated with a well constrained geological model allows to provide relevant management tools to stakeholders both in terms of quantification and protection of their resources.  

How to cite: Aumar, C., Nevers, P., Celle, H., Mailhot, G., Huneau, F., Vergnaud, V., Yvard, B., and Clauzet, M.-L.: A multidisciplinary study to evaluate the sustainability of a volcanic hydrosystem: Chaîne des Puys’s watersheds use by Clermont Auvergne Métropole for drinking water supply, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1280, https://doi.org/10.5194/egusphere-egu23-1280, 2023.

A.143
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EGU23-3840
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ECS
Márk Szijártó, Zsuzsanna Vatai, and Attila Galsa

Numerical simulations focusing on groundwater age have not yet been carried out in the Buda Thermal Karst system (BTK) (Hungary), although isotopic and chemical data from thermal springs [e.g. Fórizs et al., 2019] are available to compare calculated and measured results. The main objective of this study was to improve understanding of regional-scale heat transport processes and groundwater flow associated with ageing in complex hydrogeological system, such as the BTK including deep carbonate sequences and adjoining sedimentary basins (“DC&SB”).

A comprehensive sensitivity analysis was completed to validate the numerical method [Zimmermann, 2006] implemented with ‘age mass’ concept [Good, 1996], and to reveal the influence of crucial hydrogeological parameters on the groundwater age distribution in 2D and 3D synthetic models. It was established that the average (τav) and the maximum (τmax) groundwater mean age correlate with the permeability anisotropy, heterogeneity (exponential permeability decrease with depth), the model depth, while the values anti-correlate with the amplitude of water table and the permeability.

For general investigation of the “DC&SB” type groundwater flow systems, two “half-basins” [Wang et al., 2017] were combined into a single asymmetric basin. The “DC&SB” model was characterised by (i) a water table configuration with higher amplitude and a homogeneous (unconfined) aquifer on the left-hand side; (ii) a lower water table amplitude and a three-layered (unconfined aquifer – aquitard – confined aquifer) domain on the right-hand side. As a result of the forced convection, decreased temperatures and reduced groundwater mean ages are noted in unconfined parts of the model, while heat accumulation and increased ages were calculated in the aquitard and the confined aquifer. Using experiences from synthetic tests, the groundwater age calculation was integrated into the preliminary 3D hydrogeological model of the BTK system. The results showed that the measured and the calculated mean groundwater age values sampled the different parts of the hierarchically nested flow system are of the same order of magnitude.

The results are very important to uncover the groundwater flow in complex hydrogeological systems which is unavoidable both in regional-scale (e.g. drinking water management, geothermal exploration and geothermal energy utilisation) and local-scale explorations (e.g. managed aquifer recharge, environmental remediation). The research was supported by the National Research, Development and Innovation Office in the framework of project No. PD 142660; and by the National Multidisciplinary Laboratory for Climate Change, RRF-2.3.1-21-2022-00014 project.

References

Fórizs, I., Szabó, V.R., Deák, J., Halas, S., Pelc, A., Trembaczowski, A., Lorberer, Á. (2019). The Origin of Dissolved Sulphate in the Thermal Waters of Budapest Inferred from Stable S and O Isotopes. Geosciences 9(10), 433, p. 13.

Good, D.J. (1996). Direct simulation of groundwater age. Water Resources Research 32, pp. 289-296.

Wang, J.Z., Jiang, X,W., Zhang, Z.Y., Wan, L., Wang, X.S., Li., H. (2017). An analytical study on three-dimensional versus two-dimensional water table-induced flow patterns in a Tóthian basin. Hydrological Processes 31, pp. 4006-4018.

Zimmermann, W.B.J. (2006). Multiphysics modeling with finite element methods. Singapore: World Scientific Publishing Company, p. 422.

How to cite: Szijártó, M., Vatai, Z., and Galsa, A.: Numerical investigation of the groundwater age and heat transport processes in asymmetric hydrogeological situations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3840, https://doi.org/10.5194/egusphere-egu23-3840, 2023.

A.144
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EGU23-4742
Sung-Ho Song, Byungsun Lee, and Jaenam Lee

To evaluate the effects of drought on groundwater system in rural areas, the standardized groundwater level index (SGI) was applied to groundwater monitoring wells over S. Korea. Moreover, accumulation period (AP), representing the month with the highest correlation coefficient between SGI and the standardized precipitation index (SPI), was calculated for monitoring wells. In this case, correlation analysis was performed to investigate differences in the response of precipitation and groundwater level to drought using SPI. Groundwater level data from 68 monitoring wells were used for the analysis. The response time of groundwater level to precipitation appeared to be very short, but the groundwater level did not go with SPI during the long-term drought. Results of correlation analysis between reservoir level and SPI show high correlation on the relatively long AP. The results of analysis between SGI and SPI appeared that the AP values ranged from 1 to 3 months for most of the wells indicating that the total amount of groundwater will not decrease significantly in long-term drought periods unlikely it of reservoirs with the high AP values. The nationwide maximum AP values between SGI and SPI were around 4 in the central part of S. Korea, while the minimum AP values were around 2 in the eastern and western part of S. Korea. Consequently, it could be concluded that the wells with low AP value tend to respond to short-term drought, but it has little effect on groundwater system when the long drought occurs. 

Acknowledgement: This research was supported by the Institute of Planning and Evaluation for Technology in Food, Agriculture, and Forestry (IPET) [Grant number 320046053HD020].

How to cite: Song, S.-H., Lee, B., and Lee, J.: Assessment of agricultural drought effects on groundwater system using the standardized groundwater level index (SGI) in S. Korea, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4742, https://doi.org/10.5194/egusphere-egu23-4742, 2023.

A.145
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EGU23-8022
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ECS
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Francesco Maria De Filippi and Giuseppe Sappa

Karst aquifers are characterized by different types of groundwater flow, related to different types of permeability due to the simultaneous presence of matrix, fractures and conduits. The presence of a well-developed karst conduit system leads to a fast circulation of groundwater, within the aquifer and an impulsive response of the spring flow to the rainfall inputs, with a potential fast transport of contaminants from the hydrogeological basin surface to the output.

In this study, the internal structure of the karst system is not investigated and considered as a black-box model, which modifies the input signal (rainfall) into an output signal (spring discharge). With the help of hydro chemical analyses on spring water samples and single discharge measurements, it is possible to set specific mass balance models correlating ion content to spring flowrates. In particular, Mg2+ revealed a reliable application for spring baseflow separation in karst settings. Once the local model has been set, its conservative behaviour, in mostly limestone dominant aquifers, allows using it as a natural tracer of groundwater flow, distinguishing conduit flow and diffuse flow occurrence in the spring outlet, without additional discharge measurements. In karst settings, the difficulty in setting a fixed cross-section for continuously monitoring of spring discharge values makes this application interesting for exploitation management.

This study shows the results obtained for two springs located in Central Italy, confirming that monitoring groundwater quality in karst environments is often the key to successfully characterize springs and assess the total yield when direct measurements are not frequent.

How to cite: De Filippi, F. M. and Sappa, G.: Magnesium content and groundwater flow in limestone aquifers: a relationship with potential developments for exploitation management of karst springs., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8022, https://doi.org/10.5194/egusphere-egu23-8022, 2023.

A.146
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EGU23-10167
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ECS
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Etienne Marti, Sarah Leray, and Clément Roques

Seepage areas, i.e., areas where the water table intersects the land surface, are strong indicators of groundwater-surface water interaction and have a critical role on ecosystems and on water quality. Numerous studies have been carried out aiming at characterizing seepage areas and the factors controlling their occurrence. Still, most of literature focused on theoretical or synthetic systems. Then seepage areas in complex environments, such as mountain systems, are to be further studied. In this context, we propose to test the pertinence of well-known and widely used frameworks, either analytical or numerical, against 3D complex systems aiming at proposing corrections to better represent the complexity inherent to mountain systems.

The methodology follows the development of 3D homogeneous and uniformly recharge numerical models at steady state using MODFLOW. The system complexity specifically lies in its 90m-resolution topography based on a real mountain catchment, the Quebrada de Tarapacá (North Chile). Regional scale catchment area (~900km2) allows incorporating various sub-catchments, hence studying a panel of geomorphological settings differing in slope variation and characteristic length. We perform a sensitivity study of the seepage area to recharge rate which is varied over 6 orders of magnitude as a proxy for variable climatic conditions. Results are analyzed in relation to the ratio between hydraulic conductivity and recharge (K/R).

Consistently with previous studies, the K/R ratio highly influences seepage distribution showing the contraction of the river network and groundwater flow redistribution. At high recharge rates (low K/R), seepage area tends to 100% of the catchment area, a fully saturated catchment. On the other hand, at low recharge rates (high K/R), seepage tends to be null, without totally disconnecting the water table from the surface. At intermediate recharge rates (10-1 < K/R < 10), the seepage area linearly decreases while K/R increases. Numerical results differ from estimation of theoretical solutions or 1D numerical models as those tend to overestimate seepage area except when fully saturated. Even though K/R exerts the principal control on seepage distribution, the geomorphological characteristics illustrated by the characteristic length influences seepage organization. Defining the characteristic length can be challenging in mountain context due to the high variability of geomorphologic features. Various definitions of the characteristic length were then tested: (i) from drainage density; (ii) from the relation between slope and drainage area and (iii) from the equivalent hillslope method. The first two methods tend to underestimate the characteristic length, and hence, catchments appear to be only recharge-controlled following Haitjema and Mitchell-Bruker criterion (2005), counter-intuitively even at high recharge rates. Contrarily, the equivalent hillslope method shows promising results, as the balance between topographic and recharge control catchment is respected, following the same criteria.

Therefore, we show a significant overestimation of seepage area from theoretical models in comparison to 3D fully distributed models due to their inability to incorporate details of the topography such as very high hilltops. Consequently, 3D model development in mountain system is crucial as other analytical or 1D numerical models cannot illustrate the geomorphological details influencing seepage areas distribution.

How to cite: Marti, E., Leray, S., and Roques, C.: Topographic controls on seepage distribution in 3D mountain systems, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10167, https://doi.org/10.5194/egusphere-egu23-10167, 2023.

A.147
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EGU23-10202
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ECS
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Marco Sabattini, Francesco Ronchetti, Diego Arosio, Gianpiero Brozzo, and Andrea Panzani

The objective of the research is applying geophysical techniques (including seismic noise interferometry) to investigate the effects of climate change on groundwater resource availability and quality.

The research area is the lower Val Magra alluvial plain, in the Ligurian region (Italy), between the Municipality of S. Stefano Magra and the Tirrenian seacoast. It is an intensely urbanised area, with widespread industries that are potential sources of contaminants.

The main aquifer of the Val Magra is qualitatively and quantitatively vulnerable to the effects of climate change. It is an unconfined aquifer in coarse alluvial deposits, characterized by high permeability. The water table is generally very close to ground level (3-7 m in depth). The aquifer is closely connected to the Magra river and continuously exchanges between the surface water and groundwater exist. Furthermore, near the seacoast, the aquifer is influenced by interaction with seawater. In this area, periods of drought favor marine intrusion phenomenon, which occurs through the rising upstream of salt-water along the Magra river. Seawater intrusion is the main responsible of the deterioration of the groundwater quality in this lower part of the Val Magra.

An integrated approach of hydrogeological survey methods and geophysical techniques will be used to achieve the objective of the research. This allows a redundancy of data from a multidisciplinary approach and new monitoring surveys with less invasive and more efficient methods.

The traditional hydrogeological used methods are: continuous piezometric level measurements of groundwater (wells), electrical conductivity measurements of groundwater (wells) and surface water (river Magra) and isotopic analyses (Oxygen and Deuterium).

The geophysical techniques used are: 2-D geoelectrical surveys (SEV), active and passive geoseismic surveys (1-D and 2-D) and seismic noise interferometry (SNI).

Groundwater storage is estimated by monitoring the piezometric surface changes over time. The groundwater surface is interpolated from direct groundwater head measurements (wells and river) and indirect measurements from geoseismic and geoelectric surveys and the SNI technique. Isotopic measurements of water samples are used as tracers to evaluate the groundwater-surface water exchanges. The data confirm that the main source of recharge of the aquifer is the River Magra.

In the area, groundwater quality, that could be compromise mainly by marine intrusion phenomenon, is evaluated by the monitoring of the physics and chemical parameters. Geoelectrical surveys and water electrical conductivity measurements allow to investigate underground the presence of the salt water and to define the extent of the marine intrusion phenomenon. Preliminary water electrical conductivity result highlights that, during the strong drought period in the last summer, the marine intrusion reached the Romito groundwater well field by rising upstream for 7 km along the Magra river from the coastline. 

How to cite: Sabattini, M., Ronchetti, F., Arosio, D., Brozzo, G., and Panzani, A.: Geophysical techniques for monitoring the climate change effects on groundwater availability and quality, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10202, https://doi.org/10.5194/egusphere-egu23-10202, 2023.

A.148
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EGU23-10611
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ECS
Hsin Yu Chen, Wei-Cheng Lo, and Chih-Tsung Huang

  The development of civilization and the preservation of environmental ecosystems are strongly dependent on water resources. Typically, the insufficient supply of surface water resources for domestic, industrial, and agriculture needs is often supplemented by the ground water resources. However, the groundwater is a natural resource that must be accumulated over many years and cannot be recovered after a short period of recharge. Therefore, the long-term management of groundwater resources is an important issue for the sustainable development. The accurate prediction of groundwater levels is the first step to evaluate the total water resources and its allocation.

  However, in the process of data collection, data may be missing due to various factors. Thus, retracting the missing data is a main problem which any research field must deal with. It has been well known that to maintain the data integrity, one of the effective approaches is to choose missing value imputation (MVI) for tackling the problem. In addition, it has been demonstrated that the method of the machine learning may be a better tool. Therefore, the main purpose of this study is to utilize a generative adversarial network (GAN) that consists of a generative model and a discriminative model for imputation. Our result shows that GAN can improve the accuracy of water resource evaluations.

  In the current study, two interdisciplinary deep learning methods, Univariate and Seq2val, are used for groundwater level estimation. In addition to addressing the significance of the parameter conditions, the advantages and disadvantages of these two models in hydrological simulations are also discussed and compared. Finally, Seq2seq is employed to examine the limit of the models in long-term water level simulations. Our result suggests that the interdisciplinary deep learning approach may be beneficial for providing a better evaluation of water resources.

Keywords: GAN,CNN,LSTM,Imputation,Groundwater prediction

How to cite: Chen, H. Y., Lo, W.-C., and Huang, C.-T.: Using GAN for Imputation of Missing Recorded Data to Improve Groundwater Level Prediction Based on Deep Learning Methods, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10611, https://doi.org/10.5194/egusphere-egu23-10611, 2023.

A.149
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EGU23-12264
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ECS
Davide Fronzi, Stefano Palpacelli, Mirco Marcellini, Christian Massari, and Alberto Tazioli

Over the years the scientific community underlined several problems related to the use of isotopic hydrology techniques in areas characterized by a complex orography, usually occurring in mountain areas, or in those cases where the hydrological setting is complicated by contacts between different aquifers (Nanni et al., 2013).

In this study, an innovative isotopic model, able to identify the most probable recharge area for several springs exploited for drinking purposes, has been developed and applied to the Nera catchment in the Sibillini Mountain National Park (central Italy). The isotopic investigation consists of a preliminary definition of a new δ18O - elevation relationship, considering the morphological and meteorological heterogeneities within the area and their possible influences on the precipitation isotope values (e.g., shaded areas, snow drift effect, etc.). Second, an advanced δ18O distribution model, supported by statistical and GIS-based procedures, has been implemented by clipping the precipitation δ18O values (depicted from the δ18O – elevation relationship) over an upstream area for each analyzed spring. The new isotopic modeling approach can be conveniently applied if the infiltration rate of the meteoric water is fast enough to avoid fractionation processes that may alter the isotopic signal of the precipitation input within the aquifer, and if peculiar meteoric recharge phenomena, altering the springs' isotopic signal, are treated as outliers.

This research highlights if the most used isotopic approach based on the determination of groundwater recharge areas starting from δ18O - elevation gradient (Jeelani et al., 2010; Jasechko, 2019) applied to a selected spring isotopic data agrees with the hydrogeological setting of the spring recharge area which is often complicated by the topography and the contacts between different aquifers both for stratigraphic and tectonic reasons.

The ultimate goal of this study is to quantify the aquifers recharge under the impact of drought to improve the water resources management operations in the area.

How to cite: Fronzi, D., Palpacelli, S., Marcellini, M., Massari, C., and Tazioli, A.: An innovative method to determine springs recharge areas by using water isotopes: intuitions from mountain hydrogeological studies in central Italy, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12264, https://doi.org/10.5194/egusphere-egu23-12264, 2023.

A.150
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EGU23-14029
Brunella Bonaccorso, Marco Silipigni, Cristina Di Salvo, Iolanda Borzì, and Elisabetta Preziosi

The Alcantara River Basin is located in North-Eastern Sicily (Italy), encompassing the north side of Etna Mountain, the tallest active volcano in Europe. On the right-hand side of the river, the mountain area is characterized by volcanic rocks with a very high infiltration. Here, precipitation and snow melting supply a big aquifer whose groundwater springs at the mid/downstream of the river, mixing with surface water and contributing to feeding the river flow also during the dry season. In the upstream a maximum of 520 l/s are extracted for municipal use through wells and an infiltration gallery supplying the Alcantara Aqueduct. In summer 2020 and 2021, the river suffered a prolonged dry phenomenon in the middle-valley stretch with a serious loss of fish fauna, due to significant spring depletion along the stream most likely determined by a meteorological drought. Since this anomaly is of great concern, the need arises to better understand whether the interaction between the water abstraction to supply the Alcantara aqueduct and the natural recharge of the aquifer is compatible with maintaining the balance of aquatic ecosystems in the middle-downstream valley of the Alcantara River also during dry years; or if the observed changes may also be partly due to other mechanisms, such as illegal or unaccounted water abstractions or hydrogeological modification due to the volcanic activity. To this end, in this study, an attempt was made to analyze changes in the groundwater level and in the interconnection between surface and groundwater by using the widely accepted MODFLOW 6, a finite-difference numerical model that in principle can provide constraints to reduce uncertainty and address field activity in data scarce case studies. The model was calibrated in steady state by comparing simulated and observed water heads as well as the groundwater budget. Then the simulation was run in transient mode for the period 2014–2021. The model outcome showed a depletion rate compatible with the one observed during the recent dry summers, thus suggesting that more sustainable and comprehensive strategies, also including groundwater extraction regulations, should be implemented to preserve this natural resource for in-stream water use and ecosystem services.

How to cite: Bonaccorso, B., Silipigni, M., Di Salvo, C., Borzì, I., and Preziosi, E.: A conceptual model for a fractured volcanic aquifer to investigate the role of climate variability and water withdrawal on recent changes in water-table and discharge, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14029, https://doi.org/10.5194/egusphere-egu23-14029, 2023.

Posters virtual: Fri, 28 Apr, 08:30–10:15 | vHall HS

Chairpersons: Manuela Lasagna, Daniela Ducci
vHS.14
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EGU23-14159
Judit Mádl-Szőnyi, John Molson, Okke Batelaan, Hanneke Verweij, Xiao-Wei Jiang, José Joel Carrillo-Rivera, and Ádám Tóth

The theory of regional groundwater flow is sixty years old in 2023, which has made it possible to evaluate groundwater flow systems and evolution in sedimentary basins. Recently, the approach has been extended to different environments in the Earth's crust. By applying regional groundwater flow theory, we can solve groundwater issues on a larger scale than for single aquifers. Application of the concept contributes to all practical aspects of groundwater topics, including the UN’s Sustainable Development Goals for water.

However, the developed terms related to groundwater flow evaluation need to be more strictly defined and clarified for interpreting complex hydrogeological flow systems. The presentation summarizes the results of discussions among RGFC-IAH board members on this topic and tries to provide some necessary frameworks for the future application of the concept.

At regional scales, groundwater flow evaluation should include the concept of aquifer systems. The term artesian basin has become obsolete because it implies impermeable layers in natural environments; groundwater basin is preferred instead. Sedimentary basin is a broader term which can contain more than one groundwater basin. For the goals of flow system evaluation, the term groundwater basins can be used, which are characterized by siliciclastic basin fill and basement aquifer systems. The full-groundwater basin is required for 2D and 3D interpretations, because half- (or symmetric-) basin assessment can provide misleading results. Hydraulic continuity is a fundamental principle in groundwater flow evaluation, it can be assumed in groundwater basins across multiple aquifers, aquitards and faults, as long as one has no contradicting evidence. Conceptual groundwater flow models need to be tested with specific field data, numerical simulations and groundwater flow-related manifestations.

The presentation aims to initiate a discussion on improving the application of regional groundwater flow theory. The conference presentation is supported by the National Multidisciplinary Laboratory for Climate Change, RRF-2.3.1- 21-2022-00014 project.

How to cite: Mádl-Szőnyi, J., Molson, J., Batelaan, O., Verweij, H., Jiang, X.-W., Carrillo-Rivera, J. J., and Tóth, Á.: Evolving concepts and communication: what do we need to evaluate better regional groundwater flow?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-14159, https://doi.org/10.5194/egusphere-egu23-14159, 2023.