HS8.2.1

Rapid urbanization and climate change pose a serious threat to the groundwater resource of urban regions in terms of contamination and excessive groundwater abstraction. To understand and protect groundwater resources from anthropogenic activities, an index-based vulnerability assessment model which integrates future climatic variables and land use (LU) is needed. This study attempts to identify the impact of climate and land use change on future groundwater vulnerability of rapidly urbanizing South Asian city, Chennai Metropolitan Area (CMA), India using DRASTIC-LU model under RCP4.5 and RCP8.5 scenarios for near (2020-2035) and far future period (2035 - 2050). The dynamic variables of the DRASTIC-LU model such as depth to groundwater - D, net recharge - R, and land use - LU were projected using regional climatic models and land change modeler. Three regional climatic models (RCMs) namely ICHEC-EC-EARTH, MIROC-MIROC5, and CNRM-CERFACS-CNRM-CM5 were compared and selected using Taylor’s diagram. The ICHEC-EC-EARTH model was found to perform better than the other two RCMs for this region and was used to project future climatic variables under RCP4.5 and RCP8.5 scenarios for two future periods (4 scenarios). Terrset land change modeler (LCM) was used to project future land use for the years 2030 and 2050. Vulnerability condition of the base period (2018) was assessed using nitrate concentration and vulnerability indices, the developed DRASTIC-LU model produces an accuracy of (AUC = 0.796). The projected groundwater vulnerability depicts an increase in vulnerability area from the base period as 21.41%, 30.09%, 20.98%, and 22.01% for scenario-1,2,3 and 4 respectively. Variation in precipitation pattern contributes to change in future net recharge and groundwater level and increased built-up region, i.e, change in land use attributes to increase in future groundwater vulnerability. Based on future vulnerability analysis, it is identified that the CMA groundwater system is in critical condition of high vulnerability for near and far future periods. 

How to cite: Lakshminarayanan, B., Ramasamy, S., and Karuppanan, S.: Groundwater vulnerability of megacity under changing climate and land use scenarios, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-1828, https://doi.org/10.5194/egusphere-egu22-1828, 2022.

It’s now recognized that a global climate change is taking place, leading to an increase in temperatures and a variation in precipitation regime, also affecting groundwater (GW) (Taylor et al., 2013).

In this study we want to evaluate how climate variability affects GW temperature (GWT) in the Piedmont Po plain (NW Italy).

The Piedmont Po plain covers the 27% of the whole region and it’s the most important GW reservoir of Piedmont. It consists, from top to bottom, by Alluvial deposit complex (lower Pleistocene-Holocene), that hosts a shallow unconfined aquifer, the “Villafranchiano” transitional complex (late Pliocene-early Pleistocene), that hosts a multilayered aquifer, and a Marine complex (Pliocene) hosting a confined aquifer.

For this research, 41 wells in the shallow aquifer and 20 weather stations were selected throughout the Piedmont Po plain area, and GW and air temperature parameters were analysed for the period 2010-2019.

Both GW and air temperature data (respectively, GWT and AT) were firstly studied with basic statistical analysis (mean, maxima, minima) and then with the Mann-Kendall and Theil-Sen methods to evaluate the trend.
The AT monthly mean data have a mean increase of 1,69 °C/10years; the monthly mean GWT also show a general increase in all the plain, with a mean of 0.85 °C/10years.

Then to compare water and air temperature, the Voronoi polygons method was used on QGis by centring the polygons on the weather stations. From this comparison, it was possible to highlight that in most cases (37 on 41, thus 90% of the analysed couples of temperature data) there is a greater increase in the monthly mean AT than in the monthly mean GWT.

The same behaviour was observed for the monthly minima and maxima GW and AT.

These results testify a greater resilience of GWT to climate variability. Future insights will be a detailed analysis of the factors influencing the more or less evident increase in GWT in relation to AT (e.g. depth of the water table, position of the monitoring well, position of the probe inside the well).

References

Taylor R.G., Scanlon B., Döll P., Rodell M., van Beek R., Wada Y., Longuevergne L.,

Leblanc M., Famiglietti J.S., Edmunds M., Konikow L., Green T.R., Chen J.,

Taniguchi M., Bierkens M.F.P., MacDonald A., Fan Y., Maxwell R.M., Yechieli

Y., Gurdak J.J., Allen D., Shamsudduha M., Hiscock K., Yeh P.J.F., Holman I.,

Treidel H. 2013. Ground water and climate change. Nat. Clim. Change 3, 322-329.

How to cite: Egidio, E., Lasagna, M., Mancini, S., and De Luca, D. A.: The impact of climate change on groundwater temperature of the Piedmont Po plain (NW Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7242, https://doi.org/10.5194/egusphere-egu22-7242, 2022.

As groundwater does not follow human-drawn boundaries such as country borders, groundwater pollution in one country can adversely affect groundwater quality and availability in a neighboring country. It is vital to develop a conceptual understanding of shared groundwater resources not only to ensure their protection, but also to avoid future conflicts, especially in a changing climate. Both the Water Convention and EU Water Framework Directive emphasize the need for joint assessment and management of transboundary groundwater resources (commonly referred to as “transboundary aquifers” or “groundwater bodies''), and it is crucial to establish a representative transboundary groundwater monitoring network to gather the necessary data. Often, the coverage of monitoring points in the existing groundwater monitoring networks is scarce in the peripheral areas and the installation of new wells would be economically unreasonable. Springs are natural groundwater outflows that can fill gaps in monitoring networks. Monitoring springs can be cost-effective, make water sampling easier, moreover, their water can provide information on a significantly larger catchment area than monitoring wells. The spring site cannot be selected like monitoring wells, so selecting the best springs requires a thorough preliminary assessment. A good conceptual understanding of the recharge area is a prerequisite for the selection of suitable monitoring springs. In this study, 46 springs in the transboundary area of Estonia and Latvia (NE Europe) were screened in 2021-2022 for a variety of geochemical parameters (field parameters, major ions, biogenic and trace elements, water stable isotopes). Some springs were sampled more than once to assess seasonal variability. Then springs were clustered based on their geochemical characteristics using multivariate statistics. This study is the first step in the procedure established on how to select representative springs for transboundary aquifer monitoring.

This study is financed by the Interreg Estonia-Latvia cooperation program project “WaterAct”, the EEA and Norway Grants Fund for Regional Cooperation project “EU-WATERRES”, and by performance-based funding of University of Latvia Nr.AAP2016/B041 within the “Climate change and sustainable use of natural resources” program.

How to cite: Koit, O., Retike, I., Terasmaa, J., Bikše, J., Lode, E., Vainu, M., Popovs, K., Babre, A., Abreldaal, P., Sisask, K., Tarros, S., Marandi, A., Hunt, M., Männik, M., and Polikarpus, M.: What we can learn about transboundary aquifers from geochemical signatures of springs, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5008, https://doi.org/10.5194/egusphere-egu22-5008, 2022.

One of the major concerns for agriculturally driven countries like India is said to be the depletion of groundwater. Therefore, understanding the dynamics of groundwater system is prerequisite for assuring its sustainability. According to the GRACE (Gravity Recovery and Climate Experiment) satellite data, the declining TWS (terrestrial water storage) trends are apparent in north and south of India during 2003-2016, while the Narmada river basin, which is situated in the central west of the country, shows apparent increase of TWS. To unravel the possible reasons for this increasing trend, the part of the Narmada river basin was studied. Between 2003 and 2016, two dams (Indira Sagar dam (2005) and Omkareshwar dam (2008)) were constructed in the basin, and the canal systems to supply water for agricultural activities were developed. The canal system was considered to influence water resources availability in the area, and hence, groundwater fluctuations and groundwater storage. To understand the impact of the canal system on groundwater behavior, the well water levels were analyzed based on two timelines, i.e., before (1996-2010) and after the canal operation (2011-2017) in the Omkareshwar canal command area. The wells were classified into three groups, i.e., those located nearby the canal network, nearby the river network, and outside the canal command area. Pre-monsoon (dry) and monsoon (wet) seasons were chosen for the analysis. The results indicated that, after the canal operation, only the wells located nearby the canal showed the average well water level increase with about 2.56 m in pre-monsoon and 1.97 m in monsoon season, respectively. Whereas, the wells located nearby the river network showed very small changes, i.e., about 0.53 m drop in pre-monsoon and 0.84 m drop in monsoon season, respectively. Similarly, the wells outside the canal command area showed only 0.18 m drop in pre-monsoon and about 0.42 m increase in monsoon season. In summary, the groundwater well levels were observed to increase in wells located near canal system, after the canal operation, in both pre-monsoon and monsoon seasons with a considerable water depth of approximately 2 m. These distinct differences observed in the well water level changes indicated that the Omkareshwar canal system has been influential to the groundwater storage in the study area, and this may at least partly explain the reason why the terrestrial water storage has increased in this area.

How to cite: Shiradhonkar, S. and Tokunaga, T.: Changes in groundwater levels by introducing the canal system in the basaltic aquifer of Narmada basin, Central India, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6112, https://doi.org/10.5194/egusphere-egu22-6112, 2022.

Water resources are under high stress worldwide due to multiple factors. There is a general need to develop better and more efficient management practices. Understanding groundwater and surface water as one source is crucial for this determination. A clear comprehension of groundwater and surface water interactions as an integrated system requires a good knowledge of topography, geology, and climate. This research analyzes the spatiotemporal variation and availability of surface water resources and groundwater recharge in a highland basin using a comprehensive hydrological model. The hydrological model is based on the Soil and Water Assessment Tool (SWAT), allowing spatially distributed assessment using sub-basin and hydrological response units. The case study is the Upper Lerma River basin located in the central part of Mexico. Its location and topography (highland) have made its aquifer the second most source to satisfy the water demand of Mexico City since 1940. As a result, groundwater levels have declined, and springs in the surrounding mountainous regions have progressively disappeared over time. Although few studies attempted to estimate recharge and variability, a lot is unknown to analyze the declining water resources in the basin. This research contributes to understanding the basin water resources using the modeling approach, which integrates topography, land use, soil, and climate data to calculate different water cycle components in space and time. The analysis period is 1985-2017. Statistics of model calibration show a good correlation between the computed and measured discharges from 1995 to 2003 with a Nash-Sutcliffe Efficiency (NSE) value of 0.77, an R² value of 0.79, and a PBIAS of -1%. The preliminary results show that the foothills and alluvial fans are the most extensive recharge areas, which agree with the piezometric data. Detailed analysis on recharge and surface runoff is ongoing.

How to cite: Ortiz, F., Zhang, Z., Maskey, S., Zhou, Y., and McClain, M.: Assessment of spatiotemporal variations of groundwater recharge in the Upper Lerma River basin using a process-based hydrological model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6511, https://doi.org/10.5194/egusphere-egu22-6511, 2022.

Artificial recharge in urban and peri-urbans areas is not a typical practice, but the prolonged severe drought in central Chile has encouraged the study of this practice as an option for optimal and sustainable water management. The Andean piedmont of Santiago (Chile) has been urbanized that implies high water consumptions and increasing irrigation, which in turn acts as a new groundwater recharge. We simulated the period 1989-2015 using an integrated surface and subsurface model (WEAP-MODFLOW) to evaluate the impact of urbanization in groundwater recharge in a representative catchment in the area. An artificial recharge injection of 100 l/s (60,480 m3/day) was introduced in the model for a period of 26 weeks in a specific year (2009, between week 27 to 52, included). The recharge wells were implemented in key zones of the upper aquifer and monitoring wells were also implemented in different zones. The artificial recharge reproduced the hydraulic dome created by the infiltration flow, locally reaching a height of 6 m and beginning to dissipate approximately at 2.5 km (≤ 0.5 m) from the injection point. Moreover, we created a zone budget control section (2 km downstream) and we observed impacts on the water level in this sector, with a 1-year lag  year after starting artificial recharge. The maximum impact was observed after approximately 1.5 years. Not only the study watershed has a high natural storage capacity, which benefits natural water retention, but its average residence time (4 years) is quite. Thus, our results could encourage different public or private stakeholders in the watershed to implement low impact development practices that could infiltrate water to cope with water shortage periods.

How to cite: Sanzana, P., Vargas, M., Muñoz, M., Soto, C., Gironas, J., and Braud, I.: Artificial recharge effects in water balance of a peri-urban semi-arid catchment: a case study in an Andean aquifer using WEAP-MODFLOW, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10479, https://doi.org/10.5194/egusphere-egu22-10479, 2022.

Permafrost is defined as perennially frozen ground (soil or rock and included ice and organic material) with a temperature near or below 0°C that remains for at least two consecutive years. Permafrost occurs mainly in high latitudes of the Southern and Northern Hemispheres, but significant area can also be found in the middle- and low-latitude regions. In these areas, the groundwater cycle is mainly controlled by the permafrost layer that may act as an aquiclude and hence block or retard the groundwater flow. However, rapid climate changes which are observed during the last decades, markedly contribute to permafrost degradation. New connections between permafrost and groundwater are expected to form during the permafrost thawing process. This will contribute to enhance permafrost and groundwater interaction and reinforce groundwater discharge. In general, groundwater discharge is a groundwater movement from the saturated ground to the surface water bodies or submarine groundwater inflow into the sea. Increased groundwater discharge may transport a significant amount of nutrients, metals, and gases to land and ocean waters and hence may change their physicochemical parameters. Unfortunately, due to the limited number of studies, understanding the significance of groundwater discharge in the Arctic regions is limited.

The study aims to provide a comprehensive review of the present literature data that contribute to better understanding interaction between permafrost and groundwater in the Arctic regions, which are particularly vulnerable to climate changes. This review is focused on permafrost thawing, groundwater discharge, and recharge processes and their implication on the environment. We attempt to answer the following questions: How does permafrost affect groundwater discharge and recharge? Does permafrost act as a hindrance for groundwater? How does progressive global warming and thereby permafrost thawing impact the groundwater discharge? How significant is groundwater discharge? How important is the transport of different solutes to the environment by groundwater discharge?

Based on the literature, we can conclude that the degradation of permafrost greatly influences hydrological systems in cold zones. Permafrost has a strong impact on fluid dynamics caused by negligible hydraulic conductivity. This relationship, beyond all physical, chemical, and biogeochemical responses, contributes to the formation of complex permafrost–groundwater interactions. Permafrost degradation strongly affects the ecosystem through direct and indirect impacts on the transport and cycles of different compounds, elements, and ions. Moreover, all processes are dependent on topography, geomorphology, tectonics, and surface hydrology. Research conducted in other than Arctic permafrost areas also indicated that permafrost thawing is the cause of enhanced groundwater recharge and discharge rates, which resulted in deeper water tables and groundwater flow paths. However, comprehensible and systematic studies are still needed for global assessment also in terms of searching for interdependencies between different regions.

This belongs to Project No. 2019/34/H/ST10/00645 "Submarine Groundwater Discharge in a Changing Arctic Region: Scale and Biogeochemical impact", which is supported by the Norwegian Financial Mechanism and Polish national Basic Research Program.

How to cite: Diak, M., Borecka, M., Böttcher, M. E., Hong, W.-L., Knies, J., Kotwicki, L., Kuliński, K., Lepland, A., Koziorowska-Makuch, K., Sen, A., von Ahn, C. M. E., Winogradow, A., and Szymczycha, B.: Permafrost and groundwater interaction, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12719, https://doi.org/10.5194/egusphere-egu22-12719, 2022.

The aim of this study is to identify salient patterns of groundwater level dynamics in the Baltic region. The study investigates correspondence between (grouped) groundwater level dynamics and catchment, well and physiographic site characteristics. The analysis was carried out in five consecutive steps. Firstly, 1691 groundwater hydrographs were collected from Baltic surveys responsible for national groundwater level monitoring (Latvain Environment, Geology and Meteorology Centre; Estonian Environment Agency; Geological Survey of Lithuania). Observation wells represent both unconfined and confined aquifers. Groundwater level time series were checked for errors and treated according to an approach proposed by Retike et al., 2021. Secondly, the dataset was limited to the time period when daily groundwater level measurements were available in all three countries. The resulting time period covers 8.5 years at 689 wells. Then, the acceptable amount of missing values was defined as the balance between most complete hydrographs, the number of retrained hydrographs and spatial coverage of the wells. Gaps (if present) in the remaining 283 wells were filled with missForest (Stekhoven and Bühlmann, 2012). The results were visually inspected to identify groundwater hydrographs with suspicious modeling patterns and five wells were removed from further analysis based on expert judgment. Finally, 278 groundwater hydrographs (136 from Latvia, 58 from Lithuania and 86 from Estonia) were retained and clustered using Hierarchical Cluster Analysis. The identified clusters of groundwater level times series were then explained using descriptive geological (like aquifer lithology, thickness), hydrological (distance to the nearest stream), climatic (precipitation, seasonality) and anthropogenic (land use) characteristics. This research is funded by the Latvian Council of Science, project “Spatial and temporal prediction of groundwater drought with mixed models for multilayer sedimentary basin under climate change”, project No. lzp-2019/1-0165.

References:

Retike, I., Bikše, J., Kalvāns, A., Dēliņa, A, Avotniece, Z., Zaadnoordijk, W.J., Jemeljanova, M., Popovs, K., Babre, A., Zelenkevičs, A., Baikovs, A. (2022) Rescue of groundwater level time series: How to visually identify and treat errors. Journal of Hydrology, 605, 127294. https://doi.org/10.1016/j.jhydrol.2021.127294

Stekhoven, D.J., Bühlmann, P. (2012) Missforest-Non-parametric missing value imputation for mixed-type data. Bioinformatics, 28, 112–118. https://doi.org/10.1093/bioinformatics/btr597

How to cite: Retike, I., Bikše, J., Kalvāns, A., Popovs, K., and Haaf, E.: Clustering of groundwater hydrographs to reveal common patterns for the Baltic region, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-7841, https://doi.org/10.5194/egusphere-egu22-7841, 2022.

A multi-disciplinary approach for the hydrogeological assessment and characterization of groundwaters in a coastal area with high anthropogenic pressure and ongoing seawater intrusion phenomena is presented. Such phenomena are increasingly widespread in coastal areas all over the world and could seriously threaten groundwater resources and socio-economic development of territories.

The coastal plain of Muravera, in south-eastern Sardinia (Italy), has been studied since the sixties because of important seawater intrusion phenomena. Over the years, many research and studies, including geological, geophysical and geochemical, have been carried out, but dynamics and processes controlling the groundwater flow system were not fully understood. To define a three-dimensional (3D) hydrogeological conceptual model, all the available existing data were integrated within a 3D GIS environment along with those collected during new field surveys, including piezometric, hydrochemical and multi-isotope data, namely deuterium and oxygen isotopic composition of water (δ²H and δ¹⁸O), tritium(³H), strontium (⁸⁶Sr/⁸⁷Sr), and boron (δ¹¹B). Stratigraphic logs and geophysical, interpreted according to a geological–depositional model based on sequential stratigraphy, allowed to constrain the geometry of the groundwater system, resulting in a complex multilayer aquifer, mostly phreatic and locally confined. Results from bulk chemistry and isotopes provided information regarding recharge sources, flow paths and residence times of groundwaters.  Four main flow paths, including lateral recharge from bedrock, surface water infiltration from the Flumendosa river and Rio Flumini Uri, and the occurrence of young mixing processes between fresh and sea waters were recognized. Moreover, a major contribution of meteoric water to groundwater recharge has been documented.

The proposed approach improves the understanding of the aquifer system under investigation and reduces uncertainties about main groundwater dynamics. Moreover, results of the conceptualization become new input information and data required in the development of a groundwater flow numerical model. The latter represents a useful tool for an efficient management of groundwater resources aimed at improving the quality and availability of water resources by local government.

How to cite: Arras, C., Biddau, R., Botti, P., Buttau, C., Cidu, R., Funedda, A., Lobina, F., Loi, A., Lorrai, M., Porru, M. C., Testa, M., and Da Pelo, S.: A multi-disciplinary approach to characterize groundwater systems in coastal areas: the case studies of the Muravera Plain (Sardinia, Italy), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-12780, https://doi.org/10.5194/egusphere-egu22-12780, 2022.

Mountain aquifers represent one of the largest and most valuable water sources, necessary to meet the population's water needs. Over time, they have been threatened by huge anthropogenic exploitation activities, which are currently leading to the depletion of aquifers in many regions worldwide. Furthermore, the vulnerability of groundwater resources is rapidly increasing due to climate change, urbanization, massive industry production, intensive agriculture, and breeding.

Knowledge and forecasting about groundwater flow systems are required to guarantee proper management and territorial planning strategies, according to the mountain environmental evolution taking place. Besides, examining how groundwater storage mechanisms in different regions have changed in response to both climate-driven and anthropogenic effects is becoming increasingly crucial.

In remote alpine areas, continuous monitoring and data collection of springs’ hydrogeological parameters is still often hampered by technical and logistical problems. In these contexts, new automated techniques and tools need to be applied to monitor springs’ hydrogeological parameters, punctually understanding the dynamics of exhausting of the available groundwater resources.

The instrumentation and sensors complex, installed in correspondence with the Mascognaz spring basin (Aosta Valley, Italy) allows detailed analyses of the surface and underground groundwater system, recording continuously hydrogeological variables entering and leaving the spring recharge system. A cutting-edge weather station was here combined with a spring monitoring system through snowpack-hydrometeorological sensors installation. This setup, composed of a snow scale, ultrasonic and laser sensors for snow weight and snow depth reading, provides the possibility of a detailed study of the snow layer evolution during each season. Besides, a multiparametric probe allows water discharge, temperature and electric conductivity values detection.

The high quality of the data provided and the small-size basin features have permitted highlighting the variables affecting the system and standing out those are evolving in time. Besides, the relationship between changes in weather conditions and water availability can be defined by performing correlations between different hydrogeological and meteorological available data series.

The Mascognaz spring’s pilot site could be helpful as an example for other researchers and authorities who need to identify suitable instruments, sensors and methods to reconstruct the groundwater flow system and hydrogeological structure of a mountain basin.

How to cite: Mondani, M., Gizzi, M., Taddia, G., and Lo Russo, S.: Cutting-edge tools for spring monitoring and groundwater system characterization in mountain environments, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9835, https://doi.org/10.5194/egusphere-egu22-9835, 2022.

Weathering and erosion of rocks and sediments containing Naturally Occurring Asbestos (NOA), together with run off from mine tailings deposits containing non-exploitable fibrous minerals, may result in asbestos (and other asbestiform minerals non-asbestos classified) fibres dispersion in surface waters and groundwater.

Asbestos is considered highly carcinogenic to humans when is respired (Group 1 by IARC). Therefore, in the past, asbestos occurrence has been mainly monitored in air and not considered in other matrices, such as water. Nowadays, waterborne asbestos is gaining new attention since it can constitute a non-conventional exposure way. Indeed, as groundwater and surface waters resources are exploited for both agricultural and industrial activities and as a source for tap water, water contamination by asbestos could pose a risk related to possible water-to-air migration of fibres, thus being a secondary source of airborne asbestos, and to possible ingestion (particularly when present in the tap water). Therefore, asbestos could be considered as an Emerging Pollutant in water because, historically, it has not been systematically monitored in this matrix and it could actually represent a problem for human health and environment.

NOA-containing rocks are widespread in Italy, such as in northwest (NW) and Central Alps and also in the Apennines. In NW area, possible diffusion of asbestos in water has been recently considered as a consequence of interactions between water and ophiolitic rocks or related sediments. Migration through water (particularly groundwater) far away from the pollution source, which has been considered negligible until recently, has gained new attention since column-based laboratory study has highlighted asbestos mobility through porous media under particular conditions, suggesting that the same could happen in the environment.

Knowing this background, it is particularly important to investigate possible fibres diffusion in porous aquifers and their transport linked to aquifer characteristics, dimension and morphology of fibres, their chemical composition and surface charge.

To better understand groundwater flow and fibres transport, a laboratory test has been set in collaboration with Politecnico di Torino using a packed column in which polluted water movement was forced. Several tests have been done using different material to pack the column with various granulometry and changing water characteristics, such as asbestos fibres concentration and ionic strength.

Details regarding the experimental setup and first data on the tests will be presented to better define possible groundwater contamination by asbestos fibres and their movement through porous aquifers. These data will help to understand how reservoir peculiarities (geology, hydrogeology) and anthropogenic activities could influence mineral fibres presence and movement in the water system and, more generally, would help to monitor asbestos (and asbestiform) fibres transport due to water flowing in NOA rich settings or in areas where uncontrolled mine tailings deposits are present.

How to cite: Lasagna, M., Avataneo, C., Magherini, L., Belluso, E., Capella, S., Sethi, R., and De Luca, D. A.: Evaluation of possible asbestos fibres movement in porous aquifers through laboratory column tests, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4772, https://doi.org/10.5194/egusphere-egu22-4772, 2022.

The PRIMA Sustain-COAST European project aims at exploring innovative governance for sustainable coastal groundwater management and pollution reduction in the context of a changing climate by involving researchers, local citizens, water stakeholders, and policy makers in interactive dialogue. Four study sites have been selected, among them the Wadi El-Bey watershed in Tunisia, located about 40 km south of Tunis. The study area is the Grombalia aquifer whose size is approximately 391 km². It is boarded to the north by the Gulf of Tunis and the Tekelsa Hills, to the east by the Abderrahman Mountain and the oriental coastal highlands, to the south by the Hammamet Hills, and to the west by the Bou Choucha and the Halloufa mountains. The Grombalia aquifer is bounded northward by the Mediterranean Sea and westward by the Gulf of Tunis. It constitutes a complex aquifer system formed by shallow unconfined, semi deep, and deep aquifers with different exploitation levels. The interest of the study relies on the upper aquifer. Surface flow occurs mainly in 5 wadis toward the north, reflecting regional topographic gradients.

During the last few decades, the Grombalia shallow unconfined aquifer had been under stress by groundwater pumping due to the increasing population and development of agricultural and industrial activities. Recently, it has been noticed in some wells a rise in the level of the water table due to the abandonment of the exploitation of surface wells and to the irrigation by the water transferred from the north of the country, and considerable deterioration of groundwater quality due to saltwater intrusion and increased nitrate contamination as well as the organic matter in terms of COD.

A groundwater numerical model for the Grombalia aquifer has been developed using Feflow 7.4 to simulate groundwater level changes under steady state and transient conditions. The steady state flow calibration was carried out using the water levels measured 1972 in 35 observation wells and then used as initial state of the Grombalia aquifer system. To show the influence of groundwater management, especially for agricultural activities, and interaction with surface water, measurements of water level, water temperature, pH, electric conductivity and water quality data (e.g., nitrate concentration) have been conducted during the 2020 field campaign, at selected monitoring wells and in neighbouring transects of surface water.

The groundwater model constitutes a solid basis for further studies under transient flow and transport conditions to compare different water management, climate change and contamination scenarios, and is part of the calibrated multi-criteria decision supporting system developed in the PRIMA Sustain-COAST project context.

References

The project is funded by the General Secretariat for Research and Technology of the Ministry of Development and Investments under the PRIMA Programme. PRIMA is an Art.185 initiative supported and co-funded under Horizon 2020, the European Union’s Programme for Research and Innovation.

How to cite: Baccouche, H., Lincker, M., Akrout, H., Mellah, T., Anane, M., Ghrabi, A., Karatzas, G. P., and Schäfer, G.: Assessment of the influence of surface water on groundwater quality related to the Wadi El-Bey watershed (Tunisia) using field sampling and quantitative groundwater modelling, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4516, https://doi.org/10.5194/egusphere-egu22-4516, 2022.

Alluvial plains are an important agricultural area because of favourable soil properties, topography, and proximity to surface and groundwater resources. The predominant land use in the alluvial plains is agriculture, but there are also many urban and industrial areas. Groundwater bodies beneath the alluvial plains are threatened by nitrate pollution from agricultural activities and urban sources such as faulty sewage systems. For the Krško-Brežiško polje case study, an assessment of nitrate sources in groundwater was conducted using stable isotopes (δ¹⁵N) to produce maps of groundwater vulnerability. In addition, stable isotope composition of groundwater (δ¹⁸O and δ²H) was used to obtain information on the characteristics of the recharge area. Nuclear techniques (i.e., stable isotopes) are excellent for determining pathways and travel times of contaminants through the vadose zone in soil-groundwater systems, especially in areas with shallow aquifers. Results show contamination from manure application and the potential to reduce pressures on groundwater for specific sampling points.

This research was financed by the ARRS L4-8221 URAVIVO and IAEA TCP SLO5004 Improving Water Quality in Vulnerable and Shallow Aquifers under Two Intensive Fruit and Vegetable Production Zones.  

How to cite: Zupanc, V., Koroša, A., Cerar, S., Urbanc, J., Adu-Gyamfi, J., Halder, J., and Pintar, M.: Groundwater quality determination using stable isotopes, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9607, https://doi.org/10.5194/egusphere-egu22-9607, 2022.

Lake Velence is a shallow soda lake in Hungary that is located in a tectonic subsidence in the southern foreland of the Velence Hills. Since the lake is semi-astatic (the volume and level of water in the lake fluctuates frequently), climate has a serious effect on its water budget. Until recently, the groundwater inflow into the lake has been neglected and only the recharge from surface water and rainwater have been taken into account. Because increasing climate change threatens the existence of the lake and its unique ecosystem, it is important to properly assess the components of the lake's water budget.

To understand the role of groundwater for the lake-water quantity and quality, the groundwater flow patterns were mapped constructing pressure-elevation profiles and tomographic potential maps. During our research, 15 water samples were collected from groundwater wells, springs and from the  Lake Velence. Physico-chemical properties of the water (e.g. temperature, pH, redox potential, specific electrical conductivity) were recorded during sampling on the field. The samples were analyzed for major ions (Ca, Mg, Na, K, HCO₃, SO₄, Cl). To verify the results of the groundwater flow mapping, stable isotopes (O, H) and radioactive isotopes (Ra, Rn, U) were applied as natural tracers. δD and δ18O were measured by using PICARRO L2130-i δD/δ18O Ultra High-Precision Isotopic Water Analyzer. ²²²Rn activity concentration was determined by using TRICARB 1000 TR liquid scintillation detector. The ²³⁴U+²³⁸U and ²²⁶Ra activities were measured by a unique method, alpha spectrometry using Nucfilm discs.

The p(z) profiles indicated that recharge areas are dominant south from the lake, while groundwater discharges along the lake’s shoreline.  According to the tomographic potential maps, the regional groundwater flow travels from the Velence Hills toward the regional base level (River Danube). The water chemistry analysis indicated that the majority of the water samples can be classified as Ca-Na-HCO₃ and Ca-Na-HCO₃-Cl-SO₄ type waters. δD measures were between -98.4 and -13.4‰; while δ18O values were between -13.4 and 0.15‰. Most of the samples are characterized by relatively high ²³⁴U+²³⁸U activity concentration (up to 497 mBq L^–1). Based on δD and δ18O values, groups of groundwater having different recharge environment, can be distinguished. This is in line with the results of the groundwater mapping: a deep regional flow system with longer residence time and more shallow local flow systems with shorter residence time can be identified. The dominance of recharge areas and the presence of local flow systems can be further supported by the ²³⁴U+²³⁸U measurements, because uranium can be mobilized by the groundwater primarily under oxiziding conditions. It was revealed that groundwater contribute to the lake's water budget and the lake is fed by local groundwater flow systems known to be more sensible for the climate changes.

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.

How to cite: Baják, P., Hegedűs-Csondor, K., Tiljander, M., Korkka-Niemi, K., Izsák, B., Vargha, M., Pándics, T., Horváth, Á., and Erőss, A.: Investigation of the contribution of groundwater to the water budget of a shallow soda lake in Hungary by using stable and radioactive isotopes as natural tracers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10323, https://doi.org/10.5194/egusphere-egu22-10323, 2022.