Jeannin, Pierre-Yves; ISSKA, Switzerland
Jourde, Herve; HydroSciences Montpellier, France
Gill, Laurence; Trinity College Dublin, Ireland

Most hydrogeological and hydrological studies in karst environments aim somehow at characterizing the shape and time variations of the groundwater flow systems, sometimes in strong interaction with surface water and rivers.

Mahamadou, Koita; International Institute for Water and Environmental Engineering, Burkina-Faso
Lachassange, Patrick; Université de Montpellier, France
Soro, Dimitri; International Institute for Water and Environmental Engineering, Burkina-Faso

Crystalline rocks (plutonic and metamorphic rocks) are exposed over vast areas of the Earth’s surface, and their groundwater resources are of great interest for both ecosystems and anthropogenic uses on all continents, and notably Africa, India, South America. Such aquifers have been the subject of constant interest from hydrogeologists for decades; however, the conceptualization of crystalline aquifers has evolved significantly over the last 20 years, with the revelation of the predominant role played by weathering processes in the development not only of the aquifer’s upper capacitive layer (the saprolite), but also of the underlying, essentially transmissive fractured layer. This model still needs to be improved, particularly for metamorphic rocks, which have been much less studied than plutonic rocks.

Volcanic rocks are exposed over vast areas of the Earth’s surface, and their groundwater resources are of high interest for both ecosystems and anthropogenic uses.
Such aquifers have been the subject of constant interest from hydrogeologists for over 50 years. Although early research focused mainly on the Hydrogeological Conceptual Models (HCMs) in recent basaltic oceanic islands, andesitic aquifers, mainly from subduction zones, have been the subject of growing scientific and socio-economic interest for the past fifteen years, mostly for their groundwater resources but also, in some cases, as candidate rocks for hosting wastes or for geothermal energy. However, many gaps in knowledge remain to be filled, and other types of volcanic aquifers, such as the one imbedded in trapps, need to be studied.

Rausch, Randolf; Technische Universität Darmstadt, Germany
Scheytt, Traugott; Technical University Bergakademie, Freiberg

Most of our society’s future challenges will be linked to geoscientific issues such as the limited availability of geo resources, like water, soils, fossil and renewable energies. It is widely predicted that global water consumption will double, from the consumption levels of the 1960’s to that predicted in 2025. This is of great concern especially in arid and semiarid areas where water resources are often dramatically overexploited. Considering this, it is understandable that in arid regions sustainable use of water resources is challenging.
Smart and efficient concepts are needed to manage water resources with the greatest possible benefit for the society. This requires a fundamental understanding of hydrodynamic processes of the local and regional hydrogeology, as well as a precise quantification of the water resources. Good management can be achieved only on robust data rather than based on general estimates. For scientists is a great responsibility and opportunity at the same time.

The objective of our session is to understand the dynamics of groundwater resources under changing climate and hydrological conditions and to address the challenges in groundwater use. The session will focus on the assessment of the water cycle and its interactions, the assessment of groundwater resources, economic processes and aspects of water resources engineering and management in arid and semiarid environments.

Roques, Clement; CHYN, University of Neuchâtel, Switzerland
Landon, Halloran; CHYN, University of Neuchâtel, Switzerland
Arnoux, Marie; Crealp, Switzerland
Tolotti, Monica; Istituto Agrario San Michele All’Adige, Italy
Thornton, James; Mountain Research Initiative, University of Bern, Switzerland
Schaefli, Bettina; University of Bern, Switzerland
Molson, John; Laval University, Quebec, Canada

Mountains are the “water towers” of the hydrological cycle, storing water as snow, ice and groundwater, which is gradually released into valleys. The cryosphere is a key component of alpine hydrology, controlling groundwater storage and streamflow dynamics. Recent observations have shown that the degradation of the cryosphere in response to climate warming has enormous consequences for water availability and quality in mountains. As the intensity of this degradation is likely to increase in future climates, with important implications for interdependent natural and socio-ecosystem services, there is an urgent need for reliable predictions of the future evolution of cryo-hydrogeological systems in the alpine context.

This session aims to bring together a multidisciplinary group of scientists and stakeholders interested in characterising and predicting the impacts of cryosphere degradation on the availability and quality of groundwater resources and the ecosystems that depend on them. We aim to provide an overview of: 1) the data currently available on a global scale, 2) the current understanding of cryosphere controls on mountain hydrogeological function and their evolution with climate change, 3) advances in coupled cryo-hydrogeological modelling, and 4) discussion of management and adaptation solutions.

Quiroga-Jordan, Elizabeth; Ruden AS, Norway
Bertoni, Claudia; Oxford University, UK
Thomas, Ariel Tremayne; University of Malta, Malta
Lipparini, Lorenzo; Istituto Nazionale di Geofisica e Vulcanologia, Italy
Comte, Jean-Christophe; School of Geosciences, University of Aberdeen, UK

Coastal groundwater involves the complex interplay of terrestrial and marine influences in the transition zone between land and sea. In water-scarce coastal areas, the importance of coastal groundwater cannot be overstated. It serves as a lifeline, supporting ecosystems and communities with a sustainable source of freshwater. The exploration of coastal groundwater encompasses several key topics, each shedding light on different aspects of this intricate system. In this session, we invite communities to contribute to the discussion of the following facets of coastal groundwater research: i) Shallow groundwater dynamics: this includes the examination of near-surface aquifers and the influence of factors such as tidal fluctuations, precipitation, and human activities on groundwater levels; ii) Technologies and innovation for deep groundwater exploration in coastal regions; iii) Offshore freshened groundwater: the presence of freshwater beyond the coastline and below the seafloor. This incorporates the terrestrial groundwater discharges into marine environments (Submarine Groundwater Discharge), and studies on the ecological impact of submarine springs on ocean life; iv) Groundwater modeling within transitional zones, including monitoring of seawater intrusion and mitigating strategies, sustainable groundwater abstraction practices, and the application of advanced modeling techniques; v) Advanced mapping technologies for coastal groundwater studies, geophysical imaging alongside emerging technologies such as remote sensing and Artificial Intelligence enable precise mapping of subsurface structures, groundwater flow paths, and variations in groundwater quality. Accurate mapping is essential for informed decision-making in land-use planning, resource allocation, and environmental protection. This session is organized through a community effort supported by the EU-funded COST Action CA21112: OFF-SOURCE (https://off-source.eu/).

Balderer, Werner; Switzerland
Porowski, Adam; Polish Academy of Sciences, Poland
Lamoreau, Jim; University of Alabama, USA
Halaj, Elzbieta, AGH University of Krakow, Poland

All papers dealing with aspects of mineral and thermal waters are welcome, e.g. hydrogeology of occurrence, chemical and isotopic characteristics, use in spas, medical properties, indications of origin, related tectonic activity including earthquakes and volcanism. Other topics not mentioned but of interest to the mineral and thermal water community are also welcome.

Madl-Szonyi, Judit; Lorand Eötvös University, Hungary
Bresciani, Etienne; University of O’Higgins, Chile
Verweij, Hanneke; TNO, Netherlands
Jiang, Xiao-Wei, China University of Geosciences, China
Carillo Rivera, Joel, Universidad National Autonoma de México, Mexico
Simon, Szilvia; Lorand Eötvös University, Hungary
Condon, Laura; University of Arizona, USA
Kollet, Stefan; Research Centre Juelich & University of Bonn, Germany
Zheng, Chunmiao; Sustech, China
MacDonald, Alan; British Geological Survey, UK

A regional, or basinal approach to groundwater flow and transport from recharge to discharge areas is required for effectively resolving resource issues such as freshwater and energy supplies. This approach contributes to all practical aspects of the UN’s Sustainable Development Goals for water. This session encourages contributions on regional groundwater flow and transport topics such as new approaches and methods in hydrogeologic characterization, advances in modelling techniques, and scenario analysis. The evaluation of uncertainty in predictions, new insights into coupled flow, heat, and/or mass transport systems at the basin scale, and discussions about the concept of regional groundwater flow systems and associated terminology are also welcome. Relevant fields of application include but are not limited to water and energy transition; offshore assessment of fresh groundwater discharge; mountain-block hydrogeology; interpretation of various tracers in groundwater (heat, hydrochemistry, and isotopes); and regional aspects of managed groundwater recharge. Presentations discussing the role of regional groundwater flow systems in the expected transition period due to climate change, intensive extraction, quality concerns, and ecosystem services also align with the session’s objectives. Regional groundwater governance, water conflicts, societal response, and the role of education and outreach will also be considered. This session is proposed by the RGFC-IAH.

Dubois, Emanuel; EPFL, Switzerland
Perona, Paolo; EPFL, Switzerland
Boano, Fulvio; Politecnico di Torino, Italy

Ecohydrogeology can be defined as the topic assessing the interactions between ecology and hydrogeology, therefore implying the study of ecosystem-groundwater feedback loops. Groundwater can be a crucial source of water for entire ecosystems, just as ecosystems can significantly impact groundwater dynamics, both positively and negatively. These ecosystem-groundwater feedback result in quantitative and qualitative impacts on groundwater resources, involving a wide range of ecological and hydrological processes such as vegetation-atmosphere interactions, stream-aquifer exchanges at the riparian corridor scale and beyond, the hydro-geochemical reactions in aquifers, and more. As ecosystem-groundwater feedback loops are strongly connected to the Earth’s surface conditions, they are highly sensitive to anthropo-hydro-climatic conditions, making them responsive to the impacts of global change. In the case of Nature-based solutions, specific ecosystem services on groundwater resources are targeted to mitigate the impacts of global change on water resources. Therefore, better understanding the diverse processes involved in the ecosystem-groundwater feedback loops becomes critical, as they drive the propagation of the impact of global change on the groundwater-dependent ecosystems and on groundwater resources themselves. The goal of this session is to investigate all types of processes involved in these feedback loops, from both ecological and hydrogeological perspectives.

Moeck, Christian; EAWAG, Switzerland
Stumpp, Christine; University of Natural Resources and Life Sciences, Austria
Dubois, Emmanuel, EPFL, Switzerland
Hartmann, Andreas, TU Dresden, Germany
Jimenez-Martinez, Joaquin, EAWAG, Switzerland

Understanding flow and transport processes in the unsaturated zone is critical in mitigating climate change impacts and environmental risks. This session explores the intricate interplay of factors, impacted by extreme events or land use, affecting soil water storage and fluxes as well as water quality, both for local and large scales. Knowledge of chemical fate and transport is crucial for assessing soil functions and risks from microplastics, fertilizers, pesticides or any other chemical components and their storage and transformation in the unsaturated zone. This necessitates a profound comprehension of the dynamic processes in the soil-groundwater-plant system, including unsaturated water flow, solute transport, and plant interactions. Flow and transport processes in the unsaturated zone encompass both the subsurface matrix and preferential flow paths, contributing to water flow, storage, groundwater recharge and chemical fate. The influence of vegetation extends beyond the subsurface’s upper boundary, making it an active participant in the fate of water and chemicals. Moreover, processes in the unsaturated zone control groundwater quantity and quality largely.

Gmünder, Christian; Simultec, Switzerland
Fleckenstein, Jan; UFZ, Germany
Frei, Sven; Universität Bayreuth, Germany

Groundwater is an integral part of the hydrologic cycle and interacts with surface waters (rivers, wetlands, lakes) across different spatial and temporal scales. These interactions modulate the exchange of water, solutes and energy across critical interfaces to rivers, floodplains, wetlands and costal zones with implications for water quantity (e.g. environmental flows, groundwater recharge), water quality (e.g. eutrophication, pollutant buffering) and aquatic ecology (e.g. aquatic fauna, spawning habitat). Understanding groundwater (GW) – surface water (SW) interactions is therefore vital to sustain water quantity and quality as well as healthy aquatic ecosystems.

For example, degraded river systems with clogged river beds may affect drinking water supply form bank filtration due to low infiltration rates and low oxygen saturation. River revitalization projects may improve the situation, but their effects on river – groundwater interactions are still poorly understood. While revitalization may enhance river bed permeability, which would benefit water supply from bank filtration, longer and more frequent drought periods due to climate change could in turn threaten minimum flows vital for the aquatic fauna.

Goeppert, Nadine; Karlsruhe Institute of Technology (KIT), Germany
Doummar, Joanna; American University of Beirut, Lebanon
Schiperski, Ferry; Technical University of Berlin, Germany
Scheytt, Traugott; Technical University Bergakademie, Freiberg

Waterborne diseases caused by pathogenic microorganisms are of major concern in countries where inadequate water quality, insufficient sanitation and water treatment result in preventable illnesses and fatalities. Inorganic particles and colloids in groundwater systems, such as micro- and nanoplastics, tire wear, many metal oxides, micropollutants and other contaminants associated with clay minerals, are of great concern because of their potential adverse effects on human and animal health. At the same time, some selected particles and biocolloids are crucial for the remediation of contaminated aquifers and the subsurface biocenosis is important for a proper functioning of the ecosystem.
Global change scenarios indicate more frequently occurring hydrological extremes (e.g. heavy rainfall leading to extensive flushing, intense hail events and drought) worldwide. This will strongly influence the transport of particles, biocolloids, but also dissolved substances in groundwater. The development of new approaches and methods for vulnerability assessment, modeling, and chemical, biological, and field methods has become eminent to help protect our important groundwater resources and the associated ecosystem and mitigate any adverse effect on the pristine freshwater. This session focuses on state-of-the-art approaches for the characterization of karst, fractured or porous aquifers that inform flow and specific transport assessment. We welcome all research on vulnerability and risk assessment, contaminant transport, and field methods from all disciplines and their application in groundwater protection.

Stigter, Tibor; IHE Delft Institute for Water Education, Netherlands
Chen, Jianyao; Sun Yatsen University, China
Miller, Jodie; International Atomic Energy Agency, Austria
Batelaan, Okke; Flinders University, Australia
Birk, Steffen; University of Graz, Austria
Fan, Xinyang; University of Berne, Switzerland

As the largest and most resilient liquid freshwater reservoir on earth, groundwater has a vital role in adaptation to climate change (CC). On the other hand, CC is impacting groundwater systems worldwide, such as through increasing rainfall intensity, a more frequent occurrence of dry periods and sea level rise. Meteorological drought affects the hydrological processes, but the propagation to groundwater drought is complex, largely influenced by aquifer characteristics and human activities, particularly where water shortage is met by an uncontrolled increase in groundwater abstraction. The impact of increasing rainfall intensity on groundwater recharge is still poorly understood and depends on the intricate interactions between topography, climate, geology and land use. Intense rainfall can further promote the leaching of contaminants, especially in urban and agricultural settings, jeopardising groundwater quality. Sea level rise can enhance seawater intrusion into coastal groundwater systems and is further aggravated by land subsidence caused by excessive pumping, an underrated problem with notorious examples worldwide.

von Freyberg, Jana; Federal Office for the Environment FOEN, Switzerland
Brauns, Bentje; British Geological Survey, UK
Van Loon, Anne; Vrije Universiteit Amsterdam, Netherlands
Lena Tallaksen; University of Oslo, Norway
Bloomfield, John; British Geological Survey, UK
Möck, Christian; EAWAG, Switzerland

The frequency of drought events has increased worldwide, including in Switzerland, and climate forecasts indicate a further increase in the future. While surface water systems such as rivers and lakes are extensively studied for the effects of droughts, our ability to collect and interpret data from groundwater systems remains limited. There is an urgent need to better understand the processes to assess and predict the impact of droughts on groundwater quantity and quality, especially in regions that are highly dependent on groundwater for purposes such as drinking water production, agriculture and ecosystem functioning. In addition, overexploitation of aquifers in times of drought can further exacerbate the stress on groundwater resources. For sustainable water management, it is therefore necessary to assess the vulnerability of groundwater systems to droughts and develop strategies to improve the resilience of groundwater-dependent ecosystems and human communities and activities to drought events.

This session invites contributions that address the following questions How can we assess the vulnerability of aquifers to drought? What methods exist to quantify the impact of droughts on groundwater quantity and quality? What modeling approaches are best suited to predict groundwater response to drought? How can these metrics and modeling results be incorporated into effective aquifer management? The session also aims to identify key knowledge gaps and research priorities in the area of groundwater and drought.

Epting, Jannis; University of Basel, Switzerland
Menberg, Kathrin; Karlsruhe Institute of Technology (KIT), Germany
Egidio, Elena; Università degli Studi di Torino, Italy

Increased thermal use of the subsurface, including passive heat inputs from infrastructure development and active usage of aquifers for cooling purposes or increased managed groundwater recharge in the summer months inevitably lead to an increase in groundwater temperatures. Future global warming combined with anthropogenic adaptation strategies, such as an increased use of groundwater for thermal purposes, will put even more pressure on the thermal state of groundwater resources.

Rising groundwater temperatures in the context of global warming come along with risks and opportunities. On the one hand, solutions have to be found to mitigate the negative effects of climate change on water resources, such as temperature-induced changes in chemical composition and potentially detrimental impacts on groundwater ecosystems. On the other hand, there is great potential for the simultaneous use of thermal energy, in particular for storage and heating purposes. Climate change adaptation strategies should therefore be an integral part of the sustainable management of water resources. In particular, there are opportunities related to unused anthropogenic waste heat, especially in the subsurface of urban areas, and the energy potential that could be tapped through suitable construction measures.

We welcome contributions that introduce new monitoring and modelling approaches, as well as strategies and feasibility studies for the thermal management of urban and rural groundwater resources in the context of climate change, (geo)thermal potentials and possibilities for adaptation measures. Moreover, we also encourage the submission of abstracts on the subject of the impact of temperature variations in groundwater on groundwater ecosystems.

Schirmer, Mario; EAWAG, Switzerland
Hartog, Niels; KWR Water Research Institute, The Netherlands
Nlend, Bertil; University of Douala, Cameroon
Fallas, Helen; British Geological Survey, UK
Dassargues, Alain; University of Liège, Belgium
Cetinkaya, İrem Daloglu; Bogazici University, Turkey
Jampani, Mahesh; International Water Management Institute, Sri Lanka
Gogu, Radu; Technical University of Civil Engineering, Romania

Urban groundwater is an endangered resource as urban land use exerts enormous and very complex pressures on this resource. This session will provide an overview of urban groundwater studies in the context of urban water management, advances in hydrogeological investigation, monitoring and modelling techniques for urban areas, and highlight the challenges. Techniques for measuring pollutant concentrations, water balancing, and pollutant load estimations will be presented. To fully understand and quantify the complex urban water systems, we need to further develop our methods and combine them with new modelling approaches. In addition, it is essential to enter into an in-depth dialogue with people from urban planning, urban drainage and politics as well as the general public to raise awareness of groundwater. Only in this way will we be able to sustainably manage our water resources in and around our urban areas and incorporate them into future urban planning.
For this session we invite especially but not exclusively contributions on the following subtopics:
1. Sustainable management of urban groundwater resource, including water supply from urban groundwater, urban groundwater resource assessment and system analysis, urban groundwater protection, soil and groundwater contamination and remediation, urban water balance, drainage and recharge
2. Groundwater interactions with ecology and the built environment, including dewatering during urban construction, groundwater interactions with urban structures (e.g. subsidence, foundations, infrastructure)
3. Urban groundwater as source and storage for sustainable heating and cooling, including the use of groundwater source heat pump systems, ground source heat pump systems, aquifer thermal energy storage (ATES) systems

Liu, Jiaqi; University of Tokyo, Tokyo

Flood monitoring, modeling, and forecasting are critical components of effective flood management. Recent advancements in technology and scientific methodologies have opened new possibilities for enhancing our understanding of surface water and groundwater processes integral to floods, as well as the underlying controlling mechanisms. This has resulted in improvements to early warning systems and the creation of more precise flood models. This proposed session aims to showcase and discuss cutting-edge approaches in flood monitoring, modeling, and forecasting, with a focus on their practical applications for building resilience in communities exposed to flood risks. The spectrum of flood hazards covered includes not only river floods, but also groundwater floods, tsunamis, storm surges, as well as compound floods driven by multiple types of floods.

Polemio, Maurizio; CNR-IRPI, Italy
Tiwari, Shubham; CNR-IRPI, Italy
Yadav, Brijesh Kumar; Indian Institute of Technology, India

The prospect of a world population of 9 billion by 2050, growing urbanization, intensive irrigated agriculture and climate change will add extra pressure on the water resources and environment. Groundwater is the prevalent source of domestic supply and irrigation. The salinization of groundwater resources, caused by natural phenomena and anthropogenic activities, could be considered the main cause of groundwater quality degradation.

Otero, Neus; Universitat de Barcelona, Spain
Torrento, Clara; Universitat de Barcelona, Spain
Bicalho Bizet, Cristina; SCE Aménagement & Environnement, France
Moinet, Francois Xavier; SCE Aménagement & Environnement, France
Kloppmann, Wolfram; BRGM, France
Baran, Nicole; BRGM, France
Gooddy, Daren; BGS, UK

The 2030 Agenda for Sustainable Development acknowledges the importance of water quality and includes a specific water quality target in Sustainable Development Goal 6. From an environmental perspective, agricultural activities, including crop production and livestock, remain at the core of water quality problems in many parts of the world. The intense use of synthetic fertilizers has increased nitrate content in groundwater to distressing levels for both human and ecosystem health. The global P cycle has also been affected by crop fertilization. Organic fertilizers are also responsible for the introduction of veterinary pharmaceutical products, such as antibiotics, to the subsurface. Moreover, the use of pesticides and their leaching to surface and groundwater can pose risks for aquatic life and water supply. In a context of decreasing water quality, diagnosis, monitoring tools, and mitigation techniques are key aspects for water management.

This session aims to address the challenges and latest advancement with regards to diagnosis (who is the main responsible of pollution), monitoring tools (what is the fate of contaminants in the environment) and mitigation techniques (how can we enhance water quality) of groundwater pollution from agricultural sources, including N, P, and contaminants of emerging concern (CECs) such as pesticides and livestock antibiotics. Topics of interest include, but are not limited to, advances in the characterization of CECs from agricultural origin (including novel compounds and transformation products), multi-tracer techniques for source apportionment (e.g. chemical, isotopic methods, microbial source tracking,…), measurements to trace the fate of contaminants in the environment (chemical, multi-isotopic, non-target analysis and compound specific isotopic analyses of CECs, microbial characterization, estimation of water and contaminant transfer times, and modelling), and mitigation techniques for non-point sources of pollution (specially in situ prevention and remediation techniques and nature-based solutions).

We invite submissions from researchers, and industry experts to share their knowledge and experience in these topics. We also welcome water managers to share their challenges when dealing with agricultural-derived pollution. We aim for a broad geographical representation in the session, and invite all career stage (students, junior, senior, retired) participants to contribute.

Boumaiza, Lamine; University of Waterloo, Canada
Huneau, Frédéric; Université de Corse, France
Re, Viviane; University of Pisa, Italy
Otero, Neus; University of Barcelona, Spain
Blarasin, Monica; Universidad Nacional de Ri­o Cuarto, Argentina
Karthikeyan, Brindha; Freie Universität Berlin, Germany
Stotler, Randy; University of Waterloo, Canada
Stump, Christine; University of Natural Resources and Life Sciences, Austria

Anthropogenic stresses on groundwater quality could be a result of (i) uncontrolled agricultural practices including the excessive use of synthetic/organic fertilizers and pesticides in agricultural fields -to promote crop growth- combined with return flow of irrigation water; (ii) improper industrial waste disposal including discharge of untreated/partially treated wastewater and disposal of solid wastes; and (iii) uncontrolled urbanization leading to potential leakage from sewage systems and/or inadequate sanitation systems. In addition, urbanization may also lead to increase in groundwater extraction causing salinization of inland aquifers or aggravating seawater intrusion in coastal aquifers. Understanding the effects of anthropogenic activities on groundwater quality, distinguishing the sources of groundwater contamination, and identifying the processes controlling groundwater quality are fundamentally important for sustainable groundwater resource management. Multi-tracer approaches, integrating chemical and isotopic tracers, constitute a powerful tool not only for distinguishing the sources of groundwater contamination but also for identifying the processes governing groundwater quality in complex aquifer systems. It is in this context that researchers and professionals, at all levels of their careers, applying chemical and isotopic tracers to investigate the effects of anthropogenic activities on groundwater quality are invited to submit their abstracts to this session. Overall, we encourage the submission of contributions that: (i) demonstrate the influence of anthropogenic activities on groundwater; (ii) investigate the hydro-bio-geo-chemical processes that may affect groundwater quality; (iii) assess the resulting potential impacts on related ecosystems including wetlands, springs, and tributaries; and (iv) develop new methods integrating environmental tracers for investigation of all the above.

Krause, Stefan; University of Birmingham, UK
Yadav, Brijesh Kumar; Indian Institute of Technology, India
Schirmer, Mario; EAWAG, Switzerland
Schneidewind, Uwe; University of Birmingham, UK

Microplastic pollution is almost omnipresent and has been detected in almost all environments around the globe. While the understanding of pollution sources of microplastics, their fate and transport in terrestrial and aquatic ecosystems as well as their accumulation in long-term storage zones such as the oceans or inland seas has been improving over the last couple of years, very little is known about the fate, transport and impact of micro- and nano-plastics in subsurface systems including soils and groundwaters. This critical knowledge gap prevents urgently required assessments of the risks to groundwater resources, sub-terranean ecosystems and the services they provide. This session therefore invites contributions that present advances in:
– Field and lab analytical approaches for the detection and analysis of micro- and nano-plastics in soils, sediments and groundwater systems
– Experimental and model-based investigations aiming to quantify the fate and transport of micro- and nano-plastics in the vadose and phreatic zone
– Ecotoxicological and functional studies that analyse the ecosystem impacts of micro- and nano-plastics in underground ecosystems
– Predictions of residence time of micro- and nano-plastics in subsurface ecosystems and their potential interactions with other contaminants in porous media
– Understanding the degradation and fragmentation mechanisms of micro- and nano-plastics under variable subsurface conditions, including the leaching of potentially harmful additives
– The fate of new biodegradable polymers in subsurface ecosystems and potential impacts on their transport behaviour
We encourage contributions from laboratory to planetary scale in order to identify new avenues for interdisciplinary research with the capacity to integrate knowledge across traditional disciplinary boundaries.

Boving, Tom; University of Rhode Island, US
Lapworth, Dan; BGS, UK
Wanner, Philipp; University of Gothenborg, Sweden
Sakambari, Padhi; University of Tokyo, Japan

Groundwater quality is at the forefront of 21st-century concerns, encompassing environmental, social, and economic dimensions. Even as an ‘invisible’ freshwater resource, it plays a foundational role in sustaining both human activities and ecosystems. As we delve deeper into the complexities of groundwater resources management, it becomes increasingly evident that groundwater quality is a pivotal factor in ensuring the well-being of millions who rely on it for drinking water, food production and manufacturing, as well as for preserving natural ecosystems. It is thus imperative that we continue efforts to monitor and protect this precious resource, especially in the face of increasing pollution and emerging challenges, including direct human activities such as industrial processes, agriculture, and urbanization, as well as climate change induced processes including droughts and sea-level rise induced salinization of fresh groundwater reserves. In this session, we aim to shed light on the multifaceted challenges that groundwater quality encounters in the 21st century, emphasizing its crucial role as the largest global freshwater resource and help to secure its status as a reliable and accessible water source for generations to come. We invite contributions spanning a wide spectrum of topics, including:
1. Emerging Contaminants
2. Climate Change and Hydrogeochemical Processes
3. Groundwater Salinity related to Food, Health and Biodiversity
4. Innovations in Modelling
5. Innovations in Monitoring and Observation
6. Environmental Consequences of Economic Activities
7. Health Challenges
8. Groundwater Treatment Technologies
9. Knowledge Transfer and Governance
10. Financing and Funding

Wanner, Philipp; University of Gothenborg, Sweden

Per- and polyfluoroalkyl substances (PFAS) have been widely detected in groundwater systems worldwide questioning the usage of untreated groundwater as a drinking water resource.

Despite the widespread detection of PFAS in groundwater systems, the knowledge is limited regarding the physical and (bio)chemical processes that affect PFAS in groundwater system and how we can benefit from them to develop effective PFAS treatment techniques.

To address this research gap, this session is welcoming abstracts that contribute to both A) an improved understanding the behaviour of PFAS in groundwater systems and B) the development of innovative treatment techniques. In this context a discussion of different PFAS threshold values for drinking water in different countries and their rationales is also of high interest in this session.

Foster, Tim; University of Technology Sydney, Australia
Priadi, Cindy; Universitas Indonesia, Indonesia
Nam, Nguyen Dinh Giang; Can Tho University, Vietnam
Kotra, Krishna; The University of the South Pacific, Fiji

More than a billion people globally rely on private wells (self-supply) to obtain water for drinking and domestic purposes. Yet self-supply is often overlooked in policy and beyond the reach of regulation, particularly in low- and middle-income countries where it is most prevalent. Evidence suggests self-supply through private wells presents both opportunities and risks across a range of domains, including public health, sustainable groundwater management and economic welfare. What is less clear is in which contexts self-supply should be supported or averted, and what policy and regulatory mechanisms are best able to achieve these goals. This interdisciplinary session will invite presentations on a wide range of issues relevant to the use of private wells in both urban and rural areas. The session will explore case studies from across low-, middle- and high-income countries, with the aim of identifying ‘best practices’ so self-supply – where it exists – can be a positive contributor to Sustainable Development Goal 6. Topics that will be explored in this session include:
• Policy and regulatory aspects of self-supply
• Risks to water quality and quantity (and strategies to address those risks)
• Gender Equality, Disability and Social Inclusion analysis
• Climate resilience of self-supply
• Economics of self-supply
• Self-supply and multiple use services (MUS)
• Self-supply in the context of SDG6 (safe water for all)
• Historical perspectives of self-supply as a temporary or permanent approach

MacDonald, Alan; British Geological Survey, UK
Mudimbu, Dee; University of Harare, Zimbabwe
Re, Viviane; University of Pisa, Italy
Kebede, Seifu; University of KwaZulu-Natal, South Africa

Many in the world are still gripped by a water supply crisis. One in four people lack access to safe water at home, and approximately 750 million still lack access to even basic water services in their community[1]. For example, in Africa it is estimated that 190 million children are at risk due to poor water supply and sanitation, and US$170 bn per year is lost to GDP as 40 billion hours are used for water collection[2]. The solutions are not simple but increasingly involve the development and supply of local groundwater resources. Sustainable groundwater supplies that are resilient through drought and functional over the long-term have been demonstrated to increase the resilience of people living in marginalised environments. Securing groundwater for food security is also a growing challenge in many low- and middle-income countries, as rainfall becomes increasingly unreliable, and demand for food grows.

In this session we will explore how groundwater is being developed to help transform some of the world’s most vulnerable and fragile communities. We will examine both the challenges and successes in locating, developing and supplying safe groundwater in low-income countries and discuss innovative methods for developing groundwater and how these can be scaled up. In the session we will also discuss how the hydrogeological environment impacts on the feasibility, cost and sustainability of groundwater development and how this interacts with the local social, economic and institutional context. We welcome case studies in addition to methodological and theoretical submissions and hope to facilitate fruitful discussions on sharing best practice and build consensus on the priorities for the groundwater community to address this continuing water crisis.
[1] WHO / UNICEF 2023 https://data.unicef.org/resources/jmp-report-2023/
[2] African Union 2023. Africa’s Rising Investment Tide https://aipwater.org/high-level-panel/

Milnes Ellen; University of Neuchâtel, CHYN, Switzerland
Rochat, Pierre-Yves; UNHCR, SDC
Matta, Jay; UNICEF, SDC
Bünzli, Marc-André; SHA-SDC

The session on hydrogeology in humanitarian contexts seeks contributions in all fields of applied hydrogeology which address the water supply needs encountered in humanitarian contexts, from groundwater exploration, exploitation to protection and sustainable groundwater management. Humanitarian contexts characterized by conflicts and violence, population displacements and/or natural disasters require to rapidly provide tangible results in data and water scarce settings. Additionally an extra layer of complexity arises when the effects of climate change are superimposed, exposing already vulnerable populations and their livelihoods to life threatening situations.
Over 400 million people are in need of humanitarian assistance, with water supply being one of the life saving and sustaining needs, and approximately 4 billion people experience water scarcity for at least 1 month per year. Humanitarian crises are increasingly evolving into protracted situations and from rural towards urban and peri-urban settings, with significant consequences on water supply. The humanitarian community, including donors, increasingly recognizes the importance of developing sound hydrogeological approaches in search of innovative and sustainable solutions, which account for the context specific challenges as well as the financial constrains affecting the whole sector.
The session is an opportunity for all stakeholders involved in hydrogeology in humanitarian contexts to present their developed tools and approaches, to show case examples and lessons learnt and to bring forward valuable collaborations and partnerships namely with national partners such as universities, local governments and water utilities. Additionally, given the increase in demand to develop groundwater supplies in these contexts, the session seeks to address the challenges to conduct both groundwater assessments, development and subsequent monitoring. Such approaches should seek to address how groundwater can be better ‘made visible’ to allow safe access to sustainable water supplies and to meet the needs during emergencies, and to demonstrate how such interventions are contributing to the humanitarian development nexus.
This session is also an opportunity to reinforce a professional community around the specific field of hydrogeology in humanitarian contexts, creating a dedicated space in the landscape of the WASH sector, within which it is often scattered.

Re, Viviana; University of Pisa, Italy
Haley, Adrien; University of Cardiff, UK
Boumaiza, Lamine; University of Waterloo, Canada
Huggins, Xander; University of Victoria, Canada
Frommen, Theresa; Hessian Agency for Nature Conservation, Germany

Socio-hydrogeology is a discipline addressing complex groundwater-related issues in a more holistic and integrated manner. By focusing on the reciprocity between humans and groundwater, Socio-hydrogeology aims to explore and understand their dynamic interactions with a final goal of developing transdisciplinary solutions for transdisciplinary problems. Due to the more “private” (i.e., individual household/community supply) and local nature of groundwater in many instances, socio-hydrogeology seeks to explore individuals and communities as a primary source of information including their local knowledge, beliefs, risk perception, consumption, tradition/history, and perspectives. Socio-hydrogeology embodies sociology with multiple focuses including social, cognitive, long-term behavior and socio-epidemiological sciences.The aim of this session is to explore and discuss connections between societies and groundwater in a world undergoing rapid change. Contributions from diverse fields and disciplines are welcome, including but not limited to: (1) Examples of participatory monitoring, stakeholder engagement, public participation and gender-disaggregated data collection, citizen science, involvement of citizens and local populations in groundwater projects and/or in the design of solutions;
(2) Integration of multiple knowledge systems (e.g., Indigenous knowledge) within quantitative and qualitative hydrogeological studies; (3) Social and political approaches to groundwater resources research; (4) Groundwater geo-ethics; (5) International/transboundary conflicts; (6) Integration of behavioral, experiential, or knowledge-based data in hydrogeological assessments; and (7) Educational goals for future socio-hydrogeologists

Puri, Shammy; Centre for Sustainable Solutions in Practical Hydrogeology
Salminen, Erik; UN ECE
Trombitcaia, Julia; UN ECE
Villholth, Karen; Water Cycle Innovation
Aureli, Alice; IAH
Dumont, Aurelien; UNESCO
Koeppel, Sonja; UN ECE
Krogulec, Ewa; University of Warsaw, Poland
Rivera, Alfonso;  IAH Commission on transboundary aquifers
Samaniego, Lucia; CeReGAS

Conference session co-hosted by UNESCO-IHP, UNECE, IGRAC, GEF-IW:LEARN, SADC-GMI, IAH Transboundary Aquifers Commission

Conjunctive management of water resources is known to be a powerful means to addressing crises from climate change, water shortages and quality deterioration. So many of the world’s river basins are facing declining surface resources, in which groundwater is now being spontaneously utilised as replacement. Unfortunately, groundwater remains the ‘Cinderella’ of water resources – it is there in the background, but remains unseen in explicit policies, legal regimes, and accessible financing. This, ‘spontaneous conjunctive use’ approach, is becoming more widespread, and is resulting in chaotic resources governance thus further undermining water security. These symptoms have been recognised by many actors in the water sector. There is a real interest in moving from “chaos to order” and the recognition that aquifers are at the heart of fundamental hydrological interactions and hence need to be explicitly addressed (see for example UNECE 2023 https://unece.org/environmental-policy/events/global-workshop-conjunctive-management-surface-water-and-groundwater  and GEF IW:LEARN https://iwlearn.net/gwcwmhub/conjunctivewater). Enhanced conjunctive management, where groundwater is at the centre of attention, may require retrofitting of policies and practices, which may be complex in some situations, but holds great potential to address the common issues faced in many regions.
The session of the congress is devoted to improving measures, policies, and practice for how to ensure that conjunctive management, with aquifers at its core, can be adopted to enhance water security and sustainability under greater water demands and climate change, from local to transboundary xcales. Contributions from practitioners in all relevant disciplines are invited:
• Firstly, to increase understanding and awareness of the benefits of conjunctive water management, especially for climate change adaptation
• Secondly, to move from spontaneous conjunctive use to planned conjunctive water management

In particular, papers are invited covering the following areas:
Analyses and evaluation: of current/planned practices: modelling the management of conjunctive use, data requirements, analytical methods, evaluation of the move from spontaneous to planned management.
Best practices: case histories that yielded political, legal, and social attention to the benefits and opportunities of conjunctive water management, especially in agriculture, but also in water supply, and ecohydrological enhancement.
Policies: legal, financial, and technical approaches; cost-benefit and risk-sharing strategies for retrofitting conjunctive management; methodological approaches to the use of various instruments, including economic (taxes, subsidies), legal, other.
Capacity development: skill sets and tools required, institutional strengthening needed for effective adoption of sound conjunctive management.
Transboundary scale: transition from national to transboundary scales, support from international instruments such as the 1992 Water Convention and its tools (e.g. Model Provisions on Transboundary Groundwaters) and the 2009 UN ILC Draft Articles on Transboundary Aquifers. Support to negotiation of agreements/arrangements and resource allocation conjunctive management.

Reimann, Thomas; TU Dresden, Germany
Birk Steffen; University of Graz, Austria
Batelaan, Okke; Flinders University, Australia
Cohen, Andrew; GroundwaterU, USA
Lotti, Francesca; Symple, Italy

Groundwater, a significant share of the globally available freshwater, is a hidden resource that receives little public attention because of its nature. In academic teaching, hydrogeology or groundwater hydrology is usually part of geology or civil engineering study courses, but often without getting too much focus. The study of groundwater is very challenging because to fully understand groundwater hydrology and hydrogeology, a large variety of competencies are required, ranging from applied field and laboratory methods to quantitative analysis that involves advanced mathematical and physical concepts. Because of the limitations of traditional teaching methods, groundwater education is rapidly evolving into a large pool of innovative methods and didactics, such as interactive documents, videos, and electronic questions for various assessments. In combination with a philosophy of openness and accessibility of these innovative materials, the quality and outreach of groundwater teaching can be enhanced.
The session aims to showcase recent developments, innovative approaches, applications, and experiences in sharing hydrogeological knowledge. We seek contributions about innovative teaching materials and methods, as well as efforts and experiences with updated and enhanced teaching methods and recent developments to improve open and accessible groundwater education. We also welcome presentations about informative and training efforts at various levels, from the non-technical public to the non-hydrogeologist decision-makers, eventually responsible for groundwater-related courses of action.
Contributions to this session are welcome from academic education, continuing education for professionals, companies’ training and development for their employees, and education intended to reach general audiences, e.g., to promote and raise groundwater awareness.

Collenteur, Raoul; EAWAG/WSL, Switzerland
Renard, Philippe; University of Neuchâtel, CHYN, Switzerland
White, Jeremy; Intera, USA
Reimann, Thomas; TU Dresden, Germany

Sterckx, Arnaud; IGRAC, Netherlands
Ruz-Vargas, Claudia; IGRAC, Netherlands
Schürch, Marc; Federal Office for the Environment (FOEN), Switzerland
Mishra, Sulagna; World Meteorological Organization (WMO), Switzerland

Knowledge of the quantitative and qualitative status of aquifers is critical for water resources planning and management, for policy-making and for collective action, at all levels and in a variety of sectors. Access to this information on a regular and timely basis is crucial because the stress on groundwater resources is increasing due to e.g. the rise of water demand, pollution, and the effect of climate change on water availability. Information on the quantitative and qualitative status of aquifers can be produced based on groundwater monitoring data and other physical evidences. It can be complemented with information about the recharge rate and the services provided by aquifers to the communities and the ecosystems. Monitoring and reporting strategies exist in Europe under the Water Framework Directive, in California under the Sustainable Groundwater Management Act, and in many other parts of the world. Under SDG indicator 6.3.2 (Progress on ambient water quality), countries report on the qualitative status of groundwater bodies, based on several groundwater quality variables.
This session will gather practical experiences in groundwater monitoring, reporting, or other data-driven activities raising awareness about groundwater issues and promoting collective action. It will cover a variety of topics, such as existing monitoring networks and programmes, reporting methodologies and strategies (time-series analysis, indicators, and other technical aspects), enabling legal and institutional environments for groundwater reporting, communication channels for effective dissemination of groundwater information and data, etc. Case-studies are sought from hydrogeologists and professionals from other disciplines (including social sciences), representing various stakeholders (governments, communities, private sector, media, research institutions), at different scales and from various regions.

MacAllister, Donald John; British Geological Survey, UK
Upton, Kirsty; British Geological Survey, UK
Kebede, Seifu; University KwaZulu-Natal, South Africa
Van Dalen, Daniela Benedicto; Acacia Water, Netherlands

In a changing climate the role of groundwater in global water security is becoming increasingly important. For example, there has been a renewed interest in groundwater as a resilient resource in areas such as the Horn of Africa where persistent drought has led to increased groundwater development highlighting the importance of groundwater mapping to inform this. In other areas such as the continental USA or South Asia where groundwater is heavily over exploited there is a need to assess temporal changes and new technology allows these to be mapped in near real time. Multilateral agencies have also taken an increased interest in the role of groundwater for climate change adaption and as an important economic resource. Finally, the development of deep continental and offshore groundwater can be supported and better managed when mapped effectively. This session will present recent progress in methodologies and approaches to groundwater mapping. It aims to provide the opportunity for sharing of experiences, highlight recent scientific advancements, and promote discussion of future priorities within the hydrogeological community. The session will invite contributions which showcase recent groundwater mapping initiatives from across the world and across multiple scales: from sub-national up to regional, continental, and possibly even global scale. Through case studies, the session will examine different groundwater mapping approaches for a variety of purposes and end-users. Given the growing use of big data and artificial intelligence, the session will seek to critically assess the importance of these approaches in groundwater mapping at different scales. The session will examine potential barriers and opportunities presented by the digital transformation. Finally, we will discuss how digital methods can be merged with traditional mapping approaches, the role of citizen science or community led mapping, and the on-going importance of traditional groundwater mapping.

Kadhila, Alina; Namibia Water Corporation, IAH, and the Namibian Hydrogeological Association , Namibia
Gustavo, Ester; SLR Namibia, Namibia

Groundwater sources worldwide are under increasing pressures: if it’s not due to the increased water supply demand, it’s competing uses and users , and or climate change effects. There’s never been as more crucial time to consider the holistic management of groundwater resources. Everything from the quantity, qualities, implementation of IWRM at all levels (local, national , regional and international), also for various organizations, individuals, experts, both from the groundwater and other water related fields, the multidisciplinary experts and stakeholders as well as water users. In this session, I hope to see what the rest of the world is doing with the globally accepted approach of integrating water resources management, what are the success stories , what are the challenges being experienced, how can we improve or optimize the benefits from IWRM and any advancements in research or innovation as it relates to this .

Cochand, Fabien; CSD Engineers, Switzerland
Formentin, Giovanni; HPC, Italy
Lotti, Francesca; Symple, Italy

Decisions require information. Information resides in data. Data is processed to harvest its information. Data-processing can be as simple as basic time series analysis, or as complex as environmental model history-matching. Regardless of how data are processed, the goal is the same. It is to present information to decision-makers in forms that they can use.

Rivera, Alfonso; IAH-TBA Commission
Sanchez, Rosario; Permanent Forum of Binational Waters, and TAMU-TWRI, USA
Sterckx, Arnauld; IGRAC, The Netherlands
Moix, Patrice; UNESCO
Pietersen, Kevin; SADC-Groundwater Management Institute, South Africa
Aureli, Alice; Centre for Sustainable Solutions in Practical Hydrogeology

When dealing with a shared aquifer with groundwater crossing from one jurisdiction to another, we often face difficult decisions regarding the assessment of the transboundary aquifer. We need to decide whether the assessments should be based on the whole aquifer (often the most expensive approach), or on aquifer zoning, hotspots, transboundary corridors, groundwater flow systems, groundwater residence time, radius of influence, or capture areas. To do that correctly, however, the dynamics of groundwater within the aquifer (time and space scales) must be well understood closer to the jurisdictional boundary. Further, to complement the knowledge of groundwater dynamics, new elements and/or variables need to be added, e.g., social, economic, and political needs.

Although a full aquifer-wide transboundary assessment may be essential, often transboundary impacts are limited to border regions, or zones with troubling spots. Here, to alleviate data scarcity, financing and capacity issues, it might be useful to focus on a more detailed assessment at smaller scales. However, a major challenge exists in identifying the appropriate transboundary groundwater management units, where transboundary implications are important (i.e., active groundwater flow across the international border, presence of well fields or pollution, etc.). This concept is still within its infancy and methodologies to carry out such a task are limited.

This special session will examine those approaches with a series of key presentations and a panel discussion. The session will discuss existing approaches on how to prioritize TBA areas (e.g., estimate zones) within transboundary aquifers that need additional attention to guide groundwater policy and decision makers. The session will discuss the needs and the advances in this specific domain.

Escalante, Enrique Fernandez; Tragsa Group, Spain
Catalin, Stefan; TU Dresden, Germany
Zheng, Yan; Sustech, China
Van Dalen, Daniela Benedicto; Acacia Water, Netherlands

Managed aquifer recharge (MAR) or the intentional recharge of groundwater aquifers has become a fundamental technique in the global water management effort for conjunctive sustainable use, the restoration of aquifer storage, increased resilience to droughts, and improvement of base flow and eco-systems.

Traditionally it has not been deployed to the extent it deserves due to a lack of awareness, limited knowledge of aquifers, the inadequate perception of risk, and incomplete or contradictory policies for integrated water management, including linking MAR with demand management. Scientific knowledge, practical experience and advocacy shall build on expertise and dissemination of MAR technique.

MAR is part of the integrated and collective approach to water management, and can also achieve much towards solving the innumerable local water scarcity problems, including multilevel governance schemes. How the world will develop resilient groundwater use in the face of continued growth, climate change, and endangered water security includes MAR as a first-line technology; and the time is now to push MAR to the forefront of the integrated water resources management techniques, policy development, and modern hydrogeology.

This session provides a platform for discussing the effectiveness, benefits, constraints, and applicability of MAR in a wide range of technical and socio-economic conditions. This session has been proposed by the Commission on Managing Aquifer Recharge of the International Association of Hydrogeologists, and aims at supporting the scientific advances of MAR in the context of the Annual IAH Congress in Davos, Switzerland.

Bronders, Jan; VITO, Belgium
Dams, Jef; VITO, Belgium
De Louw, Perry; Deltares, Netherlands

Climate change is leading to more extreme meteorological and hydrological conditions, with for example increased droughts periods and amplified precipitation in wet seasons. The groundwater system often functions as a substantial natural freshwater buffer, providing essential water during periods of drought. However, the increasing pressure on groundwater reserves results in competition for the available water that can be extracted sustainably. Enhancing the storage of water within groundwater systems is crucial for averting water scarcity during changing climatic conditions. On the other hand, drought measures may unintentionally increase flood risks which should be considered as well. This session invites abstract submissions that explore diverse measures including nature-based solutions and strategies aimed at increasing the buffering capacity of phreatic aquifers. We seek contributions on innovative modelling techniques, data-driven insights, and case studies that address the sustainable management of aquifers and the resilience of groundwater-dependent ecosystems. Topics may include, but are not limited to, quantification of the impact of measures such as increasing infiltration, restriction in groundwater extractions, managed aquifer recharge in the phreatic aquifer, increasing drainage base by removing drainage channels, installing wells, re-meandering rivers… By fostering a comprehensive understanding of groundwater buffering capacity, this session aims to facilitate interdisciplinary discussions and advance our collective efforts toward ensuring the long-term sustainability of water resources. Assessing the effectiveness of these nature-based solutions in buffering freshwater but also taking the increase of flood risks into account, is essential for evaluating the need for additional man-made measures, such as the construction of surface water buffers and Aquifer Storage and Recovery (ASR).

Antunes, Margarida; University of Minho, Portugal
Lasagna, Manuela; University of Turin, Italy
Ackermann, Markus; ERM
Benaabidate, Lahcen; University of Sidi Mohammed Ben Abdellah, Fes, Morocco
Stoll, Andreas; ERM
Kitiashvili, Nana; LEPL National Environmental Agency, Georgia

The growing water crisis is having a major impact on ecosystems, society, and businesses. By 2030, the global population will have only half the amount of fresh water available that would be required. Groundwater has been recognized as the predominant water supply source for diverse communities. Climate change is one of the most important challenges humankinds faces today. Despite the potential role of groundwater storage in climate change adaptation strategies, this impact on groundwater resources remains to be determined. The pathways through which changes in natural and human factors (e.g., groundwater withdrawals, water degradation, water management strategies) impact groundwater resources are only partially understood due to the complexity and the many (unknown) feedback mechanisms of the atmosphere-land-subsurface system, including humans as an agent. Furthermore, inadequate water management can lead to the overexploitation and depletion of groundwater storage and create potential conflicts between various water consumers. Therefore, a thorough investigation of groundwater availability that inspires sustainable water consumption and facilitates groundwater management is of high importance. This session seeks contributions from institutions, industries, companies, and organizations who prioritize groundwater by working on strategic and novel technical solutions to address shared water challenges and/or working towards meeting their ambitious water goals. So, we are inviting presentations taking up these challenges and especially encouraging (but not limited to) contributions on the following topics:
– Water quality indicators
– Water scarcity indexes and availability
– Groundwater recharge and climate change
– Anthropic and natural impact on groundwater resources
– Geothermal water as a source of renewable energy
– Global social and economic challenges/strategies on water management
– Nature Based Solutions, water management, and digital solutions
– Advances in water treatment technologies
– Groundwater-surface water management strategies to increase resilience.

Valley, Benoit; University of Neuchâtel, CHYN, Switzerland
Brehme, Maren; ETH, Switzerland
Saar, Martin O.; ETH, Switzerland
Villasenor, Eileen; WSP, UK
Gizzi, Martina;  Politecnico di Torino, Italy
Taddia, Glenda; Politecnico di Torino, Italy

In the evolving landscape of the energy transition, the exploration and harnessing of subsurface resources emerge as an important avenue for developing energy solutions. This session delves into the intricate interplay between geothermal energy and hydrogeology, spotlighting the potential synergies and challenges that arise in the pursuit of sustainable energy alternatives. This includes the thermal exploitation of shallow or deep aquifers, but also the possibility of storing and recovering heat in aquifers.

Daniele, Linda; University of Chile, Santiago, Chile
Blessent, Daniela; University of Medellin, Medellin, Colombia
Raymond, Jasmin; Institut national de la recherche scientifique, Quebec Canada
Alcaraz, Mar; Polytechnic University of Cartagena, Cartagena, Spain
Somma, Renato; INGV, CNR-IRISS and CNR-ISMAR, Naples, Italy

Ensuring a secure and sustainable water supply is a major challenge for the 21th century. Population growth, urbanization, and industrial/agriculture expansion need an increasing water provision. Furthermore, under the current climate scenarios (i.e. surface water depletion) groundwater is fulfilling the growing water requirement for food and energy production.
2010’s estimations indicate that groundwater supplied 36% of potable water, 40% of irrigated agriculture, and 24% of direct industrial water supply. Groundwater use is growing at a rate of 5% per year, and by 2050, the food, energy and water demand will increase by 50%.
These considerations highlight the need of innovative and integrated solutions to tackle the intertwined challenges of the complex interlink between water, energy, and food supply systems under current climate variability for the near future.
The study of the water–energy–food nexus has received increasing attention from the global scientific community, focusing on how these three elements can interact sustainably. The interdependence of water resources, energy generation, and food production depends on reliable data and information. In this context, groundwater can supply water and energy demand, strengthening food security and reducing fossil fuel dependence providing water and thermal energy. Shallow geothermal is a clean baseload resource which could significantly contribute to energy needs, improving air quality and food production as well as reaching the decarbonization targets.
This session topic on the key role of aquifers and underground in providing water and thermal energy to improve water, energy and food security under global climate change scenarios (drought, heat waves, extreme rains). The central idea is to have a scientific interchange of experiences, perspective and challenges on how aquifers and underground may help to reduce fossil fuels dependence promoting the Sustainable Development Goals (SDGs) of United Nations (UN).

Stevanovic, Zoran; University of Belgrade, Serbia
Malik, Peter; Geological Survey of Slovak Republic, Slovakia

Karst aquifers supply potable water to approximately 9% of the world’s population, or some 700 million people, in more than 150 countries where karst is present to a certain extent. Karst aquifers and springs are important because they provide precious quality water, sustain ecosystems, and maintain the baseflow of many rivers in the world. Europe is the continent with the highest percentage of karst extensions, and many large cities such as Vienna, Rome, and other capitals of SE Europe are obtaining water for their citizens from karst springs.

Burg, Avi; Geological Survey of Israel, Israel
Goldscheider, Nico; Karlsruhe Institute for Technology, Germany

Karst regions offer a wide variety of natural resources and ecosystem services that require a holistic and sustainable approach. Approximately 9% of the world’s population depends largely or entirely on groundwater obtained from karst. Because the movement of water in karst terrains is usually fast, karst aquifers are highly vulnerable to chemical and biological pollution from natural and anthropogenic sources, which subsequently can bring hazards to human life and aquatic ecosystems. Many studies around the world focus on these pollution processes using a variety of hydrochemical tools, isotopic and tracers.Karst regions offer a wide variety of natural resources and ecosystem services that require a holistic and sustainable approach. Approximately 9% of the world’s population depends largely or entirely on groundwater obtained from karst. Because the movement of water in karst terrains is usually fast, karst aquifers are highly vulnerable to chemical and biological pollution from natural and anthropogenic sources, which subsequently can bring hazards to human life and aquatic ecosystems. Many studies around the world focus on these pollution processes using a variety of hydrochemical tools, isotopic and tracers.

Pryet, Alexandre; University of Bordeaux, France
Coulon, Cécile; Intera, France
Hugman, Rui; Intera, USA
Standen, Kath; Stantec, UK
White, Jeremy; Intera, Perth, Australia

Numerical modelling serves as a potent instrument in aiding decision-making processes within the realm of water resource management. These models have the capacity to illustrate the behaviour of hydro(geo)logical systems under prospective scenarios, such as pumping or climate change. This can significantly contribute to the formulation of industrial and societal strategies aimed at managing and safeguarding water resources.
However, the task of modelling intricate natural systems, especially with limited data, time, and budget, presents a unique set of challenges. The question then arises – how can we surmount these obstacles to ensure that modelling provides reliable and valuable information to decision-makers?
This session offers a platform to exchange experiences of broad interest, introduce tools, and engage in discussions about effective strategies. Specifically, we will focus on approaches where groundwater modelling is coupled with one or more analyses, including but not limited to data assimilation, uncertainty analysis, and management optimization. We look forward to your participation and contribution to this important conversation.

Specific topics of interest include:

• Advances and implementations of algorithms for parameter estimation, uncertainty quantification, data assimilation, and management optimization.
• Conceptual and numerical approaches to get tractable models (e.g. simplicity/complexity trade-off, surrogate and hybrid models, integration of machine learning).
• Optimized collection and processing of observations (site characterization & monitoring).
• Effective parameterization of distributed hydraulic properties, boundary conditions, and decision variables.
• Real-world environmental modelling challenges and efforts to overcome them.

Elçi, Alper; Dokuz Eylül University, Turkey
Copty, Nadim K.; Bogazici University, Turkey
Guardiola-Albert, Carolina; Instituto Geoliogico y Minero de Espana (IGME), Spain
Teatini, Pietro; University of Padova, Italy

Modeling of groundwater flow and contaminant transport has evolved into an indispensable tool for the analysis of subsurface systems across multiple scales ranging from the pore to the global scales. Flow modeling is used in a wide range of applications including risk assessment, water resources management, as a decision support system and guiding remediation activities. Numerous studies have shown that the hydrogeochemical and biological processes influencing flow and transport in heterogeneous porous media are highly complex. These processes are often interdependent, highlighting the need for coupled modeling of flow and contaminant transport.
The objective of this session is to discuss the state-of-the-art and future directions in groundwater flow modeling and simulation of contaminant fate and transport. This session provides a special opportunity to promote inter-disciplinary studies and the sharing of knowledge and experiences related to analytical and numerical, physics-based, and data-driven approaches.
We invite researchers, academics, and consulting professionals at all career levels to present their work on the following topics:
• Groundwater flow modeling studies at the global, regional and watershed scale
• Pore scale modeling of flow and transport
• Modeling of unsaturated/saturated flow and transport (also in the context of managed aquifer recharge systems)
• Simulation of subsurface flow-surface water interaction
• Modeling the impact of climate change on groundwater resources
• Variable-density flow, and seawater intrusion modeling studies
• Multi-phase flow and contaminant transport modeling in support of groundwater remediation (especially for problems where the flow and transport are highly coupled)
• Modeling of coupled physical, hydrogeochemical and biological processes
• Modeling the impact of subsurface heterogeneity on flow and transport
• Reactive transport modeling (chemical, sorption, bio-mineralization processes in porous media)

Belitz, Kenneth; US Geological Survey, USA
Stahl, Mason; Union College, New York, USA
Stackelberg, Paul; US Geological Survey, USA

There is a long history of applying models to representing hydrogeologic systems, including analytical mathematics and numerical methods. These methods have greatly advanced our understanding of the movement and transport of groundwater, solutes, and heat in the subsurface. The analytical and numerical methods incorporate fundamental physics and(or) chemistry, but still require additional information on the relevant hydrologic processes. It is generally incumbent on the analyst to provide that knowledge. Machine learning (ML) methods, which have been enabled by recent advancements in computation and the availability of large datasets, takes a different approach. ML methods both differ from and share similarities with the more traditional methods. ML methods are generally empirical, rather than being based strictly on fundamental physical and chemical principles. ML methods, however, can incorporate additional information on relevant hydrologic processes. ML methods need not be seen as competing with traditional methods, but rather as a complement to those methods.
This session seeks papers that apply ML methods and big data analytics to complex hydrogeologic systems. Topics could include, but are not limited to: (1) perspectives on hydrogeologic problems that have previously resisted traditional approaches and for which ML may provide new insights, (2) application of ML to better understand complex hydrogeologic systems, (3) coupling process-based and physically based models with ML, (4) generation of new explanatory datasets in support of ML, and (5) quantification of uncertainty in ML.

Halloran, Landon; CHYN, University of Neuchâtel, Switzerland
Linde, Niklas; University of Lausanne, Switzerland
Ferré, Ty; University of Arizona, USA
Lesparre, Nolwenn; University of Strasbourg, France
Neven, Alexis; Geo2X SA, Switzerland

Hydrogeophysics involves taking advantage of physical phenomena to gain indirect, yet valuable, knowledge about the subsurface. As most of the subsurface is not directly accessible without modifying natural conditions, hydrogeology is, in essence, a data-poor science. Hydrogeophysics aims to help close data gaps by enabling spatially-distributed, non-invasive and mobile measurements. Ground penetrating radar, electrical resistivity tomography, hydro-gravimetry, and seismic refraction are just some of the many methods that exploit the dependence of various physical properties (density, conductivity, compressibility, etc.) on quantities relevant for hydrogeologists.
This session aims to showcase two themes: 1) novel methodological developments in hydrogeophysics and 2) innovative applications of hydrogeophysical methods to improve our understanding of subsurface processes, properties, and spatial variability.

Musy, Stephanie; University of Basel and University of Berne, Switzerland
van Rooyen, Jared;  EAWAG and University of Basel, Switzerland
Tomonaga, Yama; University of Basel and Entracers GmbH, Switzerland
Schilling, Oliver S.; University of Basel and EAWAG, Switzerland

Recent developments in field-based sampling and analytical techniques have significantly expanded the scope of hydrological tracer applications and greatly improved our understanding of the many complex physical and biochemical processes across the hydrosphere.
For instance, with the novel portable gas-equilibration membrane inlet mass spectrometers (GE-MIMS) it is now possible to simultaneously measure concentrations of dissolved noble gases as well as N2, O2, CO2, CH4, and H2 directly in the field and continuously in near-real time, providing unprecedented temporal insights into recharge processes, surface water-groundwater dynamics, and groundwater modulated greenhouse gas emission dynamics. Similarly, with the recently developed portable on-line flow cytometers (OFC), it is now possible to monitor aquatic microbes present in water and measure their varying cell counts as well as community compositions continuously and in near-real time, providing a completely new avenue for water quality monitoring and subsurface pathogen transport investigations. Recent innovations in field-based passive and active membrane technologies as well as high-precision autosampler techniques have moreover dramatically simplified the logistics of obtaining temporally resolved samples of water and dissolved (trace) gases, allowing for much more spatially and temporally distributed field investigations of groundwater origins, flow paths, travel times and mixing processes. Combined with important advances in high-precision lab-based analytical methods, these new field-based technologies have significantly enhanced the breadth of tracer-based groundwater studies. Complemented by richer-than-ever hydrological, geological, and environmental information, we now have a much deeper understanding of the natural variability of hydrological processes in both space and time compared to just a few decades ago.
In line with these developments, this session aims to spotlight recent advances, innovations, and emerging methods in sampling, measurement, and interpretation within the frame of the assessment of hydrogeological systems. Emphasis will be placed on multidisciplinary approaches that enhance conceptual and quantitative understanding of complex hydrological, hydrogeological, and ecohydrological systems. Beyond technical advancements, the session seeks to showcase applied studies demonstrating how innovative field-based approaches and hydrological tracer acquisition techniques support decision-making processes, contributing to improved water resource management and fostering sustainability in the utilization of our vital water resources amid evolving anthropogenic and climatic challenges.

Mhanna, Saeed; University of Neuchâtel, CHYN, Switzerland
Mariethoz, Gregoire; University of Lausanne, Switzerland
Scanlon, Bridget R.; Jackson School of Geosciences, Texas, US

Remote sensing technologies constitute a powerful tool for monitoring the hydrological cycle across different spatial and temporal scales. The use of remote sensing in hydrogeology witnessed significant growth over the past years, most notably in the fields of: (1) process-understanding: geophysical measurements including gravimetry, airborne electromagnetic systems, and soil moisture/evapotranspiration estimates provide unique insights into hydrogeological processes, (2) data assimilation: by integrating space-borne observations in hydro(geo)logical models and (3) new platforms: UAVs are capable carrying a wide range of sensors, opening new opportunities for monitoring and mapping hydrogeological processes.
For this session, we welcome presentations focusing on the utilization of remote sensing in hydrogeological studies, including advancements in both processing and employing remote sensing data. We further encourage submissions that demonstrate how earth observation data informs water-related decisions.

Therrien, René; University of Laval, Quebec, Canada
Molson, John; University of Laval, Quebec, Canada
de Deuzy, Jean-Raynald; Université de Rennes, France

Groundwater professionals now routinely use hydrogeological models to simulate groundwater flow and solute or heat transport, reflecting a significant level of maturity in the field of hydrogeological modelling. However, there is still room for improvement. Ongoing efforts are directed at extending modelling capabilities to improve performance, incorporate additional processes and parameters, and address emerging simulation needs. We invite contributions that go beyond the standard application of groundwater models, focusing instead on recent developments and innovative field-scale applications in water resources management. Examples of model advances include the integration of physical, chemical, or biogeochemical processes for hydrogeological applications, and the coupling of groundwater with other components of the hydrological cycle. Also of interest are simulations that assess the impact of various factors and stresses on groundwater resources, such as climate change or human activities that affect groundwater flow systems such as pumping, irrigation, or natural resource exploitation. We are particularly interested in submissions that address the variability and heterogeneity of natural groundwater flow systems and aim to quantify the associated uncertainty in input parameters and model predictions. Real-world applications that compare different modelling approaches, such as simplified versus more complex methodologies, are also welcome.

Tang, Qi; Universität Basel & Université de Neuchâtel, Switzerland
Delottier, Hugo; Université de Neuchâtel, Switzerland
Camporese, Matteo; Università di Padova, Italy
Schilling, Oliver S.; Universität Basel & Eawag, Switzerland

Hydrogeological models are important tools for the characterization and management of groundwater resources. However, due to the extreme heterogeneity of environmental processes and parameters, and our inability to fully characterize that heterogeneity, all hydrogeological models must be calibrated against relevant geological and hydrological data in order to reduce improve the robustness of hydrogeological model predictions and reduce model uncertainty. To find optimal model structures and parameters, model outputs are compared to data, and parameters are then estimated inversely. Broadly, we can group inverse methods into two conceptually separate groups: Classic history matching, whereby hydrogeological model parameters are calibrated inversely against a defined set of historic observations, and data assimilation, whereby hydrogeological model simulations (and parameters) are sequentially updated with information from newly available observations to achieve optimal model predictions in a Bayesian sense.
The theory of inverse problems, however, is much richer than just parameter estimation. Inverse theory can also be used estimate the impact that different kinds of observations, with the many different temporal and spatial scales that they cover and the many different degrees of uncertainty that are associated with, have on model parameters and the accuracy of model solutions. This in turn allows identifying the most valuable types of observations, measurement locations and measurement accuracy for a given model and modelling purpose. Moreover, by quantifying the uncertainty of parameter estimates, the uncertainty of model predictions can be estimated as well, and strategies for optimization under uncertainty or for risk analysis may be developed.
This session aims to showcase recent advances, innovations, and emerging methods in inverse methods, history matching, data assimilation, data worth analysis and uncertainty quantification in hydrogeology. We seeks presentations which highlight novel inverse methods, applications of data assimilation to operational hydrogeological problems, innovative combinations of interdisciplinary observations with hydrogeological models, and case studies which provide an improved conceptual and/or quantitative understanding of complex hydrogeological systems. We also welcome contributions on algorithmic innovations and numerical implementations of inverse methods, including approaches to uncertainty quantification and data worth estimation. Studies which employ machine learning-based approaches to solve hydrogeological inverse problems are equally invited.