This challenge is particularly acute in urban regions, where pressures from climate change, growing energy demand, environmental pollution, and social transformation converge. Densely populated cities are hotspots of resource consumption and vulnerability, but also key sites of innovation where resilient, low-carbon and just futures can be actively co-designed. At the same time, urban growth increasingly depends on subsurface resources located beyond city boundaries that support cities through the provision of energy and water, as well as through the removal of waste.
Understanding urban resilience and transformation therefore requires an integrated view of surface and subsurface systems across urban and extra-urban spaces, and across spatial and temporal scales. Yet, the role of surface and subsurface geo-processes within broader socio-technical and socio-ecological dynamics remains underexplored. Addressing this gap is essential for ensuring that subsurface resources are used in ways that are environmentally sustainable, socially just and mindful of future needs.
Orals: Fri, 8 May, 14:00–18:00 | Room D3
Cities are hubs of resource consumption and hotspots of vulnerability, yet they are also places where climate-neutral solutions need be co-designed, tested, and scaled. A central gap in many transformation pathways is that urban energy strategies are still planned largely “from the surface”, while the subsurface and its capacities and constraints remains underexplored in socio-technical and governance-oriented transformation research. This talk positions the subsurface as a core element of integrated urban energy infrastructure within the blue–green–red framing: ensuring groundwater and water quality (blue), and shaping land-use, nature-based solutions (green) interacting with low-carbon heat and power supply (red). We focus on geothermal heat as a practical, scalable option for decarbonizing urban heat supply, while it is reducing exposure to volatile fuel imports and supporting resilient district heating concepts. With a specific subsurface focus using Potsdam as an illustrative case, we outline what it takes to make geothermal a planning-ready solution. The key message is that the subsurface is not only a boundary condition but an indispensable factor and an enabling infrastructure layer for climate-neutral urban transformation. Bringing it systematically into planning and governance is essential for robust mitigation and adaptation strategies that meet cities’ sustainability and resilience targets.
How to cite: Fuchs, S., Blöcher, G., Norden, B., Schmidt-Hattenberger, C., Spangenberg, E., Regenspurg, S., Hofmann, H., Kranz, S., Milsch, H., and Sass, I.: Decarbonizing cities from below: deep geothermal energy as a pillar of urban transformation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14432, https://doi.org/10.5194/egusphere-egu26-14432, 2026.
In the Lower Bavarian–Upper Austrian Molasse Basin, a regionally extensive and water-resources–relevant thermal groundwater system occurs within the Upper Jurassic carbonate rocks (Malm aquifer), extending from Regensburg to areas west of Linz. This resource has long been utilized on both sides of the national border for balneological purposes as medicinal and bathing water, as well as for geothermal energy production. It therefore represents a significant economic asset for the region and is of particular importance for regional water resource management.
Long-term monitoring and data obtained from pumping tests indicate hydraulic interference among some of these uses. To quantify and assess these interactions, a three-dimensional numerical model was developed and calibrated using observational data collected over several decades. The model will serve as a decision-support tool for future permitting processes, including new applications and modifications of existing uses.
Critical issues comprise the harmonization of heterogeneous datasets and the complex hydrothermal behavior of a steeply dipping aquifer, with localized geothermal gradient anomalies promoting thermally induced convection phenomena.The key innovations of the approach include full transient calibration of the whole reservoir over an analysis period of 100 years; consideration of thermal convection and density effects throuth uni-directional coupling;
Although the current application is restricted to geothermal systems, the modeling approach is methodologically transferable to other forms of subsurface utilization, such as carbon capture and storage (CCS), underground thermal energy storage (UTES), and related technologies as well as their interactions.
The results presented are based on a work under the commission of the Thermal Water Expert Group, acting on behalf of the Permanent Water Commission established under the Regensburg Treaty, and represented by the following institutions:
• Office of the Upper Austrian Provincial Government,
• Bavarian Environment Agency,
• Austrian Federal Ministry of Agriculture and Forestry.
The main publication is available for download (in German language) here: https://www.land-oberoesterreich.gv.at/files/publikationen/w_thermalwasser_bayern_ooe.pdf
How to cite: Hoyer, S., Bottig, M., and Schubert, G. and the ARGE Thermalwasser: Numerical modelling of a carstic aquifer body as decision support tool for deep geothermal applications and their interference. The transboundary upper jurassic carbonates as a case study., EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-5331, https://doi.org/10.5194/egusphere-egu26-5331, 2026.
The subsurface represents a critical frontier for achieving sustainability goals, yet current development approaches remain largely uncoordinated and reactive. As societal challenges intensify —from climate change mitigation to urban densification— the underground is increasingly recognized as essential infrastructure space. However, the prevailing "first-come, first-served" or "last-resort" principles governing subsurface allocation result in fragmented management practices that overlook valuable synergistic opportunities between different underground uses. The question therefore arises how subsurface synergies can be strategically integrated into regulation and planning frameworks to promote sustainable, long-term underground development.
We identify three core principles that enable effective subsurface synergies: multifunctionality, circularity, and repurposing. Multifunctionality recognizes that underground spaces can serve multiple purposes simultaneously or sequentially, such as combining geothermal energy extraction with thermal energy storage, or integrating transport infrastructure with utility corridors. Circularity emphasizes cascading energy uses and resource efficiency, exemplified by utilizing waste heat from data centers for district heating networks or repurposing abandoned mines for energy storage. Repurposing extends the lifecycle of underground investments by adapting existing infrastructure to new functions, thereby reducing environmental impacts and optimizing resource utilization.
Through real-world case studies, we demonstrate how these principles can be operationalized within master planning and regulatory frameworks. These cases reveal both the opportunities for synergistic subsurface planning and the governance challenges that emerge from competing uses, jurisdictional fragmentation, and temporal mismatches between planning horizons and underground resource dynamics. Moreover, our analysis highlights critical barriers to achieving subsurface synergies: inadequate legal frameworks that fail to recognize three-dimensional property rights and long-term resource claims; sectoral silos separating energy, water, infrastructure, and environmental governance; insufficient data sharing and transparency about existing and planned underground uses; and lack of coordination mechanisms between stakeholders with different temporal perspectives and priorities. Overcoming these barriers requires moving beyond conflict resolution toward proactive synergy identification and facilitation.
We propose that effective subsurface governance must adopt a holistic, interdisciplinary, and integrated approach combining technical assessment with policy innovation. This includes developing spatial planning tools that visualize underground uses across multiple dimensions; establishing coordination platforms that bring together geoscientists, engineers, policymakers, and affected communities; creating legal mechanisms that recognize and incentivize synergistic developments; and implementing monitoring frameworks that track interactions between subsurface uses over time.
Our presentation contributes to the session's objectives by demonstrating how governance frameworks can either enable or constrain subsurface synergies, and by providing practical insights for researchers, policymakers, and practitioners seeking to leverage underground resources more sustainably. As pressure on subsurface space intensifies, the ability to identify, evaluate, and implement synergistic solutions becomes essential for ensuring that underground development serves both current and future societal needs while respecting environmental limits and intergenerational equity.
How to cite: Pakizer, K. and Sierro, F.: Leveraging Synergies: From Fragmented Development to Integrated Underground Planning, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13999, https://doi.org/10.5194/egusphere-egu26-13999, 2026.
Venice and its lagoon form a tightly coupled coastal socio-ecological system in which urban fabric, cultural heritage, lagoon ecosystems and regional infrastructures jointly determine vulnerability and resilience to sea-level rise. As relative sea level continues to increase due to climate change and subsidence, adaptation in Venice cannot be limited to incremental risk reduction but requires transitions between fundamentally different strategies.
This contribution applies an adaptation pathways perspective to the Venice–lagoon system to examine how the available solution space decreases under rising sea level. Four adaptation strategies are considered: an open-lagoon configuration based on mobile barriers and accommodation measures, ring-diking that isolates the historic city and other settlements from the lagoon, (closed-lagoon configuration with permanent coastal barriers), and retreat through relocation or abandonment. The analysis focuses on how physical constraints, ecological impacts, social acceptability and long lead times interact to shape transitions between these strategies as sea level rise continues.
The Venice case illustrates how climate and geo-processes, infrastructures, available technical solutions and cultural values condition the timing and characteristics of adaptation tipping points, beyond which strategies can no longer meet their intended goals. By explicitly linking alternative strategies to distinct socio-ecological transformations of the city and its surrounding environment, the pathways approach helps clarify trade-offs, irreversibilities and decision time windows for urban transformation under deep uncertainty.
The results highlight the importance of early, anticipatory planning for coastal cities facing long-term sea-level rise, and demonstrate how geoscience-informed adaptation pathways can support governance of transformative change in complex urban regions.
How to cite: Lionello, P., Di Fant, V., Pasquier, U., Tosi, L., Goneri, L. C., Nicholls, R. J., Cramer, W., Cremades Rodeja, R., Giupponi, C., Hinkel, J., Sfriso, A., T. Vafeidis, A., Umgiesser, G., and Haasnoot, M.: Venice and its lagoon under sea-level rise: transformative choices for a coastal socio-ecological system, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13739, https://doi.org/10.5194/egusphere-egu26-13739, 2026.
Urban areas face intensifying socio-ecological and socio-technical challenges – from climate change impacts and resource depletion to increasing polarization – demanding innovative approaches to build societal resilience. Digital twins (DTs) are touted as transformative tools for urban management, promising enhanced monitoring and modelling to ultimately make cities more sustainable and adaptable (Patel et al., 2024; Silva et al., 2018). However, Helbing and Sánchez-Vaquerizo (2023) highlight potential controversies relating to the limitations of DTs in complex dynamical systems and the ethical implications of treating society as something to be managed and optimised (Helbing and Sánchez-Vaquerizo, 2023). Although the concept of DTs is frequently employed to integrate and analyse various data streams, simulate complex urban processes, and facilitate informed decision-making regarding climate change strategies, their actual deployment appears to fall short of this potential (Ferré-Bigorra et al., 2022; Patel et al., 2024; Stufano Melone et al., 2025). Our contribution provides a critical assessment of the application of urban DTs, comparing their theoretical potential for sustainable development with the limitations and tensions affecting sustainability outcomes that have been observed in their practical implementation.
Drawing on a review of recent literature and case studies highlighting successful and problematic implementations, we analyse digital transformation initiatives, with a focus on the co-creation of digital technologies. We identify discrepancies between aspirational goals, such as holistic systems thinking and citizen engagement, and realised functionalities, which are often focused on infrastructure management and operational efficiency. The aim is to raise awareness of unintended social and ecological effects in urban DT initiatives and foster discussions for a more reflective modelling process.
- Abdeen, F. N., Shirowzhan, S. and Sepasgozar, S. M. (2023). ‘Citizen-centric digital twin development with machine learning and interfaces for maintaining urban infrastructure’. Telematics and Informatics, 84, 102032.
- Ferré-Bigorra, J., Casals, M. and Gangolells, M. (2022). ‘The adoption of urban digital twins’. Cities, 131, 103905.
- Helbing, D. and Sánchez-Vaquerizo, J. A. (2023). ‘Digital twins: potentials, ethical issues and limitations’, In Handbook on the Politics and Governance of Big Data and Artificial Intelligence: Edward Elgar Publishing, 64–104.
- Ibrahim, M., El-Zaart, A. and Adams, C. (2018). ‘Smart sustainable cities roadmap: Readiness for transformation towards urban sustainability’. Sustainable Cities and Society, 37, 530–40.
- Patel, U. R., Ghaffarianhoseini, A., Ghaffarianhoseini, A. and Burgess, A. (2024). ‘Digital Twin Technology for sustainable urban development: A review of its potential impact on SDG 11 in New Zealand’. Cities, 155, 105484.
- Shahat, E., Hyun, C. T. and Yeom, C. (2021). ‘City Digital Twin Potentials: A Review and Research Agenda’. Sustainability, 13, 3386.
- Silva, B. N., Khan, M. and Han, K. (2018). ‘Towards sustainable smart cities: A review of trends, architectures, components, and open challenges in smart cities’. Sustainable Cities and Society, 38, 697–713.
- Stufano Melone, M. R., Borgo, S. and Camarda, D. (2025). ‘Digital Twins Facing the Complexity of the City: Some Critical Remarks’. Sustainability, 17, 3189.
- Weil, C., Bibri, S. E., Longchamp, R., Golay, F. and Alahi, A. (2023). ‘Urban Digital Twin Challenges: A Systematic Review and Perspectives for Sustainable Smart Cities’. Sustainable Cities and Society, 99, 104862.
How to cite: Niehoff, S., Beier, G., Reißig, M., and Kunkel, S.: Is there a Gap Between Promise and Practice? A Critical Assessment of Digital Twins for Sustainable and Resilient Smart Cities , EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17873, https://doi.org/10.5194/egusphere-egu26-17873, 2026.
Urban digital platforms (UDPs) increasingly mediate how cities are governed, which services are provided, and to what extent citizens engage in urban life. A growing body of research—often discussed under the label of platform urbanism—has explored the development of UDPs in urban studies, however mostly in relation to phenomena such as the gig economy, short-term rentals, and platform-mediated urban services as profit-driven corporate tools.
This article instead focuses on a smaller but increasingly important category of UDPs developed by municipalities, research institutions, and civic actors, aimed at functioning as supporting elements for decision-making. Designed for planning, participation, and co-design, these platforms, however, often remain temporary pilots rather than evolving into infrastructures for sustained collaboration and reflexive governance. Therefore, our research question is as follows: how can UDPs be technically designed and institutionally embedded so that they evolve from pilots into infrastructures and support long-term, reflexive urban governance?
Here we conceptualize UDPs as research infrastructures for transformation-oriented urban research: socio-technical arrangements that organize how knowledge is generated, validated, and circulated in cities, laying the groundwork for more democratic, just, and sustainable urban co-production. Drawing on German experiences with Real-world Labs (RwLs) as practice-oriented research settings—which have become central inter- and transdisciplinary arenas for addressing sustainability and urban transformation challenges—we identify three recurring dimensions that shape whether UDPs evolve into infrastructures: (1) their capacity to function as a science–policy interface enabling knowledge transfer across academic, political, and civic domains; (2) the risk of quantitative bias over qualitative insights, drawing boundaries on inclusion in decision-making and creating a struggle to accommodate the qualitative and contextual forms of knowledge that are equally vital for reflexive urban transformation; and (3) their role in institutional learning, particularly how organizational routines and governance structures adapt to embed experimentation over time.
These dimensions suggest that the future of UDPs depends not primarily on technical design but on their institutional embedding. As infrastructures of reflexive urban governance, they can support urban resilience and sustainable urban transformation if they balance efficiency with inclusivity and connect short-term experimentation to long-term urban change. Otherwise, digital urban futures risk being shaped predominantly by technocratic or corporate agendas.
How to cite: Javanmardi, L. and Fraske, T.: Beyond Pilots: Urban Digital Platforms as Enduring Research Infrastructures, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19923, https://doi.org/10.5194/egusphere-egu26-19923, 2026.
Singapore relies heavily on energy imports to sustain urban development and ensure energy security, given its absence of extractable natural resources. Currently, natural gas dominates the energy mix. Singapore is considering several clean energy pathways to decarbonise and diversify, including solar photovoltaics, clean energy imports from neighbouring countries, hydrogen-ammonia, and nuclear power. Solar is among the most cost-effective domestic options, yet its extensive land requirements pose challenges for a land-scarce nation. By contrast, geothermal energy warrants investigation as a potential local low-carbon energy source, subject to the confirmation of sufficient subsurface heat resources.
Two deep exploratory slimholes were recently drilled in northern Singapore, reaching depths of 1.12 km and 1.76 km. Their bottom-hole temperatures measured 70°C and 122°C, respectively. From these results, geothermal gradients based on conductive heat transfer evaluated at 40–44°C/km. If such gradients persist to depths of 4–5 km, rock temperatures could exceed 200°C, enabling both electricity generation and direct-use applications. Scenario-based techno-economic and environmental assessments indicate that, if the high geothermal gradients inferred from recent drilling persist to greater depths, geothermal energy could become cost-competitive with existing electricity and cooling supply options under favourable development conditions. Competitiveness is contingent on substantial reductions in well development costs and the successful deployment of advanced subsurface heat-extraction concepts.
Despite these encouraging findings, geothermal remains a nascent technology in Singapore. Research and development are still at an early stage, though the recent drilling campaign marks a revival of efforts first initiated in 2002. Global technological advances in heat extraction and drilling are on the cusp of being demonstrated in the field. Successful deployment could serve as a model for other countries away from tectonic and volcanic settings. However, several challenges must be addressed in Singapore before geothermal can be fully realized. Chief among these are limited data availability and a shortage of local expertise. Building a robust talent pool and expanding the dataset are critical steps to reduce uncertainty and accelerate development. By overcoming these barriers, Singapore can strengthen its position to adopt and assist future geothermal within and in other neighbouring countries, complementing its broader clean energy strategy and enhancing long-term sustainability.
How to cite: Poh, J., Romagnoli, A., Lim, J. W. M., Massier, T., Chidire, A., Wu, W., and Hamacher, T.: Navigating geothermal development for Singapore, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20347, https://doi.org/10.5194/egusphere-egu26-20347, 2026.
Carbon capture and sequestration (CCS) is believed to play a critical role in achieving the European Union’s climate neutrality targets, particularly for emissions from hard-to-abate sectors. Recent policy developments in Austria, including renewed discussions on geological CO₂ storage and increased integration into the EU carbon market, have intensified interest in evaluating domestic CCS potential. The Vienna Basin represents Austria’s most promising onshore CCS candidate, owing to its extensive subsurface dataset, long production history, and proven performance as a storage province.
This study assesses the feasibility of CCS in the Vienna Basin with a specific focus on pressure-driven interactions between CO₂ injection and other subsurface operations. A basin-scale reservoir model is developed to represent the key stratigraphic units, structural elements, and hydraulic connections relevant for CO₂ storage. Using this model, multiple injection scenarios are simulated to evaluate pressure evolution, pressure propagation away from the injection site, and the resulting pressure footprints at the basin scale.
Rather than focusing solely on CO₂ plume migration, the analysis emphasizes pressure waves generated by CO₂ injection and their transmission through permeable formations and fault zones. These pressure perturbations may extend well beyond the immediate storage complex and potentially affect neighboring subsurface activities, including underground gas storage, geothermal energy exploitation, and prospective hydrogen storage sites. Scenario results are used to quantify the magnitude and spatial extent of pressure increases and to assess their implications for operational pressure limits, injectivity, and fault stability in adjacent reservoirs.
The results are synthesized into a feasibility framework that links geological suitability, pressure management, and multi-use compatibility. This framework provides guidance on favorable storage domains, critical constraints, and key uncertainties associated with CCS deployment in the Vienna Basin.
How to cite: Abdellatif, M. and Ott, H.: Evaluating Carbon Capture and Storage Feasibility in the Vienna Basin: Pressure Propagation, Formation Integrity, and Multi-Use Subsurface Impacts, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-6712, https://doi.org/10.5194/egusphere-egu26-6712, 2026.
Functional urban areas have to adapt to ever evolving challenges from climate change to digitalization to become sustainable and resilient. These complex transformation processes also require an evolution of scientific approaches. Towards this end, we explore the question: How can we better understand, anticipate, and enable transformations towards resilient and sustainable cities through interconnected Urban Transformation Lab research? In this paper we outline a comprehensive conceptual framework to guide the establishment and operation of 3-5 interconnected Urban Transformation Labs that shall be established in a multi-year approach in several cities in Germany run by several Helmholtz Centers. The framework is built on three central pillars: observation, simulation, and experimentation. The overarching goal is to use insights from urban observatories (pillar 1) gathering various environmental and spatial data as a basis for both the digital tools, such as simulation and visualizations (pillar 2), as well as the experimentation together with stakeholders in the real world (pillar 3). Ultimately, the conceptual framework will enable transferability of the approach as well as cross-case comparison between multiple labs in different contexts tackling a variety of challenges and employing a number of solutions.
How to cite: Baack, F., Brennecke, F., Weiser, A., and Lang, D.: Connecting Urban Transformation Labs to understand, anticipate and leverage resilient and sustainable cities and their surrounding areas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20020, https://doi.org/10.5194/egusphere-egu26-20020, 2026.
Urban areas are focal points of resource consumption, innovation, and governance, but they are also hotspots where environmental stressors such as air pollution and climate change impacts disproportionately affect human health and ecosystem resilience. Improving urban air quality is therefore a central challenge for transformations to sustainable and resilient cities. In Berlin, Germany, a series of mobility-related laws enacted over the past five years aim to transform the city’s transport system toward greater environmental sustainability and climate neutrality. However, due to Berlin’s size, historical development, and fragmented governance structures, these measures—such as new bicycle lanes and temporary street closures—are implemented incrementally across diverse urban districts, complicating the assessment of their localized environmental impacts.
Using the transdisciplinary research approach of the Research Institute for Sustainability (RIFS) at GFZ, measurement campaigns to accompany policy implementations were co-designed with local stakeholders from the Berlin Senate Department for the Environment, Urban Mobility, Consumer Protection and Climate Action (SenUMVK). This research contributed to broader evaluations of the policy implementations and the decision-making processes in the city. Building on these experiences, at a larger scale, a similar transdisciplinary approach was implemented as the foundation for Net4Cities, a project with the aim of facilitating the realization of the EU Green Deal’s Zero Pollution Action Plan by advancing air and noise pollution monitoring infrastructure and providing evidence-based support for implementing effective transport policies and thereby improving air quality and mitigating noise pollution. A harmonized transdisciplinary approach was developed and applied during the first year of the project to build on and establish relationships with the 11 partner cities. This approach formed the basis for the project, and in line with the localized Berlin work, was designed to facilitate exchange among the project and partner cities, integrate interests and perspectives from science and policy stakeholders, and increase uptake and the utility of the project outputs. The presentation will discuss the transdisciplinary framework, its application, how this influenced the results and their uptake, as well as reflections on such an approach to influence transformation processes. This contribution highlights how transdisciplinary research can support the monitoring and mitigation of urban environmental stressors, address synergies between air quality improvement and climate action, and facilitate the uptake of scientific evidence into urban policymaking processes.
How to cite: von Schneidemesser, E., Schmitz, S., Caseiro, A., Blyth, L., and Kerschbaumer, A.: A Transdisciplinary Approach to Urban Air Quality Research, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18464, https://doi.org/10.5194/egusphere-egu26-18464, 2026.
Densely populated urban regions are dual focal points of vulnerability and innovation, where socio-ecological dynamics fundamentally shape regional resilience to global environmental transformation. To decipher this dynamic process, this study adopts ecosystem health (EH) as the core lens to conduct a 30-year (1990–2020) empirical analysis of China's Guanzhong–Tianshui Economic Zone (GTEZ) — a region serving as both a key corridor of the Belt and Road Initiative and a typical area of urban expansion. Its spatial structure, bordered by the ecologically sensitive Loess Plateau to the north, sheltered by the Qinling Mountains ecological barrier to the south, and containing the densely populated Guanzhong Plain in the center, makes it an ideal case for investigating the response mechanisms of human-environment systems. The study period spans three critical transformative phases: rapid industrialization, the gradual establishment of an environmental regulatory framework, and the widespread awakening of ecological conservation awareness.
This research integrates multi-source remote sensing and statistical data within a “Vigor–Organization–Elasticity–Services” assessment framework to systematically characterize the spatiotemporal evolution of EH. It further synthesizes natural drivers (temperature, precipitation, downward longwave radiation) and anthropogenic drivers (PM₂.₅, population density) to reveal the underlying mechanisms. By comparing multiple machine learning models, the CatBoost model with superior performance was selected and combined with the SHAP method for attribution analysis. The main findings are: (1) EH changes followed a clear “deterioration-to-improvement” trajectory. The initial decline was linked to rapid industrialization and a lack of ecological protection, while subsequent improvement benefited from the refinement of environmental regulations and increased public ecological awareness. (2) The dominant drivers shifted significantly from socio-economic factors to natural factors, indicating that after initial containment of anthropogenic pressures, the influence of natural processes like climate change on regional environmental health has become increasingly prominent. (3) EH exhibited significant spatial heterogeneity, with high-value areas consistently distributed in the southern ecological barrier zone, while low-value areas were concentrated in the western and central basin regions, reflecting a spatial gradient of human disturbance intensity.
By employing explainable artificial intelligence methods, this study deepens the understanding of the dynamics within complex urban socio-ecological systems and provides a methodological reference for related monitoring and modeling research. The results not only offer a scientific basis for climate-adaptive spatial planning and ecological risk management in similar urbanizing regions but also help identify key intervention points for resilience building. Ultimately, this research provides empirical insights into how cities and their surrounding areas can proactively adapt to and shape sustainable socio-environmental transformation pathways through collaborative governance and systematic planning. It contributes to translating global sustainable development goals into localized, actionable implementation strategies and offers context-specific guidance for coordinating development and conservation in comparable regions.
How to cite: Xiao, W., Fan, W., Wei, Y., Kelleher, L., Yuan, W., Zheng, S., and Shi, Z.: Decoding Socio-Ecological Dynamics for Urban Resilience: A 30-Year Study of Ecosystem Health and Its Drivers in the Guanzhong–Tianshui Economic Zone, China, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15773, https://doi.org/10.5194/egusphere-egu26-15773, 2026.
Understanding the mechanical deformation and pore characteristics of sandstone at high temperatures is crucial for optimizing its application in subsurface energy systems such as Geological carbon sequestration, underground coal gasification (UCG), and geothermal energy extraction. In this research, the impact of mild heat exposure on the mechanical properties and pore structure of sandstone from the Barakar Formation, Jharia Basin, India, was investigated. Low-pressure gas adsorption (LPGA), helium pycnometry, and water immersion porosimetry (WIP) were used to measure porosity and pore evolution quantitatively. Brazilian tensile strength (BTS) and uniaxial compressive strength (UCS) tests were used to assess the mechanical performance of the sandstone with temperatures.
Low-Pressure Gas Adsorption (LPGA) investigations reveal the presence of silt-shaped pores in the studied samples. Both the specific surface area and pore volume increase with an increase in temperature. Additionally, WIP and He pycnometer data indicate that porosity increases with an increase in temperature, although the change is not significant. BTS and UCS data show a steady decrease in strength characteristics with rising temperatures. This degradation is attributed to the creation of microcracks, the enlargement of pre-existing pores, and thermally driven mineral changes. The study emphasizes the importance of considering thermal effects in subterranean reservoir planning and geotechnical systems, particularly in assessing long-term stability and safety in thermally active environments.
How to cite: Sahoo, A., Verma, A. K., Tripathy, A., and Singh, T. N.: Pore Structure Development and Mechanical Degradation of Sandstone Under Thermal Loading for Geotechnical Applications, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19906, https://doi.org/10.5194/egusphere-egu26-19906, 2026.
Co-producing geothermal energy and critical elements (notably lithium, Li) from deep subsurface brines is emerging as a “two-for-one” subsurface use[1,2]: renewable heat/power plus domestic supply of battery materials. Yet, the feasibility of geothermal-Li co-development is shaped by coupled constraints spanning reservoir deliverability, fluid chemistry, process integration, and permitting regimes[3,4]. Here we compare technological and policy designs of geothermal-Li co-development using two representative deep saline aquifer systems: (1) the Devonian Leduc Formation in the Western Canadian Sedimentary Basin (Alberta, Canada), and (2) the Triassic Buntsandstein (Bunter Sandstone) reservoirs of the Upper Rhine Graben (Germany/France).
For the Leduc Formation, we expand on our prior feasibility work[1,2] focused on deep (>1.5 km) aquifers and regulatory pathways that already combine geothermal development and brine-hosted mineral considerations within Alberta’s existing energy and injection governance (e.g., Directives 089 and 090). A Python-based, multi-criteria geospatial screening analysis[1] integrated temperature, Li occurrence, geologic constraints, proximity to recorded seismicity, and Indigenous rights-holder considerations to narrow to a preferred candidate locality near Whitecourt/Fox Creek region. This quantitative screening analysis first targeted areas where modeled subsurface temperatures exceed 100 °C and then intersected these “hot spots” with formation-water datasets indicating elevated dissolved Li, through a basin-scale mapping approach[2]. Among the candidate areas, there were regions that fall within multiple Indigenous territories (e.g., Treaty 6 and 8), located within 10s km radius of nearby First Nations reserves (e.g., Alexander 134A), highlighting stakeholder engagement as an operational constraint alongside technical screening.
For the Buntsandstein of the Upper Rhine Graben (Germany/France), we build on existing works, targeting deep (~2.5–5 km) Triassic sandstone reservoirs[5]. Published datasets indicate geothermal brines with Li concentrations in the ~160–200 mg/L range, hosted in settings where the Buntsandstein can form a principal reservoir unit[6,7]. Lithium enrichment is linked to a complex hydrothermal history and interaction with sedimentary and evaporitic components of the rift fill, implying that resource sustainability cannot be inferred from “static” brine grades alone. Recent reservoir-scale modeling based on Upper Rhine Graben stratigraphy indicates that, under plausible reinjection–production connectivity, Li concentrations may decline over multi-decadal operation (order-tens of percent), even while heat production remains comparatively stable, making flow rate, reinjection strategy, and extraction efficiency the dominant levers for long-run performance[5,7]. On the German side, this co-development is governed through state mining authorities by issuing exploration titles explicitly covering “Erdwärme, Sole und Lithium” under the Federal Mining Act (BBergG)[8,9], with project execution governed parallel with water-law permissions for brine handling/reinjection.
Across both regions, we identify a practical policy design lesson: geothermal-li projects would benefit under integrated regulation as “closed-loop” subsurface systems, with adaptive monitoring triggers tied to (a) reservoir pressure, (b) reinjection breakthrough and Li decline trajectories, and (c) scaling/corrosion and waste streams from direct lithium extraction process. By aligning and comparing subsurface governance with coupled thermo-hydro-chemical characteristics of these resources globally, regulators can better capture synergies (energy + minerals) while containing shared risks, accelerating responsible deployment in both mature hydrocarbon basins and geothermal provinces.
How to cite: Ghanizadeh, A., Elmeligy, A., Westerlund, K., Khaleghifar, N., Joisar, N. P., Younis, A., Ghanizadeh, A., Hamdi, H., Clarkson, C. R., Brömme, K., König, T. M., König, C., Eaton, D., Tutolo, B., Pedersen, P. K., Morris, N., and Pugh, K.: Geothermal-lithium co-production from subsurface brines: comparing technological and policy pathways across the Leduc Formation (Canada) and the Buntsandstein (Germany/France), EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-13055, https://doi.org/10.5194/egusphere-egu26-13055, 2026.
Superhot geothermal systems, characterized by pressures exceeding 22 MPa and temperatures above 374°C and therefore water being found in its supercritical state, offer a unique opportunity to integrate renewable energy production with carbon capture and storage (CCS). In these systems, supercritical CO2 (sCO2) has a higher density than water, enabling the formation of a sinking CO2 plume that minimizes leakage risks while simultaneously utilizing in-situ geothermal fluids for energy supply. In this presentation, we demonstrate our recent study on the dynamics of CO2 injection and migration in both unfractured, homogeneous, and fractured geothermal reservoirs. Our simulation workflow includes a stochastic fracture network generator that can incorporate various parameters, such as fracture dimensions, strike and dip angles, and fracture network restrictions. Furthermore, the exchange of heat and mass between fracture networks and the surrounding matrix was realized using transfer coefficients rather than a combined grid. This poses numerical challenges that will be discussed during the presentation.
In addition, results from selected simulation runs will be presented, based on different reservoir permeabilities and specific fracture network characteristics, regarding CO2 plume behavior, breakthrough dynamics, and temperature distributions within the reservoir. Overall, high permeability is favorable, while fractured reservoirs exhibit complex migration patterns. Temperature analysis confirmed minimal cooling effects, ensuring long-term operation. In conclusion, our study highlights the conditions necessary for combining CCS and superhot geothermal energy utilization and provides a 3D model for future evaluations.
How to cite: Scherounigg, C. and Ott, H.: A Model for sCO2 Storage in Superhot Geothermal Systems, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20579, https://doi.org/10.5194/egusphere-egu26-20579, 2026.
One of the key elements to achieve a low-carbon and sustainable future is to utilize the porous media in the subsurface. Carbon dioxide capture, utilization and storage is a promising way to use the subsurface and reduce anthropogenic greenhouse gas emissions, especially carbon dioxide. The Pannonian Basin, shared by Central-Eastern European countries, is one of the most prospective areas of onshore CO2 geological storage in Europe. Late Miocene sedimentary rocks of the Pannonian Basin offer significant potential for storing large gas volumes. Storage potential assessment focused on two major groups of geological structures: depleted hydrocarbon reservoirs and saline aquifers. The CO2 storage capacity of the potential fields was estimated based on volumetric parameters. The total CO2 storage capacity of the depleted hydrocarbon fields is estimated to be ~97 Mt whereas in deep saline reservoirs is estimated to fall ~760 Mt. The reservoir rock with the highest storage potential consists of turbiditic sandstone, which is widespread and has regional extent in the Pannonian Basin.
The mechanisms of storage and the effect of CO2 on porous rock still raises questions. Natural CO2 occurrences have developed in similar geological structures to hydrocarbon reservoirs and represent a unique opportunity to study and understand the long-term fate of CO2 in reservoir structures. Core samples from natural CO2 reservoirs were investigated by detailed modal, textural and geochemical analysis. With isotope geochemistry (stable C, O and H isotopes in carbonates) and geochemical modeling (with PHREEQC) tools, we aim to shed light on which carbonates precipitated as a response to CO2 flooding, and to estimate the mineral interactions on geological time scale (Falus et al., 2025).
How to cite: Cseresznyés, D., Király, C., Szamosfalvi, Á., Szabó-Krausz, Z., Szabó, C., and Falus, G.: Potential of CO2 storage opportunities and the role of natural CO2 reservoirs in the Pannonian Basin, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10966, https://doi.org/10.5194/egusphere-egu26-10966, 2026.
Austria’s energy system is characterised by a high share of bioenergy, resulting in substantial biogenic
CO2 emissions from industrial and energy-sector point sources. These emissions represent a potential
carbon feedstock for geo-methanation, enabling the production of renewable methane that is compatible with
existing gas infrastructure. This study presents a national-scale assessment of Austria’s geo-methanation
potential by integrating (i) a spatially resolved inventory of biogenic CO2 point sources, (ii) benchmarked
capture efficiencies by sector, (iii) green hydrogen production constrained by surplus renewable electricity
and electrolyser deployment, and (iv) experimentally observed biological methane yields. Results indicate
that 9–12 Mt CO2 a−1 of biogenic point-source emissions occur nationally, of which 5–8 Mt CO2 a−1 are
technically capturable [1, 2]. Using Austria’s net electricity export balance of 6.8 TWh a−1-derived from
annual import–export statistics, as an upper-bound proxy for surplus electricity, ∼0.7 Mt CO2 a−1 could
currently be methanated [3]. Laboratory geo-methanation experiments achieving approximately 20 % of the
stoichiometric methane yield reduce the methane output potential to 5–8 TWh a−1, corresponding to 7–11 %
of Austria’s current natural gas demand [4, 5]. A phased ramp-up strategy is proposed to reach 10 %, 25 %,
and 50 % utilisation of the biogenic CO2 pool through progressive electrolyser deployment and renewable
electricity expansion. The results demonstrate that Austria’s geo-methanation potential is fundamentally
constrained by the availability of renewable electricity and hydrogen, rather than CO2 supply.
How to cite: Jasek, P., Stiedl, G., and Holger, O.: Assessment of Geo-methanation Potential from Biogenic CO2 inAustria under Renewable Electricity Constraints, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19673, https://doi.org/10.5194/egusphere-egu26-19673, 2026.
Hydrate-based geological storage of CO₂ is a solid-state CCUS technology characterized by high thermodynamic stability and long-term safety, and is therefore regarded as a promising pathway for large-scale CO₂ sequestration. Sandstone formations widely distributed in marine sediments provide substantial pore volume and are considered favorable targets for CO₂ storage. In this study, the pore-scale formation behavior of CO₂ hydrates in sandstone was systematically investigated, and the global CO₂ storage potential in marine sandstones was further assessed.
In the first part of this work, sandstone pore structures were characterized using thin-section petrography, mercury intrusion porosimetry (MIP), and nuclear magnetic resonance (NMR) measurements. The NMR-derived pore size distribution was calibrated against the MIP results, showing excellent agreement (R² = 99.5%) and indicating that the pore sizes of the tested sandstone mainly ranged from 0.005 to 500 μm. Subsequently, in situ CO₂ hydrate formation experiments were conducted using an NMR-based hydrate formation and monitoring system at temperatures of 1–7 °C and pressures of 2–8 MPa, revealing both the kinetic and thermodynamic characteristics of CO₂ hydrate formation in micro- and nanopores. In the second part, global standard datasets were employed to estimate the volume of marine sedimentary sandstones suitable for hydrate-based CO₂ storage, and these results were combined with the water-to-hydrate conversion ratios obtained from laboratory experiments to quantify the total amount of CO₂ that could be stored in marine sediments.
The results indicate that due to the combined effects of pore confinement and the Kelvin effect, the equilibrium pressure of CO₂ hydrates at 7 °C in pores with a pore diameter of approximately 10 nm is elevated from about 2.87 MPa under bulk conditions to 6–8 MPa. When pore sizes exceed 0.1 μm, the influence of pore size on hydrate formation efficiency becomes negligible. Moreover, the large specific surface area provided by rock pores (2.186 m²/g for the samples used in this study) substantially reduces the nucleation energy barrier, leading to rapid hydrate formation kinetics, with all experimental groups reaching approximately 90% of the final conversion within 140 min. Under the investigated pressure–temperature conditions, the water-to-hydrate conversion ratio in pores larger than 0.1 μm ranges from 0.35 to 0.85.
Global-scale estimation suggests that the effective volume of marine sediments suitable for CO₂ hydrate formation within water depths shallower than 4000 m is approximately 3.48 × 10¹⁵ m³. Assuming a sandstone fraction of 1%, the corresponding theoretical CO₂ storage capacity reaches about 1324 Gt, which is close to half of the cumulative anthropogenic CO₂ emissions since the Industrial Revolution. This study provides strong scientific support for large-scale and safe geological sequestration of CO₂ and offers a potential technological pathway toward achieving global carbon neutrality.
How to cite: Zhong, X., Guo, W., Linga, P., Zhang, P., Chen, C., and Wang, X.: Pore-scale formation of CO₂ hydrates in sandstone and global assessment of hydrate-based CO₂ storage potential in marine sediments, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-8850, https://doi.org/10.5194/egusphere-egu26-8850, 2026.
In this paper, the role of Earth-to-Air Heat Exchangers (EAHEs) in improving the energy efficiency of large-scale buildings is examined. Particular attention is given to its applicability in facilities, where high ventilation rates, large internal volumes, long operating hours, and the frequent need for air quality control create favorable conditions for upstream air tempering. Integration pathways are outlined in relation to typical ventilation architectures and control strategies, emphasizing the potential for demand reduction under design conditions and improved part-load performance during seasonal operation.
Finally, EAHEs are positioned within broader sustainable energy management strategies for logistics buildings, including hybrid configurations with heat recovery ventilation, heat pumps, and renewable energy systems. The potential contribution of EAHEs to operational energy reduction and associated emissions mitigation is discussed, while noting that robust performance assessment requires careful consideration of site-specific constraints and the use of dynamic simulation and monitoring frameworks to support design optimization and verification.
How to cite: Czapka, M. and Kaczmarczyk, M.: Earth-to-Air Heat Exchangers and Their Role in Energy Efficiency of Large-Scale Buildings, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19355, https://doi.org/10.5194/egusphere-egu26-19355, 2026.
The URBAN LE project advances climate-resilient urban development by establishing an integrated blue-green-red (BGR) infrastructure framework that reinforces water security and supports sustainable urban transformation. Based in Leipzig and involving five Helmholtz Centers (UFZ, HZDR, HIOH/HZI, GFZ, and KIT), it integrates inter- and transdisciplinary research with co-designed implementation alongside the City of Leipzig and a broad network of municipal, national, and international cities. URBAN LE addresses stormwater management, water-energy coupling, water quality, and governance innovation through real-world pilot implementations at the UFZ campus, and at different sites throughout city. Using functional digital twins and co-designed planning tools, the project evaluates scalable solutions for reducing potable water demand, enhancing water retention and treatment, and integrating aquifer thermal energy storage (ATES). A central focus is the identification of chemical and microbial pollutants mobilized during extreme weather events, including their quantification, accumulation, fate, and transport within BGR systems. Functional digital twins enable comprehensive urban system analysis by combining numerical modeling of hydrological and hydrothermal processes, scenario integration of climatic, demographic, and economic drivers, and infrastructure planning and optimization—such as evaluating interactions between irrigation methods and thermal networks in sponge-city scenarios.
URBAN LE contributes to “Urban Blue-Green-Red Water Systems” and tackles challenges such as decentralized infrastructure planning, digitalization, and institutional governance. Its systemic design positions Leipzig as a model city and facilitates replication in at least ten further German and European cities. By merging rigorous scientific innovation with municipal co-creation, URBAN LE delivers robust tools for climate adaptation, energy transition, and urban water reuse, ensuring long-term impact.
How to cite: Friesen, J., Hampel, U., Schaufler, K., Lang, D., Moeller, L., Scheck-Wenderoth, M., Hofmann, H., Brandenburg, F., and Müller, R.: Systemic blue-green-red urban development (URBAN LE) – A Helmholtz Solution Lab, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-10035, https://doi.org/10.5194/egusphere-egu26-10035, 2026.
Decarbonising district heating systems poses a significant challenge in Central and Eastern Europe, as high-temperature networks predominantly rely on coal-fired power stations. State policy has expanded the number of sites, facilitating the exploration and development of geothermal energy resources while prioritising subsidies for drilling new wells in regions with intermediate geological exploration. A rise in new activity pertaining to the exploration and development of geothermal resources has been observed. One of such locations is Konin in central Poland. However, exploring geothermal resources in urban environments is hindered by limited data availability, dense infrastructure, and legal constraints. Access may also be restricted and constrained by open spaces and road accessibility. Conventional geothermal evaluations in Polish cases predominantly rely on well-drilling data, geophysical surveys, and thermal-gradient measurements. In addition, most geothermal systems utilise saline geothermal fluids as the energy carrier. Regrettably, most geothermal systems face several technological challenges associated with the disposal of saline geothermal fluids. In the presented work, the limitations of available data are analysed, and the necessity of advanced exploration methods, such as seismic surveys, is highlighted for the Konin site as a case study. To facilitate the development of the geothermal system, seismic surveys tailored to the urban area's specific characteristics have been planned. The surveys are being carried out as part of the URGENT project, which aims to provide sustainable and affordable solutions for urban seismic exploration of geothermal resources. Alternative methods of obtaining geothermal energy are also indicated in this case, thereby limiting problems related to high water mineralisation and enabling closed-loop systems, evaluated as part of the HOCLOOP project. In this configuration, the system can also be used for underground surplus energy storage, enabling wider use of underground structures. The results highlight the essential importance of data integrity and completeness in reducing investment risks and enhancing geothermal resource utilisation. They point to the importance of a comprehensive approach to the use of geothermal resources in urban areas. The application of such a solution enables a rational transition from coal-based heating systems to low-emission systems and multi-use of the subsurface structures.
How to cite: Wojnarowski, P., Pająk, L., Tomaszewska, B., Kaczmarczyk, M., and Janiga, D.: Challenges and opportunities for the multi-use of geothermal resources in urban areas, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-12313, https://doi.org/10.5194/egusphere-egu26-12313, 2026.
To quantitatively assess the increasingly severe light pollution in recent years, approaches capable of estimating night sky brightness with high spatial-temporal precision is crucial. However, Falchi et al. (2016) global model did not adequately represent variations in environmental conditions such as aerosols. Therefore, this study developed a new regional-scale night sky brightness model capable of accounting for local characteristics.
This model inputs aerosol, ground-based artificial light, and surface reflectance, and performs radiative transfer calculations that consider multiple scattering in the atmosphere and multiple reflections at the surface. Furthermore, it considers a point spread function based on the Monte Carlo method and calculates the night sky brightness as a hemispherical mean radiance.
The results enabled a better reproduction of the spatial distribution of brightness in urban areas and provided estimates closer to observed values in Japan compared to Falchi et al. (2016).
Fig. 1 The areas and their distribution of night sky brightness, calculated for seven urban areas in Japan.
Additionally, analysis of long-term variations in seven large cities in Japan using this model suggests that night sky brightness generally correlates with population size while also being influenced by urban structure. Although no significant increasing trend was observed between 2013 and 2023, brightness decreased in many cities during the COVID-19 pandemic period, with contributions from both ground-based artificial light and aerosol changes indicated.
This study provides a new assessment methodology, applicable not only within Japan but also extendable to regions worldwide, for quantitatively understanding the current state and variation factors of light pollution.
How to cite: Sano, M. and Iwabuchi, H.: Reproduction of night sky brightness variations in urban areas of Japan caused by aerosols, artificial ground-based light, and surface reflectance, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-15384, https://doi.org/10.5194/egusphere-egu26-15384, 2026.
Achieving national carbon neutrality requires actionable implementation at the municipal level. In Seoul's Dongdaemun-gu, buildings account for 65.2% of greenhouse gas emissions (998 ktCO₂eq, 2018) with ambitious reduction targets of 34% by 2030, 44.3% by 2034, and net-zero by 2050. However, most urban energy studies focus on individual buildings or employ national-level statistics, leaving a critical gap at the district (Gu) scale—where policy authority, infrastructure planning, and technical feasibility converge. This study addresses two key questions: which decarbonization pathway is more viable for district-scale implementation, and can these municipal targets be technically and economically achieved?
We employ City Energy Analyst (CEA) to simulate district-wide building energy systems for all buildings in Dongdaemun-gu. The model encompasses building thermal performance, heating and cooling systems, occupancy patterns, and district energy infrastructure, calibrated against national energy statistics and actual public building consumption data. We compare four scenarios: Current Policy (S0), Heat Pump Electrification Pathway (S1), District Energy & Fuel Cell Pathway (S2), and Integrated Net-Zero Pathway (S3). For each scenario, we quantify final energy consumption, direct building-sector emissions while separating grid decarbonization effects, and economic costs to identify the most feasible route to meeting municipal targets.
By conducting Urban Building Energy Modeling at the district administrative scale, this research bridges the gap between theoretical decarbonization scenarios and implementable municipal climate policies. The findings will quantify the trade-offs between distributed electrification and centralized geoenergy infrastructure, providing evidence-based guidance for how local governments can translate national carbon neutrality commitments into concrete technology deployment strategies. This approach demonstrates the critical role of district-scale analysis in advancing urban energy transformation and climate policy implementation.
This research was supported by Carbon Neutrality Specialized Graduate Program through the Korea Environmental Industry & Technology Institute(KEITI) funded by the Ministry of Climate, Energy and Environment(MCEE).
How to cite: Jeong, S., Choi, Y., and Park, C.: Evaluating Pathways and Feasibility of District-Scale Building Decarbonization: A Municipal Case Study in Seoul, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16068, https://doi.org/10.5194/egusphere-egu26-16068, 2026.
Urban rainwater represents a realistic but often simplified exposure pathway for cement-based construction materials used in small-scale urban infrastructure. In this study, we investigated the time-dependent interaction between natural rainwater and cementitious materials, focusing on pH evolution, CO₂-related processes, and elemental mobility in both normative mortars and systems incorporating incinerated sewage sludge ash (ISSA). Rainwater collected in Kraków (southern Poland) exhibits near-neutral pH values that decrease slightly with storage time, reflecting equilibration with atmospheric CO₂ and the absence of strong acidic inputs, consistent with buffering from alkaline, potentially carbonate-bearing, urban aerosols.
Leaching experiments conducted over 1, 3, and 6 months show systematically higher pH values in leachates compared to the original rainwater, reaching approximately 8.1–8.4 after one month and gradually decreasing toward near-neutral values (≈ 7.0–7.3) after six months. These pH variations demonstrate effective alkalinity buffering by the cementitious matrix, dominated at early stages by portlandite dissolution and alkali release. With increasing exposure time, leachate pH shifts toward that of the incoming rainwater.
Mortars containing ISSA exhibit pH trends comparable to those of conventional systems, with slightly moderated alkalinity release, suggesting the influence of additional aluminosilicate, phosphate, and iron-bearing components on the overall buffering capacity of the composite matrix. The observed pH evolution and associated changes in elemental mobility are linked to early alkalinity buffering, intermediate carbonation, and long-term diffusion-controlled stabilization. Throughout the exposure period, near-neutral to mildly alkaline pH conditions suppress the solubility of trace elements and promote sorption and encapsulation mechanisms, with no evidence of delayed contaminant release.
The results indicated that under realistic urban rainwater conditions, both conventional and ISSA-containing cementitious materials maintain chemical stability and environmental compatibility. Therefore, it is essential to consider natural rainwater chemistry and time-dependent pH evolution when evaluating the long-term durability and environmental safety of small-scale infrastructure. In addition, ISSA, when incorporated into cementitious matrices in appropriate proportions, does not represent a secondary source of contamination and may be valorized as a construction additive rather than disposed of in landfills
Acknowledgment: The research for this publication has been supported by the budget of the Anthropocene Priority Research Area (Earth System Science Core Facility Flagship Project) under the Strategic Programme Excellence Initiative at Jagiellonian University
How to cite: Kasina, M., Wierzbicki, A., and Popów, W.: Rainwater interactions with ISSA-modified mortars: pH evolution, CO₂ buffering and implications for urban infrastructure and waste valorization, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-16808, https://doi.org/10.5194/egusphere-egu26-16808, 2026.
The subsurface (geological space beneath Earth’s surface) is increasingly treated as a multifunctional resource that must serve multiple purposes in the era of the low-carbon economy. The most important current and near-future energy-related uses may include:
• conventional and enhanced geothermal systems (EGS)
• low- and medium-temperature aquifer thermal energy storage (ATES)
• borehole thermal energy storage (BTES)
• underground hydrogen storage (porous reservoirs or salt caverns)
• etc.
Exergy analysis offers a rational way to compare different applications while answering the question: how much useful energy could theoretically be obtained from each cubic meter of subsurface space used in a given way?
Purely volumetric approaches („how many m³ do we have?") can be very misleading – exergy density is usually a much better indicator of real resource value. In this view, priority should be given to high-exergy applications in the most valuable parts of the subsurface. In the case of energy storage technologies, exergy loss is proportional to the entropy change due to heat dissipation to the environment. This effect will be greater the higher the temperature of the stored heat. The article considers temperature ranges typical for heat storage technologies.
How to cite: Pajak, L., Halaj, E., and Wachowicz-Pyzik, A.: A preliminary comparison of subsurface energy applications from the exergy perspective as a tool for sustainable use of subsurface resources assessment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19988, https://doi.org/10.5194/egusphere-egu26-19988, 2026.
Geophysical surveys are widely used to characterize lithological and structural variability in the subsurface. They support the design of shallow, low-temperature geothermal systems, the delineation of freshwater aquifers, and the assessment of investment risk associated with subsurface interventions. Evidence from the authors’ projects and from published case studies shows that a detailed ground model is central to environmental impact assessment, definition of technical boundary conditions, and planning of synergies between operation and its interactions with existing infrastructure, local communities, and the natural environment. In practice, this requires translating interpretation results into project-relevant parameters, including lithology distribution, layer thickness, key boundary geometries, disturbed zones, and hydrogeological conditions, together with risk indicators that describe the likelihood of adverse ground and groundwater conditions at the planned site. Interpretation remains challenging because ambiguity arises from limited resolution and survey coverage and from the inherent heterogeneity of unconsolidated sediments.
This paper presents an integrated workflow for shallow investigations that combines seismic, electrical resistivity and electromagnetic methods to reduce ambiguity through consistent multi-method integration and explicit uncertainty quantification. The workflow assumes that the geological model must both respect method-specific limitations and represent the subsurface architecture realistically enough to support engineering decisions. Spatial geostatistical modelling is used to capture variability and to propagate uncertainty into maps and cross-sections of key boundaries and properties. Geostatistical and Artificial Intelligence tools support data fusion, recognition of structural features and lithological zones, and systematic comparison of alternative geological scenarios. The resulting ground model is delivered as a most-likely realization accompanied by uncertainty products, including probability-based representations of lithology and confidence intervals for boundary positions, so that the outputs can be used directly in technical and environmental risk assessment and in selecting the preferred design variant.
The workflow is demonstrated on experimental field data collected during a seismic project carried out in Poland, in an area with unfavorable geological conditions that generate highly ambiguous seismic responses. Although the survey was not originally intended for shallow geothermal design, it enabled development and testing of the integrated workflow and the formulation of practical guidance for siting shallow installations. The study focuses on ambiguity drivers such as strong attenuation and scattering in unconsolidated deposits, lateral and vertical velocity variability, and locally changing saturation, and on mitigation measures based on survey design, processing choices, and integration with electrical methods. The site is representative of settings with heterogeneous Quaternary cover and thick unconsolidated sediments under variable hydrogeological conditions, which also supports transfer of the methodology to the exploration and characterization of shallow freshwater resources. The final outcome is a coherent methodological description and decision oriented recommendations that support transparent, defensible assumptions during planning and implementation under uncertainty.
How to cite: Cygal, A., Ząbek, G., Stefaniuk, M., and Maćkowski, T.: Tools for Compatibility Screening in Shallow Subsurface Uses via Integrated Geophysical Ground Modelling with Uncertainty Assessment, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-18661, https://doi.org/10.5194/egusphere-egu26-18661, 2026.
Geothermal potential in Poland is mostly associates with low-temperature resources accumulated in four geothermal provinces: Polish Lowlands, Carpathians, Carpathians Foredeep and Sudetes Region. Each provinces is characterized by different geological, and geothermal parameters, determination of which can be supported by magnetotelluric and gravimetric data. Magnetotelluric methods are frequently used as auxiliary under Polish conditions predominant by geothermal resources associated with sedimentary complexes and predominantly in resources connected with crystalline rocks, where seismic method is not effective. Gravimetric methods are used to identify deep and shallow fault zones, which may correspond to geothermal hotspots.
The paper presents examples of hydrogeothermal investigation supported by those two methods in Jurassic sedimentary complexes of Polish Lowlands. The results clearly shows that magnetotelluric and gravimetric methods can effectively support the selection of perspective areas for future low-temperature geothermal investments.
An integrated interpretation of magnetotelluric, gravimetric and seismic results (where available) in the exploration area, supported by existing hydrogeological data, improves the reliability of conceptual models of geothermal systems in the Polish Lowlands by reducing interpretational ambiguity. Comprehensive interpretation helps to distinguish conductive zones related to saline aquifers from structural features controlling fluid circulation, such as fault and fracture zones. This approach reduces exploration risk at the early stage of project development by narrowing the target area for detailed surveys and by constraining the location and expected depth of exploratory wells. In practice, the proposed workflow can be used as a cost-effective screening tool to identify the most promising sites for low-temperature geothermal heat production.
How to cite: Wachowicz-Pyzik, A., Cygal, A., and Stefaniuk, M.: The use of magnetotelluric and gravity studies to identify geothermal conditions – case study from the Polish Lowlands, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-17959, https://doi.org/10.5194/egusphere-egu26-17959, 2026.
Global municipal solid waste (MSW) generation reached 1.2 billion tonnes in 2022 and is projected to increase to 3.8 billion tonnes by 2050, driven mainly by urbanization and changes in consumption patterns (UNEP & ISWA). In Colombia, MSW generation amounted to 31.31 million tonnes in 2022, of which the organic fraction of MSW (OFMSW) represents between 36% and 58% of the total, depending on the urban context (DANE, 2024). The predominant disposal in sanitary landfills, combined with inadequate technical management, has generated critical environmental impacts, including the emission of nearly 20% of global anthropogenic methane (CH₄) (UNEP, 2021), a gas with a global warming potential approximately 80 times higher than CO₂ (Calvin et al., 2023), as well as the production of highly contaminating leachates and risks to public health (UNEP, 2021).
A paradigm shift has recently been identified, moving from linear collection-and-disposal schemes toward circular-economy-based energy recovery models, in which advanced Mechanical–Biological Treatment (MBT) technologies (Nanda & Berruti, 2021)—including anaerobic digestion (AD), advanced composting, co-digestion, gasification, and pyrolysis—enable the transformation of OFMSW into biogas, bioenergy, and other bioproducts, thereby reducing pressure on final disposal systems and contributing to the achievement of the Sustainable Development Goals (SDGs) (Sharma et al., 2021; Nanda, 2021).
This research is grounded in the formulation of integrated OFMSW management models that consider the physicochemical characterization of waste, which serves as the basis for technology selection and performance assessment (Sondh et al., 2024). Within this framework, Life Cycle Assessment (LCA) is applied to quantify the environmental impacts associated with the implementation of these treatment technologies, and multi-criteria decision-making tools are incorporated to integrate technical, economic, and social variables, enabling comparative scenario evaluations among emerging technologies with the aim of maximizing OFMSW valorization under circular economy principles.
It is estimated that technified OFMSW management could contribute to a potential reduction of 29 to 57 million tonnes of CH₄ emissions globally by 2030 (UNEP, 2021). In Colombia, the implementation of MBT systems for at least 5% of OFMSW, combined with biogas utilization, constitutes a key strategy for the country to achieve its target of a 51% reduction in greenhouse gas emissions by 2030 (Minambiente, 2020). Likewise, the energy recovery of OFMSW provides a strategic contribution to the energy security of Latin American megacities during drought periods, reducing dependence on conventional thermoelectric sources (Sond et al., 2024). Consequently, integrated OFMSW management based on LCA has the potential to reduce environmental impacts and public health risks, transforming waste into assets for resilient urban development.
How to cite: Becerra Quiroz, A. P., Ramírez2, D. G., Rodrigo-Clavero, M.-E., and Rodrigo-Ilarri, J.: Integration of Life Cycle Assessment for the Management of the Organic Fraction of Municipal Solid Waste (OFMSW) under a Circular Economy Approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-23206, https://doi.org/10.5194/egusphere-egu26-23206, 2026.
Geothermal energy in Poland is currently used primarily for heating purposes, with an increasing emphasis on recreational and therapeutic applications. These trends are particularly evident in the southern part of the country, in the Małopolska Voivodeship. Geothermal waters occurring in the porous-fissure aquifer of the Podhale Basin are characterized by high flow rates, temperatures close do 90oC and low mineralization.
Advanced Geothermal Systems (AGS) may prove a significant opportunity for utilizing geothermal resources in the coming years. These systems utilize closed-loop heat systems, in which the medium circulates in a closed system, transferring energy stored in the deep, hot layers of the earth crust to the surface. The implementation of AGS requires reservoirs with temperatures exceeding 100 °C, high thermal conductivity, and very low natural permeability. This creates an opportunity for the deployment of such systems in areas with high energy demand, especially for district heating applications, where natural hydrogeothermal resources with suitable temperature and flow characteristics are absent. A potential recipient in the Małopolska Voivodeship is Kraków, second largest city in Poland with population around 800,000, whose area is geologically poorly explored due to its dense development and lack of hydrocarbon deposits. Consequently, no detailed seismic surveys have been conducted in this region. As a result, significant uncertainties exist regarding the thickness of the overlying sedimentary sequences, the depth of the crystalline basement, its petrophysical properties, and the structural configuration of fault zones. To determine the feasibility of implementing an AGS system, an attempt was made to analyze the possibilities of geological exploration for the Kraków region by designing geophysical surveys along seismic profiles, which would enable the identification of deep geological structures.
How to cite: Stefaniuk, M., Lukaj, K., Wachowicz-Pyzik, A., Cygal, A., Hodiak, R., and Nowak, M.: Analysis of the Possibility of Recognizing the Deep Geological Structure of the Krakow Region for Advanced Geothermal Systems (Ags) Implementation, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19410, https://doi.org/10.5194/egusphere-egu26-19410, 2026.
Urban resilience in the face of climate change and increasing hydrometeorological risks depends not only on technical solutions, but also on social practices, local knowledge, and governance structures that shape how adaptation is understood and enacted. Although the importance of social and cultural dimensions in climate adaptation is widely recognised, there are still few approaches that explicitly address them. One approach that has gained increasing attention in recent years is the use of playful methods, particularly games. These approaches typically aim to foster civic engagement, community resilience, and adaptation literacy. Their playful nature creates space for participants to articulate concerns, desires, and tensions while granting them agency—an experience that can be both empowering and motivating.
Drawing on two case studies from Kampung Akuarium, a flood-prone coastal neighbourhood in Jakarta, we examine memory mapping with children and speculative gameplay involving residents and local government officials. These methods are discussed as experimental interfaces between lived experiences of environmental stressors and formal planning processes. We analyse their methodological affordances and limitations, particularly with regard to their capacity to open spaces for collective reflection on spatial transformation and to elicit social and cultural values, including emotional attachments, that are often excluded from technocratic planning.
Creative mapping enabled residents to document their own spatial narratives and experiences with recently implemented flood protection structures. It also revealed that the disconnection of local residents from their familiar environments reflects a broader shift in the cultural landscape of kampungs, where access to the sea has increasingly been restricted through redevelopment, protective infrastructure, and displacement. Aiming to (re)claim cartography as a means of situated storytelling and collective agency, the workshops sought to create spaces for articulating and negotiating relationships with the environment and for imagining alternative futures of life along the waterfront—an endeavour that proved only partially successful. While challenging technocratic mapping practices, the workshops also demonstrated that playful forms of mapping alone cannot counter the realities of spatial planning. They can document experiences and provoke reflection, but re-establishing access to space requires broader structural change. Without explicit links between workshop outcomes and institutional responsiveness, such mapping approaches risk remaining symbolic rather than transformative.
We argue for a context-sensitive and strategic deployment of creative mapping methods as part of broader socio-technical adaptation efforts. When embedded in sustained research and planning processes, they can contribute to more resilient urban futures by linking local knowledge and lived experiences with governance in rapidly transforming urban environments.
How to cite: Erbach, T.: Creative Mapping for Climate Adaptation: Two Case Studies from Jakarta´s Coast, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-20062, https://doi.org/10.5194/egusphere-egu26-20062, 2026.
Most existing studies on ecological vulnerability assessment focus on large-scale regions, which limits their ability to accurately capture the ecological specificity and underlying driving mechanisms of small-scale areas. Small-scale ecosystems, such as those at the county level, often exhibit pronounced regional characteristics. Their natural endowments, industrial structures, and socio-cultural factors not only shape local ecological conditions but also play an important role in the sustainable development of surrounding areas. Consequently, there is an urgent need for targeted research on such regions and for the formulation of corresponding management strategies.
Taking Shunping County as a case study, this research extends the traditional SRP (Sensitivity–Resilience–Pressure) framework by introducing a “Characteristic” dimension and develops a CSRP (Characteristic–Sensitivity–Resilience–Pressure) model. By integrating the Analytic Hierarchy Process (AHP) and the entropy weight method, the ecological vulnerability of Shunping County was quantitatively evaluated. The spatiotemporal evolution patterns and driving factors were further analyzed, and corresponding management strategies were proposed.
The results indicate that ecological vulnerability in Shunping County exhibited a “deterioration followed by improvement” trend in 2010, 2015, and 2020. These changes were influenced not only by natural factors but also closely associated with the implementation of local policies. Spatially, ecological vulnerability was relatively high in the southeastern plain areas due to intensive human activities and pollution from characteristic industries, whereas the northwestern mountainous and hilly areas showed comparatively lower vulnerability. The driving factor analysis reveals that the interactive effects of socioeconomic development, industrial structure, and population distribution exert a stronger influence on ecological vulnerability than any single natural factor. In addition, pollution control related to industrial activities remains a key issue requiring particular attention in the region.
The findings provide both theoretical and practical implications for ecological management and sustainable development in Shunping County. The proposed CSRP model offers a transferable analytical framework for assessing ecological vulnerability in small-scale regions with distinct local development characteristics. It is particularly useful for understanding socio-ecological interactions in urban areas and their surroundings under environmental pressures and adaptive governance processes, and it can serve as a reference for monitoring, assessment, and sustainable strategy design in the context of urban–rural coordinated transformation.
How to cite: Li, J., Liu, H., Wan, W., Liu, S., and Liu, Z.: How the “One County, One Product” model reshapes regional ecological vulnerability : Evidence from Shunping county, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-9250, https://doi.org/10.5194/egusphere-egu26-9250, 2026.
Although extensive information exists on the chronological evolution of the fortified monastic complexes on Mount Athos, data regarding the construction dates of their hydraulic infrastructure remain comparatively limited. Since water constitutes a fundamental prerequisite for sustained settlement and construction, the development of a monastery presupposes access to reliable and sufficient natural resources essential for its establishment and long-term survival. This study applies a quantitative reverse-engineering approach to estimate the water demands associated with the construction of Dochiariou Monastery's principal fortified elements, namely the katholikon, the tower , and the perimeter walls. By approximating the number of monks, draught animals , and construction workforce, as well as the volumes of building materials (brick, stone , and lime mortar), we quantify minimum water requirements for mortar production, brick making, human and animal consumption, and material transport along the steep kalderimi (stone-paved path) from the Αrsanas (dock). Order-of-magnitude calculations indicate that the annual water yield of local springs provides only a marginal surplus, insufficient to sustain intensive, multi-year construction phases in the absence of engineered storage or supplementary water sources. The central aqueduct—terminating directly into the tower—exhibits a high potential discharge capacity and a strategically integrated layout, suggesting that it may have predated the major building campaigns. This analysis indicates that the aqueduct and associated hydraulic works were likely among the earliest infrastructural interventions, enabling subsequent expansion in an isolated, topographically constrained environment. The findings demonstrate the value of reverse engineering as a methodological tool for inferring the relative chronology and functional role of medieval hydraulic systems, particularly where direct archaeological or archival evidence is scarce. These insights further underscore adaptive water-management strategies that underpin long-term settlement resilience in resource-limited environments.
How to cite: Papadodimas, N., Laoutaris, G. D., Mamassis, N., and Sargentis, G.-F.: Reverse Engineering for the Chronology of Medieval Aqueducts: A Case Study of the Holy Monastery of Dochiariou, Mount Athos, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-14910, https://doi.org/10.5194/egusphere-egu26-14910, 2026.
Posters virtual: Tue, 5 May, 14:00–18:00 | vPoster spot 4
EGU26-7454 | Posters virtual | VPS19
Spatiotemporal Patterns of Ecological Vulnerability in Malta: An Empirical Analysis Using the PVOR ModelTue, 05 May, 14:39–14:42 (CEST) vPoster spot 4
Accurate assessment of ecological vulnerability in island systems under natural and anthropogenic pressures is crucial for ecosystem stability and sustainable development. Constructing an adaptive and scientific framework for evaluating ecological vulnerability in island regions remains a key challenge. This study introduces a novel Pressure–Vigor–Organization–Resilience (PVOR) model for assessing ecological vulnerability, applied to the main island of Malta. A combined weighting approach using game theory was used to determine composite indicator weights, while multi-source data (e.g., remote sensing and geospatial data) were integrated to investigate the long-term spatiotemporal evolution of ecological vulnerability from 2000 to 2020 and its driving factors.
The results show that: (1) Over 20 years, the ecological vulnerability index (EVI) of Malta fluctuated but declined from 0.65 to 0.58. From 2000 to 2015, vulnerable areas were mainly located in the eastern built-up zones. By 2020, the area of highly vulnerable zones decreased by 86% due to ecological protection policies and the COVID-19 pandemic, with minor increases in vulnerability (less than 5 km²) along the southwestern coastline. (2) Ecological vulnerability exhibited significant spatial clustering (global Moran’s I > 0.80, p < 0.01), with high-value clusters in the east and low-value clusters in the west and north. (3) Key driving factors include habitat quality, landscape fragmentation, population density, and development intensity, with interaction effects being stronger than individual factors. (4) Based on both static and dynamic vulnerability assessments, ecological zoning was defined, and targeted management strategies were proposed.
This study provides a scientific foundation for ecological restoration and sustainable development in Malta, offering a transferable framework for other island systems.
How to cite: Wang, L., Chi, J., and Xiao, X.: Spatiotemporal Patterns of Ecological Vulnerability in Malta: An Empirical Analysis Using the PVOR Model, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-7454, https://doi.org/10.5194/egusphere-egu26-7454, 2026.
EGU26-19295 | Posters virtual | VPS19
Assessing and Designing a Pilot Aquathermal System on the TU Delft CampusTue, 05 May, 14:42–14:45 (CEST) vPoster spot 4
An aquathermal energy system is a sustainable heating and cooling technology for buildings by utilizing low-grade thermal energy from water sources. This contribution presents a full scale pilot at the TU Delft campus that investigates and show-cases the potential of a campus pond to supply thermal energy to the Firma van Buiten (FvB) building, which is a restaurant/meeting location.
The contribution focuses on sensor integration and data acquisition, heat balance modeling, and design considerations for an aquathermal system. Initially, a field campaign was conducted to assess the pond's dimensions, collect bathymetric data, and install temperature sensors at various locations and depths.
The heat balance model uses data from the pond and a nearby weather station to quantify temperature effects on the surface water system. By performing a heat balance of the water body, considering various factors, including solar radiation, wind speed, air temperature, and heat fluxes, the study evaluates the extractable thermal energy from the pond and assesses its suitability for low-temperature heating and cooling applications.
Finally, a design analysis of the pilot aquathermal system is presented, considering technical feasibility, integration with existing building energy systems, and potential scalability across the campus. The contribution also provides recommendations for implementing a more sophisticated data acquisition and monitoring system.
The findings provide practical insights for advancing sustainable energy solutions in dense urban environments and support the broader implementation of aquathermal technologies in the Netherlands.
How to cite: Fremouw, M., Koulidis, A., and Bloemendal, M.: Assessing and Designing a Pilot Aquathermal System on the TU Delft Campus, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-19295, https://doi.org/10.5194/egusphere-egu26-19295, 2026.
