FT1 – Szeged: Geothermal transformation of urban heating: the Szeged District Heating System

The largest geothermal district heating system in Eastern Europe is located in Szeged, in south-eastern Hungary. The Szeged District Heating Company (SZETÁV), a municipally owned SME, operates the city's district heating and cooling system, supplying heating and hot water to 27,256 households and 433 public buildings. The system comprises 23 heating circuits with a total installed capacity of 204 MW.

Since 2018, SZETÁV and its partners have been working on a large-scale project to integrate geothermal energy by 2025. Co-financed by the EU and private investors, the €70 million development includes 27 wells (9 production and 18 injection), drilled to depths of 1,700–2,000 metres into a Late Miocene sandstone reservoir. The 90 °C thermal water is transported through a newly constructed 30 km pipeline to heating plants, where heat exchangers transfer the energy to the district heating network.

During the visit, participants will tour selected parts of the system and related facilities, including a nearly 100-year-old Turkish-style bath.

FT2 – Danube–Tisza Interfluve: From recharge to discharge – hydrogeological controls on wetlands and alkaline landscapes

The Danube–Tisza Interfluve, located within the Great Hungarian Plain, is a key region where the recognition of groundwater flow systems has significantly improved our understanding of the spatial distribution of diverse surface phenomena, including freshwater and saline wetlands, sandy dunes, wet meadows, and alkaline plains.

During the field trip, participants will visit characteristic wetland, vegetation, and soil zones, and explore their connections to underlying groundwater flow systems. Following the natural topographic gradient from recharge areas toward discharge zones, systematic changes will be observed both at the surface and in groundwater conditions.

As this region is among the most climate-vulnerable and water-scarce areas of Hungary, the demand for water retention and managed recharge interventions is high. The program includes a visit to a surface water retention site, where infiltration processes and groundwater responses are being monitored. To conclude the day, participants will have the opportunity to enjoy a traditional Hungarian lunch at a local csárda, a regional tavern offering authentic cuisine and atmosphere.

FT3 – Veresegyház: Thermal water utilization and geothermal energy

Veresegyház is a small city with a population of approximately 22,000, yet it features an extensive district heating system exceeding 10 km in length. The first thermal water well was drilled nearly 40 years ago, although its success was initially uncertain due to local geological conditions. Over time, five additional thermal water wells have been drilled.

Today, the thermal water-based district heating system supplies the Mayor’s Office, the Community Centre, the largest elementary school, several public buildings, the GE Vernova turbine factory, and the Sanofi Aventis pharmaceutical factory.

During the field trip, participants will visit a 1,725 m deep thermal water well (constructed in 2015) and its heating control room, which supplies heat to the GE Vernova factory. The next stop will be the Mézesvölgyi Elementary School, the largest elementary school in Hungary, designed in the distinctive style of the famous architect Imre Makovecz. Here, in the heating control room, participants will see how the district heating system is integrated into the building’s heating network.

The program highlights local agricultural applications of geothermal energy. A visit to the Veresi Paradicsom greenhouses will demonstrate how tomato production is supported by geothermal energy. Veresegyház is known not only for its Women’s Choir and Bear Farm, but also for producing one of the sweetest tomatoes in the world, the “Sugarloaf”, grown in geothermal-energy heated greenhouses.

FT4 – Tata: The City of Waters – springs, karst, mine recovery and cultural highlights

Tata, located at the foot of the Gerecse Mountains in north-western Hungary, is known as the “City of Waters” due to its abundant springs, lakes, and wetlands. Its landscape and cultural identity is shaped by a karst aquifer system composed of Mesozoic limestone and dolomite, recharged from the Gerecse highlands and discharging toward the Tata Basin, where lukewarm springs historically fed the Old Lake (Öreg‑tó), Cseke Lake, and the surrounding marshlands.

In the mid‑20th century, intensive coal and bauxite mining caused significant depressurization of the karst system. Groundwater levels declined by more than 40 m, leading to the disappearance of Tata’s springs and major changes in flow patterns and water chemistry. Since mining ceased in the 1990s, the system has been recovering, with rising groundwater levels and the reactivation of springs.

A key example of this recovery is the Fényes Nature Trail, an elevated boardwalk through a restored spring area in the northern part of Tata. Here, visitors can observe crystal‑clear karst water emerging to the surface within a wetland environment rich in aquatic vegetation, illustrating the strong connection between groundwater dynamics and surface ecosystems.

During the field trip, participants will walk along the Fényes Nature Trail, then continue to the English Garden and the 18th‑century Esterházy Castle on the shore of the Old Lake, where additional karst springs can be observed. After lunch we will take a short walk along the lake before returning to Budapest.

FT5 – Lake Velence: From groundwater-fed wetlands to traditional Hungarian pálinka

Discover the natural and cultural treasures of Lake Velence. For more than eight years, our research team has been investigating surface water–groundwater interactions in this remarkable soda lake, one of the westernmost occurrences of soda lakes in Eurasia. The lake, the third largest in Hungary, has an average depth of only about 1.5 meters and hosts a unique mosaic of open water, reed beds, and floating bog vegetation.

The excursion begins at the Lake Velence Inspectorate, where a brief presentation (approximately 30 minutes) will introduce the methodology used to investigate groundwater-surface water interaction. Next, participants will visit the protected wetlands of Dinnyési-Fertő, once an integral part of the lake and today a paradise for birdlife. Walking along the Dinnyési-Fertő Hiking Trail, participants will have the chance to observe numerous bird species that find ideal nesting and feeding habitats in the Fertő’s protected waters and extensive reed beds. Next, participants will visit Szúnyog (Mosquito) Island and take a closer look at the lake with its reed beds and floating bog vegetation that shapes the lake’s hydrology and ecological character, followed by lunch on the island.

Additionally, a guided tour and tasting is available at the renowned Agárdi Distillery in Agárd, where visitors will gain insight into the art of traditional Hungarian pálinka production (from orchard to bottle) and enjoy a tasting of premium fruit spirits.

This field trip is co‑organized with the Central Transdanubian Water Directorate and the Duna-Ipoly National Park Directorate.

FT6 – Bükkábrány: Dewatering system of an open-pit mine

This field trip introduces the hydrogeological challenges and dewatering strategies associated with open-pit lignite mining. The mining operation near the town of Bükkábrány is operated by MVM Mátra Energia Zrt. and extracts lignite using open-pit methods. To ensure safe working conditions and protect the mine pit from water ingress, continuous dewatering is carried out under the supervision of the company's hydrogeologists. The dewatering process is performed using an advancing well network with a lead time of approximately three years.

The program begins with a presentation (up to one hour) explaining the dewatering system, followed by a guided visit to the mine using company-provided vehicles. Within the mining operation, there will be several stops: participants could observe the well network, the different types of wells, the drainage system, the open water retention in the mine pit, the management of residual waters, and the production equipment. Beyond the dewatering system, an interesting feature is the visit to the mine pit itself and visiting the production-transport-dump forming equipment, such as Europe's largest compact rotary bucket-wheel excavator located here.

FT7 – Miskolc: Drinking water and thermal water utilization of the Bükk karst aquifers

This field trip provides an overview of the complex utilization of karst water resources in the Bükk Mountains region, combining drinking water supply and geothermal energy use in the area of Miskolc. The program begins at the University of Miskolc, where participants will be introduced to the activities of the Institution of Water Resources and Environmental Management. A presentation will provide an overview of the hydrogeological characteristics of the Bükk and Miskolctapolca karst system, including its special features and the well-known Cave Bath.

The excursion continues to Miskolctapolca, where participants will visit one of the drinking water supply systems of the city of Miskolc. The site includes two large-diameter wells producing karst water for drinking water purposes, as well as Central Europe’s largest ultrafiltration system, offering insight into advanced water treatment technologies and process control.

In the final part of the program, the group will visit the geothermal system at Mályi-Kistokaj. This system features three production wells (one of which was recently constructed using special directional inclined drilling technology) and three reinjection wells. The system taps thermal karst reservoirs at depths of 1,800–2,000 m to provide district heating for a significant part of Miskolc, with water reinjected after heat extraction. The produced water is reinjected after heat extraction. Participants will also visit the heat exchange facilities and learn about the operation of this sustainable energy system.

FT8 – From the Balaton Highland to the Tihany Peninsula: Groundwater flow systems, lake–groundwater Interactions and cultural landscapes

The Balaton Highland is part of the largest continuous carbonate aquifer system of the Transdanubian Mountains and is hydraulically connected to Lake Balaton, the largest lake in Central Europe. This field trip introduces the hydrogeology of the Balaton Highland along a route from recharge areas in the highlands to discharge zones at the lake, highlighting groundwater–surface water interactions through springs, lakes, and wetlands within a landscape rich in cultural heritage.

In Balatonfüred, a historic spa town on the northern shore of Lake Balaton, participants will examine the origin and geological controls of CO₂‑rich medicinal waters. The excursion concludes on the Tihany Peninsula, a unique volcanic landscape formed by maar volcanism, where groundwater–surface water interactions will be directly observed using the peninsula’s lakes as examples, which exhibit contrasting hydraulic relationships with groundwater. Special emphasis will be placed on the sensitivity of groundwater‑dependent ecosystems to climate‑change‑driven reductions in recharge, declining lake levels, and the resulting challenges for nature conservation and tourism in this protected area.

The program also includes a visit to the Tihany Benedictine Abbey, a historic 11th-century monastery, offering panoramic views of Lake Balaton and its surroundings.

This field trip is co‑organized with the HUN‑REN Balaton Limnological Research Institute.

FT9 – Szentendre Island: From the Danube to the tap – exploring a 150-year-old riverbank filtration system in Budapest

This field trip provides a behind-the-scenes look at one of Europe’s largest and longest‑operating riverbank‑filtration systems, a truly unique natural infrastructure that has supplied high-quality drinking water to Budapest for more than 150 years. Participants will discover how Budapest’s world‑renowned riverbank‑filtration system provides clean, safe, and reliable drinking water to approximately 1.8 million people.

The program begins at the iconic main pumping station of Budapest Waterworks, where participants will visit the historic engine house and attend a presentation on water production, distribution, and network operations. Experts will also provide insights into ongoing research and innovations in safe and sustainable drinking water supply.

After lunch, the excursion continues to the Szentendre Island well field, one of Budapest’s most important drinking water resources. Participants will walk along the impressive line of production wells, visit the pump house, and learn more about the hydrogeological conditions that make riverbank filtration along the Danube possible.

This field trip is co‑organized with the Budapest Waterworks.

FT10 – Szentkirály: From aquifer to bottle – the Szentkirályi Mineral Water Plant

This field trip offers participants the opportunity to visit the bottling plant of Szentkirályi Magyarország Ltd., part of the Mattoni 1873 group, and gain insight into the production of Hungary’s leading mineral water brand. Recognised for its excellent quality, Szentkirályi was awarded the world’s best mineral water at the Aqua-Eauscar Award in 2004 and has since received numerous national and international distinctions.

During a guided tour of the facility, participants will learn about the bottling process and the journey of the mineral water from the protected aquifer near the village of Szentkirály (approximately 90 km from Budapest) to the market. The water is naturally pure, moderately low in total dissolved minerals, and particularly low in sodium chloride.

The Szentkirályi plant is a state-of-the-art facility that has undergone significant technological development in recent years. Major investments have expanded production capacity and efficiency, including new high-performance bottling lines capable of producing up to 32,000 bottles per hour. Ongoing developments also include the introduction of capabilities for bottling carbonated soft drinks, further strengthening the plant’s role within the regional beverage industry.

The excursion provides a unique opportunity to explore the connection between groundwater resources, mineral water extraction, and the beverage industry in Hungary.

FT11 – Budapest Rose Hill: Natural discharge and cave development in the Buda Thermal Karst

This field trip focuses on the Buda Thermal Karst (BTK), a classic example of hypogene karstification driven by regional groundwater flow and thermal water discharge along the Danube fault zone. Participants will explore the Szemlő-hegyi Cave as a fossil, visitor-accessible hypogene cave, and contrast it with the active, water-filled Molnár János Cave system. The trip concludes at the Lukács Thermal Bath, where the same thermal karst waters are used in balneology.

Key topics include the interpretation of hypogene morphologies and speleothem-based evidence for multi-phase cave development, with emphasis on hypogene cave formation and subsequent overprinting. The active, submerged Molnár János Cave system provides a direct window into present-day karst aquifer, enabling discussion of contemporary discharge conditions, cave formation and aquifer vulnerability in a dense urban setting. Hydrochemical and isotope-based studies add regional context on recharge, residence time, and geochemical evolution relevant to BTK springs and production wells supplying the city’s baths.

The field trip concludes at the Lukács Thermal Baths, where participants have the option to enjoy a bath at their own expense.

FT12 – Budapest Gellért Hill: Drinking water reservoir and thermal springs in the Buda Thermal Karst

The field trip begins with a panoramic overview from the Gellért Hill hilltop, introducing the geological setting of the Buda Thermal Karst and the structural controls that concentrate rising thermal waters along the Danube. Next, participants descend to one of the largest drinking water reservoirs, holding 80 million liters of water. The reservoir is named after József Gruber, who is internationally renowned for his research on fluid dynamics. Here a short overview will be provided about the drinking water supply of Budapest.

The field trip will continue in the Gellért Tunnel, 1 km-long underground tunnel where production wells and springs supplying the iconic Gellért and Rudas Baths can be directly observed. Within the tunnel, participants may also visit the Aragonite Cave, which demonstrates hypogene speleogenesis through its mineral paragenesis and the geological record of ancient thermal water phenomena. The trip concludes at a spring cave at the Török Spring, illustrating active discharge points and related precipitates from the Buda Thermal Karst system.

FT13 – Budapest: From thermal baths to sustainable geothermal use

This half-day field trip focuses on geothermal energy utilisation and Budapest’s long-standing balneological tradition, where thermal waters have been used for centuries and continue to play an important role in the life of the city. The program highlights different examples of how deep groundwater resources are integrated into urban recreational, cultural, and sports facilities. Sites are located within the city and will be visited by public transport and short walks, making the excursion easy to follow and not physically demanding.

At the MTK Budapest Sportpark, participants will learn about a recently implemented geothermal heating system supplying a modern sports complex. The visit introduces the hydrogeological background of the project, its operational experience, and the monitoring system. The trip also includes the historic Széchenyi Thermal Bath, one of Europe’s largest thermal bath complexes, where deep thermal water has been in continuous use since the early 20th century, illustrating the city’s balneological tradition in a geological and hydrogeological context.

Finally, the cascading use of thermal water will be presented through the heating system of the Budapest Zoo & Botanical Garden and its Biodome. This example illustrates how residual heat from spa operations can contribute to the energy supply of neighbouring buildings, including the iconic Elephant House. The trip provides an overview of the geological background, technical solutions, and sustainability aspects of geothermal energy use in a densely built urban environment.

The field trip concludes at the Budapest Zoo & Botanical Garden, where participants have the option to visit the zoo at their own expense.