The debate-format plenary sessions centre around major groundwater challenges, providing a platform for groundwater experts from different fields, backgrounds and domains to explore how science translates into policy and discuss the future of groundwater education and
research. Delegates are invited to participate in surveys for some plenary topics that will feed into the debates

How are mountain climates changing, and what are the consequences for the cryosphere (glaciers, snow, and permafrost)? How can the water resources stored in seasonal snowpacks be quantified? And what do future projections of snow water resources reveal?
How important is mountain groundwater for sustaining streamflow during dry periods? What proportion of mountain groundwater is derived from cryosphere melt (compared with other sources)? And what do the latest models indicate regarding the impacts of cryosphere decline on groundwater systems and, ultimately, catchment run off?
What are the major outstanding research gaps in the fields of mountain snow hydrology and mountain hydrogeology? How can these communities work together to better understand and predict cascading effects of cryosphere change, and thereby ultimately provide actionable insights for mitigating and adapting to the adverse impacts in communities and ecosystems – both in the mountains and downstream. 
In this Plenary session, short invited presentations will first be given by two renowned experts – Dr. Tobias Jonas (“Snow Hydrology” Group Leader at SLF, Switzerland), and Dr. Laurent Somers (Assistant Professor, Dalhousie University, Canada). Then, outstanding challenges in the respective fields and at their interface, as well as possible solutions, will be debated from the different perspectives.

What do hydrogeologists need to know? What do academics want to teach them? Why do companies hire hydrogeologists and what do they expect from them? What skills do public administrations and NGOs expect? Why do students decide to study hydrogeology? How many hydrogeologists does a country need?

In the context of climate change, the importance of groundwater as a reliable source of water for society and ecosystems is increasing, with the risk of overexploitation. Based on the most comprehensive global overview of groundwater level trends, the plenary session will explore what is needed to prevent and reserve groundwater depletion trends. The role of sound hydrogeological understanding, long-term data sets and effective groundwater policies will be discussed, illustrated by case studies from around the world.

Do we only know the tip of the iceberg when it comes to contaminants in groundwater? What comes after PFAS? Do we need to get away from the idea that we can just pump and drink without advanced treatment? Do we know enough about what the subsurface can take and what is a problem? Are groundwater protection concepts effective and will groundwater, where impacted, be soon good enough again?

The subsurface is in high demand for energy extraction, energy storage, waste disposal, extraction of raw materials, infrastructure…and groundwater. Should groundwater have priority? Are there only conflicts among groundwater and other uses of the subsurface or also synergies? Are regulations adequate and based on sound hydrogeological concepts? Three brief keynotes in this Plenary will illustrate how these potential conflicts have been handled in examples of heat storage, CO₂ storage and geothermal energy exploitation. The talks will be followed by an open discussion of key problems and new ideas on these issues.

This session will identify key challenges and opportunities in hydrogeology, exploring how to address them through research and technical innovation. We aim to provoke discussion on the future of the discipline, focusing on the primary obstacles hindering hydrogeological progress, how the field might evolve over the next 50 years, and the research that is essential for advancing the discipline. Additionally, we will discuss ways to bridge the gap between research and practice. A panel of experts will share insights and engage in a lively discussion, encouraging bold, imaginative thinking about the future of hydrogeology.