Climate crisis, societal change and geopolitics are increasingly combining to make achieving water security ever more challenging. Conversely, sustainable and secure water systems are increasingly recognised as core to achieving sustainable outcomes in other domains such as food production, urbanisation and women's empowerment. And, as yet, there is relatively little attention paid to the countries of Eastern Europe, especially those around the Black Sea basin and in the Balkans. We propose a permanent topical collection on “regional water security issues”, which could include papers covering:

• Climate models showing changes in water availability
• Reflections on the impacts of the above for hazard and risk
• Regional and sub-regional papers – e.g. western Balkans, eastern Balkans, distinctions between Danube plain and other catchments
• Urban water issues
• Challenges for particular communities such as Roma, ethnic minorities
• Food, water, energy nexus
• Transboundary water sharing.

All accepted papers will be immediately published within the currently opened issues.