Adaptation to climate change and enhancing resilience is a key challenge for water management and economic sectors in the European Union that are depending on the use of water and/or the services water bodies are providing. Droughts and heavy rain events already show effects on the condition of many water bodies. Higher variabilities in rainfall and runoff patterns, increasing water scarcity, deteriorating water quality as well as inertial changes of water balances and water ecosystems have serious consequences, not only for drinking water supply or the health of ecosystems, but also for other sectors and infrastructures, such as agriculture and forestry, energy production or inland navigation. More frequent and more intense floods and storm surges threaten settlements and cities in coastal areas and along rivers. Hydrological extreme events intensified by climate change are now among the most serious risks that threaten societies. Severe floods in Southwest and Central Europe in 2016 and 2018 as well as the repeating drought periods in large parts of Europe in recent years have clearly shown Europe’s vulnerability.