Door: Erik van Erne

COP26 Mitigating floods and droughts – innovative approaches for closing urban water cycles by SIWI Too much and too little water - these two conditions are expected to increase with climate change in many regions, challenging urban water systems around the globe. Especially in cities with fast growing populations and economies, prolonged droughts and extreme rainfalls can become major disasters, as recent examples from Cape Town and Chennai show. In some places, the crises led to a fundamental re-thinking of the way water is handled in the city. New concepts, like the ‘sponge-city’ concept, go beyond the traditional supply-collect-discharge-paradigm and propose to close urban water cycles, e.g. by decentral storage, infiltration and reuse. Integrated approaches address not only water challenges, but look also for cross-sectoral benefits such as cooling and improve living conditions. The session presents two cities that took new ways in urban water management. The city of Windhoek suffered from severe drought in the past, but took innovative water management approaches to mitigate future disasters. The city stores excess water underground through a managed aquifer recharge scheme and treats wastewater to potable water in direct reuse facilities, and is a global forerunner for both approaches. In Hamburg, climate change is expected to lead to more frequent heavy rainfall events, droughts and hot spells. Since the existing infrastructure, mostly build decades ago, was not designed for the changed conditions, the water utility together with the city administration launched a collaborative process of rainwater infrastructure adaptation, where ‘sponge city’ principles are becoming more and more important. The session will present lessons learnt and recommendations for other cities in closing urban water cycles to build drought resilient water supplies <iframe width="685" height="385" src="https://www.youtube.com/embed/6SK3Jh2Ov54" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>