Management of urban waters with nature-based solutions in circular cities-exemplified through seven urban circularity challengesManagement of urban waters with nature-based solutions in circular cities-exemplified through seven urban circularity challenges Peer-Reviewed Journal Publication Δημοσίευση σε Περιοδικό με Κριτές 2022-08-232021enThe APC was funded by COST CA 17133.The work was carried out within the COST Action CA17133 Circular City (“Implementing nature-based solutions for creating a resourceful circular city”, http://www.circular-city.eu (accessed on 12 April 2021), duration 22 October 2018—21 October 2022). COST Actions are funded within the EU Horizon 2020 Programme. Nature-Based Solutions (NBS) have been proven to effectively mitigate and solve resource depletion and climate-related challenges in urban areas. The COST (Cooperation in Science and Technology) Action CA17133 entitled “Implementing nature-based solutions (NBS) for building a resourceful circular city” has established seven urban circularity challenges (UCC) that can be addressed effectively with NBS. This paper presents the outcomes of five elucidation workshops with more than 20 European experts from different backgrounds. These international workshops were used to examine the effectiveness of NBS to address UCC and foster NBS implementation towards circular urban water management. A major outcome was the identification of the two most relevant challenges for water resources in urban areas: ‘Restoring and maintaining the water cycle’ (UCC1) and ‘Water and waste treatment, recovery, and reuse’ (UCC2). s Moreover, significant synergies with ‘Nutrient recovery and reuse’, ‘Material recovery and reuse’, ‘Food and biomass production’, ‘Energy efficiency and recovery’, and ‘Building system recovery’ were identified. Additionally, the paper presents real-life case studies to demonstrate how different NBS and supporting units can contribute to the UCC. Finally, a case-based semi-quantitative assessment of the presented NBS was performed. Most notably, this paper identifies the most typically employed NBS that enable processes for UCC1 and UCC2. While current consensus is well established by experts in individual NBS, we presently highlight the potential to address UCC by combining different NBS and synergize enabling processes. This study presents a new paradigm and aims to enhance awareness on the ability of NBS to solve multiple urban circularity issues. http://creativecommons.org/licenses/by/4.0/Water1323Oral_et_al_Water_13(23)_2021.pdfChania [Greece]Library of TUC2022-08-23application/pdf1.1 MBfree Oral Hasan Volkan Radinja Matej Rizzo Anacleto Kearney Katharina Andersen Theis Raaschou Krzeminski Pawel Buttiglieri, Gianluigi Ayral-Cinar Derya Comas Joaquim Gajewska Magdalena Hartl Marco Finger David C. Kazak Jan K. Mattila Harri Vieira Patrícia Piro Patrizia Palermo Stefania Anna Turco Michele Pirouz Behrouz Stefanakis Alexandros Στεφανακης Αλεξανδρος Regelsberger Martin Ursino Nadia Carvalho Pedro N. MDPI Blue-green infrastructure Climate change and mitigation Sustainable water management Urban circularity challenges Water reuse