Management of Urban Waters with Nature-Based Solutions in Circular Cities—Exemplified through Seven Urban Circularity Challenges

Hasan Volkan Oral,David C Finger,Gianluigi Buttiglieri,Theis Raaschou Andersen,Katharina Kearney,Martin Regelsberger,Magdalena Gajewska,Matej Radinja,Marco Hartl,Behrouz Pirouz,Nadia Ursino,Pedro N Carvalho,Harri Mattila,Patrícia Vieira,Patrizia Piro,Michele Turco,Anacleto Rizzo,Stefania Anna Palermo,Paweł Krzemiński ,Jan Kazak ,Derya Ayral-Çınar ,Alexandros Stefanakis ,Joaquím Comas

doi:10.3390/w13233334

Abstract

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.

Highlights

Water is a natural and essential resource for human life [1]
Each urban circularity challenges (UCC) is central to achieving circularity, and should be viewed as interdependent objectives in a broader system context
A visual representation of the UCC interconnections was developed based on the experiences of these experts researching and working in water-related fields (Section 3.1)

Summary

Introduction

Water is a natural and essential resource for human life [1]. Water consumption has doubled in the last century as a result of global population increase, making water scarcity one of the most pressing issues of the twenty-first century [2,3,4]. Rapid industrialisation and economic growth [5], as well as the generation of substantial amounts of industrial effluents, place a significant strain on limited water resources [6,7]. Climate change is expected to have a significant impact on the water cycle [8,9], resulting in issues in cities such as droughts, floods, water resource pollution, and heat waves [10,11]. The regeneration and reuse of wastewater is a priority only for nations with considerable hydric stress or water shortages (e.g., China, Mexico, the United States, and Israel), yet this regeneration can occur without extra water treatment in some instances [12]

Methods

Results

Conclusion