In many countries of the Global South, aquatic ecosystems such as streams, rivers, lakes, and wetlands are severely impacted by several simultaneous environmental stressors, associated with accelerated urban development, and extreme climate. However, this problem receives little attention. Applying a DPSIR approach (Drivers, Pressures, State, Impacts, Responses), we analyzed the environmental impacts and their effects on urban hydrosystems (including stagnant waters), and suggest possible solutions from a series of case studies worldwide. We find that rivers in the Global South, with their distinctive geographical and socio-political setting, display significant differences from the Urban Stream Syndrome described so far in temperate zones. We introduce the term of ‘Southern Urban Hydrosystem Syndrome’ for the biophysical problems as well as the social interactions, including the perception of water bodies by the urbanites, the interactions of actors (e.g., top-down, bottom-up), and the motivations that drive urban hydrosystem restoration projects of the Global South. Supported by a synthesis of case studies (with a focus on Brazilian restoration projects), this paper summarizes the state of the art, highlights the currently existing lacunae for research, and delivers examples of practical solutions that may inform UNESCO’s North–South–South dialogue to solve these urgent problems. Two elements appear to be specifically important for the success of restoration projects in the Global South, namely the broad acceptance and commitment of local populations beyond merely ‘ecological’ justifications, e.g., healthy living environments and ecosystems with cultural linkages (‘River Culture’). To make it possible implementable/practical solutions must be extended to (often poor) people having settled along river banks and wetlands.

Nature-based solutions (NBS) are inspired and supported by nature but designed by humans. Historically, governmental stakeholders have aimed to control nature using a top-down approach; more recently, environmental governance has shifted to collaborative planning. Polycentric governance and co-creation procedures, which include a large spectrum of stakeholders, are assumed to be more effective in the management of public goods than traditional approaches. In this context, NBS projects should benefit from strong collaborative governance models, and the European Union is facilitating and encouraging such models. While some theoretical approaches exist, setting-up the NBS co-creation process (namely co-design and co-implementation) currently relies mostly on self-organized stakeholders rather than on strategic decisions. As such, systematic methods to identify relevant stakeholders seem to be crucial to enable higher planning efficiency, reduce bottlenecks and time needed for planning, designing, and implementing NBS. In this context, this contribution is based on the analysis of 16 NBS and 359 stakeholders. Real-life constellations are compared to theoretical typologies, and a systematic stakeholder mapping method to support co-creation is presented. Rather than making one-fit-all statements about the “right” stakeholders, the contribution provides insights for those “in charge” to strategically consider who might be involved at each stage of the NBS project.

Living Labs are recognized as a progressive form to foster innovation and the strengthening of collaborative planning. The concept has received strong attention by the European Union (EU) research and innovation agendas recently. This contribution investigates how a Living Lab approach could be used for the design and implementation of Nature-Based Solutions (NBS). NBS are gaining acceptance as a more sustainable solution for reducing the exposure to natural hazards and vulnerability to events, such as increased flooding in changing climate. However, a lack of collaborative approaches hinders their broader implementation. A literature review on the theoretical aspects of the Living Labs concept in the context of NBS is conducted, and we compare the theoretical findings with practices that were observed by case studies implementing NBS in a collaborative manner. The Isar-Plan River Restoration in Munich, Germany, and the Mountain Forest Initiative (Bergwaldoffensive). Both of the case studies have already started well before the concept of Living Labs gained wider popularity. Both award-winning cases are recognized good practice for their exemplary in-depth stakeholder involvement. The paper discusses the concepts and approaches of Living Labs and reflects on how it can serve and support in-depth participatory stakeholder involvement.

Nature-based solutions (NBS) for mitigating climate change are gaining popularity. The number of NBS is increasing, but research gaps still exist at the governance level. The objectives of this paper are (i) to give an overview of the implemented NBS for flood risk management and mitigation in Germany, (ii) to identify governance models that are applied, and (iii) to explore the differences between these models. The results of a hierarchical clustering procedure and a qualitative analysis show that while no one-size-fits-all governance model exists, polycentricism is an important commonality between the projects. The study concludes by highlighting the need for further research on traditional governance model reconversion and paradigm changes. We expect the findings to identify what has worked in the past, as well as what is important for the implementation of NBS for flood risk management in future projects.

Human welfare depends on the health of nature. Decades of ill-conceived management practices caused a decline in the quality of human life, as well as in biological and cultural diversity. Simultaneously, they increased social and ecological risks. For instance, mismanagement of urban rivers jeopardizes their ecological health and ability to provide ecosystem services. While demands for responsible urban riverscape design that fulfill both human and ecosystem needs are increasing, explicit recommendations to achieve these ambitious goals are still lacking. We present a first attempt of a conceptualization of Human–River Encounter Sites for urban rivers that targets reconciliation between humans and nature within urban river corridors. It builds upon the River Culture Concept with literature reviews and experiences from river restoration projects. We identify six tenets that are important to develop guidelines for Human–River Encounter Sites: health, safety, functionality, accessibility, collaboration, and awareness. This paper presents how these tenets can collectively help to harmonize the needs of citizens and biota, and to mitigate the current urban river crisis. This contribution feeds the debate on sustainable socio-ecological management of urban rivers and provides guidelines for the implementation of future urban river restorations and management efforts.

Sub-Saharan Africa (SSA) is the region most vulnerable to climate change and related hydro-meteorological risks. These risks are exacerbated in rapidly expanding urban areas due to the loss and degradation of green and blue spaces with their regulating ecosystem services. The potential of nature-based solutions (NBSs) to mitigate hydro-meteorological risks such as floods is increasingly recognised in Europe. However, its application in urban areas of SSA still needs to be systematically explored to inform and promote its uptake in this region. We conducted a multidisciplinary systematic review following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) protocol to establish the general patterns in the literature on NBSs and hydro-meteorological risk mitigation in SSA. We searched scientific journal databases, websites of 12 key institutions and 11 NBS databases and identified 45 papers for analysis. We found at least 1 reported NBS in 71 % of urban areas of SSA across 83 locations. Of the papers, 62 % were clustered in South Africa, Kenya, Tanzania and Nigeria only, while the most studied cities were Dar es Salaam and Kampala. Moreover, 66 NBS practices were identified, most of which (n=44) were for flood mitigation. With only Mozambique (n=2) among the most at-risk countries reporting NBSs, we found that NBSs are implemented where risks occur but not where they are most severe. Mangrove restoration (n=10) and wetland restoration (n=7), reforestation (n=10) and urban forests (n=8), and agroforestry (n=3) and conservation agriculture (n=2) were the most common NBS practices identified for floods, extreme-heat and drought mitigation, respectively. Traditional practices that fit the definition of NBSs, such as grass strips and stone bunds, and practices that are more popular in the Global North, such as green roofs and green façades, were also identified. These NBSs also provided ecosystem services, including 15 regulatory, 5 provisioning and 4 cultural ecosystem services, while 4 out of every 5 NBSs created livelihood opportunities. We conclude that the reported uptake of NBSs for hydro-meteorological risks in SSA is low. However, there could be more NBSs, especially at the local level, that are unreported. NBSs can help SSA address major development challenges such as water and food insecurity and unemployment and help the sub-region progress towards climate-resilient development. Therefore, we recommend that NBSs be mainstreamed into urban planning and knowledge exchange opportunities between SSA and Europe and that other regions be explored to promote uptake.