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Integrating Nature-based Solutions for urban water security in global south

Correction

31 Oct 2025: Abera LE, Jumani S, van Rees CB, Krishnaswamy J, Seigerman CK, et al. (2025) Correction: Integrating nature-based solutions for urban water security in global south. PLOS Water 4(10): e0000461. https://doi.org/10.1371/journal.pwat.0000461 View correction

Abstract

Nature-based solutions (NbS) leverage the power of ecosystems and biodiversity to address societal challenges. NbS for addressing water security challenges in cities are widely recognized for accelerating sustainability and delivering multiple co-benefits. However, peer-reviewed studies and implementation guidance have primarily focused on the Global North, necessitating adaptation for the Global South. While NbS could provide environmental and socio-economic benefits, the specific adaptations required for planning, designing, and implementing in the context of the Global South remain unclear. During the 6th Symposium on Urbanization and Stream Ecology (SUSE 6) held in Brisbane, Australia, in May 2023, a group of interdisciplinary experts discussed these challenges. This was followed by in-depth discussions with additional experts spanning various sectors across the Global South and a comprehensive literature review. This paper presents the outcomes of these efforts specifically focused on three objectives: understanding the NbS planning context in the Global South, identifying unique challenges for implementing NbS in these regions, and identifying “bright spots” as learning opportunities for implementation. We outline the contextual differences between the Global North and Global South in the context of water security and NbS, and then the challenges and opportunities to mainstream urban water NbS in the Global South are discussed across four thematic categories: environmental; socio-economic and perceptional; capacity, knowledge and expertise; and management and governance. We highlight select bright spots to foster a broader understanding of ongoing efforts in the Global South. Ultimately, we seek to highlight opportunities for more efficient and socially-just pathways for adoption of NbS to address urban water security in the Global South. We also recommend practical steps such as capacity building in NbS design and implementation, development of best practices and support tools, monitoring of outcomes, consideration of other effective area-based conservation measures (OECM) as NbS and building partnerships for all of these with stakeholders.

Citation: Abera LE, Jumani S, van Rees CB, Krishnaswamy J, Seigerman CK, Nelson DR, et al. (2025) Integrating Nature-based Solutions for urban water security in global south. PLOS Water 4(6): e0000372. https://doi.org/10.1371/journal.pwat.0000372

Editor: Alicia Correa, Justus Liebig University, GERMANY

Published: June 5, 2025

This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication.

Funding: This work was supported by the U.S. Army Corps of Engineers Engineering With Nature initiative (SKM) and in part by appointment to the Department of Defense (DOD) Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy (DOE) and the DOD managed by ORISE under DOE contract (LA and JH). IIHS acknowledges the support from Agence Française de Développement (AFD) through their search project— “Greening Urban Food Systems: Building Sustainable urban agriculture practices in Bengaluru through nature-based solutions”(JG). The funders had no role in study design, data collection and analysis, decision to publish, or manuscript preparation.

Competing interests: The authors have declared that no competing interests exist.

1. Introduction

Many urban water management activities are, at their core, centered on providing communities with safe access to water and sanitation, reducing hazard risks, and balancing infrastructure performance with ecological and social outcomes. Said differently, urban water management seeks to increase water security for city residents. While no universal definition exists [1] water security can be broadly defined as “an acceptable level of water-related risks to humans and ecosystems, coupled with the availability of water of sufficient quantity and quality to support livelihoods, national security, human health, and ecosystem services” [2–4]. In cities, water security involves the set of systems for managing waterways, moving potable and sanitary flows, recycling water, and coping with (and facilitating) natural variability [5,6]. Urban water managers apply multiple actions in pursuit of this goal, including conventional infrastructure, policy mechanisms, and nature-based solutions.

Nature-based solutions (NbS) are well-recognized as a potential strategy to achieve sustainability goals and deliver multiple co-benefits from water infrastructure and other systems with potential applications globally. NbS “leverage nature and the power of healthy ecosystems to protect people, optimize infrastructure, and safeguard a stable and biodiverse future” [7]. While experts typically think about NbS from their particular disciplinary perspective [8], this and other definitions of NbS involve the integration of multiple fields in the natural and social sciences. In this review, NbS are understood as interventions inspired by nature that address societal challenges, provide multiple ecosystem services and ecological benefits, and perform infrastructure services related to water security.

NbS represent a promising suite of methods for simultaneously addressing multiple societal challenges and bridging the historic divide between infrastructure planning and biodiversity conservation [9,10]. Nowhere is the promise of NbS more relevant than in regions of the so-called “Global South”. Urban areas of the Global South face water security challenges due to rapid urbanization, population growth, climate change impacts, and often inadequate infrastructure [11–13]. However, much of the current NbS literature focuses on the context of wealthier countries in developed regions and temperate climates (e.g., [14,15]), with limited research on NbS in the Global South (see for example: [16–19]. One reason for this perceived lack of NbS adoption is the use of different lexicons depending on the region and context. Some alternative terms common in the Global South include green infrastructure [20], ecological solutions, natural resource management, landscape-based solutions [21], urban greenspaces, stormwater best management practices, biological engineering, ecosystem-based adaptation, and social technology [22]. In this paper, we use the term NbS to collectively capture these actions that meet the spirit and goals of NbS but are referred to by different terms.

Here, we examine the unique challenges of applying NbS to address urban water security in the Global South. Our objectives are to 1) understand the different contexts for NbS implementation between the Global South and North, 2) identify unique challenges for implementing NbS for urban water security, and 3) describe opportunities for NbS implementation by learning from“bright spots” (i.e., examples of especially successful implementation, [23] in the Global South). We acknowledge that binary terms like Global North vs. Global South, developed vs. developing, or high- vs. low-income present a false dichotomy for several reasons. For example, the magnitude and rate-of-change of development are not uniform within regions, simple economic metrics do not differentiate nuanced global differences, local context is crucial, and exceptions exist to any dichotomy [24]. However, we use these terms to draw contrasts between the context of NbS implementation for urban water security with the goal of identifying potential challenges in transfer of planning and design recommendations across these regions.

2. Approach

A multi-pronged approach, based on an in-person workshop, virtual discussions, and literature review, was used to understand how NbS could address urban water security challenges in the Global South. The in-person workshop was conducted in two sessions at the Sixth Symposium on Urbanization and Stream Ecology (SUSE 6), held in Brisbane, Australia, in May 2023. A workshop proposal with the background and purpose of the workshop was used to announce andcommunicate the sessions and 12 experts registered for and participated in them. The workshop proposal is provided in supplementary documents (S1 Text). Following the in-person discussions, we conducted virtual discussions with 20 experts working across the Global South to expand the topical and geographic breadth of perspectives. Participants were selected based on expertise and regional location to encompass a range of countries within the Global South and were identified via professional networking and recommendations. They were then invited via email for a discussion session. A consistent set of topics were covered with all participants using a discussion guide. A list of discussion guide questions is provided in the supplementary document (S2 Text). Participants shared their experiences working in a diverse cross-section of countries, including the Bahamas, Brazil, Ecuador, El Salvador, Ethiopia, India, Nepal, Nigeria, South Africa, Sri Lanka, Thailand, and other locales. The participants also drew from diverse disciplinary backgrounds, including environmental economics and policy, landscape architecture, life sciences, anthropology, social sciences, and engineering. In addition, we conducted a literature review to supplement discussion findings.

During the in-person workshop, initial insights were collected from the participants after a brief introductory presentation. Experts reflected on current practices and identified challenges and opportunities to implement NbS based on experiences in home countries, including Australia, Ethiopia, India, New Zealand, Niger, the Philippines, and the United States of America. Participants discussed key topics in smaller breakout sessions and reconvened with the large group to reflect. An interactive online discussion platform (Miro) was used to collect input and notes during the workshop and to facilitate the discussion. Participant inputs were then summarized into the themes of challenges and opportunities. The virtual discussions were conducted in two phases. First, discussions were conducted in small groups (one-to-one or a maximum of two participants). Then, a more extensive group discussion was conducted with the experts who wanted to become involved in the development of this manuscript. Audio recordings and manual note-taking were used to collect data during these discussions. Informed consent was given by all participants before data collection.

The findings from the SUSE 6 conference workshop and the data collected from experts’ interviews were synthesized and cross checked. The findings from virtual discussions were summarized by the Author team using the interactive online platform (Miro) and combined with workshop input. The findings from the workshops and virtual discussion were analyzed thematically, resulting in four categories: environmental; socio-economic and perceptional; capacity, knowledge and expertise; and management and governance.

In addition to the qualitative, lived experience and professional expertise represented in these dialogs, we conducted a review based on targeted literature search of NbS practices to cross-validate and support the discussion findings. The review included peer-reviewed journal articles and “gray literature” (conference proceedings, reports, etc.) on urban water security and NbS practices from both the Global South and North to understand contrasting practices and opportunities for knowledge sharing. We organized our search around urban water security NbS and specific search terms used in Google Scholar, Scopus, and Web of Science™ are provided in the supplementary file (S3 Text). The resulting set of literature was analyzed to cross-validate discussion themes and findings and identify additional challenges and opportunities. Combined discussion and literature review findings were checked again by sending the final draft of the paper to workshop participants for their review and input. We collated “bright spots” as unique opportunities to further learn from regional practices and support the findings.

All efforts were made to support regional and disciplinary representation for the in-person workshop and virtual discussions. However, gaps inevitably remain. Further, since most of the participants are from academia, the authors acknowledge the lack of certain voices, such as practitioners, government representatives, and city planners.

3. Findings and discussion

The barriers to mainstreaming NbS for sustainable development in higher income, Global North countries are increasingly well understood. These include a lack of monitoring records of NbS performance, persistent disciplinary silos among researchers and practitioners, and the difficulty of achieving joint action across governance institutions [25,26]. Due to their different economic, ecological, and cultural contexts (Table 1), Global South countries may face distinctive challenges in addition to those that manifest in other regions. Here we discuss the different contexts for NbS implementation for urban water security between the Global South and North. We also synthesize challenges and opportunities for NbS implementation in urban contexts in the Global South based on the SUSE 6 conference workshop and experts’ interview output. These are divided into four categories: environmental; socio-economic and perceptional; capacity, knowledge and expertise; and management and governance. One effective way to transfer scientific knowledge into use is by learning from bright spots [23]. These “instances where science has successfully influenced policy and practice” [23], can help develop more practical guidance for successful NbS implementation by increasing understanding of the unique challenges faced by a region and the approaches that led to success. Here, we highlight opportunities to help overcome the challenges and point to bright spots to guide a path forward. The bright spots are embedded under each of the four thematic categories that are the closest fit, though most case-studies involve all themes.

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Table 1. A general comparison of the fundamental assumptions contextualizing the implementation of NbS for urban water security in the Global North and Global South.

https://doi.org/10.1371/journal.pwat.0000372.t001

3.1 Nature-based solutions for urban water security

Achieving urban water security in the Global South remains a major challenge for several reasons. Over the past two decades, these countries have experienced the highest levels of urban population growth globally [27]. Rapid urbanization and increased population densities often overwhelm the capacities of existing water infrastructure systems for water supply, wastewater treatment, and stormwater management and can have significant negative consequences for urban watersheds [28,29]. These risks are further compounded by the fact that cities in the Global South are particularly susceptible to climate change impacts [30] and high rates of pollution of freshwater bodies such as streams and rivers from different sources and land uses [31]. Even when access to water services is guaranteed, intermittent water supply can lead to inequitable water access and experiences of water insecurity [32]. The growing demand for water across economic sectors, limited availability, and high costs of additional supplies, combined with the relatively recent recognition and consideration of environmental water demands, has led to competition for existing water resources [33].

The United Nations (UN) Agenda for 2030 introduced the Sustainable Development Goals (SDGs) in part to address issues like global water security. Incorporating NbS in the Global South presents opportunities for sustainable development aligned with the SDGs. Improved water security achieves multiple SDGs, such as good health and well-being (SDG3), clean water and sanitation (SDG6), sustainable cities and communities (SDG11), and climate action (SDG13). The primary SDG related to urban water security in the Global South is SDG6, “to ensure availability and sustainable management of water and sanitation for all by 2030.” The selected targets in the context of urban water infrastructure are to improve water quality (Target 6.3), integrate water management, and restore water-related ecosystems (Target 6.6) through capacity-building support to developing countries (Target 6.a) and participation of local communities (Target 6.b). This paper frames the differences of NbS planning contexts in the Global North and South using an existing framework [1] for urban water security that aligns each element with the SDGs (Fig 1). The dimensions of this framework were modified to the context of urban infrastructure relative to five components: water quality, water availability, ecosystem conservation, protection against water-related hazards (such as urban floods), and resilience to climate-related hazards.

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Fig 1. Urban water security elements align with SDGs.

https://doi.org/10.1371/journal.pwat.0000372.g001

Many countries with emerging economies support large, highly concentrated urban populations with new water infrastructure developments. The overlap of infrastructure proliferation with high population densities can reduce water security and result in misalignment with the SDGs. NbS, particularly when integrated with conventional gray infrastructure, have great potential to address water security-related challenges and other societal goals. However, their implementation in the Global South has been less widely integrated into policies and funding programs relative to the Global North. Protecting and restoring water-related ecosystem services through NbS is essential to mitigate growing water scarcity, unsafe water access, and water availability [34], although potential NbS benefits have not been rigorously assessed [9,29,35].

While many aspects of NbS planning and implementation may translate directly from the Global North, some of these contextual factors may lead to gaps in transferability to the Global South. Table 1 presents a qualitative comparison of key topics that could hinder the implementation of NbS methods from the Global North in the Global South.

3.2. Challenges and opportunities for NbS in global south

3.2.1. Environmental and Ecological.

Cities and urbanizing spaces in the Global South, like elsewhere, have their share of ecological, environmental and water footprints both within and in nearby areas [27,29,31,33]. The environmental challenges for water security NbS design and implementation in the Global South include high levels of water and solid waste pollution and large quantities of untreated wastewater [36], severe loss of permeable spaces for rainwater infiltration and groundwater recharge [37], and hydrological changes [38,39]. The loss of natural habitats and native biodiversity coupled with the proliferation of invasive species in water bodies further limit the implementation of NbS that rely on healthy ecosystems [40]. Furthermore, space to develop NbS [41] and implementation of interventions such as sewage treatment plans and subsequent use of treated wastewater are limited. This is especially true when retrofitting is required and acquisition of land for projects is often expensive and difficult due to competing demands on land. Integration of blue, green and grey infrastructure [41] is challenging under these circumstances. Like elsewhere, the effective implementation of NbS is further complicated in the face of a changing climate [42]. The increasing frequency and severity of extreme weather events, such as floods and droughts, and related changes to flow regime make planning for effective NbS outcomes more challenging. Finally, since NbS rely on ecological processes, the temporal scales over which significant outcomes are realized can be longer than conventional grey infrastructure [9], which can contribute to perceptions of inefficiency (further discussed in section B below).

Despite the challenges, several emerging opportunities exist. Examples include the use of treated wastewater for rejuvenating water bodies and/or supplying water for irrigation and other uses (Box1 and 2). Integration of NbS approaches with conventional grey infrastructure (Box 3), particularly for water management and storage strategies (Box 4) also provide opportunities to scale NbS implementation. This is particularly pertinent in regions with seasonal precipitation that have frequent droughts or water scarce periods. Other effective area- based conservation measures (OECMs), a category of global conservation instrument, also hold potential as a pathway to secure source water catchments and aquifers that supply water to urban centers. Protected and managed watersheds are not only vital for water provisioning, but also other biodiversity and climate co-benefits. For example, the source catchments of 4000 cities were found to supply water to over 1.7 billion people and overlap by 85% with freshwater ecoregions of high biodiversity value [43]. OECMs (and other protection mechanisms) that are thus NbS opportunities to link water security to ecological security in the Global South where fresh-water biodiversity is now highly endangered. Finally, the significant advancements in technical and scientific support for identifying and mapping the potential for NbS and pathways to benefit people and climate in the past decade [14,44] also enable NbS scaling. Similarly, platforms highlighting global case studies provide insights into best practices and guidance [45]. These resources can enable preliminary assessments of NbS potential and help quantify potential benefits, even in resource scarce regions.

Box 1. Bright Spot 1: Wetland restoration for water security, Bengaluru, India

Bengaluru’s original network of more than 1000 interconnected and managed wetlands, which were originally built over several centuries for irrigation water security, fisheries, and livestock were rapidly degraded by pollution and land use conversion. In recent years, an initiative involving government agencies, research institutes, corporate social responsibility funds and civil society has led to a remarkable revival of several water bodies using treated wastewater. This involved investments in sewage treatment plants, desilting of polluted lakes, and the use of treated wastewater for irrigation in nearby regions and to rejuvenate groundwater reserves. Around 76% of the wastewater produced by the city (~1470 million liters per day) is currently treated by centralized and decentralized wastewater treatment plants. The shallow aquifers have been revived near the restored lakes, providing high-quality water for marginalized communities reliant on wells tapping nearby aquifers. Waterbirds thrive in some of these restored wetlands. The restored wetlands and their associated green spaces have contributed significantly to improved water quality, local water security, and heat stress mitigation in hot summers, in addition to providing aesthetic and recreational opportunities for citizens and increased in some components of biodiversity. The recycling of wastewater for use in agriculture and the potential reduction of its demand on distant rivers and local groundwater is a big step towards resilience in water security. Bengaluru’s strong academic and scientific community has been monitoring the progress, concerns, and opportunities for the social-ecological restoration of the city’s water infrastructure and providing adaptations as necessary in case of emergent problems [46–48].

3.2.2. Socio-economic and perceptional.

The urban planning context in the Global South is characterized, in part, by colonial legacies and rapid rates of urbanization, which contribute to an infrastructure deficit and emergent settlement patterns significantly different than in the Global North [36,49]. These characteristics pose challenges for infrastructure planning in general and are particularly relevant for discussions of NbS. The Global South is home to most of the global population residing in peri-urban areas, where informal settlements house a large proportion of the urban population [50]. Informal settlements combined with rapid urbanization contribute to heterogeneous land uses that often defy local regulations to limit mixed-use development and complicate infrastructure development and service provision [51]. In this context, land titling is difficult and leads to contradictory systems of land management [52], further challenging infrastructure development.

High poverty levels and stark wealth inequalities provide additional planning challenges. First, economic development is often a key priority for Global South countries and cities. Investments are directed toward activities with quick returns, which often come at the expense of environmental conservation and of a focus on climate resilience [53,54]. The lack of many services, such as water, health, and housing, among others, means that NbS planning may be in direct competition with pressing development needs. As a result, the master planning needed to design site-based NbS and integrate them with urban developmental plans is often deprioritized.

Second, there is real concern about how the implementation of NbS may further influence urbanization and service delivery. For example, similar to in the Global North, projects intended to benefit residents of informal settlements may promote gentrification and displacement in the Global South [55], but also, public greenspaces created by NbS may promote further informal settlements [56,57]. NbS design and implementation that is sensitive to social justice and political ecological concerns [58] may garner greater support from all sections of society.

Public perception of NbS is a consistent challenge across all regions, wherein successful implementation requires local buy-in, and the management and monitoring of ecological components of NbS may rely heavily on community participation [25,59,60]. In the context of the Global South, consulted experts in this study cited the higher perceived reliability of conventional infrastructure approaches and confusion over the definition of NbS as major obstacles to implementation. Practitioners also noticed distrust by local people regarding expectations and advice from Global North countries, as NbS were viewed as another form of environmental imperialism, placing a higher burden on the countries in the region to address ecological degradation driven by colonial practices. Others were distrusting or resistant to the utilitarian natural capital view of nature inherent to conventional approaches to NbS. In many cases, the application of NbS designs to contexts outside of those for which they were designed can result in poor performance or negative outcomes, leading to low confidence or perceptions about NbS among local communities. del Pino et al. (2020) suggest that broad public disinterest in environmental issues in Latin American cities is also a source of apathy and lack of support for NbS measures [61].

The challenges outlined above could be addressed by partnerships among governments, NGOs, academia, private sectors, local communities, and financial sectors, which should jointly develop and implement NbS projects. Collaborative efforts can leverage diverse expertise, resources, and networks. Several international and local NGOs provide services and support in the Global South, addressing various social, economic, and environmental challenges. Also, engaging communities in the planning and implementation of NbS projects can enhance local ownership, social acceptance, and long-term success [62]. NbS planning should approach problems from a co-benefits perspective, including biodiversity conservation, social vulnerability reduction, and Indigenous customs and knowledge preservation [63,64]. These approaches can effectively improve public perception of local populations (Box 3) and create coalitions of organizations working together on NbS (Box 4). In addition, increased investment in NbS can protect biodiversity and bring parity to the infrastructure-conservation investment divide [10,65–68]. Also, monitoring NbS projects’ performance with various metrics that can be shared with decision-makers, planners, and citizens creates a positive perception and understanding of the values.

Box 2. Bright Spot 2: Treatment wetlands in Embera Indigenous communities, Colombia [68]

Due to armed conflicts, the Colombian Embera Indigenous populations have been forced to migrate to peripheral urban areas without access to safe water and sanitation. The international cooperation project “Bana Do Bari” was set up in these areas to design and implement treatment wetlands (TWs) for treating wastewater mainly produced in sanitary infrastructure and guarantee adequate living conditions and improved basic hygiene for Indigenous communities. The sanitary infrastructure was designed collectively with the participation of the Indigenous community. The sanitary system was designed and adapted to community customs following a consultation and participation process with the community. Furthermore, a qualitative assessment of community members’ perception on the project was carried out to confirm that they were satisfied with the services provided by the infrastructure. Adaptive language was also used, and the perception of the Indigenous community was qualitatively assessed. Having been involved in the project from the start, community members were satisfied with the project’s services and the infrastructure built, as indicated through their daily use of the blue/green infrastructure.

3.2.3. Capacity, Knowledge and Expertise.

A lack of example projects and reliable streams of monitoring data on NbS development and performance are oft-cited barriers to mainstreaming NbS for urban water systems [10,25,69]. This problem is exacerbated in the Global South, where well-documented case studies are even scarcer, with limited reporting and few formal methods for quantifying benefits [70–72]. Since the majority of NbS research and development has been undertaken in the Global North [73], available design standards, guidelines, and expertise may not be appropriate outside of that context [74,75]. Accordingly, lack of technical capacity has been highlighted as a salient barrier to NbS implementation in Africa and South America [76–78]. This problem is particularly recalcitrant because the vast majority of available technical literature exists only in English, a well-known obstacle to conservation science [79].

Furthermore, ecological knowledge is often siloed among select groups (academics, naturalists, and local communities) and agencies (such as environmental or forestry departments), who conventionally have limited input in NbS planning or direct interactions with outside experts (like civil engineers and city planners) responsible for implementing water infrastructure [80]. This can create a knowledge gap, where practitioners have insufficient knowledge of local ecology and natural history to implement successful NbS. These factors complicate the use, integration, and management of native species in NbS development [74,81,82]. A large and demographically young population is typical in many Global South regions. For example, Africa has the youngest population in the world, with 70% of sub-Saharan Africa under the age of 30 [83]. Empowering this population with training and knowledge is a tremendous regional opportunity to overcome the knowledge and experience challenges of broader NbS implementation. Developing knowledge exchange platforms and communicating resources in mutually beneficial collaboration with the Global North and including NbS in curricula from the elementary level to higher education, including in civil infrastructure courses and training for young professionals, could contribute to this effort. Table 2 lists some potential capacities and expertise needed for planning and implementing NbS practices. Also, when Indigenous knowledge and cultural practices are respected and integrated into NbS planning, they may contribute to sustainable water and land management and conservation, enhancing community engagement and ownership of NbS initiatives [63]. For example, Colombian Embera Indigenous communities have been involved in the design and successful implementation of wetlands for treating wastewater (Box 2).

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Table 2. Capacities and expertise needed for planning and implementing NbS.

https://doi.org/10.1371/journal.pwat.0000372.t002

Box 3. Bright Spot 3: Kibera Green Infrastructure Project, Kenya [84]

Cities in sub-Saharan Africa face the intersecting challenges of rapid urbanization and informal settlement. Kenya is home to several informal settlements, including Kibera, one of the largest overcrowded areas in Africa. The area faces numerous challenges, such as inadequate waste management and water supply infrastructure and vulnerability to flooding. Regarding the implementation of NbS, funding and space constraints have limited the ability to implement large-scale infrastructure projects, making it challenging to prioritize NbS. The Kibera Green Infrastructure Project aimed to improve the living conditions of residents through the implementation of NbS. The Project focused on restoring natural ecosystems, enhancing green spaces, and improving water management in the settlement. The Project integrated urban planning and slum upgrading with the development of small-scale green-blue-grey infrastructure that included the construction of community parks, green corridors, as well as restoring riparian zones at the local community scale. Community involvement was a cornerstone of the project, with residents actively participating in the green infrastructure’s design, implementation, and maintenance. Flexibility in design and implementation was essential to meet the diverse needs of residents. The installation of bio-digesters and the promotion of waste recycling transformed waste management in Kibera, reducing pollution and providing residents with a sustainable energy source. Introducing small green spaces reduced flooding in Kibera and significantly enhanced the overall environmental quality of the settlement.

3.2.4. Management and Governance.

Mainstreaming NbS requires collaborative, integrative governance that crosses organizational, jurisdictional, and administrative boundaries to support joint action. This may be an especially strong challenge in Global South countries, where the governance capacity of institutions may be diminished [26,61]. Entrenched power dynamics, often stemming from legacies of colonial exploitation, can negatively affect historically excluded groups and be unintentionally reinforced by NbS implementation [57]. Although stakeholder involvement and participatory planning may mitigate such potential impacts, the insufficient involvement of local communities is a known shortfall in current NbS implementation in the Global South [81].

Experts and practitioners consulted in this study highlighted how scale mismatches and disconnects between bodies of policy governing urban development, climate change mitigation and adaptation, and biodiversity conservation further hamper the necessary coordinated action for effective NbS development for urban water resources. Overlapping responsibilities, lack of transparency, and potentially conflicting objectives among agencies can create confusion around who is charged with developing, managing, or monitoring NbS features [31]. Furthermore, respondents mentioned that rigid regulations in some settings may not have the necessary flexibility to allow for nature-based approaches to urban water resources problems. In addition, it is essential to note that governments’ priorities vary in different countries, which affects the consideration given to NbS.

Unlike the Global North regions, Global South regions are in the process of developing infrastructure systems and thus do not have the constraints typically associated with extensive pre-established infrastructure networks. NbS can thus more easily be incorporated into present and future growth. Multipurpose master planning provides a key leverage point for developing a shared vision with communities that also meets infrastructure and environmental needs. However, space limitation will constrain NbS use and some contexts may require retrofitting or modifying existing infrastructure. Local regulations could include requirements for mixed-use development designed to prevent gentrification and improper displacement. Also, in the case of mandatory displacement due to informal settlements in a public area, best practices should be followed for relocation, and proper compensation should be made. The Kebera Green Infrastructure Project (Box 3) highlights how a holistic and inclusive planning approach can successfully address the complex challenges of implementing NbS in urban landscapes and informal settlements, providing valuable insights for similar contexts in other developing regions [84].

NbS requires collaboration across various sectors to create synergies between climate, biodiversity, and development goals [42]. Aligning national and local policies with NbS can enhance the effectiveness of interventions, ensuring that climate action, disaster risk reduction, and sustainable development are mutually reinforcing [85]. Corporate social responsibility (CSR) and environmental, social, and governance (ESG) funds could be leveraged to foster innovative NbS designs through awards in competitions [86]. The example of national greengrowth policy instruments in South Korea and elsewhere in Asia [87,88] to oversee NbS for supplying water and to reduce urban heat island effects can be looked at critically for replication with modifications elsewhere. International and national funding for NbS could be linked to built-in safeguards to ensure the rigorous monitoring and incorporation of best practices. Also, legal frameworks that recognize and support NbS are needed, which can facilitate their i into national development.

Box 4. Bright Spot 4: Rainwater harvesting system (RHS) Project, Xalapa, Veracruz, Mexico [89]

Rapid, unplanned, and uneven urban development in the City of Veracruz impacted local ecosystems by reducing forested areas, urban wetlands, and other green spaces while straining infrastructure and essential services such as drinking water. As a result of the uncontrolled urban expansion, the urban footprint has increased pressure on a previously vulnerable and resilient water system, exacerbating weaknesses in the drinking water infrastructure. At firs, ten rainwater harvesting system (RHS) units were installed in schools and other public buildings to address the water security issue. After realizing the benefit, the local government and the Rio Arronte Foundation, with the support of the civil association Sendas, A.C., invested in over 100 additional systems for household units in schools and other public buildings. The solution is a pivotal component of an initiative known as CityAdapt, which is funded by the Global Environment Facility (GEF) and executed by the United Nations Environment Programme (UNEP) to bolster climate change adaptation efforts in cities across Latin America and the Caribbean. The RHS helps with water availability and security by harnessing a resource that, without the technology, would go untapped. It mitigates the risk of water stress, reducing pressure on the drinking water system and thereby decreasing overexploitation of bodies of water and aquifers. This intervention has indirectly benefitted biodiversity and aquatic ecosystems in the water bodies due to reduced abstraction for drinking water.

By leveraging the opportunities described above, Global South countries can accelerate the adoption of NbS to enhance urban water security. Region-specific planning and design guidancethat consider nuanced regional factors related to social, biogeographic, and engineering context, have the potential to normalize NbS within engineering practice in the region. Learning from other regions’ experiences -both failure and success- can also help make systemic changes that integrate NbS with conventional water infrastructure for urban water security challenges.

4. Summary

This article is a response to a scholarly body of literature that focuses on NbS in the Global North and the implicit assumptions that this knowledge is equally applicable to other regions of the globe. The highlighted bright spots direct attention to the considerable NbS work currently undertaken in the Global South. The challenge, therefore, is two-fold: to develop a broader scholarly appreciation for ongoing work in the Global South and to incorporate this knowledge into a generalized understanding of the roles, pathways, and possibilities of NbS across theglobe. Although some obstacles are particularly salient in the Global South, many of these also exist within the Global North, even if to a lesser or different degree. Learning that draws from multiple contexts contributes to more robust understanding and can lead to greater creativity in the planning, design, and implementation of NbS.

NbS systems can potentially provide Global South regions a pathway to enhance urban water security and achieve SDGs. However, the integration of NbS with conventional infrastructure systems is a prerequisite for effectiveness and viability, and this requires collaboration across disciplines from ecology to civil engineering and across institutions from researchers to practitioners. Leveraging local and Indigenous knowledge and involving local communities in the planning and implementation process is crucial for the success of NbS.in addition to increasing the likelihood of socially just and publicly supported projects.

NbS planning in the Global South countries could approach problems from a climate-change adaptation and co-benefits perspective that considers biodiversity conservation, social vulnerability reduction, environmental justice, and Indigenous customs and knowledge preservation. A close scrutiny of the evolving political economy, political, and spatial ecology dimensions of NbS in the context of urbanization and urban development priorities would be useful. Since NbS practices have a relatively smaller track record in the Global South, incorporating NbS conceptual frameworks and best practices across education levels may increase the incorporation of these practices in future development and implementation. Including NbS in urban planning policy and planning NbS in portfolios rather than single projects in isolation would be a great approach. Also, understanding the benefits of NbS for urban resilience would help planners and decision makers maximize the implementation of NbS in their cities. Also, financial allocation support and funding for climate adaptation based on ecosystems (i.e., NbS) is needed to overcome financial barriers.

This paper outlines the challenges and opportunities for implementing NbS in the Global South. Building on the findings outlined above, it is crucial to consider actionable steps to address the identified challenges. The following recommendations are proposed.

Practical recommendations

  • A regional best practices manual and a dynamic portal for NbS for water security could be developed that includes biophysical, ecological, hydrological and environmental justice dimensions to guide donors, corporates, government agencies and civil society organizations.
  • New curricula on NbS in teaching and training of city engineers, urban planners, and landscape architects would be required for scaling up adoption of NbS in city planning and development.
  • Mapping of potential NbS sites in cities based on integration of blue, green, and grey infrastructure and potential beneficiaries would help decision makers and developers make informed decisions
  • Investment in independent monitoring of environmental and social variables as part of project design and implementation to assess performance of NbS and learn reasons for success and failure would enable improvement and accountability.
  • Partnerships among governments, NGOs, academia, private sectors, local communities, and financial sectors to jointly develop and implement NbS projects may result in fewer trade-offs and enhance synergies amongst stakeholders.
  • Other effective area-based conservation measures (OECM) where conservation of biodiversity is achieved as a co-benefit of land-use outside protected areas offers opportunities for linking water security for cities to national and global ecosystem and biodiversity conservation targets.

Supporting information

S1 Text. SUSE 6 Workshop proposal.

https://doi.org/10.1371/journal.pwat.0000372.s001

(PDF)

S2 Text. Virtual Discussion Guide Questions.

https://doi.org/10.1371/journal.pwat.0000372.s002

(PDF)

S3 Text. List of Search Terms.

https://doi.org/10.1371/journal.pwat.0000372.s003

(PDF)

Acknowledgments

This research was conducted as part of the Network for Engineering with Nature (N-EWN, https://n-ewn.org). Opinions expressed here are those of the authors and not necessarily those of the agencies they represent or N-EWN. All opinions expressed in this paper are the authors’ and do not necessarily reflect the policies and views of DOD, DOE, or ORAU/ORISE. We thank all the workshop participants at the SUSE 6 conference and all the experts involved in the virtual discussions. We also wanted to thank the reviewers of this manuscript Dr. Pedro Roberto Jacobi and other anonymous reviewers.

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