Sustaining the organisms, ecosystems and processes that underpin human wellbeing is necessary to achieve sustainable development. Here we define critical natural assets as the natural and semi-natural ecosystems that provide 90% of the total current magnitude of 14 types of nature’s contributions to people (NCP), and we map the global locations of these critical natural assets at 2 km resolution. Critical natural assets for maintaining local-scale NCP (12 of the 14 NCP) account for 30% of total global land area and 24% of national territorial waters, while 44% of land area is required to also maintain two global-scale NCP (carbon storage and moisture recycling). These areas overlap substantially with cultural diversity (areas containing 96% of global languages) and biodiversity (covering area requirements for 73% of birds and 66% of mammals). At least 87% of the world’s population live in the areas benefitting from critical natural assets for local-scale NCP, while only 16% live on the lands containing these assets. Many of the NCP mapped here are left out of international agreements focused on conserving species or mitigating climate change, yet this analysis shows that explicitly prioritizing critical natural assets and the NCP they provide could simultaneously advance development, climate and conservation goals.
NbS Target: Food & Water Security
Food and water security
Cities increasingly have to find innovative ways to address challenges arising from climate change and urbanization. Nature-based solutions (NBS) have been gaining attention as multifunctional solutions that may help cities to address these challenges. However, the adoption and implementation of these solutions have been limited due to various barriers. This study aims to identify a taxonomy of dominant barriers to the uptake and implementation of NBS and their relationships. Fifteen barriers are identified from the literature and expert interviews and then ranked through a questionnaire. Interpretive Structural Modeling (ISM) serves to identify the mutual interdependencies among these barriers, which results in a structural model of six levels. Subsequently, Cross-impact matrix multiplication applied to classification (MICMAC analysis) is used to classify the barriers into four categories. The results suggest that political, institutional and knowledge-related barriers are the most dominant barriers to NBS. Cities that intend to apply NBS can draw on these findings, especially by more effectively prioritizing and managing their actions.
The impact of local biodiversity loss on ecosystem functioning is well established, but the role of larger-scale biodiversity dynamics in the delivery of ecosystem services remains poorly understood. Here we address this gap using a comprehensive dataset describing the supply of 16 cultural, regulating and provisioning ecosystem services in 150 European agricultural grassland plots, and detailed multi-scale data on land use and plant diversity. After controlling for land-use and abiotic factors, we show that both plot-level and surrounding plant diversity play an important role in the supply of cultural and aboveground regulating ecosystem services. In contrast, provisioning and belowground regulating ecosystem services are more strongly driven by field-level management and abiotic factors. Structural equation models revealed that surrounding plant diversity promotes ecosystem services both directly, probably by fostering the spill-over of ecosystem service providers from surrounding areas, and indirectly, by maintaining plot-level diversity. By influencing the ecosystem services that local stakeholders prioritized, biodiversity at different scales was also shown to positively influence a wide range of stakeholder groups. These results provide a comprehensive picture of which ecosystem services rely most strongly on biodiversity, and the respective scales of biodiversity that drive these services. This key information is required for the upscaling of biodiversity–ecosystem service relationships, and the informed management of biodiversity within agricultural landscapes.
More than 90 systematic reviews have been conducted on the topic of nature-based solutions for climate change adaptation (NBS-CCA). These prior reviews, however, are scattered across more than 45 different peer-reviewed journals and gray literature sources, making it difficult to follow all of the knowledge generated and remaining research gaps. In this study, we conducted a systematic review of systematic reviews on the topic of NBS-CCA, with the objective of mapping and analyzing these prior reviews. We found that most of the prior systematic reviews had relatively narrow research focuses, typically focusing on a particular geographic context of NBS-CCA (mainly in urban and coastal areas) or on a particular aspect of NBS-CCA planning/implementation (mainly outcomes assessment and policy/governance issues). Fewer reviews focused on mountainous areas or on social and financial aspects of NBS-CCA planning/implementation. The majority reviews relied solely on peer-reviewed literature for analysis, with only 26% including gray literature, despite the large amount and variety of gray literature on NBS-CCA that exists. Notably, we found that no prior systematic reviews have yet attempted to comprehensively analyze all geographic contexts and all aspects of NBS-CCA, e.g. through a review and meta-analysis of all available peer-reviewed and gray literature on the topic. This would likely require a massive multidisciplinary effort, but could be a worthy endeavor considering the realized need to integrate NBS-CCA into national/subnational policies and various international environmental agreements pertaining to climate change (e.g., Paris Agreement) and biodiversity conservation (e.g., Post-2020 Global Biodiversity Framework).
Soil microbiomes drive key functions in agroecosystems, determining soil fertility, crop productivity and stress tolerance. The microbiome is intricately linked with soil structure, such as aggregation and pore connectivity, because this structure regulates the flow of water, oxygen and nutrients through the system. In this Review, we summarize the key functions of soil microbiomes in agroecosystems, highlight the dependence of these functions on the structural integrity of the soil, and discuss how agricultural practices influence the link between soil structure and microbiome functioning. System-level agricultural management practices can induce structural alterations to the soil, thereby changing the microbial processes occurring at the microscale. These changes have large-scale consequences, such as soil erosion, reduced soil fertility and increased greenhouse gas emissions. Sustainable approaches such as integrated soil fertility management and integrated pest management seek to improve soil structure and enhance microbial biodiversity, but we lack a mechanistic understanding of how multifaceted decisions at the farm level shape these context-dependent small-scale processes in the long term. Future research needs to bridge the microscale and field scale to inform agricultural management decisions for building climate-smart, resource-efficient and stress-resilient agroecosystems, and to harness the soil microbiome as a nature-based solution for sustainable agriculture.
Zero-deforestation supply chain policies that leverage the market power of commodity buyers to change agricultural producer behavior can reduce forest clearing in regions with rapid commodity expansion and weak forest governance. Yet leakage—when deforestation is pushed to other regions—may dilute the global effectiveness of regionally successful policies. Here we show that domestic leakage offsets 43-50% of the avoided deforestation induced by existing and proposed zero-deforestation supply chain policies in Brazil’s soy sector. However, cross-border leakage is insignificant (<3%) because soybean production is displaced to existing U.S. farmland. Eliminating deforestation from the supply chains of all firms exporting Brazilian soy to the EU or China from 2011-2016 could have reduced net global deforestation by 2% and Brazilian deforestation by 9%. Thus, if major tropical commodity importers (e.g., the EU) require traders to eliminate deforestation from their supply chains, it could help bend the curve on global forest loss.
There have been many calls for an agroecological transition to respond to food shocks and crises stemming from conventional food systems. Participatory action research and transformative epistemologies, where communities are research actors rather than objects, have been proposed as a way to enhance this transition. However, despite numerous case studies, there is presently no overview of how participatory approaches contribute to agroecological transitions. The present article therefore aims to understand the effect of applying participatory action research (PAR) in agroecology. We undertook a systematic review of articles reporting methods and results from case studies in agroecological research. On the one hand, our systematic review of 347 articles shows that the agroecological research scope is broad, with all three types—as science, a set of practices and social movement—well-represented in the corpus. However, we can see a clear focus on agroecology “as a set of practices” as the primary type of use of the concept. On the other hand, we found a few case studies (23) with a participatory approach while most studies used extractive research methods. These studies show that understanding the drivers and obstacles for achieving an agroecological transition requires long-term research and trust between researchers and farmers. Such transformative epistemologies open doors to new questions on designing long-term PAR research in agroecology when confronted with a short-term project-based society.
The restoration of degraded lands has received increased attention in recent years and many commitments have been made as part of global and regional restoration initiatives. Well-informed policy decisions that support land restoration, require spatially explicit information on restoration potentials to guide the design and implementation of restoration interventions in the context of limited resources. This study assessed ecosystems indicators of land degradation using a systematic approach that combines field surveys and remote sensing data into a set of multi-criteria analyses to map restoration potentials in the semi-arid areas. The indicators considered were soil organic carbon, erosion prevalence, enhanced vegetation index, Normalized differences water index and the Net Primary productivity. Three classes of restoration potential were established: (1) areas not in need of immediate restoration due low degradation status, (2) areas with high potential for restoration with moderate efforts required and (3) areas in critical need of restoration and require high level of efforts. Of the total area of the study site estimated at 88,344 km2, 59,146.12 km2, or 66.94% of the theoretically recoverable area, was considered suitable for restoration, of which 38% required moderate efforts while 28% require less efforts. The recoverable areas suitable for restoration could be restored through tree planting, soil and water conservation practices, farmers managed natural regeneration, and integrated soil fertility management. These results can help to spatially identify suitable multifunctional restoration and regeneration hotspots as an efficient way to prioritize restoration interventions in the context of limited resources.
This paper expands the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) values framing about nature and its contributions to people by exploring the notion of ‘disvalues’, which pertains to aspects of nature that reduce well being (instrumental disvalues), relationships that are detrimental to a dignified and flourishing life (relational disvalues), or the perception of badness in an absolute sense, regardless of the impact on people (intrinsic disvalues). Shedding light on how people express disvalues helps to better capture their preferences and subjective perspectives, as well as account for the socioenvironmental positions from which they speak. Considering the full spectrum of disvalues opens up new ways to better identify social–ecological trade-offs, a necessary step for seeking solutions and finding common ground on sustainability and justice.
To counteract undesirable impacts of climate change, several different mitigation instruments have been proposed to sequester carbon through reforestation or avert greenhouse gas emissions due to land use change through forest carbon offset projects. Such projects will require an explicit focus on equitable benefit sharing to generate sustainable and alternative livelihoods. However, research on the impacts of forest carbon offset projects for individuals and communities has often been conducted without baseline data or counterfactuals built into the research methods. We conducted a study in a small Indigenous community in eastern Panama with participants and non-participants in a forest carbon offset project, across wealth groups. In this mixed methods study, participants and non-participants completed surveys before, during, and after implementation over 14 years to assess changes to natural and financial assets. We also assessed major concerns and perceived benefits of the carbon offset project via open-ended questions. Quantitative data show that participants continued to engage in reforestation practices even after payment cessation. Quantitative data also suggest carbon offset payments provided financial stability for poorer participants to diversify into other sources of income over time, while income inequality remained stable across wealth groups. Qualitative data indicate that the greatest benefit of the carbon offset project for participants was economic security for future generations, while concerns about basic needs like food and money declined over time for both participants and non-participants. This research suggests that forest carbon offset projects can be effective for encouraging long-term adoption of forestry practices, specifically reforestation and agroforestry, while providing social co-benefits for rural livelihoods, across wealth dimensions.
Sustainable management of intact tropical peatlands is crucial for climate change mitigation, for biodiversity conservation and to support the livelihoods of local communities. Here, we explore whether sustainable fruit harvesting from Mauritia flexuosa palms could support these linked goals by increasing fruit production and incomes across the 2.8 million hectares of the most carbon-dense ecosystem in Amazonia: the lowland peatlands of northeastern Peru. M. flexuosa is dioecious, and fruits are typically harvested by felling female palms; the proportion of female palms therefore provides a good indicator of the health of a stand. Across 93 widely distributed sites, we found that the proportion of female palms increases with travel time to the urban market, and overall, fruit harvesting has halved the current potential production and income from this resource. However, significantly more female palms are found where fruit are harvested by climbing. We estimate that region-wide uptake of climbing could eventually increase potential fruit production by 51% and increase its gross value to US$62 ± 28.2 million yr–1. These findings demonstrate the high cost of unsustainable resource extraction in Neotropical forests and outline a practical path to conserve and sustainably exploit one of the most carbon-rich landscapes on the planet.
Although nature-based solutions (NBS) have been promoted as a key tool for solving diverse environmental and societal problems, the concept and its practical applications remain unclear. This ambiguity is linked to the fact that the NBS concept has emerged from the integration of multiple scientific fields. In addition, there has been a delay in establishing clear standards for NBS, hence a number of actions that today would be seen as complementary or related measures, are frequently branded as NBS. Thus, this paper paves the way to clarify NBS by identifying their core features and formulating criteria to exclude certain actions from the set of NBS. After reviewing 20 definitions of NBS, these actions are identified as interventions that: (1) are inspired and powered by nature; (2) address (societal) challenges or resolve problems; (3) provide multiple services/benefits, including biodiversity gain; and (4) are of high effectiveness and economic efficiency. The non-systematic review includes both peer-review research papers and relevant official reports, enabling the formulation of a set of criteria that exclude green/blue interventions from the set of NBS. These are: (1) lack of functioning ecosystems; (2) random actions; (3) post-implementation goal(s); (4) negative/no impact on biodiversity; (5) same benefits as grey infrastructure alone; (6) unfair distribution of benefits; (7) ‘copy-paste’ implementation approach; (8) top-down model of governance; (9) static management approach; (10) financial expenses disproportionate to benefits; and (11) ‘point scale’ approach. Ongoing and future practice will contribute to our understanding of the long-term operation of NBS as well as to the detection of synergies and trade-offs, thereby enabling us to better define this concept’s boundaries.
Forest restoration is being scaled-up globally to deliver critical ecosystem services and biodiversity benefits, yet we lack rigorous comparison of co-benefit delivery across different restoration approaches. In a global synthesis, we use 25,950 matched data pairs from 264 studies in 53 countries to assess how delivery of climate, soil, water, and wood production services as well as biodiversity compares across a range of tree plantations and native forests. Carbon storage, water provisioning, and especially soil erosion control and biodiversity benefits are all delivered better by native forests, with compositionally simpler, younger plantations in drier regions performing particularly poorly. However, plantations exhibit an advantage in wood production. These results underscore important trade-offs among environmental and production goals that policymakers must navigate in meeting forest restoration commitments.
The new frontiers of sustainable cities should focus on urban planning tools and strategies that are able to integrate ecosystem services in urban development. An important step could include the design of nature-based solutions (NbSs) for introducing important ecological functions aiding human well-being and mitigating the loss of soil. In this study, we propose a methodology to analyse, in a spatial way, the effect of land use scenarios generated by urban planning in the provision of ecosystem services. The methodology analyses the variation of ecosystem services, considering the ecosystem services of the study area and their potential roles in changing the functions of planned urban actions as the starting point. One scenario of analysis includes the integration of NbSs into urban planning. The case study is that of a peri-urban area, characterized by an agroecosystem, which is intended for urban development in the municipality of Gallipoli, Southern Italy. The analysis highlights a low provision of ecosystem services by the agroecosystem, which has had the effect of important olive trees being destroyed by Xylella fastidiosa bacteria. Thus, the integration of NbSs and reducing the construction of buildings in the urban neighbourhood plan could improve the quantity of ecosystem services in the area. Moreover, the ecological design of ecosystem services could improve the typology of ecosystem services provision in the area in consideration of the starting points. Therefore, the analysis of the capacity to integrate ecosystem services in urban planning at the neighbourhood scale could be a tool of ecological urban design, useful to support the decision-making processes.
Quantifying how well Nature-based Solutions can offset anthropogenic climate change impacts is important for adaptation planning, but has rarely been done. Here we show that a widely-applied Nature-based Solution in South Africa – invasive alien tree clearing – reduces the impact of anthropogenic climate change on drought streamflow. Using a multi-model joint-attribution of climate and landscape-vegetation states during the 2015–2017 Cape Town “Day Zero” drought, we find that anthropogenic climate change reduced streamflow by 12–29% relative to a counterfactual world with anthropogenic emissions removed. This impact on streamflow was larger than corresponding reductions in rainfall (7–15%) and reference evapotranspiration (1.7–2%). Clearing invasive alien trees could have ameliorated streamflow reductions by 3–16% points for moderate invasions levels. Preventing further invasive alien tree spread avoided potential additional reductions of 10–27% points. Total clearing could not have offset the anthropogenic climate change impact completely. Invasive alien tree clearing is an important form of catchment restoration for managing changing hydroclimatic risk, but will need to be combined with other adaptation options as climate change accelerates.
Forest carbon projects can deliver multiple benefits to society. Within Southeast Asia, 58% of forests threatened by loss could be protected as financially viable carbon projects, which would avoid 835 MtCO2e of emissions per year from deforestation, support dietary needs for an equivalent of 323,739 people annually from pollinator-dependent agriculture, retain 78% of the volume of nitrogen pollutants in watersheds yearly and safeguard 25 Mha of Key Biodiversity Areas.
There is increasing global interest in employing nature-based solutions, such as reforestation and wetland restoration, to help reduce water risks to economies and society, including water pollution, floods, droughts and water scarcity, that are likely to become worse under future climates. Africa is exposed to many such water risks. Nature-based solutions for adaptation should be designed to benefit biodiversity and can also provide multiple co-benefits, such as carbon sequestration. A systematic review of over 10 000 publications revealed 150 containing 492 quantitative case studies related to the effectiveness of nature-based solutions for downstream water quantity and water quality (including sediment load) in Africa. The solutions assessed included landscape-scale interventions and patterns (forests and natural wetlands) and site-specific interventions (constructed wetlands and urban interventions e.g. soakaways). Consistent evidence was found that nature-based solutions can improve water quality. In contrast, evidence of their effectiveness for improving downstream water resource quantity was inconsistent, with most case studies showing a decline in water yield where forests (particularly plantations of non-native species) and wetlands are present. The evidence further suggests that restoration of forests and floodplain wetlands can reduce flood risk, and their conservation can prevent future increases in risk; in contrast, this is not the case for headwater wetlands. Potential trade-offs identified include nature-based solutions reducing flood risk and pollution, whilst decreasing downstream water resource quantity. The evidence provides a scientific underpinning for policy and planning for nature-based solutions to water-related risks in Africa, though implementation will require local knowledge.
Entering the UN Decade on Ecosystem Restoration, interventions referred to as nature-based solutions (NBS) are at the forefront of the sustainability discourse. While applied in urban, natural forest or wetland ecosystems, they are underutilized in agricultural landscapes. This paper presents a technical framework to characterise NBS in agricultural systems. NBS in the agriculture sector is proposed as “the use of natural processes or elements to improve ecosystem functions of environments and landscapes affected by agricultural practices, and to enhance livelihoods and other social and cultural functions, over various temporal and spatial scales.” The framework emerges from a review of 188 peer-reviewed articles on NBS and green infrastructure published between 2015 and 2019 and three international expert consultations organized in 2019–2020. The framework establishes four essential functions for NBS in agriculture: 1) Sustainable practices — with a focus on production; 2) Green Infrastructure — mainly for engineering purposes such as water and soil, and slope stabilization; 3) Amelioration — for restoration of conditions for plants, water, soil or air and climate change mitigation; and 4) Conservation — focusing on biodiversity and ecosystem connectivity. The framework connects the conventional divide between production and conservation to add functionality, purpose and scale in project design. The review confirmed limited evidence of NBS in agricultural systems particularly in developing country contexts, although specific technologies feature under other labels. Consultations indicated that wider adoption will require a phased approach to generate evidence, while integrating NBS in national and local policies and agricultural development strategies. The paper concludes with recommended actions required to facilitate such processes.
- Restoring the degraded Atlantic Forest is one of the biggest conservation challenges in Brazil. In a biome with high human presence, understanding the potential for restoration approaches, such as agroforestry, to provide benefits to smallholder farmers and biodiversity is essential in developing equitable restoration strategies.
- Smallholder or family farmers are essential to national food security, producing most fruit and vegetables consumed in Brazil. Their farms can also provide ecological stepping stones for biodiversity. To better understand their role in Atlantic Forest restoration, this study explores the use of agroforestry by smallholder farmers from the Movimento Sem Terra (MST), the Rural Landless Workers’ Movement, in Pontal do Paranapanema.
- We use quantitative and qualitative data to assess farmer perceptions of the measures which support agroforestry farming, barriers to implementation and its impact on indicators of wellbeing. We find agroforestry farmers report significant benefits in 8 of 18 tested indicators. Attitudes to agroforestry are varied, but common themes emerge including the high value of tree cover for shade and cooling effects, and the difficulties in selling agroforestry products. Our results show lack of policy support and initial investment needs are the biggest constraints to agroforestry, but opportunity cost is not considered a large barrier.
- Tailored policies and financial measures are needed to integrate thousands of smallholder farmers into the Atlantic Forest restoration agenda, helping to reach biome restoration targets while supporting rural livelihoods and national food security. Further research is required into links between additional socio-economic and biogeographical variables and agroforestry uptake in the region
There has been a recent surge of interest in Nature-based Solutions, a concept encompassing a broad suite of ideas that have arisen from the intersection of ecology, engineering, sociology and economics. Solutions founded in nature are promised to resolve many issues resulting from global change, including reducing flood risk and air pollution, building social cohesion and enhancing resilience. However, what a Nature-based Solution means in practice remains unstructured and vaguely defined. Specifically, what is meant by Nature-based is not well defined and there has been little effort to rigorously understand how a solution is created. In response, we propose an integrated conceptual framework, extending the service-benefit relationship to include solutions, while acknowledging that multiple types of service exist (ecosystem services, technological services and labour). We present a method to measure the degree to which a solution is Nature-based: calculate the relative contribution of ecosystem services, compared with technological services and labour. The method and framework are applied to projects dealing with problems related to water pollution, demonstrating their applicability. The framework can be a useful tool to guide environmental managers in identifying both the scale and context at which, and the problems to which, Nature-based Solutions are applicable.
Nature‐based solutions (NbS)—solutions to societal challenges that involve working with nature—have recently gained popularity as an integrated approach that can address climate change and biodiversity loss, while supporting sustainable development. Although well‐designed NbS can deliver multiple benefits for people and nature, much of the recent limelight has been on tree planting for carbon sequestration. There are serious concerns that this is distracting from the need to rapidly phase out use of fossil fuels and protect existing intact ecosystems. There are also concerns that the expansion of forestry framed as a climate change mitigation solution is coming at the cost of carbon rich and biodiverse native ecosystems and local resource rights. Here, we discuss the promise and pitfalls of the NbS framing and its current political traction, and we present recommendations on how to get the message right. We urge policymakers, practitioners and researchers to consider the synergies and trade‐offs associated with NbS and to follow four guiding principles to enable NbS to provide sustainable benefits to society: (1) NbS are not a substitute for the rapid phase out of fossil fuels; (2) NbS involve a wide range of ecosystems on land and in the sea, not just forests; (3) NbS are implemented with the full engagement and consent of Indigenous Peoples and local communities in a way that respects their cultural and ecological rights; and (4) NbS should be explicitly designed to provide measurable benefits for biodiversity. Only by following these guidelines will we design robust and resilient NbS that address the urgent challenges of climate change and biodiversity loss, sustaining nature and people together, now and into the future.
Nature-based solutions (NBS) can protect, manage and restore natural or modified ecosystems. They are a multidisciplinary, integrated approach to address societal challenges and some natural hazards effectively and adaptively, simultaneously providing human well-being and biodiversity benefits. NBS applications can be easily noticed in circular cities, establishing an urban system that is regenerative and accessible. This paper aims to offer a review on NBS for urban water management from the literature and some relevant projects running within the COST Action ‘Implementing nature-based solutions for creating a resourceful circular city’. The method used in the study is based on a detailed tracking of specific keywords in the literature using Google Scholar, ResearchGate, Academia.edu, ScienceDirect and Scopus. Based on this review, three main applications were identified: (i) flood and drought protection; (ii) the water-food-energy nexus; and (iii) water purification. The paper shows that NBS provide additional benefits, such as improving water quality, increasing biodiversity, obtaining social co-benefits, improving urban microclimate, and the reduction of energy consumption by improving indoor climate. The paper concludes that a systemic change to NBS should be given a higher priority and be preferred over conventional water infrastructure.
Enhancing biodiversity in cropping systems is suggested to promote ecosystem services, thereby reducing dependency on agronomic inputs while maintaining high crop yields. We assess the impact of several diversification practices in cropping systems on above- and belowground biodiversity and ecosystem services by reviewing 98 meta-analyses and performing a second-order meta-analysis based on 5160 original studies comprising 41,946 comparisons between diversified and simplified practices. Overall, diversification enhances biodiversity, pollination, pest control, nutrient cycling, soil fertility, and water regulation without compromising crop yields. Practices targeting aboveground biodiversity boosted pest control and water regulation, while those targeting belowground biodiversity enhanced nutrient cycling, soil fertility, and water regulation. Most often, diversification practices resulted in win-win support of services and crop yields. Variability in responses and occurrence of trade-offs highlight the context dependency of outcomes. Widespread adoption of diversification practices shows promise to contribute to biodiversity conservation and food security from local to global scales.
This article provides a perspective on nature-based solutions. First, the argument is developed that nature-based solutions integrate social and ecological systems. Then, theoretical considerations relating to relational values, multifunctionality, transdisciplinarity, and polycentric governance are briefly outlined. Finally, a conceptual model of the social–ecological system of nature-based solutions is synthesised and presented. This conceptual model comprehensively defines the social and ecological external and internal systems that make up nature-based solutions, and identifies theoretical considerations that need to be addressed at different stages of their planning and implementation The model bridges the normative gaps of existing nature-based solution frameworks and could be used for consistent, comprehensive, and transferable comparisons internationally. The theoretical considerations addressed in this article inform practitioners, policymakers, and researchers about the essential components of nature-based solutions. The conceptual model can facilitate the identification of social and ecological interconnections within nature-based solutions and the range of stakeholders and disciplines involved.
Purpose: This paper aims to advance the idea of sustainable flood reduction. Flood reduction through the use of the drainage system is considered an unsustainable approach that decreases the use of water. In contrast, the Water Sensitive City is a sustainable concept aimed at increasing the value of water for human needs and reduce flooding. Design/methodology/approach: The current approach of relying on drainage systems is ineffective and must be combined with green infrastructures to reduce flooding. Green infrastructures can increase infiltration rates or facilitate rain harvesting. The study developed four scenarios that combine green and grey infrastructures and used the Soil and Water Assessment Tool (SWAT) model to select the most effective scenario based on the remaining amount of flood volume in every scenario. Findings: Green infrastructures that are related to increased infiltration and rain-harvesting instruments reduced flooding by 22.3 and 27.7 per cent, respectively. Furthermore, a combination of the two types of green infrastructures reduced flooding up to 45.5 per cent. Conversely, applying only grey infrastructures (by increasing drainage capacity) to reduce the flooding to zero is unfeasible, as this requires more than double the current capacity. Therefore, a combination of green and grey infrastructures can significantly reduce flooding in a water sensitive and feasible manner. Originality/value: Applying a combination of green and grey infrastructures is a new and effective approach to reduce flooding in the Kedurus Catchment Area.