Nature-based Solutions are often praised for their benefits, but often encounter obstacles in their integration in applied natural resources management. In particular, there is no clear framework for incorporating NbS within a WEFE Nexus management perspective.In REXUS Work Package 5, partners UNEP-WCMC, Deltares, UNIPD and ETIFOR have developed a detailed framework to guide the selection of suitable Nature-based Solutions, as well as their practical integration with grey infrastructure. ENG Reinaldo Peñailillo, Senior Advisor in Integrated Water Resources Management at Deltares, explains the “REXUS Solution Selection Framework”, a detailed “how-to” guide for selecting among NbS and integrating them within Nexus management strategies.
Interviewed by GWP-Med, REXUS Communication & Dissemination leader.
Implementing Nature-based Solutions is key for maintaining well-functioning ecosystems, which underpin the entire WEFE Nexus.
- In your view, are Nature based Solutions a desirable add-on, or a necessary part of sustainable WEFE Nexus management?
[R] Managing the Nexus means managing the interlinkages, synergies and trade-offs between water, energy, food and ecosystem resources and services to meet the worldwide demands for water, energy and food. Ecosystems in fact underpin all Nexus interactions, as they provide valuable services that play a role in the quality and quantity of those services and in supporting livelihoods. Nature-based Solutions (NbS) are those actions that protect, conserve, restore and sustainably manage ecosystems to address societal challenges, including water, energy and food challenges, while providing human well-being and biodiversity benefits; therefore NbS are an integral part of sustainable Nexus management.
Some situations may warrant a focus on grey solutions, for example where space is limited and in areas where physical forces may be very high (e.g. high flows). But in general, if ecosystems and biodiversity in watersheds and river basins don’t maintain a healthy status, then grey infrastructure for irrigation, hydropower generation, and water supply will not function adequately to ensure the provision of water, energy and food. Therefore, ecosystem goods and services provided by the natural environment should at the very least be combined with the services provided by grey infrastructure.
- Why do decision makers usually tend towards grey solutions, rather than NbS? What are the main weaknesses of NbS vis-a-vis grey solutions, and are they real or perceived weaknesses?
[R]: Policymakers, regulators, and/or permitting agencies prioritize grey infrastructure because it is familiar and well understood with respect to compliance and permitting. Specific characteristics of NbS, such as large space scale, particular ecological dynamics and long timescales do not make them a good fit for existing planning and investment decision-making processes, which create an uneven playing field for NbS.
Also important is that hard data on the performance of NbS is scarce. Monitoring NbS that covers large spatial areas may require data collection and analysis across sectors, while monitoring ecological trends may require a different set of expertise and metrics than would be used for conventional infrastructure.
NbS are also often seen as more cumbersome, since they require the involvement of a multitude of stakeholders. Large spatial scales often mean NbS cross jurisdictions as well as sectoral responsibilities, causing confusion over responsibility, while engagement and negotiation with multiple stakeholders can be time consuming and costly. To be successful, NbS require the active support of local citizens and landowners,in contrast to the long-term operation and maintenance of grey infrastructure, which is typically the sole responsibility of the service provider.
The upshot is that government, local authorities and the private sector often overlook the potential of NbS in favour of ‘known’ grey solutions.
- Both WEFE Nexus management and NbS are praised in theory, but they are much less applied in practice. Also, there is hardly any methodology for managers who wish to integrate NbS within a Nexus framework. Please explain your work on the “REXUS solution selection framework”and explain how it can help close the gap between theory and practice.
[R] Our work presents an overall structure for guiding the process of identifying solutions and developing strategies to address Nexus challenges, which we call the “REXUS solution selection framework”. It gives a central role to NbS as well as ecosystems, which form the link NbS and WEFE Nexus challenges.
Some of the key pillars of this framework are:
- Recognize Ecosystems as a main domain of the WEFE Nexus.
- Address main considerations in relation to Ecosystems and NbS in the inception phase, in the situation analysis and when building the preferred strategy (combination of solutions).
- Define main dimensions of considerations for identifying NbS by means of a roadmap, which consists of a mapping of the ecosystem services components of WEFE Nexus challenges, the scale of application and degree of intervention of NbS, and the enabling factors for implementing NbS with a Nexus approach.NbS (For this we developed factsheets for each one of the 51 NbS listed in the Inventory of Deliverable 5.2 “Roadmap to navigate among Nature-based Solutions for addressing Nexus challenges”.)
- Clearly structure the process of strategy building, starting from a screening of potential solutions, through designing strategies and assessing their impacts, comparing and ranking strategies, then finalising with the selection of the preferred strategies.
- Use specific evaluation modules, for the technical effectiveness assessment, socio-economic assessment and enabling environment assessment, to take into account the special characteristics of NbS which require that these solutions be assessed differently than grey infrastructure. We have developed these modules in details and can therefore evaluate solutions on the primary functioning and co-benefits (which can be biophysical, sociocultural or economic, as used values or non-used values), as well as the appropriateness for the existing enabling environment.
The REXUS team visiting the Iron Gates dam, one of the largest hydropower plants in Europe, on the border between Romania and Serbia. Integrating NbS with existing grey infrastructure is a key aim of REXUS.
- Although NbS are the goal, grey solutions are still more often the reality. Is your work within REXUS addressing the combination of grey and green solutions?
[R] Our “Rexus solution selection framework” includes a spectrum of options spanning NbS, hybrid, through to grey solutions, under the technical (structural) solutions pillar. Our view is that combining individual solutions into an overarching strategy should follow the principle ‘green where we can, grey where we must’: users must be aware of the wide range of NbS options available next to the more ‘traditional’ solutions that might otherwise be selected by default. We also proposed additional other guiding principles for combining NbS and grey solutions, such as:
- Mapping NbS opportunities within the landscape and connecting with grey infrastructure. For example, for flood peak reduction upstream, natural water retention wetlands or ponds may help in reducing the sharp peak discharge that might otherwise be experienced further downstream. At the same time, these measures will provide a groundwater-recharging function, as water is being kept in the area longer, allowing it to infiltrate into the soil.
- Identifying the linkages between ecosystems and grey infrastructure systems; such as the linkages between forest, wetlands, agricultural land use and the water infrastructure functions, as NbS can reduce requirements or enhance services of grey infrastructure or safeguard assets as first line of defense.
- Evaluating solutions on their primary functioning, co-benefits and trade-offs. For example, in many cases multiple goals need to be reached, such as water supply, water purification and biodiversity gain. This may go beyond a single-domain objective of grey solution and may require the combination with other solutions, such as NbS.
- What are the key steps in your analysis to make the NbS concept operational?
[R] The “Rexus Solution Selection Framework” addresses three general phases of analysis: Inception, Situation Analysis and Strategy Building, with key steps recommended for each phase:
- When examining Nexus challenges in the inception phase, include ecosystems as a domain that can be affected by actions of water, energy and food sectors and vice versa.
- Once Nexus challenges are identified, define clear management objectives related to ecosystems.
- Identify and analyze the enabling conditions, including constraints and enablers in relation to the management, protection and restoration of ecosystems and the deployment of NbS options. These can be for example, existing policies, institutional arrangements, management instruments.
- Perform a detailed ecosystem baseline assessment, including the type and location of natural and semi-natural assets and their services.
- Define socio-economic and environmental scenarios that create pressure on ecosystems, for example, climate change and natural hazards, developments such as mining and land conversion.
- Quantify problems in terms of impacts on ecosystem functioning and service provision by setting up detailed models that assess current and future situations under the defined scenarios, including synergies and trade-offs with the other Nexus domains.
- Start the Strategy building phase by setting clear primary and secondary objectives in order to help build an inventory of potential solutions in the spectrum of NbS to hybrid to grey solutions. In the Nexus context, solutions are designed to i) secure and improve services related to water, energy, food and ecosystem sources, and/or to ii) build climate resilience and contribute to climate adaptation of the Nexus domains and their interactions.
- Screen the solutions before combining them into alternative strategies. Screening criteria can be for example, effectiveness, efficiency, minimization of trade-offs, legitimacy and sustainability. The strategy development can start on the basis of a single management objective at a time, and following the principle “green where we can, grey where we must”.
- After a strategy is designed, evaluate its impacts to indicate the degree to which objectives are achieved. Recognizing the special characteristics of NbS, evaluation criteria are grouped in three categories: technical effectiveness, socio-economic feasibility and enabling environment. For assessing these categories, the “Rexus solution selection framework” provides guidance through specific modules that facilitate the selection of evaluation indicators and evaluation approaches, both quantitative and qualitative. This is the core of the framework and its added value.
- Compare the results of the impact assessment of alternative strategies and prioritize the strategies by performing a multi-criteria assessment to finally inform decision making with the preferred strategy.
- How important is stakeholder participation in terms of NbS selection and implementation?
[R] Strong involvement of local stakeholders is needed throughout the process of selecting, planning and implementing solutions in order to integrate their perceptions, knowledge and preferences, and ensure that their views and interests are taken into account. However, due to the large spatial and temporal scales involved in NbS and the wide range of potential benefits they provide, stakeholders from different backgrounds (local communities, research institutions, private sector, NGO and governmental offices) need to be involved in various stages of the assessment of solutions. As different stakeholders will provide different information and perspectives around NbS and their implementation over time, effective stakeholder engagement depends on an understanding of the relations among stakeholders and their roles. For example, engaging and negotiating with multiple stakeholders, working across regulatory jurisdictions and collaborating with dispersed landowners can be time consuming and costly, but it is necessary. Also, not all stakeholders may have the same capacities. For example, the flood management authority may not have the capacity or legal legitimacy to engage with landowners.
Stakeholders evaluating Nature-based Solutions for the REXUS Pinios pilot, in Greece.
- What are the next steps regarding the application of this selection framework in the REXUS pilot cases?
[R] Indeed, now we are in the phase of applying and testing the “Rexus solution selection framework” in the different pilot cases, depending on their level of development and progress. Some pilots have been engaging with stakeholders through workshops to start the discussion on the criteria for screening solutions and the preliminary identification of potential solutions to address their specific Nexus challenges. This has been the case for the Pinios and Nima pilots. The Rexus partners have supported these pilots in these processes and with the use of the AirNbS, a first list of potential NbS per case has been prepared. In the workshops, stakeholders have also received an introduction to NbS.
Next steps include the screening of solutions (grey solutions and NbS) together with stakeholders and the formulation of alternative strategies. Afterwards, Pilots need to define if the impacts of solutions will be assessed quantitatively or qualitatively, depending on the availability of proper models and data.
