Feeding the future world population sustainably and satisfactorily requires, among others, accessibility to water resources of adequate quantity and quality. Yet, conventional interventions solely based on ‘hard’ engineering solutions and infrastructural development have provided valuable lessons as they can compromise various ecosystem services that are required for stable water flows. Hence, calls for a shift in water management paradigms are justified and should prioritize in the political agendas. Nature-Based Solutions (NBS) offer a promising contribution on how to enhance the availability and quality of water for productive purposes and human consumption, while simultaneously striving to preserve the integrity and intrinsic value of the ecosystems. Implementing successful NBS for water management, however, is not an easy task since many ecosystems are already severely degraded, and exploited beyond their regenerative capacity. Furthermore, ecosystems are large and complex and the impact of interventions can only be assessed and analysed at a system-wide level. As a rule, many stakeholders are involved, as owners, users or caretakers, each with their own set of interests and values and it is not an easy task to reconcile these complex objectives and interests into a coherent set of principles and procedures. Simple market-based solutions such as partitioning of an ecosystem, attributing property rights and applying the polluter-pays-principle are often not sufficient for devising viable strategies.
Implementation of NBS requires a structured and comprehensive approach that starts with the valuation of the services provided by the ecosystem. The whole set of use and non-use values, in monetary terms, provides a factual basis to guide the implementation of NBS, which ideally is done according to transdisciplinary principles, i.e. complemented with scientific and case-specific knowledge of the eco-system in an adaptive decision-making process that involves the relevant stakeholders. To maximize intended sustainability and scale of NBS results, a system-wide, country-driven capacity enhancement approach needs to be applied that independently empowers people, strengthens organizations, institutions, multi-stakeholder processes as well as the enabling policy environment based on assessed needs.
In this discussion paper, twenty-one case studies of water management processes are analysed, using a non-representative literature survey, and checked to what extent they meet the requirements of the NBS implementation based on the criteria presented. It emerges that transdisciplinarity, stakeholder involvement, and well-designed funding schemes are important elements for successful implementation of NBS. Often, lengthy periods to organize participatory and transdisciplinary platforms are needed, which makes this process costly and as a result, complete implementation is often strained by funding shortages. Another common challenge in the surveyed examples is the minor role given to valuation of ecosystem services, an area for which the literature is still developing guidance while available valuation methods remain scattered, incomplete or imprecise. The less successful water management projects tend to suffer from inadequate factual and scientific basis and uncoordinated or insufficient stakeholder involvement. Successful case studies point to a satisfactory understanding of the functioning of ecosystems and the importance of multi-stakeholder platforms, well identified funding schemes, and realistic monitoring and evaluation systems.