This document concerns the first presentation about defining the framework of NBS, presented by Emmanuelle Cohen-Shacham during the first ThinkNature webinar about "NBS: Concept, Practices and Benefits". This webinar invited scientists, business/market actors, policy makers and authorities’/organizations’ representatives to discover the concept, practices and benefits of NBS.

There is extensive experience in adaptive management of exposed sandy coastlines through sand nourishment for coastal protection. However, in complex estuarine systems, coastlines are often shortened through damming estuaries to achieve desired safety levels. The Dutch Deltaworks illustrate that this approach disrupts natural sediment fluxes and harms ecosystem health, which negatively affects derived ecosystem services, such as freshwater availability and mussel and oyster farming. This heavily impacts local communities and thus requires additional maintenance and management efforts.

Coastal lowlands are increasingly exposed to flood risks from sea-level rise and extreme weather events (1). Megacities like Shanghai, London, New York, and Bangkok that lie in vast river deltas are particularly vulnerable. Dramatic flood disasters include the Indian Ocean tsunami in 2004, Hurricane Katrina in New Orleans in 2005, Hurricane Sandy in New York in 2012, and Typhoon Haiyan in the Philippines in 2013.

The idea of ‘nature-based solutions’ (NBS) is now being used to reframe policy debates on biodiversity conservation, climate change adaptation and mitigation strategies, and the sustainable use of natural resources, among other issues. While interesting and potentially useful for those debates, it is a concept that still needs to be clearly defined; its use is not confined to discussions about ecosystem services and natural capital.

In this paper, we reflect on the implications for science, policy and practice of the recently introduced concept of Nature-Based Solutions (NBS), with a focus on the European context. First, we analyse NBS in relation to similar concepts, and reflect on its relationship to sustainability as an overarching framework. From this, we derive a set of questions to be addressed and propose a general framework for how these might be addressed in NBS projects by funders, researchers, policy-makers and practitioners. We conclude that:

"There is great interest in the restoration and conservation of coastal habitats for protection from flooding and erosion. This is evidenced by the growing number of analyses and reviews of the effectiveness of habitats as natural defences and increasing funding worldwide for nature-based defences–i.e. restoration projects aimed at coastal protection; yet, there is no synthetic information on what kinds of projects are effective and cost effective for this purpose.

Nature-based solutions (NBS) aim to help societies to address a variety of environmental, social and economic challenges in sustainable ways. They are actions which are inspired by and supported by nature. Some involve using and enhancing existing natural solutions to challenges, while others are exploring more novel solutions, for example, based on how non-human organisms and communities cope with environmental extremes. NBS are energy and resource-efficient, and resilient to change, but to be successful they must be adapted to local conditions.

This Report provides a description of the procedure and the outcomes of the work performed within the domain of NBS Impact Evaluation Framework.