We review published references on 'deculverting' (also known as 'daylighting') projects in the United Kingdom and internationally. The aim of the review was to assess the objectives of implemented projects and to establish where evidence exists for the purported social, economic and environmental benefits of deculverting. The outcomes highlight the need for collaboration to collate detailed information on such projects, to support the further development of evidence-based policy. It is clear that deculverting schemes can indeed exert considerable positive impacts, including ecological benefits, reduced flood risks, recreation for local communities and a stimulus for regeneration, but that the evidence for these impacts is sparse. We conclude that improvements in policy will help to maximise these opportunities, by encouraging the implementation of good practices.

Suites of concepts and approaches have been launched during recent years to promote urban nature and greener cities. However, it is doubtable whether tinkering within the current economic and political system can provide adequate solutions. Nature-based Solutions can be seen as a new conceptual approach to the human-ecological connection, and as an outcome of an evolutionary development of socio-ecological concepts. In this Communication, we argue for drawing up inspiration by nature as an outset for the development of more sustainable and inclusive cities, balancing anthropocentric and ecocentric values and acknowledging the importance of the social and governance dimensions in a more balanced socio-ecological perspective. We call this approach Nature-based Thinking.

The valuation of urban water management practices and associated nature-based solutions (NBS) is highly contested, and is becoming increasingly important to cities seeking to increase their resilience to climate change whilst at the same time facing budgetary pressures. Different conceptions of 'values' exist, each being accompanied by a set of potential measures ranging from calculative practices (closely linked to established market valuation techniques) - through to holistic assessments that seek to address wider concerns of sustainability. Each has the potential to offer important insights that often go well beyond questions of balancing the costs and benefits of the schemes concerned. However, the need to address - and go beyond - economic considerations presents policy-makers, practitioners and researchers with difficult methodological, ethical and practical challenges, especially when considered without the benefit of a broader theoretical framework or in the absence of well-established tools (as might apply within more traditional infrastructural planning contexts, such as the analysis of transport interventions). Drawing on empirical studies undertaken in Sheffield over a period of 10 years, and delivered in partnership with several other European cities and regions, we compare and examine different attempts to evaluate the benefits of urban greening options and future development scenarios. Comparing these different approaches to the valuation of nature-based solutions alongside other, more conventional forms of infrastructure - and indeed integrating both 'green and grey' interventions within a broader framework of infrastructures - throws up some surprising results and conclusions, as well as providing important sign-posts for future research in this rapidly emerging field.

No abstract

Impact assessment is a key step in mainstreaming urban nature-based solutions (NBS). Yet, it remains unclear if and how assessment frameworks influence urban planning, design and management. We contend that the potential of current NBS assessment frameworks is not fully exploited due to: (1) limited contextualisation of monitoring and assessment to place-specific contexts and (2) the depoliticisation of co-production. To address this, we present a practical five-step action framework to guide inclusive participation across different stages of monitoring and assessment of urban NBS, including indicator selection. Unlike previous approaches, applying selection criteria at the level of individual indicators, we also use criteria at the aggregate level of the indicator set. We conclude that participatory assessment contributes to mainstreaming urban NBS for sustainable and just cities, provided data is contextualised to local decision-making contexts and the process is designed to amplify marginalised voices.