This paper explores the concept of “institutional readiness” (IR) applied to the adoption and mainstreaming of Nature-based solutions (NBS) to deal with climate related risks. We argue that barriers towards up-scaling and mainstreaming of NBS are a manifestation of uncertainty, and are often associated with the ‘readiness’ of the institutional setting rather than with the readiness of the NBS technology itself. We align the concepts of Institutional Readiness (IR) to the more widely used concept of Technology Readiness Level (TRL) to understand drivers and barriers for adoption of NBS and analyse the role of institutional capacity. We illustrate this with the case study of the Urban Water Buffer Spangen in Rotterdam, the Netherlands, which is an NBS with high TRL. To do so, we constructed a timeline of the design and implementation process of the NBS, identifying and classifying key uncertainties as well as the strategies applied to deal with these uncertainties, particularly in the institutional context. Our results indicate that for mainstreaming of NBS, Institutional Readiness (IR) should be at a degree where strategies to deal with uncertainties in institutional, organizational and governance contexts can be integrated in the design and planning process. We claim that the concept of IR should be considered in its role to deal with uncertainty, in order to close the documented gap of NBS implementation and mainstreaming.

Hydro-meteorological risks due to natural hazards such as severe floods, storm surges, landslides and droughts are causing impacts on different sectors of society. Such risks are expected to become worse given projected changes in climate, degradation of ecosystems, population growth and urbanisation. In this respect, nature-based solutions (NBSs) have emerged as effective means to respond to such challenges. A NBS is a term used for innovative solutions that are based on natural processes and ecosystems to solve different types of societal and environmental challenges. The present paper provides a critical review of the literature concerning NBSs for hydro-meteorological risk reduction and identifies current knowledge gaps and future research prospects. There has been a considerable growth of scientific publications on this topic, with a more significant rise taking place from 2007 onwards. Hence, the review process presented in this paper starts by sourcing 1608 articles from Scopus and 1431 articles from the Web of Science. The full analysis was performed on 146 articles. The analysis confirmed that numerous advancements in the area of NBSs have been achieved to date. These solutions have already proven to be valuable in providing sustainable, cost-effective, multi-purpose and flexible means for hydro-meteorological risk reduction. However, there are still many areas where further research and demonstration are needed in order to promote their upscaling and replication and to make them become mainstream solutions.

Water governance can be defined as a system that makes water management more effective, accountable and participatory, thus strengthening the role of multiple stakeholders in institutional capacity bUilding, improving coordination, broadening participation and consolidating partnerships Uacobi, 2009). Water governance structures in some LAC have undergone reforms that implied not only re-orientation of policy priorities and approaches, but also the restructuring of institutional frameworks. This has led to the need for new intermediate institutions that enable a negotiated approach to water governance. Two issues hamper the capacity of institutions to improve and adjust to constantly changing conditions: the lack of proper evaluation of the quality of policies - often a consequence of lack of transparency and accountability that may favour some actors and their private interests over others; and the lack of adequate control over bureaucratic systems. Institutional reforms involved changes in the ‘rules of the game’, expressed by the coexistence of formal laws, informal norms and practices, and organizational structures, as well as strengthening institutional capacity.