Strategies for mainstreaming nature-based solutions in urban governance capacities in ten European cities

This paper explores the institutional mainstreaming of nature-based solutions (NBS) to advance a process-based understanding about how to strategically develop the governance capacities needed for systemic, localised and inclusive NBS. To this end, it reports how policy officers in ten European cities have started to mainstream NBS by interacting with and changing incumbent governance arrangements when experimenting with novel governance processes and mechanisms to plan, deliver and steward NBS. The analysis identifies three mainstreaming strategies to develop capacities for (a) a systems’ approach to link NBS to policies, regulations, and departments across goals and sectors, (b) inclusive collaborations for localised and inclusive interventions, and (c) reflexivity and learning about how NBS interact with the (institutional, ecological, social, etc.) contexts and create impacts. The strategies illustrate institutional entrepreneurship in interacting with incumbent governance contexts, and how starting from NBS as a type of systemic innovation can promote broader shifts in urban governance arrangements

Flood generation and classification of a semi-arid intermittent flow watershed: Evrotas river

Hourly water level measurements were used to investigate the flood characteristics of a semi-arid river in Greece, the Evrotas. Flood events are analysed with respect to flood magnitude and occurrence and the performance of Curve Number approach over a period of 2007–2011. A distributed model, Soil and Water Assessment Tool, is used to simulate the historic floods (1970–2010) from the available rainfall data, and the performance of the model assessed. A new flood classification method was suggested the Peaks-Duration Over Threshold method that defines three flood types: ‘usual’, ‘ecological’ and ‘hazardous’. We classify the basin according to the flood type for the most serious past simulated flood events. The proportion of hazardous floods in the main stream is estimated to be 5–7% with a lower figure in tributaries. Flood Status Frequency Graphs and radar plots are used to show the seasonality of simulated floods. In the Evrotas, the seasonality pattern of hazardous flood is in agreement with other studies in Greece and differs from other major European floods. The classification in terms of flood types in combination with flood type seasonality is identified as an important tool in flood management and restoration