Connected urban green spaces for pluvial flood risk reduction in the Metropolitan area of Milan

Rethinking cities in a more sustainable and integrated way is a key opportunity for successful climate change adaptation and disaster risk management. Nature-based solutions and green infrastructures can help to safeguard urban nature and biodiversity while providing multiple benefits to reduce climate risks and improve human well-being. Nature-based solutions help to mitigate flood risk by regulating storm-water runoff and peak-flow. This paper investigates the effects of nature-based solutions and green infrastructure networks on pluvial flood risk in the Milan metropolitan area in terms of direct economic damage to buildings and population exposed. Results show that extending the urban green networks by 25% can potentially halve the pluvial flood damages and reduce the population exposed by 40%. For all analysed rainfall intensities, damages to buildings and share of population exposed decrease (up to 60% and 50% respectively) as green area coverage increases, with slightly higher flood risk reduction for lower-intensity events. The applied methodological framework makes it possible to identify priority-action urban areas and hence inform decision-making processes as for where green solutions are most efficient.