How can scenarios on flood disaster risk support urban response? A case study in Campinas Metropolitan Area (São Paulo, Brazil)

Abstract

This paper highlights the effects of sealed surfaces in flood hazard in order to identify population exposure to heavy rain within Cabras watershed located in Campinas Metropolitan Area (Sao Paulo). We applied a set of methods compiled into an integrated system by the Department of Hydraulic Engineering of University of Sao Paulo (USP). We observed that, for relatively frequent flood events with 10y of return periods, changes in LULC represent an increase of maximum water depths that vary up to 0,036 m to 0,043 m, respectively. For less frequent events, with return periods of 100y, the maximum increase of water depth varies from 0,064 m to 0,071 m. Although the water depth reached is not considered risky (e.g., for an adult walking in flows), the water velocity (v = 2,32 m/s) and the amount of water downhill (∼5,000 litters) are considered high (i.e. pedestrians can be swept along streets during major storm events). Our scenarios project more than 5,000 people exposed, with a significant parcel at slums. Summarizing, an explicit innovation strategy helped us to identify the number of people at risk in ungauged basins, which can be beneficial for municipal decisions, especially if effectively implemented to reduce disaster risk and nature based solutions.