Is There a Historical Relationship Between Urban Growth and Resilience Loss? The Case of Floods in Belo Horizonte (Brazil)

Reducing the negative effects associated with floods in cities constitutes one of the highest-priority contemporary social challenges on the global sustainability agenda. In general, most historical studies focus on the consequences, but not on the causes of the phenomenon, which is essential for moving towards sustainable and resilient territories. The aim of this research is to quantify the effect that urban expansion has exerted on floods, taking the city of Belo Horizonte as a critical and representative case study. To this end, an integrative, qualitative, and quantitative approach has been developed, based on previous studies and on distributed hydrological modelling for the period 1940–2024. The results show that urban growth has contributed to a 7%, 14%, and 21% increase in the first three quartiles of annual floods. Likewise, the increase in the magnitude and frequency of the floods is also attributable, since it is more noticeable in the events of higher frequency than in those of lower frequency, in a range from 15% to 7%. The above results show the way in which the application of quantitative knowledge derived from the environmental history is highly useful for decision-making regarding the measures required to increase resilience, considering the possible effects of climate change. Thus, the recovery of the infiltration capacity of the soil constitutes a priority measure to reverse the effect that urban growth has exerted on the hydrological cycle.