Assessment of economic impacts in flood events in Lages/SC, Brazil

Flood processes become increasingly harmful to communities due to factors such as climate change and land use. This study aims to evaluate the economic damages of flood events in an area of the urban basins of Lages/SC. Thus, four plans were considered for economic evaluation: one referring to conditions without protective measures and three with the application of elevation of structures at different heights, as well as two scenarios of the evolution of urban occupation. The rainfalls were obtained through the Gumbel probabilistic model to estimate the maximum accumulated precipitations over 5 days, with the hydrological modeling carried out at the HEC-HMS. The hydrodynamic modeling was performed in HEC-RAS through the simulation of a 1D model. The HEC-FDA model was used to perform the risk reduction analysis of damage caused by floods, where the expected annual damages (EAD) were calculated for the four proposed plans as well as for the urban growth scenarios. The results showed that the application of the mitigating measure of raising the structures reduced the EAD by up to 83.10%. As for the scenario of the evolution of urban growth, there was an increase in EAD of 62.09%, in the interval of 20 years. The HEC-FDA model has been demonstrated as good software for assessing the economic damage of floods in different scenarios, showing results that can help decision-makers in the development of public policies.