Áreas de risco a alagamento e inundação na foz do rio Cachoeira, em Ilhéus (Bahia – Brasil)

Flooding and inundation risk areas at the mouth of the Cachoeira River in Ilhéus (Bahia – Brazil)

Abstract

Hydrometeorological phenomena have been increasingly recurrent due to urban growth, since this waterproofs the soil, intensifies surface runoff and increases the accumulation of water on the surface. This work aimed to map the areas at risk of flooding at the mouth of the Cachoeira River in Ilhéus - BA, where several neighborhoods are located in its surroundings and are frequently affected by these natural phenomena. For this, a multicriteria spatial analysis was carried out using the Analytic Hierarchy Process (AHP) method, where environmental covariates were combined using map algebra in the QGIS 3.26 software. RStudio was used to create graphics. It was possible to identify with the maps and graphs how each environmental covariate and their respective classes are distributed in each risk class. The results showed that more than 75% of the area is subject to Moderate, High and Very High risk, and that the Urban Area is highly inserted in Very High-Risk zones, where flat relief and mangroves predominate. The information generated can be used by the Secretariat of Civil Defense to guide actions that minimize the negative impacts caused by flooding, for example, occupation plans, recovery of riparian forest, drainage works, among other alternatives.

Keywords: Spatial Analysis; Multicriteria Analysis; Natural disasters.