Uso do sensoriamento remoto e estudos hidrológicos para mapeamento de áreas de enxurrada urbana em microbacia hidrográfica de Caçapava do Sul, RS

Abstract

This study aims to understand the occurrence of flash floods in Caçapava do Sul, using hydrological studies associated to Geographic Information System (GIS). A small watershed was used as a study case since the area is vulnerable to floods. A field mapping was carried out in order to localize the flash flood risk areas, the study of the hydrometric data of the analyzed watershed, which includes the creation of hydrograms and rating curves, and the investigation of the spectral signature of the study area in periods of drought and flood. The data used include flow rate, rainfall, relief of the watershed and LANDSAT-7 satellite images. The results include the value of the flow rate peaks and the rating curve, the flash flood risk areas located in the mapping, and the evidence of soil humidity in the period of flood. The importance of the research is related to the need of information about the hydrological behaviour of the small watershed in town studied due to the large susceptibility of flash floods occurrence. The conclusion was that Caçapava do Sul presents large environmental fragility for flash floods, pointed by the flow rates peaks that occur in small periods of time, which shows that the town needs to update the pluvial drainage system.