Avaliação do risco a inundação para bacia hidrográfica do Rio Jacuípe (AL/PE) a partir do método de processo analítico hierárquico – AHP e técnicas de geoprocessamento

Abstract

In view of the economic and socio-environmental damage caused by hydrological disasters, represented by floods and flooding, and combined with improper occupation of urban space near river banks, it is necessary to create tools that make it possible to prevent and control the resulting damage. The mapping of areas susceptible to flooding, using qualitative and quantitative methods and geoprocessing techniques, is a useful tool, since mapping makes it possible to promote proper planning of the region, preventing families and various enterprises from being installed in areas considered to be at risk. The aim is to identify and assess the areas susceptible to flooding in the Jacuípe River basin using the AHP (Analytic Hierarchy Process) method and geoprocessing techniques. Four variables were selected to make up the reclassification model: soil characteristics, land use and occupation patterns, and geomorphological elements such as hypsometry and slope. The data was obtained from the Annual Mapping of Land Use and Land Cover in Brazil Project (MapBiomas), the Brazilian Agricultural Company (Embrapa) and the United States Geological Survey (USGS). After using the AHP method to analyze flood susceptibility in the Jacuípe River basin, the results outlined a classification into five distinct risk categories: very low, low, medium, high and very high. A detailed analysis of the mapping indicates that around 24% of the basin's total area, equivalent to 196 km², is classified as high and very high risk of flooding. The results indicate very high risks in regions on the banks of the water bodies that form part of the basin, in areas with flat terrain, low altitudes and lower slopes. It was also noted that this class covers the cities of Jacuípe and Colônia Leopoldina in Alagoas. As such, a considerable part of these towns is more susceptible to flooding if the main river experiences a significant rise in its level. It is therefore hoped that the results found will provide support for the prevention and management of economic and socio-environmental impacts in the municipalities that make up the Jacuípe river basin. In other words, they will support public administrators in implementing structural and emergency measures to reduce these risks through effective plans and monitoring.