Análise da aplicabilidade do método AHP, para mapeamento de vulnerabilidade a inundações, na bacia do rio Mundaú, em Alagoas

Abstract

In june 2010, a tropical storm hit the states of Alagoas and Pernambuco, causing a flood in the Mundaú hydrographic region, affecting many low-income riverside families. These flooding events along river valleys frequently have major environmental and social impacts and represent a concerning national problem in Brazil, where the northeast region is the second most affected by large scale episodes. They are normally caused by a combination of high precipitation rates and environmental and socioeconomical factors and it is usually more cost-effective to invest in prevention measures than post-disaster measures. The Mundaú river spans the states of Alagoas and Pernambuco being classified as a federal river and managed by the Agência Nacional de Águas. It springs in the municipality of Caetés in Pernambuco, flowing approximately 4.126km through 15 municipalities until it reaches the Mundaú lagoon in Alagoas. The main goal of this study was to identify regions susceptible to flooding in the Mundaú hydrographic basin using the Analytic Hierarchy Process (AHP) method. We used data from the ALOS PALSAR satellite provided by the Alaska Satellite Facility (ASF). We generated maps of elevation, slope and distance from the closest drainage or HAND. Then, maps were weighted according to their susceptibility to flooding episodes and vulnerable areas were identified through map algebra using AHP. The analyses revealed extensive areas along the Mundaú and Canhoto rivers that are highly susceptible to flooding, particularly urban areas. These results can contribute to the development of public policies that mitigate and prevent impacts caused by largescale flooding events.