Interrelationships between urban drainage and geomorphological risk in Garanhuns – PE

Abstract

This research aimed to analyze the interaction between surface water drainage and the geomorphological risk in the urban area of Garanhuns, PE, Brazil. This region, driven by the national policy of coffee eradication, implemented in 1965 by the Brazilian Institute of Coffee – IBC, has maximized its urban occupation. This constant advance of the urban perimeter, combined with the geomorphological characteristics and the rainfall index that is atypical in this semiarid region, creates a scenario of high predisposition to geomorphological risks. The analysis was carried out by equating the existing interrelationships in the local landscape, based on a model of the geomorphological risk of the urban area, as well as photographs obtained on-site. The referred model was created through the application of the infinite slope theory, in order to determine the terrain’s stability. Based on the results, conclusions about the current situation of the urban occupation and drainage were inferred and a scenario of high geomorphological risk was found, originated by consequences of anthropic actions, driven by inadequate urban planning. Moreover, deficiencies were found in the urban drainage system, which aggravates the geomorphological risk in a considerable way since it amplifies the effects of erosion, allowing the occurrence of mass movements.