Dinâmica de uso e cobertura da terra entre 1998 e 2018 e avaliação do risco a movimentos gravitacionais de massa na praia de Pipa, Rio Grande do Norte

Abstract

The east coast of the State of Rio Grande do Norte, Northeastern Brazil, is marked by the presence of active cliffs with overlapping dune fields and sandy beaches facing, features shaped by erosion, transport and deposition by marine and continental forces, which interact in a complex external geodynamics on the coastal zone. On Pipa beach, in the municipality of Tibau do Sul, the active cliffs are about 15 m high and the continuous action of external forcing and anthropogenic occupation influence the loss of stability of the material that constitutes them, producing mass gravitational movements. Such material movements (soil or rock) are considered natural phenomena that, when subjected to anthropic factors, may increase their speed and intensity. As the studied location is a region of high real estate speculation and tourist movement, there is a potential for the occurrence of mass movements that, together with periods of high rainfall, can lead to natural disasters. The anthropogenic influence on geoenvironmental units with factors such as excess load on top of active cliffs, poor management of rainwater and wastewater for human use, the absence of drainage and containment systems, among others, lead to negative consequences. Therefore, the work in question proposes a methodology based on the use of free spatial databases in a Geographic Information System for the detection and classification of risk areas in the area called Morro da Velha Vicência Castelo, located in the urban area of the Pipa District. In addition, concepts that are in accordance with the methodology proposed by the Geological Survey of Brazil (CPRM) are used. Based on the analysis of the physical aspects of the terrain, as well as the local natural and environmental vulnerability, a diagnosis of risk to mass gravitational movements resulting from the complex coastal dynamics and anthropogenic interaction is resulted. The work seeks to delimit areas of high and very high risk to mass gravitational movements to enable the knowledge of populations and tourists, in addition to subsidizing managers regarding the most appropriate land uses and occupations, especially in Morro da Velha Vicência Castelo and surrounding areas, avoiding material and life losses.