Resistência do material litológico na determinação da morfologia e dos processos erosivos nas falésias costeiras em Maimbá-ES

• Ano de defesa: 2021
• Autor(a) principal: Brandão, Pedro Henrique Nascimento
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Oceanografia Ambiental; Centro de Ciências Humanas e Naturais; UFES; Programa de Pós-Graduação em Oceanografia Ambiental
• Palavras-chave em Português: Costa de falésias; movimentos de encostas; VANT; propriedades de solo; subject.br-rjbn; Ciências Ambientais
• Link de acesso: http://repositorio.ufes.br/handle/10/15781

This dissertation aimed to determine the factors involved in the sub-aerial erosion of cliffs located along Maimbá beach, south-central coastal region of Espírito Santo, and to relate these processes to the shape and erosive susceptibility of the features. In this sense, the lithological resistance of the facies, the gravitational mass movements and the land use were highlighted, factors that accelerated the coastal erosion processes. Through field descriptions, aerocartographic survey through high resolution images of unmanned aerial vehicle (UAV) and laboratory tests, cartographic products such as location maps, gravitational mass and land use motion maps, lithological and morphological profiles were generated of the cliffs in a GIS environment. The laboratory tests were used to corroborate the field observations and involved the textural properties, density, permeability, moisture, liquidity and plasticity limits, mechanics of resistance to simple compression and direct shear, and chemical, with ray diffraction test. x (DRX). The coastal cliffs belong to the Barreiras Formation and show lateral facies correlation in Maimbá-ES, with massive textures, compositions, thicknesses and similar directions. They have 4 facies, with an increase in permeability and a decrease in the lithological resistance of the base, which has a higher content of mud and kaolinite, towards the top of the sedimentary sequence, resulting in a change in the morphological profile of the cliffs. Mass gravitational movements are associated with higher cliffs, occurring mainly on the upper facies, and preserving block deposits on the beach portions protected from waves. From the south to the north of Maimbá beach, an increase in coastal erosion established by the set of factors of the physical environment of the cliffs and lithological resistance characteristics of the outcrop material was verified. In the southern sector, the lowest risk to coastal erosion was diagnosed, despite the cliff measuring 17.5m in height, its slope is considered low, ranging between 45º and 70º, with a concave morphological profile indicating subaerial erosion greater than marine erosion, thick adjacent road and strip of sand on the adjacent beach with a thickness varying between 30-50m, enough to provide greater protection from the direct attack of waves. The central sector has a cliff with the lowest height, 13m, slope between 45º and 90º, profile varying between concave, rectilinear and convex shapes, indicating sub-aerial erosion equal to marine, and a sand strip with a thickness of 15m, with an intermediate risk of erosion in relation to the other studied cliffs. The northern sector has a greater risk of coastal erosion, with the cliff measuring 18m in height, slope varying between 60º and 90º, straight and convex profile indicating greater marine erosion than sub-aerial, large amount of gravitational mass movements, adjacent road with evidence of planar and circular breaks, and a narrow strip of sand ranging from 10-20m, not supporting the spreading of the waves and providing a direct attack on the cliff. In general, there was an action of lithological resistance in the processes of the shape of the cliffs, in the gravitational movements of mass and land use in the surroundings, having a great influence on coastal erosion in Maimbá-ES.