Características intrínsecas dos horizontes de alteração da formação Alter do Chão, como diagnóstico para a erodibilidade em Manaus / Am.

Abstract

Considering the proliferation of areas of geohazard in Manaus-AM, in the last decades, because of irregular and unplanned occupation, if stimulated this research which resulted in this master dissertation. The main objective is to evaluate intrinsic characteristics of weathering horizons of Alter do Chão Formation, which are under the city of Manaus, analyzing their physical and mineralogical properties and its visual tactile description, also evaluating the geohazard, exogenous characteristics such as rainfall, to anthropization and the evolution of the local landscape from imagery satellite and aerial correlating these factors with the development of erosional features found in two fields of study, the first study area located in the neighborhood Jorge Teixeira, in the community João Paulo, encompassing the late streets, the second area is located in the neighborhood Cidade Nova between the communities Conjunto Cidadão I and Campo Dourado I. These areas are respectively the eastern and northern parts of the city. The methodology applied in this study consisted of in the bibliographical survey, analysis of base maps, satellite images and aerial photographs, field research with description and the hierarchization of geohazard sectors, characterization tests on field and samples collected by probing in auger, analyzes physical, by tests of the particle size and limits consistency and mineralogical assays by x-ray diffraction. Developments mainly lateral edges of the craters are analyzed aerial and satellite images between the years 2004 to 2013, the first area in the late gullies streets were already well evolved in pictures 2004 until 2007 he perceives the images 2010 and 2011 we see a good recovery of the vegetation and the image of 2013 gullies appear to be completely stagnant with vegetation recovered. In the second area in 2004 noted the implementation of the community Conjunto Cidadão I, with infrastructure and planning, after 2007 some houses are removed from the foot of the slope, the following images 2010, 2011 and 2013 the slope appears to be safe with vegetation recovery. In geohazard mapping performed in the field in the 1st district looked high and very high hazards sectors with several houses near of the gully, the 2nd area have only one sector at high hazard for burial at the foot of the slope, near the lower erosional features. Soundings by auger of 10 meters were enforced in the two areas, for visual and tactile analysis with sample collection. Grain size data, with calculations of curvature coefficient, degree of uniformity and tests of consistency limits of the 1st district indicate good resistance to erosion, but this site is great erosional features. In the 2nd area for a smaller anthropogenic influences and the data acquired in the analyzes are equivalent to the behavior seen in the field, up to 6.5 meters deep analysis showing good resistance to erosion of the layers, below that the erodibility of the material increases and features are observed erosive. The activities of endogenous and exogenous agents are different for each site studied. Mainly responsible for formation of gullies in the first area are exogenous agents added to anthropization and a lack of infrastructure. In the second area, the endogenous factors, the characteristics of the layers are decisive to indicate the most susceptible to erosion layers.