Análise da susceptibilidade a inundações na bacia hidrográfica do Rio Uraim, Paragominas - PA

Abstract

The phenomenon of flooding is a natural event, given by the extravasation of water to the greater river bed, a fact caused by intense precipitation causing the amount of water that arrives simultaneously to a point of the river is greater than its capacity of flow. The main objective of this dissertation was to analyze the susceptibility to floods in the Uraim River basin in the municipality of Paragominas state of Pará, based on the physical and morphometric characteristics of the basin and to evaluate the areas most prone to flooding within the urban zone. Geoprocessing techniques were used to extract the basin by SRTM images and to use digital image classification to obtain soil use in the basin and extraction of elevation and slope to compose the map algebra process by the AHP method in order to generate the map susceptibility of the basin and conduct a discussion with the urban area of the municipality of Paragominas. The Uraim River basin It has a drainage network with area and perimeter of 4,981 km² and 202 km, respectively. The basin has a maximum altitude of 255 meters and a minimum of 1 meter in the exudation, the average altitude being 136 meters. The slope of the main watercourse calculated on the basis of the extremes (S1) showed a value of 0.08 m/m expressed a value that overestimates the mean slope of the water course, and hence the peak flood. For the variable use and occupation of the soil present variables where it can be analyzed that the Uraim river basin is in the process of altering its vegetation cover, evidencing a high index in the pasture and agriculture classes, besides the deforestation in Permanent Preservation areas, the areas evidence of high impermeability in the preservation areas. It can be seen that the neighborhoods most susceptible to flooding are in regions near the river basins of the basin: Promissão, Uraim, Cidelândia, Angelim and Cidade Nova. The AHP technique used to determine the weights of classes contributing to flood susceptibility was effective because it reduces and simplifies the proposed problem, which minimizes the errors of judgment during the process.