Aspectos morfométricos relacionados ao estudo de enchentes na Bacia do Rio Sapucaí, Minas Gerais

Abstract

RESUMO: A caracterização morfométrica de bacias hidrográficas tem grande importância para a melhoria do planejamento e gestão de recursos hídricos, especialmente em áreas sujeitas a enchentes. O objetivo do estudo foi de verificar a influência da morfometria nas enchentes ocorridas na bacia hidrográfica do rio Sapucaí e em duas sub-bacias, no estado de Minas Gerais, por meio do uso de ferramentas de sistemas de informações geográficas. A base de dados consistiu de um modelo digital de elevação e da rede hidrográfica vetorial do IBGE. Em termos morfométricos, a bacia do rio Sapucaí e a sub-bacia a montante do município de Itajubá apresentaram formato irregular sendo pouco susceptíveis a enchentes em condições normais de precipitação. Já a sub-bacia a montante do município de São Sebastião da Bela Vista apresenta formato mais circular e maior potencial para a ocorrência enchentes. A elevada diferença de nível entre a região de cabeceira e o trecho a montante da cidade de Itajubá foi considerada a principal causadora das enchentes na região, devido à diminuição do tempo de concentração do escoamento e a ocorrência de picos de enchentes.Palavras-chave: geoprocessamento, morfometria, recursos hídricos.Morphometric aspects of Sapucaí River Basin, Minas Gerais state, Brazil, related to the flood studies ABSTRACT: The morphometric analysis of watershed is a very important tool to improving the planning and management of water resources, especially in basins subject to flooding. Using Geographic Information System were obtained several morphometric indexes of the Sapucaí river basin and the same was made for two sub-basins, in Minas Gerais State, to check the influence of the morphology of the basins in the floods occurred in the region. The database consisted of a digital elevation model of Shuttle Radar Topography Mission and the hydrographic network vector of IBGE. The Sapucaí river basin and the sub-basin upstream of Itajubá city had an elongated shaped, making the same less susceptibility to floods in normal conditions of rainfall. Already, the sub-basin upstream of Sebastião da Bela Vista is subject to floods because the shaped is next to circle, resulting in a shorter flow concentration and therefore greater potential for the occurrence of flood peak flows. Among the results, the considerable change in the slope values of the Sapucaí river basin, was considered the reason to flood occurrence in the region, because the time of concentration and the occurrence of peaks flooding of these areas.

Morphology of Pardo River Watershed at the Border of the States of Bahia and Minas Gerais

“…According to Elesbon et al (2011), the S3 model is the one that best represents the slope of the river, because it takes into account the water travel time along the length of the longitudinal profile. Considering the morphometric aspects related to the study of floods in the Sapucaí-MG river watershed, Almeida et al (2017) found the value of 0.01% for the S3 slope in the main river stretch, reporting that flood events are frequent in cities close to the stretch where the flow of the river is slower. The value found for the S3 slope in this study was also considered low, however the drainage shape and density characteristics of the Pardo-BA river watershed differ from that of the Sapucaí-MG river watershed.…”

“…Considering the relief characteristics, the analyses performed were: a) slope, using the MDEHC classification according to EMBRAPA ( 2006), considering 0 to 3%, flat; 3 to 8%, smooth wavy; 8 to 20%, wavy; 20 to 45%, strong wavy; 45 to 75%, mountainous; and above 75%, a mountainous fort; the slope of the main river was also calculated using three different methods: S1, slope obtained based on the difference in level between the source and the mouth; S2, slope obtained based on the area equivalence criterion; and S3, constant equivalent slope obtained based on the speed of water displacement along the longitudinal profile of the watercourse; and b) altitude, obtained by directly extracting the values of each pixel from the MDEHC. The slope of the main river in the basin is extremely important in the runoff flow and, consequently, in the magnitude of the flood peaks (ALMEIDA et al, 2017).…”

Caracterização Morfométrica E Comportamento Hidrológico Da Bacia Hidrográfica Do Rio Pardo

“…O Ff foi 0,97, indicando uma bacia mais concêntrica, comparativamente, bacias de fator de forma de maior valor têm maiores chances de sofrerem inundações (menor tempo de concentração) do que bacias de fator de forma menor (ALI et al, 2017). Almeida et al, (2017) verificaram valores distintos para o fator de forma na bacia do Rio Sapucaí-MG, onde a bacia, com forma mais próxima de um quadrado, apresentou fator de forma 0,80, sendo considerada prioritária para práticas de manejo, devido ao menor tempo de concentração da vazão.…”