Desenvolvimento urbano no município de Chapecó, Santa Catarina: uma abordagem sobre critérios geomorfológicos

Abstract

The natural environment has undergone climate, environmental and human changes over the years. In modern society, the implantation of urban spaces does not always take into account the natural elements of the landscape at the moment of intervention for the construction of cities, often generating disastrous consequences for the environment and the people who live in it. This work has the purpose of presenting the areas of susceptibility to mass movement in the urban perimeter of the municipality of Chapecó-SC, based on soil studies conducted with geological and geomorphological criteria. The methodological procedures were: soil sampling and tests carried out at 10 points of the study area, identifying the physical and geological properties of the same, elaboration of tables with the annual rainfall, verifying the average rainfall volume in the municipality, the infiltrator rings presenting the basic velocity of infiltration in the soil, calculations of the angle of friction and soil cohesion from data of 20 points of SPT probing and elaboration of thematic maps referring to the altimetry, direction of slopes and slope that provided important information for the preparation of the maps of factor of safety of the natural and saturated soil, with and without vegetation. The results show three types of soils present in the urban perimeter of the municipality of Chapecó-SC, 71% of Latosols with a maximum slope of 20%, 23% of Nitosols with a slope of 20 to 45% and 6% of Cambisols with a slope of 20 to 75%. The soil infiltration tests showed that the basic infiltration velocity of all the evaluated points ranged from 64 mm ha to 466 mm and aids in drainage projects, since the municipality has presented in recent years irregularities in rainfall and an increase in rainfall with an annual average of 1900 mm. The calculations and mapping showed that the areas of greatest susceptibility to mass movement in the study area are in narrow bands of soil in the southwest known as Road Contour and district Efapi, as well as small points in areas of the eastern region and north. Most of these areas are located on Cambisol soil with high slope. These soils when saturated and without vegetation present as unstable areas and need more attention due to the safety factor being less than 1. These results subsidize the management and urban planning actions identifying the possible risk areas, since the most of them have not yet been occupied and are within the urban perimeter of the municipality.