Geoprocessamento aplicado à estimativa de perda de solo por erosão hídrica na bacia hidrográfica do Arroio Fragata

Abstract

Water erosion is a problem that degrades soils around the world. Their measurement and delimitation are of extreme importance so that the conservationist practices get obtained expired. For this, the use of soil loss estimation models as a revised universal soil loss equation with a goal of proving a concise rate on the conservation status of soils of watersheds and sub-basins. The aim of this study was to evaluate the soil losses due to water erosion in annual average values and based on agroclimatic seasonality, supply prospects in relation to the water erosion dynamics of the soils of the Fragata stream basin (BHAF) and its basin subscales. To that end, they are geoprocessing tools to apply a RUSLE model as a model of soil loss estimation, use of erodibility data, mathematical equations, land use of 4 OLI / LandSat8 images covering the 4 periods of the year and simulating the effect of conservation practices through the geographic information system Spring 5.3. It was verified that the average annual erosivity of the BHAF was 8214.75 MJ · mm · ha · ¹ · h-¹ · year-¹ with summer being the most expressive period, with 27% of annual erosivity. The largest erodibilities are associated with the Neossolos, which occupy 15% of the watershed area. The predominant relief in BHAF is flat to wavy, from 0 to 20% slope, these classes representing 95% of BHAF and sub-basins. The same is LS found at 0.68, with more expressive sub-basins reaching the levels of 1.3306 in areas where the relief is undulating. Areas throughout the year do not apply to production areas that represent 5% to 12%, and forest and field cover of 48% and 27%, respectively. The function is used as one of the main tools for extracting 80% of the soil from agricultural areas. Seasonality increased the sub-basins that are not seen in concentrated structures, such as variations in soil and erosivity, allies in the spatialization of factors, the promotion of understanding the spatial and temporal dynamics that occur in the region. It was possible to estimate the losses of predominant soils for a BHAF in 77% of the extension, and the soils with the areas superior to the tolerance limit: Espodossolos (29%), Argissolos (28%) and Planossolos (26%).