USE THE MAP OF SOIL AS SUBSIDY FOR DEFINING AREAS ON EROSION SUSCEPTIBILITY TO BASIN SÃO JOÃO, LAGOS AND UNA

Abstract

doi: 10.12957/geouerj.2016.19660

The hydrographic basin of the river São João, Una and Lagos presents strong pedological, geomorphological and climatic contrasts. This variation creates conditions for soils to, spatially, respond differently to the actions that are submitted. The basin has also undergone rectification of river channels and the opening of drainage canals. Although it has been made soil mapping studies of part of the basin to define the agricultural potential of the land., no study to obtain knowledge of soil fragilities was developed. This article's purpose was to complement the soil map of the basin of river São João, Una and Lagos to then carry out the analysis of susceptibility to erosion of the basin soils. The methodology of the study was divided into complementing the soil map of the region from the Delphis method and, from geotechnology tools, define levels of susceptibility to soil erosion that ranged from "very low" to "very high". The soil map shows the widespread occurrence of Ultisols, which occupy about 40% of the basin. The map of susceptibility to soil erosion suggests that the very low susceptibility category is the most predominant, if spatially considered, due to the fact that most of the basin reliefs is not too steep. The second most prevailing category is that of high susceptibility where Ultisols predominate as grazing lands.