Determinação de pontos amostrais através de atributos do terreno para mapeamento digital dos solos da bacia hidrográfica do Rio Guapi-Macacu, RJ

The use of digital elevation models (DEM) are becoming increasingly common in studies related to environmental issues and especially in studies within the watershed. In regions where the geomorphological are a main factor during the genesis of soils, studies by DEM and derived attributes emerge as a great tool, providing greater efficiency during field work in order to improve the present situation of soil surveys , which proved very expensive and subjective interpretation. From the DEM it is possible to extract several attributes, enabling a more holistic analysis of the environment, but for a more consistent, it is necessary to have a better representation of the data, so that it can faithfully represent several variations within the environment. The use of a tool for pre-determination of sampling points of the DEM can be an alternative to greater efficiency and consequently a lower cost of implementation. This study aims to use statistical analysis of the attributes generated by MDE, through Latin Hypercube Sampling Software (LHS) for the sampling points which have large representation of geomorphological phenomena, determinants in the genesis of soils in the Guapi-Macacu watershed, Rio de Janeiro. The results were satisfactory, showing that this method may become a useful tool for pre-determination of sample points generated from DEM and their attributes for landscape studies.Pages: 3672-367

Avaliação de diferentes fontes de dados na obtenção do modelo digital de elevação para mapeamento digital dos solos da bacia hidrográfica do Rio Guapi-Macacu, RJ

The general goal of a soil mapping is to describe the spatial variation of the classes and their morphological, physical and chemical properties in a given area. Soil surveys are used as a basis for planning and executing projects of different nature, and they may be interpreted by different users. Among the soil forming factors, the relief has a direct influence on the soil genesis, affecting characteristics such as depth, drainage, colour, texture. The analysis of the relief allows for understanding the role and intensity of the different mechanisms of soil formation, removal, addition, translocation and transformation of materials in a certain landscape position. The aim of this study was to evaluate digital elevation models (DEM) generated from different data sources combined. The three data sources used were: topographic contour lines, topographic maps associated with elevation points, and the letters associated to the points and combined with data from SRTM sensor for the low land areas. The models had a spatial resolution of thirty meters. The best representation of terrain altitude through the DEM was obtained after the interpolation of contour lines, and the data from remote sensor (SRTM). The combination of the three data sources to study the topography and geomorphology of the watershed was a valid procedure. Mainly, since the contours were vectorized by IBGE with an equidistance of 20 meters, insufficient to allow accurate representation of data in the low land areas, even when combined with the elevation points.Pages: 9136-914