Behavior Of Morphometric Indices In Planimetric Surface Projections And Patterned In The Cuiabá River Basin - Petrópolis (RJ).
ISBN 978-85-88783-11-9
Authors
1Vieira Vargas Colares, I.; 2Felipe Barreto de Oliviera, L.; 3Sá de Araujo, R.; 4do Couto Fernandes, M.
1UFRJ Email: igor_colares@yahoo.com.br
2UFRJ Email: luisfelipe.b.oliveira@gmail.com
3UNL Email: rodrigoaraujo.ufrj@gmail.com
4UFRJ Email: manoel.fernandes@ufrj.br
Abstract
There are a number of alternatives to work with the dimensions of the elements of a landscape, such as the use of digital elevation models (DEM), and even then the GIS has a limitation established by not considering the irregularity of the space to be analyzed. In this sense, the analysis in the pattern surface has a greater accuracy regarding the measurements in the landscape, as in the case of geomorphological analysis. Aiming to understand how the different observations in planimetric surface and pattern surface behave by variations of size and morphological measurements, this work seeks to compare results of geomorphological indices obtained from these two types of observations in the Cuiabá river basin, located in the municipality of Petropolis (RJ), where the altimetric gap is approximately 1000m, ranging from 760 m to 1860 m. This variation, makes the analysis in planimetric surface be a different of real landscape, therefore is important to study the pattern projection, which bring closer to reality. Every study was developed on the scale of 1: 10,000 topographic compiled bases provided by the city of Petrópolis (RJ). From this base were built geomorphological indices in planimetric surface. Indexes works are: Topographic Gradient (Tg), drainage density (Dd) and Drain Efficiency Index (DEI), which were extracted for 41 basins second order of the Cuiabá River Valley, according to the classification STRALHER (1952). The indices Dd and DEI were applied to surface modeled after creating an MDE from hypsometry. Besides these two indices was also considered the hollow for these second-order basins, which are part of the runoff, together with the hydrographic. All these indices were compared and analyzed in both types of observations to try to understand the different behaviors generated. Results were also obtained for the IED without the addition of a hollow shaft and then relying on the sum of the hollows. Results showed a significant increase for the patterned surface in relation to the planimetric, mainly concerning measurements of area and length of drainage, with an average increase of 18.58% and 6.31%, respectively. When coupled with the hollow shaft of hydrography, where there was a percentage difference of 8.63% for the total drainage, showing a significant accretion when analyzing a projection closer to the real. For DEI, without considering the hollows there was a decrease of -10.23% comparing surfaces. Already adding hollows, this decrease was reduced to -8.68%, because this index is inversely proportional to area. The runoff velocity is closely linked to the drainage efficiency index of showing the importance of considering the relief, especially when it shows with a accentuated altimetry variation. For the use of more consistent data regarding the drainage slope influences the water runoff through the surface, thus making the importance of relevance to study pattern surface. The calculations of these geomorphological indexes, shows the opportunity to observe new information that approach the reality. Since, in this research, the relief is taken into account in the calculations, thus being able to modify the result. So opens the prospect of using this type of observations in areas of similar morphological behavior aimed at creating closer to reality readings, thereby avoiding problems of interpretation of the structure and geomorphological feature of the landscape
Keywords
drainage efficiency index; hollow; geomorphological indices