Analysis of the relationship between the real surface area and the planimetric surface area on the legal reserve index in the Tijuca massif/RJ
ISBN 978-85-88783-11-9
Authors
1Laeta, T.; 2Coutinho Ferreira da Silva, L.F.; 3do Couto Fernandes, M.
1INSTITUTO MILITAR DE ENGENHARIA - IME Email: tainalaeta@gmail.com
2INSTITUTO MILITAR DE ENGENHARIA - IME Email: felipe@ime.eb.br
3UNIVERSIDADE FEDERAL DO RIO DE JANEIRO - UFRJ Email: manoel.fernandes@ufrj.br
Abstract
The geoecology studies the interaction between life and the environment where they live, taking into account in their analyzes the planimetric area. According to Kraak & Ormeling (2010), the mapping of the land must take into consideration information from the relief. In this sense, the challenge is to transform the reality of three-dimensional information on a two-dimensional surface, where the consideration of the planimetric area can result in inaccurate analysis because it does not consider the nuances of relief in the calculation of area and distance. The objective of the research is to analyze the impact of using measurements in the area of real surface and planimetric in the geoecology analysis. In the research, fristly to possible observation of the difference between the two areas, were constructed geometric solids, which are: cone, pyramid, hemisphere and tetrahedron. The selection by such solids is due to association of features found in the relief, that is, which can be seen in the landscape. Thereafter the construction of solids, was calculated the planimetric surface area and the real surface area of these same solids, and as well the calculated difference between the two areas, and thus establishing a relationship representation. Should draw attention that construction of the solids, in the calculation of the area was carried out the process of cartographic generalization by point and equidistance. Initially the solids were constructed using 361 points automatically and then performed generalization of the number of points 181, 91 and 46.The generalization process performed by equidistance was done in the contour lines of 1m, 5m, 10m and 20m. It is noteworthy that the greater distance between the contour lines and also lower the amount the number of points in the construction of geometric solids, greater the generalization process. Preliminary results show that in the geometric solids with linear face (cone, pyramid and tetrahedron), in the generalization by number of points and equidistance, the percentage ratio between real surface area and planimetric surface area was aproximately 41%. As for the geometric solid hemisphere, the representation of percentage between planimetric surface area in relation to real surface area ranged from 93,96% from 100,28%. After the observations of the parameter behavior in geometric solids, areas of difference observations were made in the Tijuca massif and the consequence of their impacts in geoecological analysis. The Tijuca massif is located in the city of Rio de Janeiro, has an area of approximately 119,2km2 and occupies the eastern portion of the city of Rio de Janeiro/RJ. The topography of this is characterized by a very rugged relief, which for the purpose of this research is presented as appropriate as it presents great altimetric differences. In this research, environmental issues, used the legal reserve index, where it states that 20% of the native vegetation of the private properties in urban areas should be preserved. Results show that the consideration of the planimetric surface area implies the loss of area to be conserved. For example, in one of the fragments analyzed, which has a planimetric surface area of 0.622km2 and real surface area of 0.726km2, would be preserved respectively 0.1244 km2 0.1452 km2, and the difference between both of 0.208 km2. That is, the value of the preserved legal reserve area is larger considering the real surface area. Thereat, it can be concluded that the consideration of planimetric surface area in geoecology studies may in fact result in inaccurate analysis, because the calculation of indexes can generate distorted information on subsidy for urban and environmental planning.
Keywords
Planimetric surface area; Real surface area; Geoecology