Sensibilidade de fatores para valoração do ambiente com o uso de avaliação multicritério e geoprocessamento digital

Abstract

This study is about the sensitiveness of adopted factors in environmental multicriteria evaluation during the analysis of favorable aspects or restrictions when selecting the places to implant hydric infra-structural public works in the hydrographic basins context. The general focus of this study is the geoprocessing technology connected with the characteristics of multicriteria analysis. In the bibliographic review themes like: hydric resources management; digital geoprocessing: multicriteria analysis as a helper to the hydric resources management and a brief philosophy about choices were considered. Having as a case study the report Analysis of the Environmental Fragilities in the Hydrographic Basin of the rivers Apuaê- Inhandava, located in the Hydrographic Region of Uruguay River (Portuguese - Análise de Fragilidades Ambientais da Bacia Hidrográfica dos Rios Apuaê-Inhandava, situada na Região Hidrográfica do Rio Uruguai ) (UFSM/FEPAM, 2005), classified as Basin U010 in Rio Grande do Sul State. It was carried out a regular variation of the criteria values to set the new scenarios. After this value variation in the maps, it was used the statistical matrix coefficient V of Cramer, similarity indicator among the images. The values V of Cramer were tabulated as square matrix, calculating the matrix distances to do the Mantel Test which gives the correlation among the matrixes. From these coefficients became possible to carry out the sensibility analysis according to the comparison among the ponderate matrixes analysing similarity and correlation terms. The sensibility was done in two levels: basic (or in each block of thematic factors) and upper (or general among the big blocks). The more or less significant values were recognized in the scenographic composition of the multicriteria evaluation. Organizing the relative values as intervals the following phase consisted of optimizing them mathematically. The results were compared with the Saaty method and with the values from the original report. Having the set of values updated, the new and optimized scenario was processed with the purpose of discussing it or making it acceptable. The inclusion of the sensibility test in the multicriteria equation was important to compare the relevance among the maps of geoprocessing factors giving basis to take decisions.