GIS AND LINEAR REGRESSION FOR ENVIRONMENTAL ASSESSMENT OF THE RIVER “SUBAÉ” SOURCES IN “FEIRA DE SANTANA /BA” CITY - DOI 10.5216/bgg.v33i2.25557

Abstract

The lakes and the headwater of the “Subaé ” river basin are destined to several purposes, such as urban, agricultural and industrial, which may compromised the quality of these environments. To evaluate the quality of the Subaé River sources we choose to study through monitoring the physical, chemical and microbiologic parameters in fourteen water quality observation towers and through mapping the social and environmental aspects present in the surroundings. To reach this goal, along with the research, was also necessary the use of the spatial analysis techniques in GIS environment and Geostatistics (Linear Regression). The results of the water quality analysis, mainly DO, BOD and Turbidity (or cloudiness), were compared to the Resolution of CONAMA nº 357/05. They reflected the environmental status of some parts of the source that showed adverse parameters which are against Brazilian Legislation such as the DO and BOD case in parts of the ”Pedro Suzart”
source (domain of domestic effluents) and turbidity in parts of the ”Subaé” and “Salgada” lakes and to indentify the influence of one of the water quality parameter and the variability of social and environmental variables (correlations between the data of DO and the environmental variables) it was used the Linear Regression. This
analysis led us to the conclusion that the social and environmental variables, altimetry, slope of the terrain and population density are determinant factors of the DO rating in the environments in study.