Geographic Information System (GIS) applied to Environmental Assessment: Investigation of exploratory techniques in water nutrient data for environmental quality analysis

After the oil spill that occurred in January 2000 in Guanabara Bay, Rio de Janeiro, Brazil, Petrobras developed a research project for the environmental and socioeconomic characterization of Guanabara Bay. The objective of this work was to integrate data and increase the potential for knowledge and use of project information by seeking unconventional techniques in environmental studies. Physical-chemical and biological water parameter data collected every two weeks over a two-year period (2005 and 2007) at 10 sampling stations distributed throughout the bay were evaluated. An organization for the data in a spatial database model (geodatabase) was evaluated, and a spatio-temporal investigation was carried out using exploratory techniques and supervised (decision tree) and unsupervised (fuzzy) classification analyses, considering multivariate criteria. These understandings enabled the generation of a new zoning for the assessment of the bay's water quality. The potential contribution of geoprocessing tools as an interface for accessing the database and in the processes of analysis, integration, and spatial presentation of information was also explored.