GIS and ordination techniques for evaluation of environmental impacts in informal settlements: A case study from Cuiabá, central Brazil

Abstract

This study evaluates the environmental impacts caused by informal occupation in the city of Cuiabá, Mato Grosso, Brazil. In 10 selected districts, an assessment of 35 environmental indicators was conducted, evaluating secondary data as well as field survey results, air photo interpretation and geographical information system (GIS) analysis. A matrix approach was then applied to quantify the magnitude and relevance of 13 types of impacts on the following environmental components: surface water, soil, flora/fauna, air, land use and life quality. Impacts were analyzed in the spatial context of four main classes of municipal zoning. Redundancy analysis (RDA), a multivariate ordination method, was applied to evaluate the dependency of impacts from environmental and socio-economical factors. Total impact scores were the highest in areas devoted to environmental preservation according to municipal zoning, indicating a limited ability of authorities to control informal occupation processes and their impacts on the environment. Indicator analysis showed strong impacts along the stream network in areas susceptible to episodic flooding. RDA indicates that age and district organization have a significantly important impact in the sampled districts; they were found to be as important in ordination as environmental factors such as geo-technical units.