Spatial Analysis of the Geoecological Adequability Index in Semi-Arid Watersheds, Northeast of Brazil

stract This research aimed to perform a comparative analysis of Geoecological Adequability (GA) in two semi-arid watersheds in Northeastern Brazil based on a classification carried out in a GIS (Geographic Information System) environment using the algebra map tool. The GA calculation reveals the interactions between landscape components through GIS, namely soil, slope, vegetation and land cover. Weights were assigned (1, 2 or 3) to the different cartographic layers of the geoecological components measured using the algebra map tool, through the arithmetic means, to classify the semiarid basins into different adequability levels, as follows: adequate, partially adequate and inadequate to anthropic uses. These procedures verified the predominance of the “adequate” class with a territorial area above 42% in both investigated basins; the “partially adequate” level and the second most comprehensive class comprised values between 30% and 40%; and, while smaller territorial extensions, below 20%, were “inadequate”. Based on these findings, it was possible to measure the most suitable areas for anthropic use in the studied basins and indicate the areas that should be conserved, with emphasis on protection and/or regeneration of the natural vegetation cover. This is important information concerning the planning and environmental management of these semi-arid landscapes in an objective and efficient way