Land use of Alto Piauí watershed through satellite CBERS images

Abstract

This paper aims to compare land use in two different periods for the Alto Piauí watershed. The land use was characterized for 2004 and 2005 in the rainy and dry period, respectively, using satellite images and the algorithm of maximum likelihood available as a routine in the software ENVI 4.3. The statistical treatment of maximum likelihood was applied to identify the following classes: forest, water, anthropical, agriculture, and cloud cover. The software ArcView was applied to quantify the areas of each class. It was found that in 2004 the percentage of land use was characterized as: water 5.1%, forest 55.1%, anthropical 10.8%, agriculture 10.8%, and cloud cover 18%. In 2005 the results were: forest water 2.1%, 59.5%, anthropical 18.1%, agriculture 18.9% and cloud cover 1.1%. All points identified in the fields matched the results produced by the algorithm of maximum likelihood. The first validation process was developed by 10 points colleted in field by a GPS equipment and assuring it in the classified image. It was also used Kaapa coefficient and the global precision for validation, which showed excellent values. Thefore, the information generated can be used as a tool to help in the management of natural resources of the watershed.