Mapping unofficial roads with Landsat images: a new tool to improve the monitoring of the Brazilian Amazon rainforest

Landsat images were used to identify, map and quantify roads in the Amazon region. The mapping was carried out in the Central-West region of the State of Para, between 1985 and 2001. A total of 25 196 km of roads were mapped, including 20 769 km of unofficial roads-roads built without governmental incentives. The average growth rate for unofficial roads almost doubled in 10 years, going from 9.85 km/10000 km(2) per year, between 1990 and 1995, to 19.25 km/10000 km(2) per year between 1996 and 2001. Growth rate was most significant in the regions of Sao Felix do Xingu, Santarem and Novo Progresso with average rates higher than 40 km/10000 km(2) per year between 1996 and 2001. The methodology proposed can improve monitoring in the Brazilian Amazon, by prioritising areas for law enforcement, and land titling and identifying priority regions for creating protected areas.