Rapid assessment of deforestation in Mato Grosso State using MODIS and ETM+ data
Liana
Oighenstein
Anderson, INPE, liana@ltid.inpe.br
(Presenting)
Yosio
Edemir
Shimabukuro, INPE, yosio@ltid.inpe.br
Douglas
Morton, University of Maryland, morton@geog.umd.edu
Ruth
DeFries, University of Maryland, rdefries@geog.umd.edu
Marcelo
Lopes
Latorre, INPE, latav@ltid.inpe.br
Ellen
Jasinski, University of Maryland, ejasinsk@pop900.gsfc.nasa.gov
Matthew
Hansen, University of Maryland, mhansen@glue.umd.edu
André
Lima, INPE, andre@ltid.inpe.br
This work reports the findings of a rapid assessment of deforestation in the Amazon using multitemporal fraction images derived from MODIS 250 m daily surface reflectance and ETM+ data. ETM+ scenes acquired for the same days as MODIS imagery were used as ground truth for training and validation phases. A linear mixing model was applied to 8 sequential ETM+ scenes (path/row 227/68), collected during the dry season of 2002, and to the corresponding MODIS data. Fraction images for soil, shade, and vegetation were derived from the linear spectral mixing model, and the soil fraction images were used to identify new deforestation during each 16-day period. This methodology builds on the experience from PRODES Digital that applies image segmentation to the fraction images derived from Landsat TM to identify deforestation using a non-supervised classification per region algorithm. Overall, our deforestation detection results from the multitemporal analysis of MODIS and ETM+ images showed good agreement. Detection accuracy was evaluated separately for new deforestation by size classes. Due to the size and pattern of the deforestation, the MODIS data under or overestimated the total deforestation area for small clearings. As the deforested area increases, the MODIS results match the ETM+ results more closely. We present an accurate methodology for detecting deforestation activities in near real time using Terra MODIS daily data. This approach can be used to provide more frequent data for enforcement of forest protection laws.
Submetido por Liana Anderson em 16-MAR-2004
Tema Científico do LBA: LC (Mudanças dos Usos da Terra e da Vegetação)