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Years
Figure 5. Evolution of degraded areas from 1987 to 1999. If a regrowth rate similar to the 1996-1999 period remains
stable over time, degraded areas would be entirely recovered only in the year of 2037. However, recovering process will
probably take much more time, because regeneration is faster in the borders of the gold mined areas, where degradation is
less intense.
5. CONCLUSIONS
The results show that Landsat-TM images can be used to produce detailed maps of degraded areas associated with the
activities of independent miners in the Amazon region. Temporal maps obtained from the time-series images constitute
a reliable basis for monitoring evolution of degraded area over time. Additionally, the adopted image processing
procedures permitted to save time and to curtail inherent subjectivity involved in the visual interpretation, producing
accurate land use maps.
ACKNOWLEDGEMENTS
This work was supported by the National Institute for Space Research-INPE. The authors also thank the Fundacäo de
Amparo à Pesquisa do Estado de Sáo Paulo-FAPESP, for providing funds for the presentation of this paper in the XIX
ISPRS Congress.
REFERENCES
Almeida-Filho, R.; Vitorello, I.; Bins, L. S. 1997. Application of image merging and region-classification techniques as
a new approach for the detailed thematic mapping of soil-vegetation assemblages. Rev. Bras. Geociéncias 1977-27, pp.
207-210.
Almeida-Filho, R., Shimabukuro, Y. E. 1999. Detecting areas disturbed by gold mining activities through JERS-1/SAR
imageries, Roraima State, Brazilian Amazon. International Journal of Remote Sensing (Submitted)
Borges, R. F.; D'Antona, R. J. G., 1988. Geologia e mineralizaçôes da Serra Tepequém. Proceedings of the 35°
Congresso Brasileiro de Geologia, pp. 155-161.
Cämara Neto, G.; Souza, R. C. M.; Freitas, U. M. & Garrido, J. 1996. Spring: integrating remote sensing and GIS by
object-oriented data modeling. Computer & Graphics 1996-20: 395-403.
Melo, E. C.; Almeida-Filho, R., 1996. Mapeamento de áreas degradadas pela atividade de garimpos na regiäo da Serra
Tepequém (RR), através de imagens Landsat TM. Congresso Brasileiro de Sensoriamento Remoto, in CDROM.
Oliveira, Z. S., 1995. Garimpeiros e garimpos no estado de Roraima: impactos sócio-ambientais. Dissertaçäo de
Mestrado, Universidade Federal de Pernambuco.
70 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000.
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