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Mapping land cover change and terrestrial dynamics over northern Canada using multi-temporal Landsat imagery. Christopher Butson† Robert Fraser‡ †Prologic Consulting, 75 Albert Street, Suite 206, Ottawa, Ontario, Canada. K1P 5E7
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†Prologic Consulting, 75 Albert Street, Suite 206, Ottawa, Ontario, Canada. K1P 5E7
‡Natural Resources Canada, Canada Centre for Remote Sensing, 588 Booth St. Ottawa, Ontario, Canada. K1A 0Y7
Northern areas are characterized by:
Intergovernmental Panel on Climate Change (IPCC) projects an increase in global mean surface temperature of 1º to 3.5º C by 2100 and an increase in sea level by 15-95cm.
Develop automated methods for detecting past and future land cover changes in the north and use this information to report on carbon fluxes for UNFCCC and track indicators of climate change in Canada.
Four pilot sites have been setup along the forest-tundra boundary (tree line) in northern Canada. Yukon-NWT, Manitoba, Ontario, Quebec.
Use various change methods to monitor; I) Natural disturbances (tundra fires, vegetation) and II) Human induced changes (mining and settlements).
The main objective of this research is to develop an automated change detection technique for use with Landsat imagery to quantify past and present land cover changes in northern areas. More specifically, we aim to:
Map of Canada highlighting the locations of the four pilot sites.
Study sites #1-4, represent the multi-temporal sites under investigation.
Sites #5-7 represent the overlap image pairs that the change methods were tested on.
Medians are outlier resistant measures of central tendency and the method uses the median of all pairwise slopes to calculate the slope of the regression line.
The median value of the sample offsets represents the intercept.Theil-Sen Regression Analysis (TSA)
By analyzing only the overlap portion between the two orbital paths, we assumed that the land surface (and thus land cover) does not change between acquisition datesResults – Objective #1
Comparison of techniques for
regenerating vegetation (medium probability):
Study site #2: Changes 1985-2001, Churchill, MN
a) 2001, RGB b) 1985, Prob-Change c) 1991, Prob-Change
CCA – Relies on the quality/accuracy of a land cover map to identify changes. May under estimate land cover changes.
TSA- Relies on the quality/accuracy of a land cover map to correctly classify changes. Although the commission errors were much lower in the overlap analysis, the change maps were still noisy. Computationally intensive.Conclusions
Develop interactive thresholding
Spatial aggregation of change pixels
Analyze seasonal change detection limitations
Apply change methods to northern mosaic of Canada
Assess land cover/land use changes for UNFCCC reporting in the northFuture work
Circa 2000 Landsat ETM+ 90m landcover
of northern Canada – Version I (preliminary)
Olthof, I., Butson, C., Fernandes, R., Fraser, R., Latifovic, R. and Orazietti, J. (2004). Landsat ETM+ mosaic of northern Canada.
Canadian Journal of Remote Sensing, submitted 06/04.