HR: 1340h
AN: B53A-0928    [Abstracts]
TI: Mapping Methane-Significant Dambo Wetlands in Central Uganda Using Remote Sensing and Topographic Data
AU: * Dennison, P E
EM: dennison@geog.utah.edu
AF: University of Utah, 260 S. Central Campus Dr. Room 260, Salt Lake City, UT 84112, United States
AU: Hansen, M K
EM: matt.hansen@geog.utah.edu
AF: University of Utah, 260 S. Central Campus Dr. Room 260, Salt Lake City, UT 84112, United States
AU: Graves, S A
EM: scott.graves@geog.utah.edu
AF: University of Utah, 260 S. Central Campus Dr. Room 260, Salt Lake City, UT 84112, United States
AU: Brown, D J
EM: david_brown@wsu.edu
AF: Washington State University, PO Box 646420, Pullman, WA 99164, United States
AU: Matthews, E
EM: ematthews@giss.nasa.gov
AF: NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United States
AB: Dambos are gently-sloping, seasonally-saturated valley floors that occupy up to 20 percent of the land surface of elevated plateaus in Eastern and Southern Africa. While they are likely candidates for contributing substantial methane fluxes to the atmosphere, their distribution and physical characteristics are poorly understood and there is almost no published data on their methane emissions. Dambo soil, vegetative, and hydrologic characteristics change along a gradual topographic gradient from occasionally-inundated margins to more frequently-inundated floors to perennially-inundated bottoms, and dambo methane production and emission likely varies along this gradient. We report on a study using multispectral remote sensing data and topographic attributes to map upland, margin, floor, and bottom classes of representative dambo wetlands in central Uganda. Two overlapping Systeme Pour l'Observation de la Terre (SPOT) 4 multispectral scenes, with an approximate spatial resolution of 20 meters and 2500 square kilometer extent, were acquired to coincide with the beginning and end of the January-to-March dry season in Central Uganda. Spectral indices and spectral mixture modeling fractions were calculated for both SPOT scenes. Vegetation phenological changes occurring in each dambo class were quantified by comparing remote sensing metrics in each SPOT scene. These metrics were combined with topographic data from the Shuttle Radar Topography Mission (SRTM) to classify the study area into upland, margin, floor, and bottom classes. Field data were used for training the classifier and assessing the accuracy of the final wetland classification. This map of methane-significant dambo wetlands is being employed to design the first systematic, regional scale field measurements of dambo methane emissions and will be used to model dynamic methane emissions in the study area.
UR: http://www.geog.utah.edu/~pdennison/dambos.html
DE: 0480 Remote sensing
DE: 0483 Riparian systems (0744, 1856)
DE: 0486 Soils/pedology (1865)
DE: 0497 Wetlands (1890)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting