Vermeesch, Pieter and Drake, N. (2008) Remotely sensed dune celerity and sand flux measurements of the world's fastest barchans (Bodele, Chad). Geophysical Research Letters 35 (L24404), ISSN 0094-8276.
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Quantifying sand flux with field measurements is an expensive and time-consuming process. We here present an alternative approach using the COSI-Corr software package for Earth surface deformation detection. Using pairs of ASTER satellite images, we detected dune migration in the Bodélé depression of northern Chad over time intervals of one month to 6.5 years. The displacement map can be used to automatically distinguish dunes from interdunes, which is a crucial step towards calculating sand flux. We interpolated a surface between the interdune areas and subtracted it from a digital elevation model, thus obtaining dune heights and volumes. Multiplying height with celerity yields a pixel-by-pixel estimate of the sand flux. We applied this method to large diatomite dunes in the Bodélé, confirming that these are some of the world's fastest moving barchans. Plotting dune height against inverse celerity reveals sand flux at the dune crest of >200 m3/m/yr. Average dune sand flux values for the eastern and western Bodélé are 76 and 99 m3/m/yr, respectively. The contribution of the dunes to the total area-averaged sand flux is 24–29 m3/m/yr, which is ∼10% of the saltation flux determined by previously published field measurements.
|School or Research Centre:||Birkbeck Schools and Research Centres > School of Science > Earth and Planetary Sciences|
|Date Deposited:||07 Feb 2011 15:48|
|Last Modified:||11 Oct 2016 12:01|
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