Association of American Geographers
About AAG Membership Annual Meeting Projects & Programs Education Publications Calendar Of Events Jobs & Careers

GDEST 2008 Conference Sessions 

Theme 1 - Observing Africa
Disturbance, Management, and Landscape Dynamics: Harmonic Regression of Vegetation Indices in the Lower Okavango Delta, Botswana
Kelley A. Crews, University of Texas at Austin, USA

Focused on the Okavango Delta, Botswana, this research investigates (a) whether ecosystem signals derived from remotely sensed imagery can be decomposed using a harmonic regression, (b) if the deviations from the decomposed signal are correlated with observed flooding and fire regimes, and (c) the impact of explicitly including agriculture, settlement areas, and land management systems on the derived signals. A time-series of 85 TM/ETM scenes spanning the period from 1989 through 2002 was used to decompose derived landscape dynamics into trends, annual and seasonal cycles, and long term oscillations. The harmonic fit largely defined by climatic periodicities (semi-annual, annual, and quasidecadal) accounted for 63 percent to 88 percent of the variance in the trajectories. The trends were found to be robust whether or not urban settlement or landscape management regimes were explicitly included, though there was a reversal of trend in agricultural areas.