Introducing the Okavango Delta, Botswana, airborne TEM survey

The Okavango Delta, Botswana, is one of the largest inland deltas on the planet and is unique in that surface water remains remarkably fresh despite evapotranspiration being the dominant water removal mechanism. To help understand the phenomena of salt sequestration, airborne transient electromagnetic TEM data with 2 km line spacing were acquired over the entire delta in 2007-2008. These data have been inverted using a quasi-2D least-squares linear optimization scheme to produce a 5-layer resistivity model to 250 m depth. Comparison of the model with available borehole data shows a strong correlation between resistivity and lithology and salinity. Further analysis should contribute significantly to understanding the hydrogeology of the delta.