dunes across the southern terraces of the river. In
1969, Besler started a survey on an extending tip of
a small, simple linear dune close to Gobabeb,
which is now known as ‘Helga’s Dune’ (Fig. 2).
She reported (Besler 1975) that extension of this
dune was roughly 2–3 m yr−1. Subsequent, intermittent
surveys up to 2012 have confirmed this
extension rate (Besler et al. 2013, this issue).