The relationship between barchan size and barchan morphology: a case study from Northern Namibia

ABSTRACT Landform allometry has been a topic of inquiry since at least the 1970s. In this study, the presence of allometry is investigated for a barchan dunefield in northern Namibia. Using a combination of traditional morphometric parameters and techniques borrowed from geometric morphometrics it is shown that barchan allometry is present. This allometry is a combination of positive and negative allometry. Barchans show a definite change in mean shape as the size of the dune increases becoming more asymmetric. Differences in horn length, along with dune width, show positive allometry indicating that it changes faster than the shape changes. Barchan bilateral asymmetry and stoss length show negative allometry indicating that changes in these variables lag behind changes in size. Together, these results hint at the possible presence of threshold size differences beyond which distinct shape changes can be observed.