Nebkha or not? -Climate control on foredune mode

Abstract

This study examines the mode of foredune development along ~3,500 km of the west African and the Canary Islands coasts. Foredune modes are classified into either continuous and discontinuous ridges or nebkha (discrete dune mounds). The drivers determining foredune mode including temperature, winds, and sediment supply are investigated and rainfall is the principal driver. Continuous foredunes are found in the region where rainfall is above ~480–500 mm mean annual rainfall. Between around 340 mm and 480 mm the rainfall is not sufficient to sustain laterally continuous pioneer plant communities and discontinuous foredunes predominate. Below ~300 mm rainfall, xerophilous and halophilous shrub plants predominate and only nebkha occur. Our findings support the contention that climate, and particularly rainfall, plays a very significant role in driving foredune mode, and hence coastal morphological evolution.