Abstract

The formation of fluvial dunes has been usually investigated assuming an infinite availability of the mobile sediment. Field observations and laboratory experiments nevertheless indicate that the volume of sediment available for transport affects their morphology. Here we undertake a stability analysis showing the formation of small amplitude sand dunes in steady currents accounting for the effects of sediment starvation on their formative mechanisms and compare it against laboratory experiments and an application of a fully numerical commercial model of finite amplitude dunes, thus enabling an improved understanding of the genesis of starved fluvial dunes. Both small and finite amplitude dunes are shown to be affected by sediment starvation. As their growth progressively exposes a motionless substratum, both models predict the lengthening of starved dunes with increasing irregularity in their spacing. These findings conform with the outcome of physical experiments performed in a laboratory flume and existing measurements of starved fluvial dunes in the field.