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.