Abstract
Recently, Seybold et al. (2007) proposed a reduced complexity model
which simulates the process of delta formation on geological time
scales. It includes subaerial and subaqueous growth in a
three-dimensional framework. In this paper we apply this model to the
formation of a river-dominated delta and compare the model dynamics with
observations of the formation of the Balize Lobe of the Mississippi
River Delta. The model generates both subaerial and subaqueous channels
and lateral levee formations as well as a profile morphology with steep
drop-offs and a flat delta surface which is similar to natural ones. We
show that the dimensionless parameters of the model may be consistently
rescaled to match the Balize Lobe. This means that after rescaling the
water flows, the subaerial geometry and time, the deposited (subaqueous)
lobe volume, the sediment and water flows, the age, as well as the
sediment capture ratio match the observed data. Finally, we use
detrended fluctuation analysis to show that the modeled long-term
dynamics of the delta formation process shows a complex temporal
correlation structure. A characteristic time scale separates periods of
consistent delta growth by gradual sediment deposition at the mouths of
distributary channels from periods during which random large-scale
channel avulsions lead to rapid change and the formation of new channels
and subaqueous-dominated deposition.
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