Abstract
Abstract. Several studies have demonstrated the importance of
alluvial cover; furthermore, several mathematical models have also been
introduced to predict the alluvial cover on bedrock channels. Here, we
provide an extensive review of research exploring the relationship between
alluvial cover, sediment supply and bed topography of bedrock channels,
describing various mathematical models used to analyse the deposition of
alluvium. To test one-dimensional theoretical models, we performed a series
of laboratory-scale experiments with varying bed roughness under simple
conditions without bar formation. Our experiments show that alluvial cover
is not merely governed by increasing sediment supply and that bed roughness
is an important controlling factor of alluvial cover. A comparison between
the experimental results and the five theoretical models shows that (1) two
simple models that calculate alluvial cover as a linear or exponential
function of the ratio of the sediment supplied to the capacity of the channel produce good results
for rough bedrock beds but not for smoother bedrock beds; (2) two roughness
models which include changes in roughness with alluviation and a model
including the probability of sediment accumulation can accurately predict
alluvial cover in both rough and smooth beds; and (3), however, except for a
model using the observed hydraulic roughness, it is necessary to adjust
model parameters even in a straight channel without bars.
Subject
Earth-Surface Processes,Geophysics
Cited by
9 articles.
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