Modeling Fine Sediment Behavior in Gravel-Bed Rivers
Lamparter, Gabriele Johanna
Date: 11 July 2014
Publisher
University of Exeter
Degree Title
PhD in Geography
Abstract
Fine-grained sediment accumulation in the interstices of gravel beds is a key factor in
degrading riverine habitats. However, interstitial deposits are highly dynamic and are
not sufficiently understood. This work enhances the understanding of interstitial fine
sediment deposition by investigating interstitial storage and ingress, ...
Fine-grained sediment accumulation in the interstices of gravel beds is a key factor in
degrading riverine habitats. However, interstitial deposits are highly dynamic and are
not sufficiently understood. This work enhances the understanding of interstitial fine
sediment deposition by investigating interstitial storage and ingress, flow, suspended
sediment and gravel bed character. Furthermore, this work introduces a numerical
suspended sediment deposition model with the power to predict patterns of interstitial
ingress.
The investigation of interstitial deposition were carried out on two levels. Both
data orginating from flume experiments and from three locations of the River Culm,
Devon, UK was collected. The experimental data showed the significant influence
of small scale variations in flow and bed character and their influence on interstitial
ingress. The field investigation showed clear differences in interstitial fine-grained
sediment for the different river reaches and an overall higher interstitial ingress compared
to recent published data.
The numerical model development was realised in a two-step approach. First,
the model was coded and calibrated for the flume scale processes and, second,
an upscaled reach scale model was devolped for the field data. This reach scale
suspended sediment deposition model included flow information, for which depthaveraged
two dimensional hydrodynamic models were developed with the software
Delft3D. The overall explanatory power of the model at this state is not satisfactory
with regards to local deposition distribution. A separate chapter discusses the possible
causes and implications of this short coming for further research from a data
aquisition and modelling perspective.
Doctoral Theses
Doctoral College
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