Hydraulic model calibration for extreme floods in bedrock-confined channels: case study from Northern Thailand
Kidson, R., Richards, K.S. and Carling, P.A. (2006) Hydraulic model calibration for extreme floods in bedrock-confined channels: case study from Northern Thailand. Hydrological Processes, 20, (2), 329-344. (doi:10.1002/hyp.6086).
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The majority of the huge annual sediment load of the Yellow River in China is transported by a few hyperconcentrated sedimentladen
floods. Being hyperconcentrated, these floods are still so ‘‘starved’’ as to entrain enormous volumes of sediment from the bed,
triggering quick and extensive bed-tearing scour. In the recession period of the floods, river blockage might occur as characterized by
an abrupt halt of the flow. The physics of these fluvial processes has remained unclear for several decades. Previous hydrodynamic
models were built upon simplified conservation laws and are applicable only for processes with weak sediment transport. A complete
shallow water hydrodynamic model is deployed here to reveal new insights into the phenomena. A self-amplifying mechanism of the
interaction between the flow and bed scour is identified, which explains how bed-tearing scour occurs. River blockage is ascribable
to the longitudinally positive pressure gradient due to a non-uniform distribution of sediment concentration. The spatial and temporal
development of the system of flow, sediment transport and morphology is far more complicated than represented by previous
models that have evolved from fixed-bed, single-phase hydrodynamics or involved a capacity description of sediment transport. The
present approach may facilitate a better understanding of active sediment transport by flash floods in ephemeral desert rivers and by
subaqueous turbidity currents.
|Keywords:||sediment transport, sediment-laden flow, erosion and sedimentation, floods, unsteady flow, hyperconcentrated flow, alluvial rivers, The Yellow River, fluvial morphology, shallow water hydrodynamics|
|Subjects:||G Geography. Anthropology. Recreation > G Geography (General)
G Geography. Anthropology. Recreation > GE Environmental Sciences
G Geography. Anthropology. Recreation > GB Physical geography
|Divisions:||University Structure - Pre August 2011 > School of Geography > Environmental Processes and Change
|Date Deposited:||11 Aug 2008|
|Last Modified:||06 Aug 2015 02:47|
|RDF:||RDF+N-Triples, RDF+N3, RDF+XML, Browse.|
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