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Modelling the effect of time‐dependent river dune evolution on bed roughness and stage
Author(s) -
Paarlberg Andries J.,
DohmenJanssen C. Marjolein,
Hulscher Suzanne J. M. H.,
Termes Paul,
Schielen Ralph
Publication year - 2010
Publication title -
earth surface processes and landforms
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.294
H-Index - 127
eISSN - 1096-9837
pISSN - 0197-9337
DOI - 10.1002/esp.2074
Subject(s) - hydraulic roughness , surface finish , stage (stratigraphy) , flood myth , geology , roughness length , flow (mathematics) , hydrology (agriculture) , geotechnical engineering , mechanics , geomorphology , soil science , materials science , physics , geography , paleontology , wind speed , oceanography , wind profile power law , composite material , archaeology
This paper presents an approach to incorporate time‐dependent dune evolution in the determination of bed roughness coefficients applied in hydraulic models. Dune roughness is calculated by using the process‐based dune evolution model of Paarlberg et al . (2009) and the empirical dune roughness predictor of Van Rijn (1984). The approach is illustrated by applying it to a river of simple geometry in the 1‐D hydraulic model SOBEK for two different flood wave shapes. Calculated dune heights clearly show a dependency on rate of change in discharge with time: dunes grow to larger heights for a flood wave with a smaller rate of change. Bed roughness coefficients computed using the new approach can be up to 10% higher than roughness coefficients based on calibration, with the largest differences at low flows. As a result of this larger bed roughness, computed water depths can be up to 15% larger at low flow. The new approach helps to reduce uncertainties in bed roughness coefficients of flow models, especially for river systems with strong variations in discharge with time. Copyright © 2010 John Wiley & Sons, Ltd.