Modelling the effect of time‐dependent river dune evolution on bed roughness and stage

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.

[1]  D. Knighton.  Fluvial forms and processes , 1984 .

[2]  J. Allen.  Computational models for dune time-lag: General ideas, difficulties, and early results , 1976 .

[3]  Suzanne J.M.H. Hulscher,et al.  Understanding coastal morphodynamics using stability methods , 2003 .

[4]  Muthiah Perumal,et al.  Reproduction of Hysteresis in Rating Curves , 2004 .

[5]  J. Best,et al.  Response of sand dunes to variations in tidal flow: Fraser Estuary, Canada , 2005 .

[6]  J. Best.  The fluid dynamics of river dunes: A review and some future research directions , 2005 .

[7]  Jean-Philippe Vidal,et al.  River model calibration, from guidelines to operational support tools , 2007, Environ. Model. Softw..

[8]  Jord Jurriaan Warmink,et al.  Uncertainty in water level predictions due to various calibrations , 2007 .

[9]  M. Selim Yalin,et al.  Mechanics of sediment transport , 1972 .

[10]  S. Hulscher,et al.  Simulating offshore sand waves , 2006 .

[11]  M. Church,et al.  Bar and dune development during a freshet: Fraser River Estuary, British Columbia, Canada , 2005 .

[12]  Huib J. de Vriend,et al.  Stochastic Modelling of the Impact of Flood Protection Measures Along the River Waal in the Netherlands , 2005 .

[13]  G. P. Williams.  Flume width and water depth effects in sediment-transport experiments , 1970 .

[14]  A. Paarlberg.  Modelling dune evolution and dynamic roughness in rivers , 2008 .

[15]  M. Kleinhans,et al.  Opposite hysteresis of sand and gravel transport upstream and downstream of a bifurcation during a flood in the River Rhine, the Netherlands , 2007, Netherlands Journal of Geosciences.

[16]  P. Y. Julien,et al.  Case Study: Bed Resistance of Rhine River during 1998 Flood , 2002 .

[17]  L. Hwang,et al.  Closure of "Relation Between Bed Forms and Friction in Streams" , 1968 .

[18]  Ray Kostaschuk,et al.  A field study of turbulence and sediment dynamics over subaqueous dunes with flow separation , 2000 .

[19]  M. Werner.  Spatial flood extent modelling. A performance based comparison , 2004 .

[20]  Pierre Y. Julien,et al.  SAND-DUNE GEOMETRY OF LARGE RIVERS DURING FLOODS. DISCUSSION AND CLOSURE , 1995 .

[21]  Sean J. Bennett,et al.  Mean flow and turbulence structure over fixed, two-dimensional dunes: implications for sediment transport and bedform stability , 1995 .

[22]  M. J. Crickmore,et al.  Effect of Flume Width on Bed-Form Characteristics , 1970 .

[23]  A. Robert,et al.  Flow and turbulence structure across the ripple–dune transition: an experiment under mobile bed conditions , 2005 .

[24]  M. Kleinhans.  Sorting in grain flows at the lee side of dunes , 2004 .

[25]  M. D. Vries,et al.  Principles of river engineering: The non-tidal alluvial river , 1979 .

[26]  W. ten Brinke,et al.  The response of subaqueous dunes to floods in sand and gravel bed reaches of the Dutch Rhine , 2003 .

[27]  Flood management research needs , 2006 .

[28]  S. Wartel,et al.  Factors influencing subaqueous dunes in the Scheldt Estuary , 2004 .

[29]  J. Ribberink,et al.  Vertical sorting in bed forms: Flume experiments with a natural and a trimodal sediment mixture , 2003 .

[30]  J. R. Allen,et al.  Current Ripples : their relation to patterns of water and sediment motion , 1968 .

[31]  S. Coleman,et al.  Sediment-Wave Development in Subcritical Water Flow , 2005 .

[32]  L. Rijn.  Principles of sediment transport in rivers, estuaries and coastal seas , 1993 .

[33]  S. Hulscher,et al.  Modeling river dune evolution using a parameterization of flow separation , 2009 .

[34]  Suzanne J.M.H. Hulscher,et al.  A parameterization of flow separation over subaqueous dunes , 2007 .

[35]  A. Casas,et al.  The topographic data source of digital terrain models as a key element in the accuracy of hydraulic flood modelling , 2006 .

[36]  A. M. Wasantha Lal,et al.  Calibration of Riverbed Roughness , 1995 .

[37]  H. Ivan Schwartz,et al.  Projected Nappes Subject to Transverse Pressure , 1963 .

[38]  Van Rijn,et al.  Closure of "Sediment Transport, Part III: Bed Forms and Alluvial Roughness" , 1984 .

[39]  Yalin M. Selim.  Geometrical properties of sand waves , 1964 .

[40]  J. Best,et al.  Mean flow, turbulence structure, and bed form superimposition across the ripple‐dune transition , 2006 .

[41]  S. Mclean,et al.  Spatially averaged flow over a wavy boundary revisited , 1999 .

[42]  Orr,et al.  The morphodynamics of fluvial sand dunes in the River Rhine, near Mainz, Germany. I. Sedimentology and morphology , 2000 .

[43]  D. Mohrig,et al.  A unified model for subaqueous bed form dynamics , 2005 .

[44]  M. Yalin.  Geometrical Properties of Sand Wave , 1964 .

[45]  Fazle Karim,et al.  Bed Configuration and Hydraulic Resistance in Alluvial-Channel Flows , 1995 .

[46]  S. Hulscher,et al.  Variability in bedform characteristics using flume and river data , 2007 .

[47]  Donald W. Knight,et al.  The concept of roughness in fluvial hydraulics and its formulation in 1D, 2D and 3D numerical simulation models , 2008 .