TY - JOUR
T1 - The role of suspended load transport in the occurrence of tidal sand waves
AU - Borsje, B.W.
AU - Kranenburg, W.M.
AU - Roos, P.C.
AU - Matthieu, J.
AU - Hulscher, S.J.M.H.
PY - 2014
Y1 - 2014
N2 - Tidal sand waves are dynamic bed patterns which are formed by the complex interaction between hydrodynamics, sediment transport, and geomorphology. Field data from the southern North Sea reveal that sand waves are absent where suspended load transport is the dominant transport mode. In order to understand the mechanisms responsible for the absence of sand waves, we study the influence of suspended load transport on the formation of tidal sand waves with a numerical process-based geomorphological model (Delft3D). Model simulations are presented in which the vertical eddy viscosity and sediment diffusivity are both spatially and temporally variable (k-ε turbulence model). First, it is shown that the preferred wavelength of sand waves for a relatively large grain size increases by the inclusion of suspended sediment, while for a relatively small grain size the flat bed is stable and no sand waves evolve. Second, it is shown that suspended load transport causes the suppression of long sand waves, resulting in a finite range of wavelengths that experience growth. Finally, by varying flow velocity amplitude and grain size, critical conditions for sand wave formation are found, i.e., conditions for which sand waves are marginally generated.
AB - Tidal sand waves are dynamic bed patterns which are formed by the complex interaction between hydrodynamics, sediment transport, and geomorphology. Field data from the southern North Sea reveal that sand waves are absent where suspended load transport is the dominant transport mode. In order to understand the mechanisms responsible for the absence of sand waves, we study the influence of suspended load transport on the formation of tidal sand waves with a numerical process-based geomorphological model (Delft3D). Model simulations are presented in which the vertical eddy viscosity and sediment diffusivity are both spatially and temporally variable (k-ε turbulence model). First, it is shown that the preferred wavelength of sand waves for a relatively large grain size increases by the inclusion of suspended sediment, while for a relatively small grain size the flat bed is stable and no sand waves evolve. Second, it is shown that suspended load transport causes the suppression of long sand waves, resulting in a finite range of wavelengths that experience growth. Finally, by varying flow velocity amplitude and grain size, critical conditions for sand wave formation are found, i.e., conditions for which sand waves are marginally generated.
KW - IR-91834
KW - METIS-289151
U2 - 10.1002/2013JF002828
DO - 10.1002/2013JF002828
M3 - Article
VL - 119
SP - 701
EP - 716
JO - Journal of geophysical research. Earth surface
JF - Journal of geophysical research. Earth surface
SN - 2169-9003
IS - 4
ER -