Characterization of intertidal flat hydrodynamics
Le Hir, P.; Roberts, W.; Cazaillet, O.; Christie, M.C.; Bassoullet, P.; Bacher, C. (2000). Characterization of intertidal flat hydrodynamics. Cont. Shelf Res. 20(12-13): 1433-1459 In: Continental Shelf Research. Pergamon Press: Oxford; New York. ISSN 0278-4343; e-ISSN 1873-6955, more |   |
| Keywords | Analysis > Wave analysis > Tidal analysis
Disciplines > Physics > Mechanics > Dynamics > Hydrodynamics
Earth sciences > Geology > Geomorphology
Energy transfer > Energy dissipation
Forces (mechanics) > Stress (mechanics) > Bottom stress
Geomorphology
Physics > Mechanics > Fluid mechanics > Hydrodynamics
Resource management > Water management > Drainage
Sedimentary structures > Mud flats
Topographic features > Landforms > Coastal landforms > Tidal flats
Water waves
Waves on beaches
Marine/Coastal |
| Authors | | Top | - Le Hir, P., more
- Roberts, W.
- Cazaillet, O., more
| - Christie, M.C.
- Bassoullet, P.
- Bacher, C.
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| Abstract | The paper reviews the different physical forcings that control tidal flat hydrodynamics. Tidal propagation and cross-shore or long-shore currents, tidal asymmetry, wind-induced circulation, wave propagation and drainage processes are successively considered. Some simple methods are described for estimating cross-shore currents and wave-induced bottom shear stresses, and the results obtained are compared to field measurements on three contrasted sites in Europe. In particular the cross-shore current is shown uniform in the lower part of the flat, and decreasing towards the shore. Bottom friction-induced wave attenuation is simply formulated on gently sloping beds, leading to a maximum wave height that a flat can experience; it is proportional to the water height according to the ratio between the slope and the wave friction factor. The maximum related shear stress occurs at high water and is also proportional to the water depth. Maximum tidal velocities are very similar in the three sites where bottom sediment is muddy, suggesting a relationship between physical stresses and sediment characteristics. The consequences of physical forcings on sediment transport are listed. The bottom shear stress is suggested as the relevant parameter for comparing tidal and wave effects. In general, tide induces onshore sediment transport, whereas waves and drainage favour offshore transport. The processes leading to a possible tidal equilibrium profile are analysed: they involve the intrinsic asymmetry that favours net deposition at high water, and an ebb dominance generated by the resulting bottom profile convexity. Eroding waves are likely to upset such a balance; this equilibrium then reduces to a trend for the system. |
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