HR: 1340h
AN: H53D-0512    [Abstracts]
TI: Laboratory Observations on the Morphodynamics of Tidal Meandering Channels
AU: * Garotta, V
EM: valeg@diam.unige.it
AF: Department of Environmental Engineering, Via Montallegro 1, Genoa, 16145 Italy
AU: Seminara, G
EM: sem@diam.unige.it
AF: Department of Environmental Engineering, Via Montallegro 1, Genoa, 16145 Italy
AB: Although tidal channels typically exhibit a meandering pattern, their morphodynamics still awaits to be fully explored. Theoretical findings (Solari et al., 2002) suggest that in a sequence of 'sine generated' tidal meanders, oscillations associated with the basic flow give rise to symmetric oscillations of the bar-pool pattern around the locations of maximum curvature with no net migration in a tidal cycle. The above authors also analyzed the bottom evolution showing that it reaches eventually a state of morphodynamic equilibrium. In order to shed further light on the process, a physical model has been constructed, consisting of a sequence of five sine generated meanders with constant width of 0.4 m. The channel is 21.3 m long, it is closed at one end and connected at the other with a basin, representing the sea, where a tidal wave is generated. The channel width was chosen, on the basis of previous experimental observations referring to straight channels (Tambroni et al., 2005), such to allow for the formation of free bars. In order to reproduce the high suspended load fluxes typical of tidal environments, the bed of the channel and of the basin has been covered with a 20 cm thick layer of polycarbonate grains, with relative density of 1.3 and mean diameter 0.2 mm. We analyze the coexistence of free bars with point bars forced by channel curvature, as well as their interactions with small scale forms and with the evolving average bed profile leading to the eventual formation of a shore.
DE: 4203 Analytical modeling and laboratory experiments
DE: 4217 Coastal processes
DE: 4558 Sediment transport (1862)
DE: 4560 Surface waves and tides (1222)
SC: Hydrology [H]
MN: Fall Meeting 2005