INVESTIGATIONS OF COMBINED WAVE/TIDE SEDIMENT DEPTH OF DISTURBANCE IN A SANDY TIDAL FLAT: STRANGFORD LOUGH, NORTHERN IRELAND

Studies of sedimentation tidal-flats have long acknowledged that tidal flows and waves are the most influential hydrodynamic forcing factors operating on surficial sediments. Tidal flows influence the long-term evolution of tidal-flats because of the asymmetry of tidal regimes (flood and ebb). Tidal current activity is mainly confined to channels. Outside the channels, mainly on the upper tidal-flats, tidal current velocities decrease and sediment entrainment is frequently ascribed to wave action. The role of wave-induced processes on intertidal-flat sediments is frequently stated but has seldom been investigated, apparently because of methodological constraints.

In this paper we describe the results of a series of experiment aimed at identifying the role of wave action for depth of disturbance (i) on various locations on a tidal flat, (ii) different wind/wave energy settings. this is achieved by empirical measurements of wave and tidal currents and numerical modelling of wave propagation.

Results document the short term evolution of tidal flats and could be used to better understand the complex relationships between ecological and geomorphologica evolution of these environments and the rated of depth of disturbance that can be associated with individual and/or combined hydrodynamic forcing factors.