Alderney Race, general hydrodynamic and particular features
Abstract
This work presents an overview of the main hydrodynamic features of the Alderney Race issued from in-situ measurements and hydrodynamic model simulations. This area encompasses a large range of tidal properties (tidal amplitude, tidal wave propagation) and particularly strong currents exceeding 5 m.s-1 with associated counter currents and gyres. Variations of depth, sea bottom roughness, coastal topography and current orientation around the La Hague Cape give access to a large variety of original hydrodynamic phenomena. Some are pointed out as places with a 0.3 m lower mean sea level associated to nearly constant average tidal currents. A resonance effect linked with the strong offshore currents is also observed close to the coasts. The "St Martin whistle" occurs in a bay whose gyre center oscillates with a reversal of the measured current every 5 – 7 minutes. The Alderney Race represents a workshop area for coastal hydrodynamic studies. The available in-situ measurement datasets are rich with recordings of: sea levels; ADCP current profiles; surface radar currents; waves; dye experiments; surface and in depth dissolved tracer surveys. Associated with 3D hydrodynamic models it allow understanding the complexity of this area and refine the knowledge of hydrodynamic process and forcing parameters that could be applied in other coastal areas
Origin : Publication funded by an institution
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