HYDRODYNAMICS AND SEDIMENTOLOGY OF A HIGH (TIDAL AND WAVE) ENERGY EMBAYMENT (SWANSEA BAY, NORTHERN BRISTOL CHANNEL)

Swansea Bay may be taken as an example of an embayment which has a complex and variable hydrodynamic regime resulting from the interaction of its bathymetry and configuration with an adjacent rectilinear, semidiurnal tidal system and with superimposed oceanic swell and more locally generated seas. Eulerian tidal current observations in Swansea Bay indicated a coastal tidal current pattern which has developed from the main currents along the northern Bristol Channel. The observed pattern consists of an anticlockwise eddy in the western part of the embayment and a zone of divergence on the eastern side, between the eddy and the main offshore flow. Wave data, as represented by refraction diagrams and the distribution of sea bed orbital velocities, have demonstrated that high energy wave conditions prevail over the area. Sediment distribution and transport in Swansea Bay are controlled by tidally and wave-induced current patterns, but are also related to bathymetry and the exposure of relict deposits. However, evidence is presented to suggest that local dredging activities influence the sedimentation processes. © 1979.