RATES AND PATTERNS OF MIGRATION OF SHOREFACE-CONNECTED SANDY RIDGES ALONG THE SOUTHERN NORTH-SEA COAST

Geological studies of shoreface ridges along the southern North Sea co ast are still at a rudimentary stage but are being intensified. This i s largely because of the growing awareness of the potential impact of the dynamics of the ridges on nearshore projects. This preliminary rep ort mainly focuses on the rates and patterns of migration of these rid ges. It is observed that (1) headward (coastwise) ridge trough elongat ion occurs at a rate ranging from 30-500 m/y; (2) in addition to the l atter pattern, ridges may migrate either diabathically, or exclusively shoreward or seaward at a maximum rate of 100-200 m/y, with the shore ward component being more significant; (3) no definite time-progressiv e variation in cross-shore migration pattern is evident; (4) compared with the deeper water ridges, those proximal to the coastline more fre quently migrate seaward, which is suggestive of a response to the stro nger impact of the recurring ebb storm-surge how; and (5) on the whole , no significant coastwise differences in cross-shore rates of ridge t ranslation were evident. The above-documented ridge migration rates re present the highest recorded anywhere in the world to date. Detailed h ow measurements, made exclusively during fairweather conditions over t he ridge morphology, lead to the conclusion that ridge migration is la rgely storm induced. Future studies in the region should aim at charac terizing the storm flow-field.