Spatial variability of tidal flats in response to wave exposure: examples from Strangford Lough, Co. Down, Northern Ireland

Abstract

Abstract Strangford Lough is a shallow marine embayment, whose present form resulted from the late Glacial and Holocene marine erosion of a drumlinized coastal lowland platform. Constriction at the Lough mouth means that most waves are generated by wind blowing over restricted fetches. Tidal flats in the northern parts of Strangford Lough show variable morphology and sediment composition. Tidal flats on the up-wind margin are muddominated and located in an intact drowned drumlin landscape. Those on the downwind margins are sandy and exist in partly or wholly eroded former drumlin topography. Our preliminary results indicate strong control by wave exposure (mediated by fetch distance) over tidal flat sediments and morphology which has led to the formation of a series of spatially variable tidal flats within a single depositional basin. At the time scale of the Holocene, exposure to wave action appears to exert a major influence on tidal flat morphology in this sediment-limited setting though its long-term control of topographical change (seen here as variable extent of drumlin erosion) and the consequent and subsequent role of this topography in determining exposure to contemporary wave action.