A reassessment of sand transport paths in the Bristol Channel and their regional significance

Abstract

Data on bedform morphology, sediment parameters, heavy mineral abundance, current measurements, sand transport rates, numerical models of shear stress, sea bed drifters and wave activity are all considered. It is concluded that the dominant transport of sand and gravel is westwards from the transverse Bristol Channel Bed-Load Parting. The notion of easterly transport of sand (apart from wave-induced transport on the beach and in the nearshore zone) by the flood tidal current in continuous zones along the northern and southern margins of the Bristol Channel is largely discounted. However, there are some small disconnected areas, where easterly transport of sand is locally induced by coastal irregularities, by sand bank relief and by a local deep. The ground for up to 2 km north of Scarweather Sands provides a rare example of the net sand transport direction being determined by the weaker but substantially longer flowing (flood) tidal current. A facies model of the deposits is outlined.