This paper presents results from a study designed to explore the effects of beach surface moisture and fetch effects on the threshold of movement, intensity of sand transport by wind and mass flux. The experiment was carried out over a period of five weeks at Greenwich Dunes, Prince Edward Island, Canada in May and June 2002. Moisture content was measured with a Delta‐T moisture probe over a 50 m by 25 m grid established on the beach. Measurements of wind speed and direction were made with arrays of cup anemometers and a two‐dimensional sonic anemometer. Transport intensity was measured at a height of 2–4 cm above the bed using omnidirectional saltation probes which count the impact of saltating grains on a piezoelectric crystal. Anemometers and saltation probes were sampled at 1 Hz. Sand transport was measured with vertical integrating sand traps over periods of 10–20 minutes. Results show that where there is a considerable supply of dry sand the saltation system responds very rapidly (1–2 s) to fluctuations in wind speed, i.e. to wind gusts. Where sand supply from the surface is limited by moisture, mean transport rates are much lower and this reflects in both a reduction in the instantaneous transport rate and in a transport system that becomes increasingly intermittent. Threshold wind speed is significantly correlated with an increase in surface moisture content near the upwind end of the beach fetch, but the relationship is not significant at the downwind end where sediment transport is initiated primarily by saltation impact from upwind. Mass flux increases with increasing fetch length and the relationship is described best by a power function. Further work is necessary to develop a theoretical function to predict the increase in transport with fetch distance as well as the critical fetch distance. Copyright © 2007 John Wiley & Sons, Ltd.

Landward migration of barriers occurs in response to a negative sediment budget and/or sea level rise. The ability of the foredune to migrate landward while maintaining its size is determined by the rate at which aeolian sediment transfers across the foredune take place. On the transgressive barrier spit Skallingen, sediment deposition on the crest and lee slope of the foredune was measured at two locations over the periods 1996–1999 and 2001–2002, respectively. Temporal and spatial variability of accretion rates occurred on different scales and annual accretion volumes up to 9 m³ per m beach width were obtained. In addition to the local sediment budget (i.e. beach width), the frequency and magnitude of storms and the pattern of wind speed and direction, the presence of a dune ramp is also important for the beach to dune sediment transfer. The study suggests that the critical ramp size for beach/dune sediment transfer corresponds to a ramp-to-crest distance of 1 m or a relative ramp height of 0.6. A conceptual model is presented which attempts to outline the controls on dune ramp development and the beach/dune sediment budget.