Map courtesy of
The map, left,
illustrates the movement of beach material (sand and gravels)
along our shoreline, driven by wave energy and direction. This
process is known as sediment transport, or longshore drift.
Sediment moves from
west to east along most of the Dorset coast, but prolonged periods
of east or southeast winds can reverse this trend.
longshore movement, sediment can be contained on a beach to provide
not only an improved recreational facility, but an effective natural
coastal defence. Groynes are the most commonly used method,
but interruption of sediment movement along any coast can cause
serious problems downdrift through sediment 'starvation', and the
potential for increased erosion.