Relationships between sand spit evolution, environmental forcing and inland inundation

Topographic field data and environmental forcing agents were used to assess morphological changes (1995-2010) at Ginst Spit, Pendine Sands, West Wales and flood potential at Laugharne, a town in the lee of the spit. Areal change between annual surveys showed variable distal end migration eastward extending into the channel of the Towy, Taf and Gwendreath estuaries. Dominant waves emanate from south toward southwest and suggest that the longshore sediment drift is from west toward east. However, sub-dominant waves from southeast are limited by fetch but engender a counter drift back toward the west at the distal end forming the customary northward hook.Wave model results showed significant modifications occurred between the inshore model boundary and the nearshore zone and overall results suggest that spit evolution is dependent on sediment movement that occurs during high spring tidal conditions within this macrotidal environment. Precipitation and flood events were correlated to spit evolution, which suggested that a combination of fluvial and coastal processes in combination contribute to the flooding of Laugharne town.