| Abstract: | The reduction in sediment volume of an ebb-tide delta, as a consequence of lagoon outlet closure on a coarse clastic barrier in southeast Ireland, initiated a sequence of beachface and barrier changes downdrift. Elimination of sediment supply to the ebb-delta caused a cessation of downdrift longshore swash bar welding, and led to beach volume reductions which in turn allowed a temporal sequence of beach and nearshore morphodynamic domains to develop. These domains then controlled the sedimentation regime of the barrier adjacent to the old outlet. A temporal sequence of (a) dissipative barrier; (b) reflective barrier; and (c) inner reflective (barrier face)/outer dissipative (subtidal) wave regimes match respectively periods of (a) barrier crest build up by crestal dune development; (b) barrier crest instability (barrier width increasing, barrier height decreasing) due to rhythmic overwash; and (c) a return to barrier crest stability with limited aeolian accretion. Two barriers at different stages in this sequence are discussed. |
