THE INFLUENCE OF OFFSHORE STORM WAVES ON GROUNDWATER DYNAMICS AND SALINITY IN A SANDY BEACH

摘要

Field observations of the response of the salinity structure in a sandy beach to oceanic fluctuations during a 15-day monitoring period are presented and discussed. There was no observable response of the salinity structure to either the semi-diurnal or neap to spring tidal cycles. During the monitoring period there was an increase in significant wave heights up to 4.5m over a period of about 4 days which resulted in a pulse in shoreline water levels due to wave setup. This induced a significant response in both the groundwater levels and the location of the salt-freshwater mixing zone. The findings have important implications for the quality of coastal groundwater resources and in particular for chemical reactions occurring within the vicinity of the mixing zone.