An investigation of the opening and closing of the tidal inlet on Sand Beach, Acadia National Park, ME

Wheeler, Bronwyn

Field work October 22 2010 - December 19, 2010 "Rising sea level is driving small, pocket beaches landward into progressively smaller embayments. With shrinking embayment size, the tidal prism of the beach-protected estuary also decreases and eventually reaches the point where tidal inlets cannot remain open. For smaller inlets, like the Sand Beach Inlet in Acadia National Park, ME, there are significant ecological implications related to the opening and closing of an inlet. Other studies on inlets in different climates implied that the status of the inlet depended largely on seasonal variations that were easily predicted. To understand the factors that control the ephemeral Sand Beach Inlet, two Aqua Troll 200s were placed in the lagoon to gather temperature, salinity and water-level data to investigate any associations the water depth had with associated tidal, precipitation events, and wave data. In the Sand Beach Inlet this is not the case, a more detailed analysis was undertaken. Precipitation, wave height data, tidal data, and storm data on an hourly to daily basis were all necessary to predict the extremely dynamic tidal inlet on Sand Beach. Precipitation events can open the inlet and storms can both open and close the inlet by depositing or removing sand from the inlet opening." Salinity range varied greatly during the period with average salinity of 13.8 PSU and a maximum of 30.5 PSU and a minimum of 0.099 PSU. When the inlet was not infiltrated with salt water, the salinity remained below 1.0 PSU. Maximum salinities occurred during period that had an influx of seawater either from high waves or tides greater than 3.5 m. Figure 14 shows historic inlet status from 1966 to 2011, which suggests that the inlet tends to be open from December through May and be closed from July through September. /STUDY LOCATIONS:/ /MOUNT DESERT ISLAND/Sand Beach/