Development of Groundwater on a Retreating Barrier Beach in Relation to Overwash and Dune Formation on Cape Cod, Massachusetts

摘要

The groundwater under a barrier beach overwashed by the Great Blizzard of 1978 on Cape Cod was studied during 1980-81. Topographic surveys were made on man-made dunes, small natural dunes, and overwash flats. Thirty-two PVC wells were installed to determine changes in water level and salinity. Soil moisture and salinity were measured at four selected locations. Water potential, leaf resistance, and chlorophyll content of Ammophila breviligulata were also measured. Results showed rapid development of a freshwater zone soon after dunes were initiated. Ammophila dunes are critical for the development of a freshwater lens under an overwashing barrier beach; the amount of freshwater held increases as the dunes grow, and the lens forms soon after a dune starts.