MONITORING SEDIMENT TRANSPORT AND INLET MIGRATION AT SEAWALL BEACH: PHIPPSBURG, MAINE

Monitoring seasonal and long-term changes of the undeveloped Seawall Beach complex in Phippsburg, Maine is crucial to understanding this dynamic barrier system as sea level rise continues to affect local coastal environments. The goal of this study throughout the summer and fall of 2009 and winter of 2010 was to document current long shore transport patterns on the barrier beach and adjacent spits in this swash aligned system. The spits accrete sediment over time, which in turn control the flow of two back barrier inlets, the Sprague and Morse Rivers, which define the margins of Seawall Beach. At the Sprague River in the southwest, progradation of the spit has caused westward migration of the inlet and erosion of two pocket beaches, Ice Box Beach and Little Beach. To the northeast, eastward migration of the Morse River has recently caused significant erosion to Popham Beach and destruction of the back barrier maritime forest. Topographical profiles, activation rod analysis and time-lapse photography were used to record beach morphology during the study period. Historical photos, satellite imagery and previous studies were used to document and compare long-term changes. Ongoing investigation of this transgressive system is necessary to predict the beach's adaptation to sea-level rise.