COASTAL GEOMORPHOLOGY OF PHILLIPS BEACH, SWAMPSCOTT MASSACHUSETTS: SEDIMENT VOLUME RESPONSE TO METEOROLOGICAL FORCINGS

Phillips Beach in Swampscott, MA is a mesotidal welded barrier beach facing southeast and is dominated by medium to coarse-grained sand with a cobble section to the south. The purpose of this study is to quantitatively determine the geomorphic responses to meteorological conditions and events during the 2017-2018 year. Previous fieldwork (2010-11) yielded evidence that Phillips Beach accreted sediment in summer and spring, yet was dominated by erosional processes in fall and winter (Surette, 2011). We hypothesize that storm events will lead to erosion and fair weather to accretion at Phillips Beach. Specifically in New England, low-pressure storms, Nor-Easters, are created off-shore and intensify, producing gale-force winds and associated large amplitude and short period waves that can lead to coastal erosion. Data have been collected through beach profiling using the stadia rod method along a constant bearing of 110°, from a permanent backstake installed in the back-barrier (42.47128°N, 070.88679°W). Approximately bi-weekly surveys have been ongoing since June 29, 2017. Meteorological and sea state conditions (wind speed, wind direction, wave height, and wave period) have been constrained using two off-shore buoys (Northeastern Regional Association of Coastal Ocean Observing Systems #44029 and National Data Buoy Center #44013). Buoy #44029 is 17.0 km off-shore (42.52278°N, 70.56556°W) and buoy #44013 is 28.3 km off-shore (42.34556°N, 70.65111°W). From June through December 2017, Northeastern Massachusetts has generally been dominated by fair weather conditions, with exceptions to five coastal storm events with high wind speeds (>8m/s), and wave heights (>2m). Generally, Phillips Beach has experienced erosion after storms, but the volume of sediment eroded has varied, as evidenced by less erosion associated with a weaker storm on July 24, as compared to October 29. Following erosion, during times of low energy waves and slower wind speeds, accretion was observed. Using transect sediment volume calculations, sediment volume changes for 2017-2018 are being quantified and will be compared to the 2010-2011 data set provided by Surette. Ongoing surveying will allow us to continue monitoring the recovery time of the sediment in the system after coastal storms.