THE BLOCK ISLAND BEACH PROFILE PROJECT 10-YEARS IN; OBSERVATIONS AND LESSONS LEARNED

Seven beach profiles on Block Island, Rhode Island have been measured by island residents using the modified Emery Method over the last decade (monthly Aug 2013 – December 2017; Quarterly 2018 – Present); an eighth site was abandoned due to site access issues. One additional profile is measured biannually (since 2015), while another was added in 2021. One of the profiles was initiated by another researcher in 2007 and was incorporated. Individual profiles begin at a backstake of known elevation (surveyed using Real-Time Kinematic GPS) and extend across the subaerial portion of the profiles. Survey dates correspond to spring low tides to maximize the exposed beach. Profile locations balance accessibility and geographic spread around the island. Four are located along the barrier spit/welded barrier east facing shoreline; five on either low-headlands or barrier spits on the western side of the island. The volunteers conduct field surveys, and data is sent to the author for plotting and interpretation. The approachability of the Emery method makes this an ideal technique for non-geologists; however, this project has benefitted immensely from the prior scientific training (and enthusiasm) of the community scientists involved. This work is in conjunction with other on-going projects examining bluff erosion and historic shoreline change of the island. The engagement of the volunteers with other aspects of local coastal management has led to cross-pollination between other efforts on the island ranging from sea-level rise planning to coastal modelling. This talk will outline the structure and workflow of the project, some tips, advice and lessons learned as well as some results of the project to date. The eastern profiles largely show an increase in profile volume, particularly as the dunes recovered following Superstorm Sandy (October 2012). This necessitated increasing the backstake elevation to account for dune growth at two profiles. The western profiles show a disparate response. Profiles south of New Harbor Inlet show little change/slight accretion while the two profiles north of the inlet have lost 15 and 50 % of their volume respectively, and the shoreline has retreated 7-10 m over the life of the project. The hypothesized driver for this is the lack of sediment bypassing the inlet to the north.