Coastal SEES (Track I), Collaborative: Sediment Supply in a Regime of Accelerated Coastal Erosion (SedS-RACE): Paleo-Perspectives, Anthropogenic Influences and Future Challenges

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Coastal SEES (Track I), Collaborative: Sediment Supply in a Regime of Accelerated Coastal Erosion (SedS-RACE): Paleo-Perspectives, Anthropogenic Influences and Future ChallengesChristopher Hein, College of William and Mary Virginia Institute of Marine ScienceElizabeth Canuel, College of William and Mary Virginia Institute of Marine SciencePeter Rosen, Northeastern UniversityJu-Chin Huang, University of New HampshireCoastal retreat and sediment supply have tremendous impacts on society, infrastructure and the ecological functioning of coastal marine ecosystems. These processes are also integral to a range of coastal policy issues since a large fraction of the world?s population lives within 150 km of a coastline and the supply of riverine sediment to coastal regions is decreasing globally. This project addresses fundamental social- and natural- science questions surrounding coastal erosion that arise in response to insufficient supplies of sediment in a regime of accelerated sea-level rise and enhanced storminess. This will be accomplished through an integrative investigation of the long-term sediment sources, anthropogenic modifications and management strategies for a sandy barrier coast that is currently undergoing both severe erosion and intense human development. The focus of this study is the Merrimack River / Plum Island (Massachusetts) barrier system. Both have undergone wide-ranging human alterations that, combined with complex climate-change impacts, have dramatically reduced fluxes of sediment from both fluvial and near-shore sources. Results for the coastal community have been devastating, with consequences that affect human populations on annual, decadal and centennial timescales. This study will evaluate the relationship between the long-term (millennial-scale) record of sediment from the Merrimack River and the stability of Plum Island through the development of an 8000-year record of organic-biomarker proxies to quantify relative changes in the contributions of fluvial and shelf sources of sediment through time. It will then employ historical records and datasets, the correlation of 60 years of coastal-process and shoreline-mapping studies along Plum Island, and the development of down-core geochemical proxy records of anthropogenic impacts on fluvial sediment delivery to the coast, to detail the history of human modifications and evidence of geological responses. Modern shoreline-erosion studies (e.g., shoreline mapping, beach profiling, sediment sampling) will be used to monitor the short-term (1-2 yrs.) impacts of specific erosional events (storms) and management strategies. This combined knowledge will then be used to determine the nature and degree to which humans have altered natural sediment supplies and transport pathways and develop feasible sustainable paths for management that balance natural processes, societal needs and constraints, and communities? monetary and non-monetary valuation of the river, barrier and associated ecosystems.A unique product of this study will be the development of a 53-min PBS-style documentary that will provide a transparent view into the complex social and scientific interactions which inform the collective decision-making process around coastal erosion. A detailed distribution and impact-assessment plan for this film will allow it to serve as a unique and broadly-impactful education and outreach tool. Additional outreach will include the incorporation of local students and community members in beach monitoring efforts, coordinated policy development with local towns, public lectures, and the development of a display at a local National Wildlife Refuge that will focus on coupled human-natural interactions in relation to the coastal erosion problem on Plum Island. Additionally, it will provide interdisciplinary training for five students (1 PhD, 1 MSc, 3 undergraduate) both within and across the natural and social sciences, and will support an early-career scientist.