Virginia Institute of Marine Science
Land clearing, river impoundments, and other human modifications to theupland landscape and within estuarine systems can drive coastal change at local to regionalscales. However, as compared with mid-latitude coasts, the impacts of human modificationsalong sediment-starved formerly glaciated coastal landscapes are relatively understudied.To address this gap, we present a late-Holocene record of changing sediment accumulationrates and sediment sources from sediment cores collected across a tidal flat in theMerrimack River estuary (Mass., USA). We pairsedimentology, geochronology, bulk- andstable-isotope organic geochemistry, and hydrodynamic simulations with historical datato evaluate human and natural impacts on coastal sediment fluxes. During the 17th to19th centuries, accumulation rates increased by an order of magnitude in the central tidalflat, likely in response to enhanced delivery of terrestrial sediment resulting from uplanddeforestation. However, the overall increase in accumulation (0.56–2.6 mm/year) withinthe estuary is subtle and spatially variableacross the tidal flats because of coincidentanthropogenic land clearing and dam building, upland sediment storage, and estuarinehydrodynamics. This study provides insight into the response of formerly glaciated fluvial-coastal systems to human modifications, and underscores the role of estuarine environmen-tal conditions in modifying upland signals of land-use change.
land-use change, sediment accumulation, estuarine dynamics, tidal flats, sediment source, Merrimack River estuary
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Shawler, Justin L.; Hein, Christopher J.; Canuel, Elizabeth A.; and et al, Tidal erosion and upstream sediment trapping modulate records of land-use change in a formerly glaciated New England estuary (2019). Anthropocene Coasts, 2(1), 340-361.