Luminescence data for: Spatially averaged Holocene-present fluvial sediment storage chronology of the Mid-Atlantic U.S. and its application to watershed scale sediment routing

New and previously published stratigraphic data define Holocene-present sediment storage timescales for mid-Atlantic river corridors. Empirical distributions of deposit ages and thicknesses were randomly sampled to create synthetic age-depth records. Deposits predating European settlement accumulated at a (median) rate of 0.06 cm yr-1, range from ~17,000 - 225 yrs. old and represent 39% (median) of the total accumulation. Sediments deposited from 1750-1950 (“legacy sediments”) accumulated at a (median) rate of 0.34 cm yr-1 and comprise 47% (median) of the total, while “modern sediments” (1950-present) represent 11% of the total and accumulated at 0.25 cm yr-1 (median). Synthetic stratigraphic sequences, recast as age distributions for the pre-settlement period, in 1900 A.D., and at present, reflect rapid post-settlement alluviation, with enhanced preservation of younger sediments related to post-settlement watershed disturbance. An averaged present age distribution for vertically accreted sediment has modal, median and mean ages of 190, 230, and 630 years, reflecting the predominance of stored legacy sediments and the influence of relatively few, much older early Holocene deposits. The present age distribution, if represented by an exponential approximation (mean age ~ 300 years), and naively assumed to represent steady state conditions, implies median sediment travel times on the order of centuries for travel distances greater than ~100 km. The percentage of sediment reaching the watershed outlet in 30 years (a reasonable time horizon to achieve watershed restoration efficacy) is ~ 60% for a distance of 50 km, but decreases to < 20% for distances greater than 200 km. Age distributions, evaluated through time, not only encapsulate the history of sediment storage, but also provide data for calibrating watershed scale sediment routing models over geological timescales.