Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States
| Author(s) | Pizzuto, James E. | |
| Author(s) | Skalak, K.J. | |
| Author(s) | Benthem, A. | |
| Author(s) | Mahan, S.A. | |
| Author(s) | Sherif, M. | |
| Author(s) | Pearson, A.J. | |
| Date Accessioned | 2022-06-09T20:31:02Z | |
| Date Available | 2022-06-09T20:31:02Z | |
| Publication Date | 2022-05-05 | |
| Description | This article was originally published in Geological Society of America Bulletin. The version of record is available at: https://doi.org/10.1130/B36282.1 | en_US |
| Abstract | New and previously published stratigraphic data define Holocene to present sediment storage time scales 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 ∼18,000 to 225 yr old, and represent 39% (median) of the total accumulation. Sediments deposited from 1750 to 1950 (“legacy sediments”) accumulated at a (median) rate of 0.39 cm yr−1 and comprise 47% (median) of the total, while “modern sediments” (1950−present) represent 11% of the total and accumulated at a (median) rate of 0.25 cm yr−1. Synthetic stratigraphic sequences, recast as age distributions for the presettlement period, in 1900 A.D., and at present, reflect rapid postsettlement alluviation, with enhanced preservation of younger sediments related to postsettlement watershed disturbance. An averaged present age distribution for vertically accreted sediment has modal, median, and mean ages of 190, 230, and 630 yr, 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 yr), 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 yr (a reasonable time horizon to achieve watershed restoration efficacy) is ∼60% for a distance of 50 km, but this decreases to <20% for distances greater than 200 km. Age distributions, evaluated through time, not only encapsulate the history of sediment storage, but they also provide data for calibrating watershed-scale sediment-routing models over geological time scales. | en_US |
| Sponsor | Financial support was provided by the Delaware Watershed Research Fund award DWRF-16-109, National Science Foundation grant EAR-1424969, and Petroleum Research Fund award PRF 57428-ND8. K. Skalak and A. Benthem assisted with stratigraphic description, geochronology, and analysis of samples from the South River and Difficult Run. S. Mahan performed OSL dating of samples from the South River and Difficult Run. M. Sherif and A. Pearson contributed 137Cs and 210Pb analyses of samples from White Clay Creek. J.E. Pizzuto participated in all aspects of the study. Stephanie Stotts assisted with dendrochronology at site 1 of White Clay Creek, Neil Sturchio assisted with fallout radionuclide analyses, and Joey George created the geomorphic map of Difficult Run. Perceptive and helpful reviews of a previous version of this manuscript were provided by Michael Church and an anonymous reviewer; the authors are grateful for their contributions. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. government. OSL data availability: OSL data sets related to this article have not yet been approved by the USGS. When approved, the data will be archived in USGS Science Base and can be accessed by typing in the name of the associated article. Interested researchers are encouraged to access the data at https://www.usgs.gov/products/data/data-releases. | en_US |
| Citation | J.E. Pizzuto, K.J. Skalak, A. Benthem, S.A. Mahan, M. Sherif, A.J. Pearson; Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States. GSA Bulletin 2022; doi: https://doi.org/10.1130/B36282.1 | en_US |
| ISSN | 1943-2674 | |
| URL | https://udspace.udel.edu/handle/19716/30975 | |
| Language | en_US | en_US |
| Publisher | Geological Society of America Bulletin | en_US |
| Title | Spatially averaged stratigraphic data to inform watershed sediment routing: An example from the Mid-Atlantic United States | en_US |
| Type | Article | en_US |
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