Natural and human impacts on centennial sediment accumulation patterns on the Umpqua River margin, Oregon

Wheatcroft, Robert A.; Goñi, Miguel A.; Richardson, K.; Borgeld, Jeffry C.

doi:10.1016/j.margeo.2013.04.015

Cited by 21 publications

(19 citation statements)

References 76 publications

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“…Sediment accumulation rate (SAR) was calculated using the constant initial concentration (CIC) model (e.g., Sanchez‐Cabeza & Ruiz‐Fernández, ; Wheatcroft et al, ) applied to the excess 210 Pb activities (Figure S2; Ritchie & McHenry, ). The CIC method was chosen over other models for analyzing excess 210 Pb‐derived accumulation rates, specifically the constant‐flux‐constant sedimentation or constant rate of supply models, as it is a straightforward and widely used model (e.g., Callaway et al, ; Mudd et al, ).…”

Section: Methodsmentioning

confidence: 99%

Controls on Sediment Accretion and Blue Carbon Burial in Tidal Saline Wetlands: Insights From the Oregon Coast, USA

2020

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Oregon estuaries provide important opportunities to assess controls on tidal saline wetland carbon burial and sediment accretion as both rates of relative sea level rise (RSLR; −1.4 ± 0.9 to 2.8 ± 0.8 mm yr−1) and fluvial suspended sediment load relative to estuary area (0.23 to 17 × 103 t km−2 yr−1) vary along the coast. We hypothesized that vertical accretion, measured using excess 210Pb in least‐disturbed wetlands within seven Oregon estuaries, would vary with either RSLR or sediment load relative to estuary area, and carbon burial would correlate strongly to sediment accretion. Mean rates of high marsh accretion (0.8 ± 0.2 to 4.1 ± 0.2 mm yr−1) indicate that Oregon tidal wetlands have mainly kept pace with twentieth‐century RSLR with the exception that the accretionary balance in the central coast is negative, suggesting drowning. Experiencing the fastest rates of RSLR, central‐coast estuaries may foreshadow the fates of other Oregon estuaries under future accelerated sea level rise. Comparison of mass accumulation rates with sediment loads, however, indicates low trapping efficiency and therefore no fluvial sediment limitation. Thus, nonlinear feedback between RSLR and sediment accretion may enhance wetland resistance to drowning. Among wetlands keeping pace with or exceeding RSLR, sediment accretion displays no significant relationship with elevation but rather appears controlled by both the rate of RSLR and relative sediment load, highlighting the importance of incorporating both factors into future studies of tidal saline wetlands. Carbon burial rates, controlled by sediment accretion, will likely increase with future accelerated sea level rise.

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Section: Methodsmentioning

confidence: 99%

Controls on Sediment Accretion and Blue Carbon Burial in Tidal Saline Wetlands: Insights From the Oregon Coast, USA

2020

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“…Recent extreme precipitation events in the area occurred in water years (WY) 1965, 1982, 1996, and 1997 (a summary of historical events can be found in the Supplementary materials section and Table S1). The Pacific Decadal Oscillation (PDO; Mantua et al ., ) has been shown to influence inter‐annual stream flow and the magnitude of peak flows in the Umpqua River basin (Wheatcroft et al ., ), of which the LL catchment is a part.…”

Section: Methodsmentioning

confidence: 99%

1500 years of lake sedimentation due to fire, earthquakes, floods and land clearance in the Oregon Coast Range: geomorphic sensitivity to floods during timber harvest period

Richardson

Hatten

Wheatcroft

2018

Earth Surf Processes Landf

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Sediment cores retrieved from landslide‐dammed Loon Lake recorded events back to the 5th century AD in a forested, mountainous catchment, thereby providing an opportunity to compare the impacts of known recent perturbations, including floods and timber harvesting with those of an early period in the cores, floods, fires, and earthquakes. High‐resolution multi‐parameter (grain size, %TC, %TN, and magnetic susceptibility) data allowed the core stratigraphy to be classified as background sedimentation and events. 137Cs and radiocarbon dating, as well as a varved record in the last 75 years provided age control. Mean mass accumulation rate from 1939 to 1978 AD, the time of peak timber harvest and a cool wet phase of the Pacific Decadal Oscillation, was 0.79 (0.74–0.92, 95% C.L.) g cm‐2 y‐1, significantly higher than mean rates of both the more recent contemporary period (coincident with the passing of the legislation that regulated harvesting practices in the region), 1979–2012 AD, at 0.58 (0.48‐0.70) and the entire early period, 0.44 (0.41–0.46). Several event deposits are coeval with independently estimated ages of eight Cascadia subduction zone earthquakes in the early period, including the 1700 AD Mw 9.0 event. These deposits are predominantly formed by hyperpycnal flows, as are the known event deposits in the contemporary period. The high mass accumulation rate and greater frequency of thick event deposits during the early contemporary period point to the extraordinary role of timber harvesting in priming the landscape for subsequent sedimentary delivery during floods. Copyright © 2017 John Wiley & Sons, Ltd.

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“…Because burial rates estimated using 210 Pb-based sediment accumulation rates represent net sequestration over decades, these carbon fluxes need to be compared to other fluxes across key interfaces (e.g., land-sea, oceanatmosphere, shelf-slope) at similar time-scales. Sedimentary carbon budget exercises should be completed for high-accumulation rate regions where seasonal to decadal data are available, such as the Gulf of Maine (Keigwin and Pilskaln, 2015) and the Pacific Northwest margin (Wheatcroft et al, 2013), and considered alongside the long-term sequestration budgets.…”

Section: Long-term Sequestration and Burialmentioning

confidence: 99%

A science plan for carbon cycle research in North American coastal waters. Report of the Coastal CARbon Synthesis (CCARS) community workshop, August 19-21, 2014

Benway¹,

Alin²,

Boyer³

et al. 2016

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Natural and human impacts on centennial sediment accumulation patterns on the Umpqua River margin, Oregon

Cited by 21 publications

References 76 publications

Controls on Sediment Accretion and Blue Carbon Burial in Tidal Saline Wetlands: Insights From the Oregon Coast, USA

Controls on Sediment Accretion and Blue Carbon Burial in Tidal Saline Wetlands: Insights From the Oregon Coast, USA

1500 years of lake sedimentation due to fire, earthquakes, floods and land clearance in the Oregon Coast Range: geomorphic sensitivity to floods during timber harvest period

A science plan for carbon cycle research in North American coastal waters. Report of the Coastal CARbon Synthesis (CCARS) community workshop, August 19-21, 2014

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