Net local removal of floodplain sediment by river meander migration

Lauer, J. W.; Parker, Gary

doi:10.1016/j.geomorph.2007.08.003

Cited by 145 publications

(124 citation statements)

References 45 publications

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“…Following previous approaches (e.g, Malmon et al, 2003;Lauer and Parker, 2008b;Pizzuto et al, 2014), we defined a characteristic length scale over which eroded sediment particles are transported before being re-deposited. While particles are transported variable distances (depending for example on particle size and current velocity), we made the simplifying assumption that the spread of the distribution of transport lengths is small relative to the mean transport length.…”

Section: Model For the Number Of Storage Eventsmentioning

confidence: 99%

Model predictions of long-lived storage of organic carbon in river deposits

et al. 2017

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Abstract. The mass of carbon stored as organic matter in terrestrial systems is sufficiently large to play an important role in the global biogeochemical cycling of CO 2 and O 2 . Field measurements of radiocarbon-depleted particulate organic carbon (POC) in rivers suggest that terrestrial organic matter persists in surface environments over millennial (or greater) timescales, but the exact mechanisms behind these long storage times remain poorly understood. To address this knowledge gap, we developed a numerical model for the radiocarbon content of riverine POC that accounts for both the duration of sediment storage in river deposits and the effects of POC cycling. We specifically target rivers because sediment transport influences the maximum amount of time organic matter can persist in the terrestrial realm and river catchment areas are large relative to the spatial scale of variability in biogeochemical processes.Our results show that rivers preferentially erode young deposits, which, at steady state, requires that the oldest river deposits are stored for longer than expected for a well-mixed sedimentary reservoir. This geometric relationship can be described by an exponentially tempered power-law distribution of sediment storage durations, which allows for significant aging of biospheric POC. While OC cycling partially limits the effects of sediment storage, the consistency between our model predictions and a compilation of field data highlights the important role of storage in setting the radiocarbon content of riverine POC. The results of this study imply that the controls on the terrestrial OC cycle are not limited to the factors that affect rates of primary productivity and respiration but also include the dynamics of terrestrial sedimentary systems.

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Section: Model For the Number Of Storage Eventsmentioning

confidence: 99%

Model predictions of long-lived storage of organic carbon in river deposits

et al. 2017

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“…This tool computes migration distance at userspecified intervals along the river (every 10 m in this study) between two points in time. The tool also extracts bank elevations at each node from high-resolution ground elevation data and combines the migration rate with the difference in bank elevation to compute local, net sediment contributions from stream banks [Lauer and Parker, 2008a].…”

Section: Sediment Storage In the Uplands And Fluvial Networkmentioning

confidence: 99%

Closing the Gap Between Watershed Modeling, Sediment Budgeting, and Stream Restoration

Smith¹,

Belmont²,

Wilcock³

2013

Stream Restoration in Dynamic Fluvial Systems

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(2011), Closing the gap between watershed modeling, sediment budgeting, and stream restoration, in Stream Restoration in Dynamic Fluvial Systems: Scientific Approaches, Analyses, and Tools, Geophys. Monogr. Ser., vol. 194 The connection between stream restoration and sediment budgeting runs both ways: stream restoration is proposed as a means to reduce sediment yields, but an accurate understanding of sediment supply is necessary to design an effective project. Recent advances in monitoring technology, geochemical techniques, high-resolution topography data, and numerical modeling provide new opportunities to estimate sediment erosion, transport, and deposition rates; upscale them in a geomorphically relevant fashion; and synthesize sediment dynamics at watershed scales. For practical application at large scale, watershed models used to predict yield often do not resolve lower-order channels, leaving an essential "blind spot" regarding sediment processes. We illustrate the challenges and emerging approaches for estimating sediment budgets using examples from two very different physiographic settings: the Mid-Atlantic Piedmont and the agricultural plains of southern Minnesota. We highlight common challenges and themes in defining an effective watershed sediment model. In both cases, reliable estimates of sediment yield depend essentially on the accurate identification of sediment sources and sinks and, hence, require careful delineation of landscape units and identification of dominant sediment sources and sinks. The primary elements needed to bridge the gap between sediment budgeting, watershed modeling, and stream restoration are (1) specificity regarding location, mechanism, and rates of erosion, (2) accurate accounting of sediment storage, (3) appropriate methods for upscaling local observations, (4) efficient means for incorporating multiple lines of evidence to constrain budget estimates, and (5) stream restoration methods that incorporate sediment supply in assessment and design procedures.

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“…1). The model assumes steady state between sediment flux from bank erosion and bar deposition, a simplification termed quasisteady state, which is valid for most fluvial conditions (Lauer and Parker, 2008). This assumption may not be valid for short periods, but on timescales encompassed by channel belt formation from sediment accumulation and aggradation (~ 10 4 y), the vertical accretion of floodplains is counterbalanced by the lateral erosion of the exposed bank (Wolman and Leopold, 1957;Trimble, 1995;Bridge, 2003;Meade, 2007).…”

Section: Model Setupmentioning

confidence: 99%

Cosmogenic nuclide budgeting of floodplain sediment transfer

Wittmann

Blanckenburg

2009

Geomorphology

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Cosmogenic nuclides produced in quartz may either decay or accumulate while sediment is moved through a river basin. A change in nuclide concentration resulting from storage in a floodplain is potentially important in large drainage basins in which sediment is prone to repeated burial and remobilization as a river migrates through its floodplain. We have modeled depth-and time-dependent cosmogenic nuclide concentration changes for 10 Be, The cosmogenic nuclide composition of old deposits in currently inactive floodplains that have been isolated for periods of millions of years from the river that once deposited them are predicted to either increase or decrease in C, nuclide concentrations modeled for the in situ-produced variety of this nuclide are, however, sensitive to floodplain storage on residence times of < 20 ky. 10 Be and 26 Al concentration, depending on the depositional depth. These conditions can be evaluated using the 26 Al/ 10 We illustrate these models with examples from the Amazon basin. As predicted, modern bedload collected from an Amazon tributary, the Bolivian Beni River, shows no systematic change in nuclide concentration as sediment is moved through 500 km of floodplain by river meandering. In contrast, in the central Amazon floodplain currently untouched by the modern river system, low Be ratio that readily discloses the depth and duration of storage.26 Al/ 10 The important result of this analysis is that in all likely cases of active floodplains, cosmogenic Be ratios account for minimum burial depths of 5 to 10 m for a duration of > 5 My. 10 Be and 26 Al concentrations remain virtually unchanged over the interval sediment usually spends in the basin. Thus, spatially-averaged denudation rates of the sediment-producing area can be inferred throughout the entire basin, provided that nuclide production rates are scaled for the altitudes of the sediment-producing area only, because floodplain storage does not modify nuclide concentrations introduced from the sediment source area.

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Net local removal of floodplain sediment by river meander migration

Cited by 145 publications

References 45 publications

Model predictions of long-lived storage of organic carbon in river deposits

Model predictions of long-lived storage of organic carbon in river deposits

Closing the Gap Between Watershed Modeling, Sediment Budgeting, and Stream Restoration

Cosmogenic nuclide budgeting of floodplain sediment transfer

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