Stochastic Theory of Particle Trajectories through Alluvial Valley Floors

Malmon, Daniel V.; Dunne, Thomas; Reneau, Steven L.

doi:10.1086/376764

Cited by 64 publications

(71 citation statements)

References 18 publications

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“…In this way, x tran represents the length of channel required to exchange the entire sediment flux with river deposits via lateral migration. This definition of x tran is comparable to previous studies (Malmon et al, 2003;Lauer and Parker, 2008b;Pizzuto et al, 2014) and was calculated with the equation…”

Section: Model For the Number Of Storage Eventssupporting

confidence: 61%

“…Most previous models of sediment storage in meandering river systems have assumed that storage durations are exponentially distributed (Malmon et al, 2003;Lauer and Parker, 2008a;Lauer and Willenbring, 2010). This assumption requires that deposits of all ages are equally likely to be eroded at any given time, which is inconsistent with some field data (Nakamura and Kikuchi, 1996;Lancaster and Casebeer, 2007) as well as the common observation that the position of the river channel is persistent in time (Bradley and Tucker, 2013).…”

Section: Application Of a Meandering Model To Determine Storage Durationmentioning

confidence: 98%

“…After being eroded from an upland source, fluvial sediments are routed through a transport network that includes multiple temporary storage reservoirs (e.g., channel and floodplain deposits; Malmon et al, 2003;Lauer and Parker, 2008a;Lauer and Willenbring, 2010;Pizzuto et al, 2017). These sediment reservoirs can also store POC, potentially leading to a decrease in its radiocarbon content due to radioactive decay.…”

Section: Generic Theory For Organic Carbon and Sediment Storagementioning

confidence: 99%

“…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%

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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 Eventssupporting

confidence: 61%

Section: Application Of a Meandering Model To Determine Storage Durationmentioning

confidence: 98%

Section: Generic Theory For Organic Carbon and Sediment Storagementioning

confidence: 99%

Section: Model For the Number Of Storage Eventsmentioning

confidence: 99%

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

et al. 2017

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“…The increased knowledge of processes involved in the catchment-scale transfers of sediments and associated contaminants led to the development of a range of conceptual and physically based models of sediment and contaminant transport (e.g. Young et al 1989;Malmon et al 2003;Owens 2005;Davison et al 2008;Armour et al 2009;Neitsch et al 2011). Yet, despite the ongoing stream of publications in the field of sediment and contaminant transport, the lack of sufficient field data and adequate descriptions of governing processes persist to be the major limitations to applying these models.…”

Section: Introductionmentioning

confidence: 99%

Preface

2017

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A probabilistic sediment cascade model of sediment transfer in the Illgraben

et al. 2014

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We present a probabilistic sediment cascade model to simulate sediment transfer in a mountain basin (Illgraben, Switzerland) where sediment is produced by hillslope landslides and rockfalls and exported out of the basin by debris flows and floods. The model conceptualizes the fluvial system as a spatially lumped cascade of connected reservoirs representing hillslope and channel storages where sediment goes through cycles of storage and remobilization by surface runoff. The model includes all relevant hydrological processes that lead to runoff formation in an Alpine basin, such as precipitation, snow accumulation, snowmelt, evapotranspiration, and soil water storage. Although the processes of sediment transfer and debris flow generation are described in a simplified manner, the model produces complex sediment discharge behavior which is driven by the availability of sediment and antecedent wetness conditions (system memory) as well as the triggering potential (climatic forcing). The observed probability distribution of debris flow volumes and their seasonality in 2000-2009 are reproduced. The stochasticity of hillslope sediment input is important for reproducing realistic sediment storage variability, although many details of the hillslope landslide triggering procedures are filtered out by the sediment transfer system. The model allows us to explicitly quantify the division into transport and supply-limited sediment discharge events. We show that debris flows may be generated for a wide range of rainfall intensities because of variable antecedent basin wetness and snowmelt contribution to runoff, which helps to understand the limitations of methods based on a single rainfall threshold for debris flow initiation in Alpine basins.

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Stochastic Theory of Particle Trajectories through Alluvial Valley Floors

Cited by 64 publications

References 18 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

Preface

A probabilistic sediment cascade model of sediment transfer in the Illgraben

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