Climate and hillslope degradation vary in concert; 85 ka to present, eastern Sierra Nevada, CA, USA

Madoff, Risa D.; Putkonen, Jaakko

doi:10.1016/j.geomorph.2016.05.010

Cited by 7 publications

(7 citation statements)

References 58 publications

(93 reference statements)

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“…We note that over timescales of 10 ka or more, values of D are likely to vary as climate changes (Hughes et al, ; Madoff & Putkonen, ; McGuire et al, ). At this time, however, we do not have information to justify choices of D through time.…”

Section: Methodsmentioning

confidence: 79%

“…Through estimating a value of D for local linear diffusion, we show that in this setting, the form of a moraine reflects only the time‐averaged value of D (Appendix A). Previous work has demonstrated this concept (Figure 6, Madoff & Putkonen, ), although it has not addressed the mathematical basis. This is easily proven when the diffusion equation is examined in the wave number domain and is a point that may be significant in efforts to unfold the record of climate in hillslope form.…”

Section: Discussionmentioning

confidence: 99%

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Nonlocal Sediment Transport on Steep Lateral Moraines, Eastern Sierra Nevada, California, USA

et al. 2018

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Recent work has highlighted the significance of long‐distance particle motions in hillslope sediment transport. Such motions imply that the flux at a given hillslope position is appropriately described as a weighted function of surrounding conditions that influence motions reaching the given position. Although the idea of nonlocal sediment transport is well grounded in theory, limited field evidence has been provided. We test local and nonlocal formulations of the flux and compare their ability to reproduce land surface profiles of steep moraines in California. We show that nonlocal and nonlinear models better reproduce evolved land surface profiles, notably the amount of lowering and concavity near the moraine crest and the lengthening and straightening of the depositional apron. The analysis provides the first estimates of key parameters that set sediment entrainment rates and travel distances in nonlocal formulations and highlights the importance of correctly specifying the entrainment rate when modeling land surface evolution. Moraine evolution associated with nonlocal and nonlinear transport formulations, when described in terms of the evolution of the Fourier transform of the moraine surface, displays a distinct behavior involving growth of certain wave numbers, in contrast to the decay of all wave numbers associated with linear transport. Nonlinear and nonlocal formulations share key mathematical elements yielding a nonlinear relation between the flux and the land surface slope.

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Section: Methodsmentioning

confidence: 79%

Section: Discussionmentioning

confidence: 99%

Nonlocal Sediment Transport on Steep Lateral Moraines, Eastern Sierra Nevada, California, USA

et al. 2018

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“…Lateral moraines have been the subject of several previous papers that document the degradation of topography (Doane et al, ; Madoff & Putkonen, ; Putkonen et al, ) because we know their initial condition and have reasonable estimates of their age. Here we focus on a lateral moraine that emerges from Bloody Canyon in the eastern Sierra Nevada.…”

Section: Applications: Natural Landformsmentioning

confidence: 99%

“…Generally, parameters of transport formulae are rate constants that reflect the magnitude of regolith churning or the activity of particles. To obtain values for these, it is common to numerically simulate land‐surface evolution and back calculate a value that results in the best fit modeled land‐surface profile (DiBiase et al, ; Doane et al, ; Fernandes & Dietrich, ; Madoff & Putkonen, ; Nash & Beaujon, ). However, fitting linear and nonlinear models to a single hillslope will result in different estimates of the hillslope diffusivity and will imply different magnitudes of soil churning (Doane et al, ), so we risk misunderstanding the mechanisms of sediment transport.…”

Section: Introductionmentioning

confidence: 99%

Compression and Decay of Hillslope Topographic Variance in Fourier Wavenumber Domain

et al. 2019

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Three mathematical models of hillslope sediment transport are common: linear diffusion, nonlinear diffusion, and nonlocal transport. Each of these is supported by a different theory, but each contains land-surface slope as a central ingredient. As such, land-surface evolution by all three of these models is largely similar in that topographic highs degrade and lows fill in. However, details of land-surface form reveal diagnostic clues to linear or nonlinear behavior of the land surface. We cast land-surface evolution into wavenumber (Fourier) domain, which effectively separates signals into coarse-and fine-scale elements of land-surface form, such as hillslope-valley sequences and pit-mound features, respectively. In wavenumber domain linear diffusion results in vertical spectral decay, which is associated with landform straightening and smoothing of sharp concavities. Nonlinear diffusion results in spectral compression toward low wavenumbers, which is associated with landform lengthening and is similar to slope replacement. Nonlocal processes share elements of linearity or nonlinearity but are modified by the particular form of the distribution of particle travel distance. Ultimately, all processes tend toward zero topographic variance, but by distinctly different styles as revealed in wavenumber domain. Spectral compression by nonlinear processes can result in temporary spectral growth over certain spectral bands and is interpreted as a signature of nonlinear processes for certain landforms. The signatures come from the evolution of topographic details and landforms with sharp concavities highlight this behavior, whereas landforms with low concavities obscure these diagnostic behaviors.

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“…Hooper and Sheridan, ; Pelletier and Cline, ), steady‐state solution of the diffusion equation in settings with known erosion rates (Roering, ; Hurst et al ., ) and direct measurements of soil flux (e.g. Saunders and Young, ; Madoff and Putkonen, ). Hurst et al .…”

Section: Previous Studies On Soil Creep Diffusivity (K)mentioning

confidence: 99%

The influence of climate and microclimate (aspect) on soil creep efficiency: Cinder cone morphology and evolution along the eastern Mediterranean Golan Heights

Ben-Asher

Haviv

Roering

et al. 2017

Earth Surf Processes Landf

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Although hillslope evolution has been subject to much investigation for more than a century, the effect of climate on the morphology of soil‐mantled hillslopes remains poorly constrained. In this study, we perform numerical simulations of volcanic cinder cones in the Golan Heights (eastern Mediterranean) to estimate soil transport efficiency across a significant north–south gradient in mean annual precipitation (1100 to 500 mm). We use the initial cinder cone morphology (constrained by stratigraphy), the modern hillslope form (surveyed with sub‐meter accuracy) and the eruption age (based on 40Ar–39Ar chronology) to predict the best‐fit value of the soil transport coefficient (‘diffusivity’) based on a nonlinear transport model. Our results indicate that the best‐fit diffusivity (K) varies from 1 to 6 m2 ka−1 among the five cinder cones in our field area. Diffusivity (K) values vary systematically with precipitation and hillslope aspect; specifically, K is higher on south‐facing (drier) hillslopes and decreases with mean annual precipitation. We interpret this climate dependency to reflect vegetation‐driven variations in apparent soil cohesion, which increases with root network density, and attenuation of rain splash and overland flow erosion, which increases with vegetative ground cover. To assess how vegetative root mass and ground cover vary with precipitation and aspect, we quantified the spatial distribution of NDVI (normalized difference vegetation index) from ASTER satellite images and observed spatial variations that correlate with our calibrated values of K. Analysis of previously studied cinder cones in the USA can be used to extend our framework to arid domains. This endeavor suggests a humped relationship between K and precipitation with maximum diffusivity at mean annual precipitation of 400–600 mm. Copyright © 2017 John Wiley & Sons, Ltd.

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Climate and hillslope degradation vary in concert; 85 ka to present, eastern Sierra Nevada, CA, USA

Cited by 7 publications

References 58 publications

Nonlocal Sediment Transport on Steep Lateral Moraines, Eastern Sierra Nevada, California, USA

Nonlocal Sediment Transport on Steep Lateral Moraines, Eastern Sierra Nevada, California, USA

Compression and Decay of Hillslope Topographic Variance in Fourier Wavenumber Domain

The influence of climate and microclimate (aspect) on soil creep efficiency: Cinder cone morphology and evolution along the eastern Mediterranean Golan Heights

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