Sand transport under increased lateral jetting of raindrops induced by wind

Erpul, Günay; Gabriëls, Donald; Cornelis, Wim; Samray, H; Guzelordu, T.

doi:10.1016/j.geomorph.2008.08.012

Cited by 16 publications

(9 citation statements)

References 52 publications

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“…The onset of differential soil splash with canopy growth is a key process by which desert shrubs 'harvest' nearby soil material, and, in concert with other erosional processes Wainwright et al, 2000], deplete the immediate vicinity of nutrients. We suggest that the formulation underlying (13) and (16) more generally provides a robust framework for describing dispersal of soil-borne substances activated by rain splash if, in addition to the effect of slope, the drift speed u and the dispersion coefficient D x are also related to wind effects via drop incident angle and transport of lofted grains [Moeyersons, 1983;Pedersen and Hasholt, 1995;Erpul et al, 2002Erpul et al, , 2008Cornelis et al, 2004;Bock et al, 2005].…”

Section: Discussionmentioning

confidence: 99%

“…[2] Broad, longstanding interest in rain splash of soil grains as an erosional process [Ellison, 1944;DePloey and Savat, 1968;Carson and Kirkby, 1972;Mosley, 1973;Sharma and Gupta, 1989;Sharma et al, 1991;Erpul et al, 2002Erpul et al, , 2008van Dijk et al, 2002;Gabet and Dunne, 2003;Legout et al, 2005;Furbish et al, 2007] and as a mechanism contributing to transport and dispersal of soil-borne pathogens, contaminants and nutrients [Dreicer et al, 1984;Wainwright et al, 1999;Bock et al, 2005;McGonigle et al, 2005] prompts the need for a unifying, and practical, description of rain splash transport that goes beyond [Dietrich et al, 2003] current semiempirical models. Recent success in clarifying the basic physics of the grain splash process [Furbish et al, 2007] allows us to formulate a description of grain motions, resulting from raindrop impacts, within the stochastic framework of the Master Equation [Risken, 1984].…”

Section: Introductionmentioning

confidence: 99%

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Rain splash of soil grains as a stochastic advection‐dispersion process, with implications for desert plant‐soil interactions and land‐surface evolution

et al. 2009

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We formulate soil grain transport by rain splash as a stochastic advection‐dispersion process. By taking into account the intermittency of grain motions activated by raindrop impacts, the formulation indicates that gradients in raindrop intensity, and thus grain activity (the volume of grains in motion per unit area) can be as important as gradients in grain concentration and surface slope in effecting transport. This idea is confirmed by rain splash experiments and manifest in topographic roughening via mound growth beneath desert shrubs. The formulation provides a framework for describing transport and dispersal of any soil material moveable by rain splash, including soil grains, soil‐borne pathogens and nutrients, seeds, or debitage. As such it shows how classic models of topographic “diffusion” reflect effects of slope‐dependent grain drift, not diffusion, and it highlights the role of rain splash in the ecological behavior of desert shrubs as “resource islands.” Specifically, the growth of mounds beneath shrub canopies, where differential rain splash initially causes more grains to be splashed inward beneath the protective canopy than outward, involves the “harvesting” of nearby soil material, including nutrients. Mounds thus represent temporary storage of soil derived from areas surrounding the shrubs. As the inward grain flux associated with differential rain splash is sustained over the shrub lifetime, mound material is effectively sequestered from erosional processes that might otherwise move this material downslope. With shrub death and loss of the protective canopy, differential rain splash vanishes and the mound material is dispersed to the surrounding area, again subject to downslope movement.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rain splash of soil grains as a stochastic advection‐dispersion process, with implications for desert plant‐soil interactions and land‐surface evolution

et al. 2009

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“…This spreading behavior is well known (Dreicer et al, 1984;Wainwright et al, 1999;Bock et al, 2005;McGonigle et al, 2005). But it is our impression that this topic has not fully received its deserved attention at a mechanistic level, where we note that effects of wind on raindrop and particle motions clearly matter (Moeyersons, 1983;Wright, 1986;de Lima, 1989;de Lima et al, 1993;Pedersen and Hasholt, 1995;Erpul et al, 2002;Erpul et al, 2008;Warburton, 2003;Cornelis et al, 2004;Bock et al, 2005;Marzen et al, 2015). As with bedload transport, tracer particle spreading in the presence of burial and exhumation must be coupled with descriptions of sediment surface evolution (Furbish et al, 2009a).…”

Section: Conclusion and Needed Clarificationmentioning

confidence: 97%

The elements and richness of particle diffusion during sediment transport at small timescales

Furbish

Fathel

Schmeeckle

et al. 2016

Earth Surf Processes Landf

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The ideas of advection and diffusion of sediment particles are probabilistic constructs that emerge when the Master equation, a precise, probabilistic description of particle conservation, is approximated as a Fokker–Planck equation. The diffusive term approximates nonlocal transport. It ‘looks’ upstream and downstream for variations in particle activity and velocities, whose effects modify the advective term. High‐resolution measurements of bedload particle motions indicate that the mean squared displacement of tracer particles, when treated as a virtual plume, primarily reflects a nonlinear increase in the variance in hop distances with increasing travel time, manifest as apparent anomalous diffusion. In contrast, an ensemble calculation of the mean squared displacement involving paired coordinate positions independent of starting time indicates a transition from correlated random walks to normal (Fickian) diffusion. This normal behavior also is reflected in the particle velocity autocorrelation function. Spatial variations in particle entrainment produce a flux from sites of high entrainment toward sites of low entrainment. In the case of rain splash transport, this leads to topographic roughening, where differential rain splash beneath the canopy of a desert shrub contributes to the growth of a soil mound beneath the shrub. With uniform entrainment, rain splash transport, often described as a diffusive process, actually represents an advective particle flux that is proportional to the land surface slope. Particle diffusion during both bedload and rain splash transport involves motions that mostly are patchy, intermittent and rarefied. The probabilistic framework of the Master equation reveals that continuous formulations of the flux and its divergence (the Exner equation) represent statistically expected behavior, analogous to Reynolds‐averaged conditions. Key topics meriting clarification include the mechanical basis of particle diffusion, effects of rarefied conditions involving patchy, intermittent motions, and effects of rest times on diffusion of tracer particles and particle‐borne substances. Copyright © 2016 John Wiley & Sons, Ltd.

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“…(, , , , , ), Erpul et al . (, , ) and Cornelis et al . (, ) (since these are referred to frequently in this paper, a single reference term of ‘ICE WDR studies’ is used in the rest of the manuscript).…”

Section: Introductionmentioning

confidence: 97%

“…For example, works performed in a wind tunnel rainfall simulator at the International Center for Eremology (ICE), Ghent University, Belgium (Gabriels et al, 1997;Cornelis et al, 2004a) on the combined effects of wind and rain had the objectives to understand mechanisms and to develop a process-based erosion model. More information on the wind tunnel studies is given by Erpul (1996Erpul ( , 2001, Erpul et al (1998Erpul et al ( , 2000, Erpul et al (2002Erpul et al ( , 2003aErpul et al ( , 2003bErpul et al ( , 2004aErpul et al ( , 2004bErpul et al ( , 2005, Erpul et al (2008Erpul et al ( , 2009aErpul et al ( , 2009b and Cornelis et al (2004bCornelis et al ( , 2004c) (since these are referred to frequently in this paper, a single reference term of 'ICE WDR studies' is used in the rest of the manuscript). Visser and Cornelis (2004) compiled the papers on 'wind and rain interaction in erosion', and Stroosnijder and Gabriels (2004) highlighted the need for future work on wind and water interaction in erosion models.…”

Section: Introductionmentioning

confidence: 99%

Mechanics of interrill erosion with wind‐driven rain

Erpul

Gabriëls

Norton

et al. 2012

Earth Surf Processes Landf

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The vector physics of wind‐driven rain (WDR) differs from that of wind‐free rain, and the interrill soil detachment equations in the Water Erosion Prediction Project (WEPP) model were not originally developed to deal with this phenomenon. This article provides an evaluation of the performance of the interrill component of the WEPP model for WDR events. The interrill delivery rates were measured in the wind tunnel facility of the International Center for Eremology (ICE), Ghent University, Belgium with an experimental setup to study different raindrop impact velocity vectors. Synchronized wind and rain simulations with wind velocities of 6, 10 and 14 m s–1 were applied to a test surface placed on windward and leeward slopes of 7, 15 and 20%. Since both rainfall intensity and raindrop impact velocity varied greatly depending on differences in the horizontal wind velocity under WDRs, the resultant kinetic energy flux (KEr, in J m–2 s–1) was initially used in place of the WEPP model intensity term in order to incorporate the effect of wind on impact velocity and frequency of raindrops. However, our results showed only minor improvement in the model predictions. For all research data, the model Coefficients of Determination (r2) were 0·63 and 0·71, when using the WEPP and the KEr approaches, respectively. Alternately, integrating the angle of rain incidence into the model by vectorally partitioning normal kinetic energy flux (KErn, in J m–2 s–1) from the KEr greatly improved the model's ability to estimate the interrill sediment delivery rates (r2 = 0·91). This finding suggested that along with the fall trajectory of wind‐driven raindrops with a given frequency, raindrop velocity and direction at the point of impact onto the soil surface provided sufficient physical information to improve WEPP sediment delivery rate predictions under WDR. Copyright © 2012 John Wiley & Sons, Ltd.

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Sand transport under increased lateral jetting of raindrops induced by wind

Cited by 16 publications

References 52 publications

Rain splash of soil grains as a stochastic advection‐dispersion process, with implications for desert plant‐soil interactions and land‐surface evolution

Rain splash of soil grains as a stochastic advection‐dispersion process, with implications for desert plant‐soil interactions and land‐surface evolution

The elements and richness of particle diffusion during sediment transport at small timescales

Mechanics of interrill erosion with wind‐driven rain

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