Nonlocal Sediment Transport on Steep Lateral Moraines, Eastern Sierra Nevada, California, USA. Issue 1 (30th January 2018)

• Record Type: Journal Article
• Authors: Doane, Tyler H.; Furbish, David Jon; Roering, Joshua J.; Schumer, Rina; Morgan, Daniel J.
• Is Part Of: Journal of geophysical research. Volume 123:Issue 1(2018)
• Page Start: 187
• Page End: 208
• Publication Date: 2018-01-30
• Subjects: nonlocal transport -- hillslope -- sediment entrainment; Geomorphology -- Periodicals; 551.3
• DOI: 10.1002/2017JF004325
• Languages: English
• ISSNs: 2169-9003

Abstract

Abstract : 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. Key Points: Numerical models involving nonlocal transport closely match observed moraine profiles The parameters of nonlocal models have clear physical definitions, and entrainment is a key value The evolution of the land surface spectra based on different transport formulae are diagnostic of the style of sediment transport