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How does grid-resolution modulate the topographic expression of geomorphic processes?

Grieve, Stuart W.D.; Mudd, Simon M.; Milodowski, David T.; Clubb, Fiona J.; Furbish, David J.

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Authors

Stuart W.D. Grieve

Simon M. Mudd

David T. Milodowski

David J. Furbish



Abstract

In many locations, our ability to study the processes which shape the Earth are greatly enhanced through the use of high-resolution digital topographic data. However, although the availability of such datasets has markedly increased in recent years, many locations of significant geomorphic interest still do not have high-resolution topographic data available. Here, we aim to constrain how well we can understand surface processes through topographic analysis performed on lower-resolution data. We generate digital elevation models from point clouds at a range of grid resolutions from 1 to 30m, which covers the range of widely used data resolutions available globally, at three locations in the United States. Using these data, the relationship between curvature and grid resolution is explored, alongside the estimation of the hillslope sediment transport coefficient (D, in m2yr−1) for each landscape. Curvature, and consequently D, values are shown to be generally insensitive to grid resolution, particularly in landscapes with broad hilltops and valleys. Curvature distributions, however, become increasingly condensed around the mean, and theoretical considerations suggest caution should be used when extracting curvature from landscapes with sharp ridges. The sensitivity of curvature and topographic gradient to grid resolution are also explored through analysis of one-dimensional approximations of curvature and gradient, providing a theoretical basis for the results generated using two-dimensional topographic data. Two methods of extracting channels from topographic data are tested. A geometric method of channel extraction that finds channels by detecting threshold values of planform curvature is shown to perform well at resolutions up to 30m in all three landscapes. The landscape parameters of hillslope length and relief are both successfully extracted at the same range of resolutions. These parameters can be used to detect landscape transience and our results suggest that such work need not be confined to high-resolution topographic data. A synthesis of the results presented in this work indicates that although high-resolution (e.g., 1m) topographic data do yield exciting possibilities for geomorphic research, many key parameters can be understood in lower-resolution data, given careful consideration of how analyses are performed.

Citation

Grieve, S. W., Mudd, S. M., Milodowski, D. T., Clubb, F. J., & Furbish, D. J. (2016). How does grid-resolution modulate the topographic expression of geomorphic processes?. Earth Surface Dynamics, 4(3), 627-653. https://doi.org/10.5194/esurf-4-627-2016

Journal Article Type Article
Acceptance Date Jul 25, 2016
Online Publication Date Aug 8, 2016
Publication Date Aug 8, 2016
Deposit Date Jul 3, 2019
Publicly Available Date Mar 29, 2024
Journal Earth Surface Dynamics
Print ISSN 2196-6311
Publisher Copernicus Publications
Peer Reviewed Peer Reviewed
Volume 4
Issue 3
Pages 627-653
DOI https://doi.org/10.5194/esurf-4-627-2016

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