Skip to content

Sediment transport by runoff on debris-mantled dryland hillslopes

Research output: Contribution to journalArticle

Original languageEnglish
Article numberF03014
Number of pages14
JournalJournal of Geophysical Research: Earth Surface
Volume117
Early online date9 Aug 2012
DOIs
DateE-pub ahead of print - 9 Aug 2012
DatePublished (current) - Sep 2012

Abstract

Hillslopes supply sediment to river channels, and therefore impact drainage basin functioning and evolution. The relationship between hillslope attributes and sediment flux forms the basis of geomorphic transport laws used to model the long-term topographic evolution of drainage basins, but their specific interactions during individual storm events are not well understood. Runoff-driven erosion of coarse particles, prevalent in dryland environments, presents a particular set of conditions for sediment transport that is poorly resolved in current models. In order to address this gap, we developed a particle-based, force-balance model for sheetwash sediment transport on coarse, debris-mantled hillslopes within a rainfall-runoff model. We use the model to examine how the interplay between hillslope attributes (gradient, length and grain size distribution) and runoff characteristics affects sediment transport, grain-size changes on the hillslope, and sediment supply to the slope base. The relationship between sediment flux and hillslope gradient was found to transition from linear above a threshold to sigmoidal depending on hillslope length, initial grain sizes, and runoff characteristics. Grain sizes supplied to the slope base vary in a complex manner with hillslope attributes but an overall coarsening of the hillslopes is found to occur with increasing gradient, corroborating previous findings from field measurements. Intense, short duration storms result in within-hillslope sediment redistribution and equifinality in sediment supply for different hillslope characteristics, which explain the lack of field evidence for any systematic relationships. Our model findings provide insights into hillslope responses to climatic forcing and have theoretical implications for modeling hillslope evolution in dry lands.

Download statistics

No data available

Documents

Documents

  • Michaelides Martin 2012 JGR

    Rights statement: Published by AGU. Copyright 2012, American Geophysical Union. Journal of Geophysical Research: Earth Surface (2003-2012), Vol. 117, Issue F3, September 2012.

    Final published version, 610 KB, PDF document

DOI

View research connections

Related faculties, schools or groups