Plot-scale sediment transport processes on a burned hillslope as a function of particle size

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Abstract

Soil moisture, rainfall, runoff, and sediment transport data were collected from four 1-m2 hillslope plots after the 2000 Hi Meadow Fire in Colorado. Data were collected daily during three summers, two of which were affected by drought. Maximum 30-minute rainfall intensities, I30, were less than 20 mm h-1 and the average runoff volumes per plot were less than 4.7 L per storm. The data were separated into three sediment transport processes based on rainfall intensity and runoff magnitude: (1) dry ravel, (2) rainsplash, and (3) rainflow and then into eight different particle size classes (Di). For each class, dry ravel transport had a non-linear dependence on initial soil moisture, θi, with a maximum at intermediate values of θi (5-9 % cm3 cm-3). Dry ravel transport rates were small for low θi , which may be caused by a cementation process, and also small for high θi , which may be caused by increased surface tension. Rainsplash transport was confined to the I30 domain from 1-7 mm h-1 was proportional to Di(Imax30)0.63. Rainflow transport (I30 > 7 mm h-1) in shallow flows (h < 2 mm) was most likely dominated by particles rolling. It had a non-linear dependence on Di with maximum transport of sediment in the 2-4 mm size class. Transport also depended on stream power, but critical stream power was essentially zero, which may indicate that the rainsplash preceding runoff detached soil for transport by overland flow.

Additional publication details

Publication type Conference Paper
Publication Subtype Conference Paper
Title Plot-scale sediment transport processes on a burned hillslope as a function of particle size
Year Published 2010
Language English
Contributing office(s) National Research Program - Central Branch
Description 12 p.
Conference Title 2nd Joint Federal Interagency Conference
Conference Location Las Vegas, NV
Conference Date June 27-July 1, 2010