Field experiments constraining the probability distribution of particle travel distances during natural rainstorms on different slope gradients

Ghahramani, Afshin and Ishikawa, Yoshiharu and Mudd, Simon M. (2012) Field experiments constraining the probability distribution of particle travel distances during natural rainstorms on different slope gradients. Earth Surface Processes and Landforms, 37 (5). pp. 473-485. ISSN 0197-9337


Rain splash erosion is an important soil transport mechanism on steep hillslopes. The rain splash process is highly stochastic; here we seek to constrain the probability distribution of splash transport distances on natural hillslopes as a function of hillslope gradient and total precipitation depth. Field experiments were conducted under natural precipitation events to observe splash travel on varying slope gradients. The downslope fraction of splash transport on 15 degrees, 25 degrees and 33 degrees gradients were 85%,96% and 96%, respectively. Maximum splash transport (Lmax) was related to the rain splash detachment of soil particles and slope gradient. An empirical relationship of Lmax to the precipitation depth and gradient was obtained; it is linearly proportional to hillslope gradient and logarithmically related to precipitation depth. Measured splash distances were calibrated to the fully two-dimensional (2D) model of splash transport of Furbish et al. (Journal of Geophysical Research 112: F01001, 2007) that is based on the assumption that radial splash distances are exponentially distributed; calibrated values of mean splash transport distances are an order of magnitude greater than those previously determined in a controlled laboratory setting. We also compared measured data with several one-dimensional (1D) probability distributions to asses if splash transport distances could be better explained by a heavy-tailed probability distribution rather than an exponential probability distribution. We find that for hillslopes of 15 degrees and 25 degrees, although a lognormal probability distribution best describes the data, we find its likelihood is nearly indistinguishable from an exponential distribution based on computing maximum likelihood estimators for all 1D distributions (exponential, log-normal and Weibull). At 33�, however, we find stronger evidence that measured travel distances are heavy-tailed.

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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to Published version, in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Historic - Institute for Agriculture and the Environment
Date Deposited: 09 Nov 2016 23:43
Last Modified: 21 Mar 2017 04:24
Uncontrolled Keywords: rain splash; probability distribution function; heavy-tailed distribution; sediment transport; slope gradient
Fields of Research : 05 Environmental Sciences > 0502 Environmental Science and Management > 050209 Natural Resource Management
05 Environmental Sciences > 0503 Soil Sciences > 050399 Soil Sciences not elsewhere classified
04 Earth Sciences > 0499 Other Earth Sciences > 049999 Earth Sciences not elsewhere classified
Identification Number or DOI: 10.1002/esp.2253

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