A METHOD FOR DEVELOPING PROBABILITY-DISTRIBUTIONS FOR RILL FLOW AND DENSITY

Citation
Sm. Lewis et al., A METHOD FOR DEVELOPING PROBABILITY-DISTRIBUTIONS FOR RILL FLOW AND DENSITY, Transactions of the ASAE, 37(6), 1994, pp. 1879-1887
Citations number
18
Categorie Soggetti
Engineering,Agriculture,"Agriculture Soil Science
Journal title
ISSN journal
00012351
Volume
37
Issue
6
Year of publication
1994
Pages
1879 - 1887
Database
ISI
SICI code
0001-2351(1994)37:6<1879:AMFDPF>2.0.ZU;2-D
Abstract
Procedures are presented and evaluated for developing probability dist ribution functions for rill numbers (density) and rill flow rates that can be used to represent the stochasticity of rill networks in recent erosion models such as PRORIL. Subsoil and topsoil data sets, includi ng photographs, collected at the University of Kentucky were used in t he evaluation. Photographic images were corrected for optical distorti on and visually analyzed to develop the rill networks. A digital terra in model (DTM) that allowed combining of channels, but not flow splitt ing, was also utilized to develop a flow network and compared to the p hotographically determined network. The DTM generated network did not provide a good fit to the photographically determined network, likely because of problems with interpolation and with the inability to predi ct rill splitting. The DTM generated networks were utilized to develop probability density functions (PDFs) for rill numbers and conditional PDFs for rill flow rates given a number of rills. The binomial distri bution provided a good fit to rill number distributions as defined by the Kolmogorov-Smirnov test. The Weibull distribution provided the bes t fit to the conditional PDF for flow rates, but the goodness of fit w as poor. This lack of fit, likely due to inadequacies of the DTM, shou ld improve with improved DTMs.