Statistical Characterization of Grain-Size Distributions in Sandy Fluvial Systems

• DOI: 10.2110/jsr.2010.020
• Publication Date: 2010-02-02T23:53:44Z
• Authors: E. A. Hajek; S. V. Huzurbazar; D. Mohrig; R. M. Lynds; P. L. Heller
• Keywords: Characterization

Measured particle-size distributions are commonly reduced to one characteristic value (e.g., median grain diameter) that is used in sediment transport modeling and other analyses. These values often interpolated from empirical or fitted distributions, usually assuming observed grain-size populations adequately represented by Gaussian Normal distributions. In order investigate the implications of this approach, we (1) statistically characterize samples bed-material load, suspended slackwater deposits sand-bedded Calamus, North Loup, Niobrara rivers (Nebraska, USA), (2) explore potential impact misfitting on estimating percentile diameters. Although log-normal complete sedimentary systems, study, transported best modeled with log-hyperbolic mixtures Despite large overlaps sizes bed-material-load suspended-load samples, estimated parameters show consistent differences between these across all rivers. Samples load have higher modes positive (coarse-grained) asymmetry, whereas lower weaker asymmetry. Because it has a general form, distribution should unimodal because its can yield both normal-shaped as well asymmetric three rivers, contain entire range present suspension significant component very fine-grained (< 0.02 mm) material not suspended-sediment samples. This suggests some degree fractionated deposition areas near-zero flow velocities. Ultimately, fitting parametric data be useful way find effective for use studies. However, particularly may result errors sizes, which considered studies relying grain-diameter values.