Author(s)

Katherine Clancy

College of Natural Resources, University of Wisconsin at Stevens Point, Stevens Point, WI, USA.

Boulders and cobbles are often used in stream restoration projects to increase flow resistance and enhance channel stability and habitat diversity. Particle size metrics determined from the particle distribution are often used as a proxy for shear stress in field equations. Clustering of large particles has been thought to contribute to shear stress, but the effect of clustering is not accounted for in equations that use a representative particle size, such as the D₈₄. In this paper, clustering is defined using the upper tail (≥84%) in a variable called Topsum. The number of clusters, average size of clusters, and shear stress are evaluated using the proposed definition of cluster. Findings suggest that the upper tail represents the roughness height better than the commonly used proxy of D₈₄ for boulder bed streams (streams which have a D84 particle 0.05 - 0.15 meters).

Boulder Bed, Shear Stress, Particle Distribution, D₈₄

Clancy, K. (2021) Characterizing Clustering in Boulder Bed Channels and the Impact on Shear Stress Equations. Journal of Water Resource and Protection, 13, 283-292. doi: 10.4236/jwarp.2021.134017.