HYDRAULICS OF A LARGE CHANNEL PAVED WITH BOULDERS

Abstract

Experience is described of a 41 m wide by 308 m long, open channel on a 0.052 slope, constructed of loose boulders and through which flows up to 140 m3/s are passed. A new expression for the Darcy friction coefficient is proposed: f = ((1 − 0.1ks /R)2log10 (12R/ks ))−2 with a theory based on published laboratory data. This equation with ks = 4.5D is shown to fit the large channel, and other published field data. Some observations are made on both the geometry and the stability of the paving.