Erodibility of Streambank Materials of Low Cohesion

Abstract

ABSTRACT EROSION rates of undisturbed channel bank mate-rials were determined in the field using a portable flume. Two erosive forces were identified. Samples that were relatively dry before testing eroded excessively, which was probably the result of the detaching effect of sample wetting. Samples that were relatively wet before testing did not exhibit this excessive erosion, and these erosion rates were singularly dependent upon bed shear stresses. Clay content of the samples correlated signifi-cantly with the shear stress-dependent erosion rates, and the maximum noneroding pinhole velocities correlated significantly with the same erosion rates for samples that had no limiting morphological characteristics. The sig-nificance of sample morphology was scale dependent, varying with the size of the test sample in relation to the size of the morphological components.