Slide 6 of 27
Notes:
In rills such as shown in the previous slide, there may be an interaction between weathering of the bedrock and detachment of weathered material by the flow. The weathering may occur either during the storm event due to wetting by the flow, or between storms by wetting and drying, weak chemical weathering, or frost action. Howard (1998, op. Cit) presented a heuristic model for how such interactions might occur. The model assumes that the partially weathered bedrock is detached as layers of thickness ?d. The cohesion, C, of the partially weathered bedrock decreases through time from an intial value, Ci, to a final value, Cf (left equation). Water flow through the channel exerts a shear stress ? which results in detachment when C= ? , which occurs after time ?t (right equation).
