Factors Affecting Soil Cohesion.

Soil erodibility is a measure of a soil’s resistance against erosive forces and is affected by both intrinsic (or inherent) soil property and the extrinsic condition at the time erodibility measurement is made.   Since soil erodibility is usually calculated from results obtained from erosion experiments, there is a strong influence of the extrinsic condition in the erodibility value.   We recently developed a simple fluidized bed system that can measure soil cohesion and showed a good correlation between laboratory measured soil cohesion and field measured critical shear stress, an erodibility parameter for erosion by concentrated flow.    In this research, we further apply the fluidized bed technique to quantify the development of soil cohesion from drainage and aging.   Preliminary results showed that profile drainage (or wet consolidation) has a greater impact in the development of soil cohesion than aging.    The results provide the basis for a soil erodibility adjustment factor to account for the wetting and drying effects.