The erodibility of a soil is determined by the material textural properties, such as particle size, structure and cohesion. The magnitude of erosive forces is determined by the quantity of surface runoff and its associated energy, which are related to precipitation and slope characteristics. Many polygons on soil maps contain complexes of two or three soil associations.
Most soils maps have accompanying reports which describe the soil associations in detail.
Included in these reports are interpretations of the erodibility of the soil associations in the event of soil surface disturbance. Erodibility is assigned to soils in erodibility groups based on slope. In British Columbia a three-class erodibility classification associated with soils mapping is most commonly used. In some cases, soils maps may not be accompanied by reports in which soils associations and potential erodibility are defined. In these cases, erodibility groups can be established for soil associations on the basis of slope and soil attributes identified in the soil polygon label.