In general, water erosion rates are high on steep slopes and in concavities because slope and slope length are maximized. Deposition occurs on weak slopes. Unlike water erosion, tillage erosion is controlled by the change in slope gradient and not by the gradient itself. Tillage erosion takes places on covexities while soil accumulation occurs in concavities. (Red = erosion; Green = deposition).

WATER	TILLAGE

Water erosion: Due to the presence of vegetation barriers and/or because of a change in crop type, overland flow will often be retarded at a field boundary. The behavior of the water erosion process at a field boundary is complex and characterized by a high spatial and temporal variability. WaTEM simplifies these processes by assuming that a fixed percentage of sediment and water is trapped at a field boundary.

Unlike water erosion, tillage redistribution will only occur within a field for each field boundary is a line of zero flux. On sloping land, this leads to important tillage erosion at the downslope side of field boundaries and deposition at the upslope side.

WATER	TILLAGE