Most soil loss due to water occurs because of high runoff
events, such as heavy rainstorms. Soils are subject to water erosion throughout
Alberta. Extreme rainstorms have led to serious soil loss events on farmland
from Medicine Hat to Fort Vermillion. Measurements on a continuously cropped farm
field near Tofield reported soil losses as high as 10 tonnes per hectare for the
summer of 1996 as a result of a number of moderate rainstorms.
Fields with poor water infiltration as a result of
clay-enriched, compacted, or hardened subsoil, are at increased risk of water
erosion. These soils rapidly reach the point where they are unable to absorb
more water. Any additional rainfall is then forced to move as surface runoff,
carrying away the topsoil. Some soils are more prone to erosion for other
reasons, such as steep slope. Protecting soil through good agricultural land
management is the single most important factor in preventing serious water
Department of the Environment. State of the Environment Report, Terrestrial Ecosystems. Edmonton: n.p., 2001. With permission from Alberta Environment.