Classic or Ephemeral Gully Erosion
Classic gully erosion is a form of erosion created when soil is detached from areas of concentrated flow in well defined drainageways. Classic gullies are created by runoff that can enlarge a channel progressively by head cutting and/or lateral widening. These gullies can be wide and deep. They generally appear on all land uses where any concentrated flow is found and vegetative cover is poor.
Classic gullies tend to form a branching pattern. These types of gullies are too wide and deep to be hidden by tillage.
Permanent vegetation and/or grade stabilization structures may be required to stabilize areas along with management practices. In South Dakota, gullies can appear anywhere in the state.
Ephemeral gullies are very much wider than they are deep. They are formed during heavy rainfall when infiltration is minimal. They tend not to go deeper than the tilled layer. They can be removed by normal tillage, but it is better to use soil health practices to reduce the chances of gully formation. If soil health practices are used and ephemeral gullies still form, a waterway can be installed. This practice is applied in areas where added water conveyance capacity and vegetative protection are needed to prevent erosion and improve runoff water quality resulting from concentrated surface flow.
To avoid excessive erosion, timing of waterway construction must allow seeding grasses immediately after completion of construction. Consider including diverse legumes, forbs, and flowering plants such as milkweeds that provide pollen and nectar for native bees and other pollinators.
If tillage and crop planting operations are done parallel to the waterway, it will reduce the amount of surface flow reaching the waterway as water will travel along the edges of the waterway. To reduce this effect, lift equipment and travel through the waterway.
Sheet and Rill Erosion
Sheet erosion is a type of erosion that occurs when topsoil from a field is removed. Sheet erosion occurs as a shallow sheet of water flowing over the ground surface resulting in the removal of a uniform layer of soil from the soil surface. Typically occurs when rainfall intensity is greater than infiltration.
Rill erosion is a type of erosion that occurs when water forms small channels as it concentrates down a slope. Rill erosion develops when surface water concentrates in depressions or low points through fields and erodes the soil. Rill erosion is common on fields with little to no crop residue resulting from tillage operations or on overgrazed grasslands.
The most effective way to control erosion is to keep the soil surface covered or armored, either with growing plants or residues from past crops to absorb the impact for raindrops, thus decreasing the kinetic energy when the raindrops reach the soil. This also slows the rate of water flow across the surface allowing more time for the water to infiltrate the soil resulting in decreasing runoff, detachment, and transportation and increasing deposition. It is also important to build healthy soils by promoting crop systems that build carbon/soil organic matter, promote soil aggregate stability, promote infiltration and water holding capacity throughout the soil profile, and feeds soil microbes that help in creating biotic glues that help in forming strong soil aggregation.
Streambank or Shoreline Erosion
Streambank and shoreline erosion results from poor land storm events, wave action, rain, ice, wind, runoff, loss of vegetation, management practices, hydrologic dynamics, stream isolation from floodplains, and/or other disturbed/altered geomorphological processes.
Shores of lakes, streams, and rivers are naturally predisposed to erosion due to the moving water. Bank erosion occurs when the banks of a stream or river are gradually worn away. The erosion in this picture is caused by flooding, mostly from the runoff of two creeks that run into the river. Streambank erosion can negatively impact water quality and reduce aquatic habitat.
Solutions to consider:
-High moisture using vegetation buffers along edge of bank
-Diverting surface runoff water away from eroding banks
-Slowing down runoff rates
-Limiting construction/buildings along the edge of banks
-Rip rap if vegetation on banks cannot be established
Wind Erosion occurs when soil particles are detached, transported, and deposited by wind. Soil particles may or may not leave the field or area from which they are eroded. Kinetic energy is the primary force in wind erosion. The effects of wind erosion were most dramatically illustrated by the Dust Bowl of the 1930’s, which was possibly the worst environmental disaster in the history of the United States.
Wind erosion is a very common event throughout the high plains of South Dakota. The most effective way to control erosion is to keep the soil surface covered or armored, either with growing plants or residues from past crops. It is also important to build healthy soils through applied agricultural management practices that maximizes biodiversity, maximizes living cover, maximize continuous living roots, and minimizing soil disturbance.