What is erosion?
Erosion is the process by which soil particles are displaced. Typically erosion is caused by water, but there are other types caused by wind and gravity. Erosion is accelerated when water is moving fast and when there is a large volume of water washing over the soil.
Erosion strips the soil of nutrient rich topsoil and deposits it in other areas that may not be suitable like creeks and roads. In fact, sediment (displaced soil) can be extremely detrimental to aquatic habitats.
What can be done to slow down erosion?
We can't avoid rain storms, but we can reduce the erosion they cause. There are some fundamental concepts that, when used effectively, can almost eliminate erosion. The key to stopping erosion is to anchor the soil in place and to slow down the water moving across it.
- The best way to hold the soil in place is to plant vegetation in the soil. Establishing a ground cover has many benefits besides controlling erosion. Grass, shrubs and trees are all effective ground covers.
- Another treatment might be to divert the water flow across an area with under ground piping or vegetative channels or berms.
- Terracing is an effective treatment to control erosion on sloping areas. The level steps of a terrace reduces the velocity water by stopping the water from flowing down hill. Terraces allows the water to be move nearly parallel to the slope of the land and discharges the water to a safe and stable outlet. By slowing the movement of water, terraces gives the water time to seep into the ground.
- Strip-landscaping is another way to stop erosion on longer slopes. Rather than building walls for terraces, plant level landscape beds across the slope to plant vegetation and slow water movement. Alternating strips of plants with strips of grass will stabilize the soil on a slope. The grass strips will act as a filter strip or buffer between areas planted with flowers or shrubs. One key point to remember when designing strip—landscapes across a slope is to make the grass strips wide enough to mow with a lawnmower. Also, the most effective landscape beds will be the ones that are the most level, just like terracing.
Why establish ground cover?
Ground cover provides excellent erosion and sediment control by stabilizing the soil. The vegetation:
- decreases the volume of soil particles dislodged due to rain and other natural forces
- slows the flow of water across the soil
- slows the scouring effect moving soil has across the yard
- provides a buffer that acts as a filter, decreasing the movement of sediment and other materials like pesticides and fertilizers
This cover has many other benefits including the addition of organic matter, aesthetic value, wildlife benefits, absorption of rain water, and many others.
If areas are left exposed, severe erosion and sediment damage can take place. Organic-rich topsoil can be completely removed leaving an infertile mineral soil on the surface. A soil's moisture content can drop so dramatically that the soil surface can crust over, dust problems occur, water infiltration reduced, and heat reflectance is increased.
Erosion is soil's worst enemy for many reasons:
- It strips the soil of the nutrient rich topsoil
- It scours vegetation from places where it is already established
- It clogs surface waters, strangling aquatic habitat
- It can leave mud on the roads
- It displaces sediment to unwanted areas