Erosion Control
Erosion control is any method used to keep soil in place and stop water or wind from washing it away.
Think of it this way
A layer of rocks at the bottom of a colander holds flour in place when you pour water through it. Without the rocks, the flour washes straight out. The rocks slow the water and keep the flour from moving. Soil stays put the same way when roots, rocks, or mulch block the flow of rain.
Explaining erosion control by grade level
Rain can wash dirt away. Plants and trees help hold dirt in place with their roots. In one project, a model swamp stops big waves from moving sand. Roots and branches slow the water down.