As development occurs, the area of land that becomes impervious--that is, the water doesn't absorb back into the ground because it is covered by concrete or buildings--increases. This means when it rains, much of the water that hits the ground runs off into a storm drain instead of infiltrating through the soil. This water is called "stormwater" and as impervious surfaces increase, the volume of stormwater increases as well.
A higher volume of water entering the stormwater system results in a greater flow and more velocity that picks up soil and pebbles and deposit them downstream; this is called "erosion." It's the same process that formed the Grand Canyon millions of years ago! Erosion changes the characteristics of a stream and can make it less stable.
Why is erosion bad?
Erosion can make land along the water unstable as water cuts away at the shore. This can result in loss of property and potential damage to homes and structures. Erosion also carries dirt and sediment downstream, where it is deposited and can cause further damage to the waterway and adjacent land. This muddy water also negatively impacts fish and wildlife.
What can I do about it?
Almost all of the tips mentioned on our Streams and Urban Runoff page will also mitigate the impacts of erosion.