Soil Erosion–Four stages and wind

[Bernard NebelKeymaster]

Soil erosion occurs in stages as described below. Whatever the extent of erosion, have students consider the farm fields left behind. Can they be as productive for growing crops?

 

1. Soil erosion begins with splash erosion. Falling rain drops, on a micro scale, “blast” soil particles apart and send them flying with the splash. See the following slow motion video of a drop impacting a sand surface. Note the fine soil particles being “blasted” outward by the splash.

2. Particles dislodged my splash are free to be carried along by water flowing over the surface, if there is any slope whatsoever. This results in sheet erosion, the removal of a sheet of topsoil. Splash and sheet erosion wash away the fine particles of soil leaving the heavier coarse sand and stones. Type into your browser: sheet erosion images/ Note the stoney, rocky surface of fields suffering from sheet erosion.

3. With any appreciable slope, water flowing from the surface gathers into rivulets which have greater capacity to carry soil particles. This leaves a field with a network of “micro gullies” known as rill erosion. Type into your browser: rill erosion images

4. In turn, rivulets combine into larger and larger streams with increasing carrying capacity. This results in the carving out of larger and larger gullies, i.e. gully erosion. Type into your browser: gully erosion images

Wind blowing over bear, dry soil, likewise, has a significant erosive force, wind erosion, with the same effects as sheet erosion. Soil is left more coarse, rocky, and stoney as larger particles resist being blown away.

A catastrophic episode of wind erosion, dubbed the Dust Bowl, occurred in the 1930s. See: https://www.history.com/news/10-things-you-may-not-know-about-the-dust-bowl

Have your kids keep their eyes out for instances of erosion they see in their surroundings. Report them to the NRCS (see below).

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