Different types of land cover interact with water moving over the landscape in different ways. Changes due to erosion and runoff sometimes occur slowly and naturally as wind and water move over the land. However, urban development and other human impacts can result in rapid loss of protective vegetation. This activity demonstrates how plants help slow runoff and prevent erosion.

• On day one, fill the two cups or bowls with an equal amount of soil and some pebbles

• In one of the cups, sprinkle on 1-2 tablespoons of grass seeds and mix them in just so they are covered

  • Gently water the seeds and store in a dark place for 3-4 days until it starts sprouting, then move to a sunny spot (store on a small plate to catch any extra water)

  • Let the grass grow until it is a few inches high (this might take a week)

  • Whenever you water the grass (just a little every day) add some water to the soil/pebble mix as well to keep it moist

• Once the grass is a few inches high, place the cup with the grass and the cup with just the soil and pebbles next to each other on the tray/cookie sheet

• Carefully remove the paper from both (some soil might fall away, but it should stay clumped together

• Place something under the tray to make it angle down like a mountainside (cups should be on the higher end)

• Then, using a watering can or cup of water, make it gently “rain” on both the grass and soil/pebble mixture

Questions to ask yourself while you work:

• What do you notice about how much soil runs down the side of the “mountain”?

• Why do you think the soil with the grass held together better than the soil without?

• What does this tell us about erosion and mudslides?

• What does this tell us about areas that have had their trees cut down?

• How would things be different if one year was very dry and another year had very heavy rains?