Rain on a Split Hillside

In the picture

1. 1Bare packed earth on the left half of the slope
2. 2One of three gullies cut into the bare earth
3. 3Brown mud fan spread at the foot of the bare half
4. 4Dense grass covering the right half of the slope
5. 5Root network in the cut soil edge under the grass

Examples

• A garden bed left bare all winter loses soil in every downpour, while the lawn beside it stays level.
• Road embankments are seeded with grass so heavy rain does not wash them onto the road surface.

Quiz: Rain on a Split Hillside (Age 15)

1. 1

   Rain falls with the same force on a bare slope and on a grassy slope right beside it. Why does the bare slope lose far more soil?

   • Rain hits bare ground harder than it hits grassy ground.
   • Grass roots hold the soil grains together, so the water cannot carry them away.
   • Bare soil is heavier, so it slides downhill more easily.
2. 2

   A farmer’s steep, bare field loses soil every time it rains. Which change would protect it best?

   • Grow a thick cover of grass or other plants over the bare ground.
   • Press the bare soil down hard so the rain cannot move it.
   • Dig channels straight down the slope so the water leaves faster.
3. 3

   Rain has stripped soil from a bare slope. Where has that soil gone?

   • It has soaked deeper into the slope and is still there.
   • It has been washed downhill and left in a pile at the foot of the slope.
   • It has been broken apart by the rain and no longer exists as soil.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.