Erosion and Deposition: Wind, Gravity, and Living Things — Quiz
Question 4 • Earth and Space Science
A team modeled how vegetation placement affects the direction and concentration of runoff and sediment build-up on a slope. In one model, curved rows of shrubs were planted to follow the slope's contours. This arrangement slowed runoff and caused sediment to accumulate in patches behind the shrub rows, often in stable zones upslope. In the other model, shrub rows were planted directly downslope. This arrangement channeled runoff straight downhill, and sediment collected more evenly at the base of the slope. Which explanation best supports how vegetation influenced deposition in this case?
Answer
A
Shrubs arranged across slope contours prevented all soil loss by blocking flow at the top of the model.
B
Vegetation placed along slope contours redirected flow laterally, concentrating sediment in stable, elevated zones.
C
Vegetation rows in both models affected runoff flow, but neither changed where sediment was most likely to collect.
D
Shrubs placed in straight lines downslope created turbulence that reduced erosion but evenly spread sediment.
Explanation
Rows following the slope’s contours crossed the downhill flow, slowing runoff and redirecting it sideways. As the water slowed, sediment accumulated in patches behind the shrubs, including stable zones higher on the slope. This supports the explanation that contour-aligned vegetation concentrated sediment in elevated areas; it did not block all soil loss, as choice A claims.
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