Question

a dam is built on a large river. backed - up water behind the dam forms a lake, like in the picture below.
the dam doesnt just hold back water; it also holds back soil and sediment. how will the dam most likely affect the river downstream?
a. natural deposition rates will decrease.
b. natural weathering rates will increase.
c. natural weathering rates will decrease.
d. natural deposition rates will increase.

Explanation:

Deposition is the process of sediment being laid down. A dam holds back soil and sediment, so less sediment flows downstream. This means the natural deposition (laying down of sediment) rates downstream will decrease. Weathering is the breakdown of rocks, and a dam doesn't directly affect weathering rates in this context. So option A is correct.

Answer:

A. Natural deposition rates will decrease.