Why is siltation such a pressing question for dam builders? ...

[Bernana]

Why is siltation such a pressing question for dam builders? Explain how you decided on your answer.
 
  What will be an ideal response?

Question 2

Material replacement is one solution to mineral resource depletion.
 
  What will be an ideal response?

[zhanghao]

Answer to Question 1

When there is silt buildup in the lake, the capacity of the reservoir decreases. Over
a period of time, the reservoir will fill with silt and the intake of water can be adversely
affected.

Answer to Question 2

This is correct, where replacement is possible. It is not always possible to replace
materials with other materials.

[Bernana]

Thanks for the timely response, appreciate it

[xiazhe]

Great answer, keep it coming