In a gravel well, what is the expected effect of screen encrustation?

• A. Increase in yield
• B. No change in yield
• C. Increased drawdown
• D. Decrease in yield

Answer: (D)

Screen encrustation reduces the open area through which water can enter the well, raising flow resistance at the intake. That added resistance means the pump cannot pull as much water for the same effort, so the yield decreases. You may also see more drawdown for a given discharge, since the pump must work harder to lift water through the crusted screen, but the main effect is a lower yield.