What is the unit used for the specific yield in the drawdown example?

• A. gpm
• B. gpm/ft
• C. ft
• D. gpd

Answer: (B)

The unit for specific yield in this drawdown context is gallons per minute per foot. The idea is that you’re relating the water released to the aquifer per unit length of the cross-section or per foot of aquifer thickness. This means you’re looking at how much water flows per unit length each minute, not just a total flow or a pure length. That per-length, per-time representation is what makes gpm/ft the appropriate unit here. The other options—gpm alone (total flow), ft (a length without flow), or gpd (total daily flow)—don’t capture the per-length flow aspect that the drawdown example uses.