Drawdown is defined as the vertical difference between which two water levels?

• A. The pumping water level and the static water level
• B. The static water level and the ground surface
• C. The municipal water level and the aquifer level
• D. The pumping water level and the dynamic water level

Answer: (A)

Drawdown is the vertical difference between the static water level and the pumping water level. The static water level is the natural water surface in the well when no pumping occurs. Once pumping starts, the water surface in the well drops to a lower level—the pumping water level. The difference between these two levels is the drawdown, reflecting how much the aquifer has been upset by pumping. Its magnitude depends on how much water is being pumped, for how long, and the aquifer’s properties like transmissivity and storativity. The other options don’t fit because drawdown isn’t measured from the ground surface or between municipal and aquifer levels, and using a dynamic water level would just repeat the pumping level rather than define a difference from the static level.