What is the term for the difference between the static water level and the pumping level in a well?

The correct answer is drawdown, which is defined as the difference in water levels measured in a well between the static water level (the level of water in the well when it is not being pumped) and the pumping level (the level of water when the well is actively being pumped). Understanding drawdown is crucial because it informs operators about the well's efficiency and the sustainability of water extraction.

In practical terms, when a well is pumped, the water level drops due to the flow of water being withdrawn. The amount by which the water level falls is the drawdown. This measurement is essential for assessing groundwater availability and can also help determine the need for adjustments in pumping practices or the design of the well system.

The other terms provided do not relate directly to the difference between static and pumping levels. For example, flow rate refers to the volume of water being delivered per unit time but does not account for the levels in the well. Casing depth pertains to the construction of the well and how deep the casing extends but is not related to the water levels. Static pressure is a term that might describe the pressure at rest within the system but does not convey the concept of water levels in the context of well operation.