What is the definition of well draw down?

Well draw down refers to the distance between the static water level and the pumping water level within a well. When water is extracted from the well, the water level drops, creating a difference between these two measurements. The static water level is the height of the water in the well when it is not being pumped, while the pumping water level reflects the height of the water when the well is actively being drawn on. Understanding this concept is crucial for monitoring well performance and ensuring sustainable water extraction practices.

The other options do not accurately define well draw down. The amount of water extracted from the well addresses the volume of water taken out, while the rate at which the well is refilled focuses on the recharge ability of the aquifer. Pressure levels within the well pertain to the hydraulic conditions but don't directly define the draw down measurement itself. Thus, the first choice clearly captures the essence of well draw down as a specific and measurable difference in water levels during well operations.