What does drawdown indicate in a well?

Drawdown refers to the difference in water level from a static (or resting) condition to a condition where water is being actively withdrawn from a well. This concept is primarily connected to the cone of depression that forms around a well during pumping. Specifically, drawdown is measured as the distance from the static water level down to the water level during pumping, which reflects how much water is being drawn out of the aquifer.

When a well is pumped, the water table around the well drops, creating a cone of depression due to the hydraulic pressure changes. The greater the drawdown, the more significant the impact on the surrounding groundwater levels. Thus, a clear understanding of drawdown helps to assess the sustainability of groundwater extraction and the overall health of the aquifer.

The other options do not accurately reflect the definition of drawdown. While the increase in water level pertains to water gains, it does not consider the active withdrawal aspect of drawdown. The average flow rate and the age of groundwater are separate concepts entirely and do not relate to the measure of drawdown in a well.