Which of the following BEST defines the cone of depression?

The cone of depression refers to the observed drop in the water level surrounding a well after it has been pumped over a certain period of time. This phenomenon occurs because the extraction of water from the well creates a decrease in hydraulic pressure in the aquifer, which results in a conical shape of lowered water levels around the well. Essentially, as water is drawn out, the surrounding groundwater flows toward the well to replace the water being removed, leading to a distinct area of lowered water levels, which is visualized as a cone.

Understanding this concept is crucial for water management and sustainability, as it can influence the availability of groundwater resources and indicates how closely groundwater levels are monitored in relation to the amount of water being extracted from wells. The other options do not accurately capture this specific hydrological phenomenon.