What is a confined aquifer?

A confined aquifer is a geological formation that is saturated with water and is bounded above and below by impermeable layers, which prevent water from readily entering or leaving. The defining characteristic of a confined aquifer is that it is typically recharged by water from surrounding areas or through specific points where the impermeable layer is absent. This recharge can occur from unconfined sources, which are areas where the water table is exposed to the atmosphere, as well as from underground rivers and cracks in the rock that allow water to flow into the aquifer.

In this context, the assertion that a confined aquifer receives water from unconfined sources, underground rivers, and cracks in rock accurately reflects the nature of these aquifers and their interaction with surrounding hydrogeological environments. Understanding this interaction is critical in hydrology, as it helps explain how groundwater systems function and how aquifer levels can change based on external conditions.