How does a confined aquifer differ from an unconfined aquifer?

A confined aquifer is indeed characterized by being under more pressure than unconfined aquifers. This occurs because a confined aquifer is bounded both above and below by impermeable layers (such as clay or rock) that restrict the movement of water, creating pressure. When a well is drilled into a confined aquifer, the water level may rise above the level of the aquifer due to this pressure, sometimes even reaching the surface without pumping, leading to what is known as an artesian well.

In contrast, unconfined aquifers are directly recharged by surface water and are only partially filled with water, meaning the water level in these aquifers is more directly influenced by local rainfall and surface water conditions, which results in less hydrostatic pressure. Understanding this pressure differential is crucial for various applications, including groundwater management, well construction, and understanding water availability in an area.