Which type of aquifer is more directly influenced by surface conditions?

Unconfined aquifers are more directly influenced by surface conditions because they are not overlain by a confining layer that restricts water exchange with the surface. In these aquifers, water can easily percolate down from the surface through the soil and permeable rocks above, allowing for direct interaction with precipitation, surface runoff, and other surface water bodies. This means changes in surface conditions, such as drought or heavy rainfall, have an immediate effect on the water levels and quality within the unconfined aquifer.

In comparison, confined aquifers are isolated from surface influence by layers of impermeable rock or sediment, which can prevent direct recharge from surface water. Perched aquifers may sit above a regional water table in a localized zone, but they are still indirectly influenced by the broader surface conditions beneath them. Sandstone aquifers refer to the geological composition of the aquifer rather than its hydraulic characteristics and can be either confined or unconfined. Thus, the nature of the unconfined aquifer makes it particularly susceptible to surface conditions.