What typically indicates the upper limit of groundwater in an unconfined aquifer?

In an unconfined aquifer, the upper limit of groundwater is typically indicated by the ground surface. This is because unconfined aquifers are directly recharged by surface water, and the water table (the upper surface of the saturated zone) meets the ground surface at various locations depending on the local topography and conditions. When precipitation infiltrates through the soil and reaches this level, it contributes to the groundwater stored in the aquifer.

The pressure head is related to confined aquifers where water is stored under pressure. The capillary fringe refers to the area just above the water table where soil pores are partially filled with water due to capillary action, and it does not serve as the upper boundary of saturated ground. The base of the confining layer applies to confined aquifers, where an impermeable layer restricts the groundwater, but it does not pertain to the upper limit in the case of unconfined aquifers.