What does the term 'water table' refer to?

The term 'water table' refers to the top of the water in an aquifer. This surface demarcates the transition between the saturated zone, where all the spaces in the soil and rock are filled with water, and the unsaturated zone above it, where air fills some of the spaces. When the water table rises or falls, it indicates changes in groundwater availability in that area.

Understanding the water table is essential for many applications, such as land use planning, agriculture, and understanding hydrology. In contrast, the other options describe different aspects of water bodies or soil saturation without specifically addressing the aquifer's top water level that defines the water table.