Which term describes areas that are completely water-filled?

The term that describes areas that are completely filled with water is "saturated zones." In hydrogeology, saturated zones refer to subsurface areas where all the interconnected pores and fractures in soil and rock are filled with water. This saturation influences groundwater movement and availability, as well as the dynamics of aquifers.

Saturated zones are critical in understanding groundwater resources and are essential for assessing the potential for water resource management, contamination spread, and ecosystem health. In contrast, unsaturated zones contain some air in the spaces between soil and rock particles, while hydrology zones refer more broadly to the study of water in the environment, and surface water bodies specifically relate to lakes, rivers, and streams rather than subsurface conditions.