Answer:
The water table and the piezometric surface are both important concepts in hydrogeology. The water table is the level below the Earth’s surface at which the ground becomes saturated with water. It is the boundary between the unsaturated zone, where the pores in the soil or rock contain both air and water, and the saturated zone, where the pores are completely filled with water. The water table can be found in both unconfined and confined aquifers.
The piezometric surface, also known as the potentiometric surface, is the level to which water would rise in a confined aquifer if a well were drilled into it. It represents the pressure of the water in the aquifer and is an important tool for understanding groundwater flow. The piezometric surface can be above or below the water table, depending on the characteristics of the aquifer .
Therefore, the statement “Piezometeric surface sits above the water table” is not always correct. The piezometric surface can be either above or below the water table, depending on the specific conditions of the aquifer. The other statements are correct: both the water table and the piezometric surface can be present in unconfined aquifers, and both represent the boundary between the unsaturated and saturated zones.