Typically, a saturated lens of sand or other permeable material in the otherwise unsaturated zone is located on top of a shale or other impermeable layer. The cone results from more water being removed from the well than flows into it from the surrounding aquifer. If the removal of water from the well is extensively greater than the ability of the aquifer to replenish the water, the well will run dry. The removal of the groundwater may cause the sediment pores in the aquifer to permanently collapse. The collapse of numerous sediment pores may result in several meters of surface subsidence or the formation of immense cracks.
Seawater is slightly denser than fresh water.
The weight of undisturbed overlying fresh water also manages to keep the salty groundwater from moving inland. This happened in Brooklyn, New York during the 1930's. The fresh groundwater table dropped by 15 meters as part of a cone of depression and seawater migrated into the wells. Potential and Kinetic Energy Energy is the ability to do work or to move or manipulate objects, including water. If water is released from the tank and moves down the hill, the potential energy is converted into heat and kinetic energy.