The code has been widely applied to aquifers throughout the United States and the world. A perched zone is typically unconfined and at a higher elevation than the regional aquifer system. Unsaturated conditions exist below a perched unit. A major doctrine defining water right systems in the western United States. The Prior Appropriation Doctrine operates on a priority system, where a priority is established based on the date water is first put to beneficial use.
Potentiometric head is measured using a sounder or similar depth gauge.
The Potentiometric head in a well in an unconfined aquifer is at the elevation of the water table. In a well in a confined aquifer, the potentiometric head is typically at a higher elevation than the top of the aquifer due to the confining pressure. In an unconfined aquifer, the potentiometric surface is at the top of the water level. In a confined aquifer, the potentiometric surface is above the top of the water level because the water is under confining pressure. Typical sources of recharge are precipitation, applied irrigation water, underflow from tributary basins and seepage from surface water bodies.