Piezometric level

Level reached by water at one point and at a given time in a pipe reaching the groundwater sheet. The piezometric level can be transferred to a piezometric map. Some non-operated wells are used to measure this level, they are piezometers or observation wells. This level corresponds to the groundwater pressure; it is usually indicated in NGF metres (French Surveying and Levelling). When this level is above ground level, the groundwater is called artesian: water is gushing out. The piezometric maps established with all measured data give a graphical representation of the groundwater surface and can track its evolution over time and identify its direction of flow.