EntityQ1929501· pop 19· linked from 113 articleswater levelSign in to saveelevation of the free surface of a stream, lake or reservoir relative to a specified vertical datumConnectionsfree surfaceEntityseaEntitylakeEntitysea levelEntityhydrologyEntityreservoirEntitystreamEntitywaterlineEntitytide gaugeEntitystream gaugeEntityhydraulic headEntitygeopotentialEntitylevel sensorEntitywater levelEntityvertical datumEntityCategoriesHydrologyVertical position