Hydrometry

“Hydrometry is the science of monitoring water in natural water resources. It focuses on monitoring the natural precipitation of water, such as rain or snow, and the change of water level in all kinds of natural water resources, such as lakes, rivers, underground or storage reservoirs.” (Wiegand, n.d.)

“In the widest sense 'hydrometry' embraces the measurement of all of the elements in the hydrological cycle but the term is primarily applied to the measurement of river flows.” (National River Flow Archive, n.d.)