ABSTRACT
Hydraulic structures existed before recorded history. Archeologists have found irrigation systems in Mesopotamia and check and diversion dams on the Arabian Peninsula dating to about 5800 BC. The first water level records on the Nile River appeared about 3050 BC. The Romans, even though they did not fully comprehend hydraulic principles relating to discharge, devised a method based on pipe areas in order to charge for water supplied to baths and private residences. Hero, a Greek of the first century AD, was the first to express the basis for flow measurement as we know it today. This important finding went unnoticed, however, for about 1500 yr until Leonardo da Vinci extended the relationship to the continuity equation, but even da Vinci’s work went unknown until his manuscripts were found in 1690. The German engineer, Reinhard Woltman, developed the spokevane current meter in 1790, a breakthrough for measuring velocities in rivers and canals. During the 18th and 19th centuries development and installation of weirs and flumes made flow measurements possible on irrigation canals, and gaging stations were constructed on many rivers to provide records of flows. New technology has provided various water measurement techniques, and stream flow data now can be accessed at over 4200 gaging stations in the United States.
