Since the beginning of irrigated agriculture, measuring the flow of irrigation water has been important, but early methods often lost accuracy because of trash or sediment in the water or unusual flow conditions. Ralph L. Parshall encountered this problem after he began working for the USDA in 1915 as an irrigation research engineer, and in 1922 he invented the flume that came to bear his name. When placed in a channel, this flume uniquely relates flow to water depth. By 1953, Parshall had developed depth-flow relationships for flumes with throat widths from 3 inches to 50 feet. The Parshall flume had a major influence on the equitable distribution and proper management of irrigation water, and thousands were used to measure irrigation water as well as industrial and municipal liquid flows throughout the world. Parshall carried out his historic experiments at the original Colorado Agricultural College Hydraulics Laboratory.

Photo: Michael O'Neill

Photo: Supplied by The Cache la Poudre National Heritage Area

Photo: Michael O'Neill

Photo: Michael O'Neill

Photo: Michael O'Neill

Fort Collins, Colorado · USA