CANAL DISCHARGE MEASUREMENTS WITH RADIOISOTOPES,
BUREAU OF RECLAMATION DENVER COLO
Pagination or Media Count:
Half-capacity tests in Feb 1962 and full-capacity tests in June 1963 using Gold- 198 were made in a straight section of a concrete-lined irrigation canal with a design discharge of 620 cfs. The pulse or total-count radioisotope method was used for 65 discharge measurements. Consistency of the radioisotope method was evaluated by using up to 4 portable Geiger counting systems. Conclusions were 1 With adequate mixing of radioisotope and canal water accuracy of 97 or greater is possible when compared with current meter discharge measurements. 2 In a canal with hydraulic characteristics similar to the one tested, a 2,500- to 3,000-ft mixing length is needed for 98 to 99 mixing. 3 Minimum mixing length may be computed for similar straight canals using a diffusion coefficient and time factor developed from these tests. 4 Simultaneous multiple injections of tracer will provide higher probability of uniform mixing in shorter lengths than will single injections and also result in higher diffusion coefficients. 5 With sufficient data from canals of various sizes mixing length equations can probably be derived for canals having a minimum of turbulence.