Capacity Tests in Large Concrete-Lined Canals

Between 1957 and 1962 a series of tests were performed by the Bureau of Reclamation to determine the hydraulic performance of nine large concrete-lined irrigation canals located in the western United States. Water surface profiles were obtained in some 170 miles of subcritical flow trapezoidal shaped canals having flows that varied from 555 to 6,820 cfs. Instruments and techniques developed to measure small changes in water surface elevations are described. Results of backwater curves computed to match measured water surface profiles in sinuous reaches and reaches with piers are described. Test results are given in terms of n values for use in Manning’s formula. Roughness coefficients varied with the degree of aquatic growth on the lining surface, canal alinement, and canal size.