. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 28 BULLETIN 181, U. S, DEPABTMENT OF AGEICULTUEE. METHODS OF COMPUTATION. In computing the sizes of ditches and levees and the capacities of the floodways, the Chezy formula, v = c-yjrs, was used. In this formula c is a coefficient depending upon channel conditions and determined by Kutter's formula, in which the coefficient of roughness, n, was taken at for ditches, for cleared channels, and for floodways. To provide a margin of safety, ditches were given a depth of 1 foot greater than that computed
. Bulletin of the Department of Agriculture. Agriculture; Agriculture. 28 BULLETIN 181, U. S, DEPABTMENT OF AGEICULTUEE. METHODS OF COMPUTATION. In computing the sizes of ditches and levees and the capacities of the floodways, the Chezy formula, v = c-yjrs, was used. In this formula c is a coefficient depending upon channel conditions and determined by Kutter's formula, in which the coefficient of roughness, n, was taken at for ditches, for cleared channels, and for floodways. To provide a margin of safety, ditches were given a depth of 1 foot greater than that computed as necessary to handle the discharge. The tops of the levees were taken at 3 feet above the high- water line as computed. In determining the capacity of the fioodway it was necessary to consider its cross section in two parts, owing to the fact that in many of the bends of the channel the water will flow in a direction opposite to that in the fioodway. Such a condition is shown at a in figure 7. The friction existing be- tween the two bodies of water flowing in oppo- site directions is with- out doubt less than that between the water and the ground surface in the fioodway; hence it should be safe to com- pute the discharge of the fioodway as though the channel did not exist, adding thereto the. Drainage Area in Sq Miles Fig. 6.âDischarge curve used in design of ditches, Big Black River, Miss. U ui > â J 3?. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Dept. of Agriculture. [Washington, D. C. ?] : The Dept. : Supt. of Docs. , G. P. O.
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