Distribution Channels with Multiple Outlets

Automated furrow or corrugation systems are usually designed to allow simultaneous discharge from several essentially identical outlets equally spaced along a graded open supply ditch. In order to insure approximately equal outflow from each of the several operating outlets, it is necessary that the head on all outlets be nearly equal. The required minimum head can be estimated using mass continuity and the gradually and rapidly varied flow equations. In the case of zero-slope channels, which are used as distributories only, the design problem is to find a minimum spile elevation that will allow a suitable minimum head on the spiles. Both of these problems are solved in the paper through application of mass continuity and the gradually and rapidly varied flow equations. For the case of the graded bays, a minimum design head on the spiles of 0.21 ft (0.064 m) insures that the flow from a spile flow by not more than 10% over a wide range of channel slopes, irrigation heads, outlet spacings, bay lengths, and roughness coefficients. The calculations for zero-slope channels result in a series of curves.