DESIGN OF STABLE CHANNEL

Abstract

Irrigation channels carrying sediment-laden water are designed as stable channels. At present many methods are available for their design. While the methods of Kennedy, Lacey, Lindley, Sim6ns and Albertson etc. do not consider sediment' transport, parameter in the design, those of Inglis, Engelund & Hansen, Kondap & Garde etc. do include it. However, all of them treat sediment as uniform and take its median size as representative. More recently Deviprasad and Rajesh Gupta treated sediment as nonuniform and proposed methods of stable channel design, keeping the water discharge and sediment concentration same throughout the year. In contrast, Khan suggested an algorithm for stable channel design with seasonal variations in water and sediment discharges but treated sediment as uniform. The most realistic design of a channel is the one in which the nonuniformity of sediment, variations of water and sediment discharges are taken into account. In such a situation, the condition of sediment transport is in non-equilibrium with varying bed slope, bed elevation and bed composition from time to time. This thesis presents an algorithm for their prediction at any time. The size of sediment which gives the same slope at the end of the year as at the beginning is defined as the representative size for the design. These variations are also studied for consecutive years till they stabilize.