DESIGN OF IRRIGATION CANALS - INTEGRATED APPROACH

A design methodology is developed to obtain the least-cost design of irrigation canals. The proposed methodology incorporates elements of the water section and the above-water section, and is applicable to both lined and unlined canals. Every reach of the canal is described by four basic design variables bed slope, bed width, upstream bed level, and upstream berm level. A systematic procedure is used to generate design alternatives covering the solution domain. Only those alternatives satisfying a group of preset functional, hydraulic, operational, maintenance, and construction constraints are considered feasible, and are screened to find the least cost. The total cost included the cost of earthwork, lining and trimming (if any), control structures, land acquisition, operation, and maintenance. A detailed cost model is used to estimate the earthwork cost taking into account excavation, deposition, haulage, and soil import or export. The usefulness of the proposed methodology is demonstrated through its application to a reach of El-Nasr Canal, a recently constructed main lined carrier in Egypt.