Control of Irrigation Canal Networks

Abstract

Control schemes which are available for the operation of canal networks for irrigation projects are examined. These control schemes include upstream control, downstream control, controlled volume control, dynamic regulation, and flow rate control. The latter method is emphasized in particular because of its usefulness in managing water. The type of control and type of structure needed at each canal bifurcation should be carefully examined and matched with the type of delivery scheme and operational constraints. The result may be that different control schemes and devices may be used in different areas of the same project. Demand deliveries are generally not feasible for most large projects, unless the project is broken down into independently controlled subunits. Arranged schedules with upstream control are currently more common. An alternative is to use constant‐flow‐rate control at the head of lateral canals with upstream control within the lateral. Deliveries are then arranged within the lateral unit with the lateral obtaining water essentially on demand, thus reducing delivery lead times. This improves regulation on the lateral (and thus to the farm) and somewhat reduces control requirements on the main canal since constant water levels are not required. Control mechanisms are available which make accurate regulation of lateral discharges feasible.