Irrigation Canal System Capacity Design Criteria

The land tenure proposed for an irrigation project can cause a variation of up to 50% in the required canal capacities. On a project in Iran, feasibility level canal design capacities were based on the government policy of subdividing project lands into small (10 hectare) parcels lease or sale to individual farmers. At the time of final design this policy has been changed to permit an agribusiness lease type of operation (units of 5 to 15,000 hectares) during initial project development. The change in policy caused in increase in the projected summer cropping intensities resulting in higher peak irrigation water requirements. To deliver the additional water, canal capacities increases of up to 50 percent were required over the original design.