Assessment of pressure variation effect along lateral pipes of hand-move sprinkler irrigation system on costs

According to the irrigation systems design standards, allowed pressure variation in lateral pipes is 20 percent. Reasons for this rate selection, which since the 60's is performed, are not known. The increased changes in allowed pressure tubes to lateral pipes design, the increased sprinkling system required pressure and the increased nonuniform sprinkler distribution, so energy supply costs and water loss will be increased. On the other hand, designed lateral pipes with lower allowed pressure variation, cause better irrigation uniformity, and decreased system required pressure, but costs of tubes per area unit will be increased. The aim of this study is investigation of allowed pressure variation effect along lateral pipes of hand move sprinkler irrigation system on purchase costs of pipes, energy supply and water economic costs. In this experiment, we designed sample farm hand move sprinkler irrigation system with allowed pressure variation 5, 10, 15, 20, 25 and 30 percent for alfalfa culture in Khuzestan, and based on these designing and economic value per cubic meter of water in this region, investment cost, current and total cost were estimated. The results showed that by calculating water supply cost, the highest cost is related to fields with pressure variation of 30 percent, and the lowest cost and water price is related to fields with pressure variation of 15 percent, and several economic values of water in Khuzestan, have no effect on the best economic selection of pressure changing ranges. Changes in pressure above 20 percent, losses and costs are high and the pressure change of 15 percent in lateral pipes is a good option to design the hand move sprinkler irrigation system in Khouzestan.