Optimization of on Demand Pressurized Irrigation Networks and On-farm Constraints

AbstractThe variability of flow regimes in on demand pressurized irrigation systems induces uncertainty in pressure head at the hydrants affecting the system hydraulic performance. However, the on-farm networks operating downstream are designed for a fixed upstream pressure head that usually corresponds to their best achievable performance.Based on these considerations, an on demand irrigation system was optimized using the Reliability based model accounting for the variability of flow regimes, the minimization of cost and the maximization of the reliability, and the interaction between the variability at hydrant level and the uniformity of on farm sprinkler systems operating downstream was analyzed. The analysis shows that on farm uniformity strongly varies in space and time and low uniformity levels were achieved despite the consideration of the reliability of the on demand distribution network during the optimization process, which may have drastic effects on crop yield.This study clearly shows that accounting for the interaction between the distribution system and the on farm irrigation network is a must in the modernization/rehabilitation processes, often promoted as tools to produce more agriculture goods with less water input at moderate investments and operational costs