Evaluation of Alternative Irrigation Technologies based upon Applied Water and Simulated Yields

Abstract

Adequate estimates of yields under comparable amounts of infiltrated water of different irrigation systems are essential for evaluation and adoption of irrigation decisions. A simulation model, crop evapotranspiration and Young's criteria for subjective probability estimates from objective data were used to simulate water management regimes for pressurized and surface-irrigation systems. Historical climatic data, representative soil series and irrigation technologies for CentralArizona were considered in the simulations. Comparable spatial and average yields for drip, graded furrow, level furrow and level basin systems with similar distribution uniformity of applied water were predicted when each irrigation system infiltrates to the same depth in the low-quarter section of the irrigated field as the average of that quarter, to meet seasonal crop evapotranspiration. This implies that a similar fraction of the field (87·5%) is adequately irrigated in each case. Irrigation reuse systems are advisable to achieve comparable, and high, water application efficiencies with furrow systems. Applied water and simulated yields were influenced by the uniformity distribution of the irrigation technologies showing that the model can be used to explore theimplications of design and management decisions. The applied water and simulated yields can be used as inputs in economic models to aid selection of farm irrigation systems.