Efficiency improvement in linear-move sprinkler systems through moderate runoff-runon control

Given the importance of achieving substantial water and operation savings, automated irrigation management has evolved toward integration of soil moisture measurements with simulation models. The main objective of this study was to develop a set of procedures to maximize irrigation efficiencies in linear-move irrigation systems. A system of field truth data collection and spatially distributed, physically based hydrological modeling was developed to evaluate the efficiencies of linear-move systems considering various naturally occurring boundary conditions and management options. Interactions among the irrigation flow depth, the evaporation conditions, the net infiltration depth and soil moisture uniformity, the irrigation turn duration and runoff-runon production were considered. Environments were of the semiarid Patagonian Monte at varying field slope and antecedent soil moisture. Plot experiments on infiltration and overland flow were used to calibrate a modified version of the CREST hydrological model adapted to the simulation of linear-move irrigation. Modeling results show that irrigation efficiencies can be improved by allowing runoff-runon to occur to an extent compatible with adequate soil moisture uniformity at the end of the irrigation turns. High efficiencies in both attaining effective infiltration depths and minimizing irrigation turn durations may be reached by adjusting the irrigation flow depth through the advance velocity of the irrigation system and/or inter-nozzle distances with due consideration to the antecedent soil moisture condition and the field slope.