Evaluation and optimization of surge and alternate furrow irrigation performance in maize fields using the WinSRFR software

Abstract

Low efficiency of irrigation is a major problem with surface irrigation methods, mainly due to poor management and improper design. The objective of this study was to evaluate and improve the performance of different surge and alternate furrow irrigation methods. A field experiment was conducted during the grain maize growing season in the Jayedar Plain of Poldokhtar City (southwest of Iran) in the years 2020 and 2021. Five different furrow irrigation methods including conventional furrow irrigation (CFI), surge irrigation with on/off cycle ratios of 1 and 0.5 (SFI1–1 and SFI1–2, respectively), fixed alternate irrigation (FFI) and variable alternate irrigation (AFI) were investigated. A total of 15 irrigation evaluations were performed at the initial, middle, and end of the growing season by measuring inflow rate, cutoff time, outflow rate, infiltration and advance time. The length and spacing of experimental furrows were 120 and 0.75 m, respectively, and the inflow rate of furrows and the flow cutoff times at the initial (3rd irrigation), middle (6th irrigation), and end (9th irrigation) of the season were 0.28 L/s and 240 min, 0.42 L/s and 360 min, 0.35 L/s and 300 min, respectively. The WinSRFR 3.1 software was calibrated and applied using field data based on the zero-inertia model. The results of the furrow irrigation sensitivity analysis with WinSRFR 3.1 software demonstrated that furrow irrigation in the studied area was most sensitive to the inflow rate, cutoff time and infiltration parameters, respectively. There were high correlations between the measured and simulated values of runoff, infiltration and advance time (coefficient of determination of 1.0, 0.94, and 0.97, respectively). The relative error values in estimating runoff, infiltration and advance time were 5.60 %, 5.09 %, and 2.14 %, respectively. Mean performance indices of different furrow irrigation methods under field experiments showed that the highest values of Application Efficiency (78.7 %), Potential Application Efficiency of the minimum (69.5 %), and Potential Application Efficiency of low-quarter (74.1 %) were observed under the AFI method. By optimizing the inflow rate and flow cutoff time, application efficiencies of 66.6–80.7 % were obtained for different irrigation methods. The results of this study show that AFI is a more suitable method for maize irrigation in the study area.