Simulation of Surge Irrigation Compared with Continuous Flow Irrigation

Surge irrigation, an intermittent release of water into furrows is an efficient method of water conservation if the flow and frequency of water delivery are optimized. It increases the advance velocity, causes uniform distribution over the furrows, and reduces deep percolation losses. The objectives of this study were to compare yield indices for surge flow and continuous flow, and to evaluate cycle ratios and suitable input discharge in the study area, and also to determine the difference of advance velocity of the wetting front between surge irrigations and continuous flow irrigations. Seventy meter long furrows, 0.5 and 2 lit/s discharge rates, and various pulse ratios were compared with the constant inflow. Field experiments were conducted including determination of the number of furrows and the number of surges, and continuous flow treatments (2 discharges and various cycle ratios for surge flow). Advance velocity, in-and-out flows, and soil water content prior and after the termination of irrigation were measured at the Khalatpoushan Research Station of the Tabriz University. Then flow parameters and infiltration rate for furrows were simulated using the SIRMOD surface irrigation model for both the surge and constant flows. In order to compare the advance velocity of wetting front for surge and continuous irrigations, the HYDRUS 2-D model was used for simulating the advance of wetting front in the wet soil volume in the furrow. The results of simulation show that the final infiltration rate during surge flow was half of continuous flow for one of the treatments. Advance velocity of wetting front in surge treatments was more than continuous treatments with the same volume of applied water. Overall, the S22 treatment (the inflow of 0.5 lit/s and the pulse ratio of 1:4) had the best performance, and S13 treatment (the inflow of 0.5 lit/s and the pulse ratio 2:3), had the poorest performance, even worse than constant flow treatments