EVALUATION OF SURGE FACTOR IN FURROW INFILTRATION UNDER NON-CONTINUOUS FLOW

One of the methods to increase water application efficiency in agricultural lands is surge irrigation. Simulation and design of this method rely on accurate estimation of infiltration equations coefficients. Common used methods to estimate infiltration equations coefficients need to numerous field measurements and to time consume. Therefore, to evaluate surge factor in furrow infiltration under non-continuous flow, a field study was conducted for surge flow with on-time of 30 min, cycle ratio of 1/2, with four surges, at two irrigation events. Surge infiltration was measured by blocked furrow infiltrometers which adapted for non- continuous condition. The results indicated that non-continuous flow has a potential to decrease cumulative infiltration with application of different surges. Decreasing infiltration due to non-continuous flow caused decreasing deep percolation and improving flow advance along furrows, consequently, it will be caused increase in irrigation efficiency and improve water distribution in the farm. With increase in irrigation events, cumulative infiltration decreased. Cumulative infiltration at the first 30 min in the first irrigation (with 9363 ml.m-1) is more than the second event (with 5858 ml.m-1). The differences between infiltration rates from two to four surges were not significant. Application flow with more than three surges did not cause changes in infiltration rate and water efficiency. Infiltration equation parameters (k and a) were obtained by regression analysis for different surges of tow irrigation events. The parameter (a) was acquired as 0.43. The parameter of K in The first irrigation was more than that was from the second irrigation. In the present study, surge factor was evaluated for two irrigation events with several flow surges. The surges factors can be used to estimate cumulative infiltration in the different surges of the first and the second irrigation events based on the first surge.