Effects of Variable Longitudinal Slope on Application Efficiency and Uniformity of Water Distribution in Furrow Irrigation System

Among surface irrigation methods, furrow irrigation is most common and adaptable method. Longitudinal slope in furrow irrigation is generally uniform and constant along the furrow. In order to access more application efficiency and more uniformity of water distribution and control runoff and deep percolation in furrow irrigation, several techniques such as surge irrigation and cut-back irrigation is used that all is need applying special equipment during operation. This study was conducted to investigate the effects changing of longitudinal slope furrow from linear to planar (concave or convex) on the parameters of the furrow irrigation. In this way an experiment with completely randomized design with three replications was taken place in the experimental field of Shahrekord University during the summer 2010. The treatments were furrows with uniform, concave and convex longitudinal slope. Indexes such as time advance, time recession and outflow was measured. Coefficients of infiltration equation were calculated by two-point method of Elliott – Walker. The indexes such as application efficiency and uniformity of water distribution in all treatments were calculated and compared statistically by SAS software. The results of this study shows application efficiency and uniformity of water distribution in the concave slope treatment was 73 and 92 percent, respectively. Corresponding values of control treatment (70 and 90 percent) were significantly different and so on that of convex slope treatment with quantity of 63 and 86 percent, respectively. Therefore it can be concluded that in furrow irrigation the assessment indexes and productivity are improved by applying the longitudinal concave slope.