Comparison and Improvement of Surface Irrigation Design Methods (Case Study Furrow Irrigation)

Low application efficiency is the main problem of surface irrigation systems. In order to compare and improve furrow irrigation design methods including FAO, SCS, volume balance, kinematic wave and zero-inertia methods, field experiments were conducted for measuring design parameters of furrow irrigation. Results showed that the volume balance method gave the most accurate results of infiltration equation. Also attributing an intake family of the SCS method for field data caused error in the computation. Adjustment of SCS advance time equation and volume balance methods increased the model accuracy. With improvement ofSCS advance time, the residual mass coefficient (CRM) and root mean square error (RMSE) of advance time changed from -0.4 to -0.019 and from 10.36 to 2.34 min, respectively. Improving volume balance method, using surface and subsurface storages and modified Kostiakov-lewis infiltration equation, decreased the RMSE and CRM advance time from 8 to 6.26 min and from 0.32 to 0.25, respectively. Results showed that short time steps and more iteration should be performing for less error in the improved volume balance method. Created contours by WinSRFR4.1 model allow user to search a set of variables by consideration of hydraulic and practical conditions to achieve high level of uniformity and efficiency at zero-inertia and kinematic wave models.