Surface irrigation type is one of the most widely used in the world due to its low cost investment. However it is complex method of applying water to soil, because of extreme difficult to achieve good control over the highly variable nature of the movement of water across a soil surface and its infiltration into the soil over a season. This study is attempted to optimize furrow irrigation decision variables at Wonji Shoa sugar estate using field experiment and two simulation models. The field data of experimental site was measured as input for models and simulated using the SIRMOD software and WinSRFR software package. Furrow lengths of 32 m, 48 m and 64 m, slopes of 0.05%, 0.075% and 0.1%and flow rates of 3 l/sec, 4 l/sec and 5 l/sec were analyzed with three replication using volume balance method and two simulation models. The study found optimum decision variables that gave maximum application efficiency and distribution uniformity were slope of 0.1%, furrow length of 32 m and inflow rate of 4 l/sec at cut-off time of 15.79 min. Thus, to improve the performance of furrow irrigation practice, optimal furrow length, inflow rates and cut-off time found by this study should be adopted. Findings from the study would serve as a source of information for use by policy makers and planners during the design and Operation of irrigation development programs. It does not focus on yield related optimization. So, it is open for the future research to conduct yield related optimization of the decision variables.

Surface irrigation type is one of the most widely used in the world due to its low cost investment. However it is complex method of applying water to soil, because of extreme difficult to achieve good control over the highly variable nature of the movement of water across a soil surface and its infiltration into the soil over a season. This study is attempted to optimize furrow irrigation decision variables at Wonji sugar estate using field experiment and two simulation models. The field data of experimental site was measured as input for models and simulated using the SIRMOD software and WinSRFR software package. Furrow lengths of 32m, 48m and 64m, slopes of 0.05%, 0.075% and 0.1%and flow rates of 3l/sec, 4l/sec and 5l/sec were analyzed with three replication using volume balance method and two simulation models. The study found optimum decision variables that gave maximum application efficiency and distribution uniformity were slope of 0.1%, furrow length of 32m and inflow rate of 4 l/sec at cut-off time of 15.79 minutes. Thus, to improve the performance of furrow irrigation practice, optimal furrow length, inflow rates and cut-off time found by this study should be adopted. Findings from the study would serve as a source of information for use by policy makers and planners during the design and Operation of irrigation development programs. It does not focus on yield related optimization. So, it is open for the future research to conduct yield related optimization of the decision variables. The authors sincerely declare that this study is the product of their own efforts.