Optimizing Furrow Irrigation Decision Parameters Using WinSRFR Model: The Case of Batu Degaga Small Scale Irrigation Scheme

Abstract

Surface irrigation simulation models have the potential to improve the efficiency of irrigation systems and thus deliver significant water savings which can be achieved by optimizing the design and management decisions at the field level. The measurement, evaluation and optimization of furrow irrigation is restricted to a single furrow or small number of adjacent furrows due to the measurement process is too intensive to be applied at the full field scale. So, it is necessary to assume that the infiltration characteristics and inflow rates of the measured furrow(s) represent the remainder of the field. Therefore, the aim of this study was to optimize decision parameters of furrow irrigation using WinSRFR model so as to improve furrow irrigation efficiency of onion field at Batu Degaga small-scale irrigation scheme. Field experiment were conducted on six blocked-ended furrows with the length of 40 meter and slope of 0.2 % and two in???ow treatments (1.0 and 1.5 l/s) for three irrigation events. All field measurements used for input parameters were collected from four middle furrows and the other two were taken as buffer furrows. The collected data?�?s were processed by Microsoft EXCEL and data analysis was conducted using WinSRFR software. The statistical indicators of NRMSE, R2, RE, d, and ?? were used for the comparison between measured and simulated advance time, recession time and performance parameters. The results of these indicators were very good and showed that WinSRFR simulation was acceptable. So, WinSRFR software was employed to optimize the combination of irrigation parameters such as in???ow rate, cut-o??� time and ???eld geometry. Then, optimum combination of furrow irrigation decision parameters were determined to obtain the maximum performance. Results showed that using combination of 40m furrow length under 0.2% bed slope with 2 l/s in???ow rate and 0.18 hour cutoff time can obtain maximum application efficiency of 95%. In addition, this study revealed that under different furrow inflow rates and furrow bed slopes (i.e. 0.1, 0.2, 0.3, 0.4 and 0.5%) using 40m furrow length has maximum hydraulic performance than other furrow lengths (i.e. 60, 80 and 100m). Finally, even though high performance was obtained under short furrow length, for effective management and use of irrigation water the longer furrow length (i.e. 100m) was suggested for the study area.