Improving performance of furrow irrigation systems using simulation modelling in the Moghan plain of Iran*

The objective of this study was to assess the different scenarios for improving the irrigation application efficiency of a two-row bed furrow irrigation system (wide furrow) using the SIRMOD model in six sugar beet fields of the Moghan plain for the 2015-2016 growing season. The Moghan plain is situated in the Ardebil province of Iran. Therefore, five scenarios including: (i) irrigation cut-off time equal to the advance time (ICTEAT); (ii) cutting off the flow discharge before it reaches the end (CTIBRE); (iii) increasing the flow discharge up to 2.5 l s over bar (1) and cutting it off when the irrigation requirement is fulfilled (IARCSI); (iv) increasing inflow discharge up to 2.5 l s over bar (1) and cutting off the flow discharge as soon as the advance phase reaches the end (IARCARE); (v) reducing inflow rate, cut-off time and furrow length (100 m in all the furrows) by blocking the end of the furrow (RICTLBE), were applied using the calibrated SIRMOD model. In addition, surge irrigation was carried out in fields with high percolation. The results indicated that the average irrigation application efficiency under the current status was 35%. However, average application efficiencies increased to 63, 74, 59, 60 and 77% in the ICTEAT, CTIBRE, IARSCI, IARCARE and RICTLBE scenarios, respectively. The application efficiency for fields with high percolation increased from 32%, in the current status, to 53, 64, 62, 60, 78 and 76% under ICTEAT, CTIBRE, IARSCI, IARCARE, RICTLBE and surge irrigation, respectively. Overall, the irrigation management scenarios could substantially reduce on-farm irrigation water losses.