Furrow infiltration and roughness prediction for different furrow inflow hydrographs using a zero-inertia model with a multilevel calibration approach

Furrow irrigation is one of the most common methods of surface irrigation. Its hydraulic behaviour is influenced by the inflow hydrograph shape. The performance of furrow irrigation system can be improved through optimal management practices such as selecting the correct inflow rates, inflow hydrographs and cut-off times. The biggest obstacle in improving the performance of furrow irrigation is the difficulty in estimating the infiltration function, especially under different furrow inflow hydrographs. This study was performed to investigate a multilevel calibration of furrow infiltration, and roughness coefficient, for furrow irrigation using three different furrow inflow hydrograph shapes such as constant, cutback and cablegation using a zero-inertia model and verifying the results with the field data. The results showed that the multilevel calibration method adopted here estimated the Kostiakov-Lewis infiltration equation parameters and roughness coefficient more precisely than the two-point method for different furrow inflow hydrograph shapes. The infiltration equation developed by the method simulated the field data more accurately than the two-point method with the zero-inertia model. The multilevel calibration method predicted the total volume of runoff, total volume of infiltration and furrow outflow hydrograph shapes with lower relative errors compared to the two-point method for the different furrow inflow hydrograph shapes.