Multilevel calibration of furrow infiltration and roughness

A stepwise multilevel scheme is developed to sequentially calibrate infiltration and roughness parameters for free-draining furrow irrigation systems. The scheme is one dimensional at each level, thereby simplifying computations and providing more robust and unique solutions using field data which exhibit variation. The scheme is easily programmed and implemented within any kinematic wave, zero inertia, or hydrodynamic analysis and will provide straightforward initiation and convergence. Applications to two comprehensive data sets are made and shown to be substantially more accurate and extensive than traditional two-point fitting algorithms. In addition to the field length and slope, the flow cross section, and the duration of the irrigation, the multilevel model only requires measurements of the inflow and outflow hydrographs. Field data collection is therefore simpler than required for traditional methods which require spatial and temporal advance and recession measurements.