Analytical Model for Furrow Irrigation
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An analytical model is developed to simulate all phases of furrow irrigation. The model transforms any real furrow cross section shape to a dischargeequivalent semicircular shape, and can therefore be applied to any form of furrow cross section. Parabolic shapes are used to describe the surface and subsurface flow profiles and their coefficients are determined from the conditions in the gradually varied flow region, rather than in the region of rapidly varied flow at the advance front. Infiltration is simulated in three dimensions rather than in one or two dimensions. The recession phases are simulated by modifying Strelkoff's model such that the time-varying rate of infiltration is taken into account. One observed data set is used to calibrate the model, and six observed data sets are used to verify it. The model is simple, accurate (less than 8% deviation for all phases), and easy to apply. ASCE.