Modeling in Water Losses Evaluation for Nonhomogeneous Furrow Set

Abstract

Due to differences in infiltration characteristics across field, uniformly delivered furrow irrigation streams advance at different rates. This “inter-row” nonuniformity is combined with the nonuniform distribution of irrigation water along the furrow length. Unlike studies based on data from one or two representative furrows, this analysis evaluates water losses in the presence of both lateral and longitudinal variation. A spatial mathematical description of the nonuniform distribution of application depth over the whole field area is made in relative terms. Formulas for evaluation of water losses were derived by integrating both “downfield” and “inter-row” deep percolation and runoff losses. The percentage losses calculated by these formulas were compared with those assessed from one and two representative furrows and differences up to twofold were found. An algorithm was developed for model application over a wide range of field conditions. The model was calibrated for irrigation on clay and silty clay loam soils and examples were given of its use.