MODELING AND ERROR ANALYSIS OF KINEMATIC-WAVE EQUATIONS OF FURROW IRRIGATION

A moving control volume approach was used to model the advance phase o f a furrow irrigation system whereas a fixed control volume was used t o model the nearly stationary phase and the runoff rate. The resulting finite-difference equations of the kinematic-wave model were lineariz ed and explicit algebraic expressions were obtained for computation of advance and runoff rate. The solutions for the advance increment and the runoff rate were compared with the nonlinear scheme, the zero-iner tia model, and a set of field data. A close agreement was found betwee n the models and the field data. Assuming a constant infiltration rate , a differential equation was derived to estimate the error between th e kinematic-wave model and the zero-inertia model in predicting the fl ow cross-sectional area along the field length. The differential equat ion and two dimensionless terms were used to define the limits for use of the kinematic-wave model in furrow irrigation.