Modeling Solute Transport in the WinSRFR Surface Irrigation Software

Abstract

A solute transport model has been added to the WinSRFR surface irrigation software package. The model uses advective-dispersive principles to predict the flow of solute with the irrigation stream and its final longitudinal distribution along the field based on water flow predictions generated by the simulation engine. Computations are based on the fractional stepping method: advection is computed using the method of characteristics from the velocity field computed by the simulation engine water flow calculations, and dispersion is calculated from the advection results using a centered-difference finite-difference scheme. The Akima interpolation scheme was used to build the method-of-characteristics solution. The computations are robust and execute in little time. The accuracy of the model was evaluated with numerical tests and by comparison with field measurements. Results suggest that the model can generate useful predictions under typical irrigation conditions.