A hybrid finite volume-finite element model for the numerical analysis of furrow irrigation and fertigation

This study presents a hybrid Finite Volume - Finite Element (FV-FE) model that describes the coupled surface-subsurface flow processes occurring during furrow irrigation and fertigation. The numerical approach combines a one-dimensional description of water flow and solute transport in an open channel with a two-dimensional description of water flow and solute transport in a subsurface soil domain, thus reducing the dimensionality of the problem and the computational cost. The modeling framework includes the widely used hydrological model, HYDRUS, which can simulate the movement of water and solutes, as well as root water and nutrient uptake in variably-saturated soils. The robustness of the proposed model was examined and confirmed by mesh and time step sensitivity analyses. The model was theoretically validated by comparison with simulations conducted with the well-established model WinSRFR and experimentally validated by comparison with field-measured data from a furrow fertigation experiment conducted in the US.