Two-Dimensional Simulation Model for Contour Basin Layouts in Southeast Australia. II: Irregular Shape and Multiple Basins

The development of a two-dimensional simulation model for single regular shape (rectangular) contour basin irrigation layout in southeast Australia is reported in a companion paper. Contour basin layouts as used in Southeast Australia are often irregular in shape and laid out as multiple basin systems. Irrigation of these basins is carried out sequentially involving back flow to the supply channel and inter-basin flow. This paper presents the extension of the earlier model to incorporate irregular shape basins and multiple basin operation. The governing equation is solved by adopting a “split-operator approach” using the method of characteristics coupled with two-dimensional Taylor series expansion for interpolation and calculation of diffusion terms. The numerical solution scheme is based on a grid of quadrilaterals for spatial discretization, to provide geometric flexibility. Infiltration is computed using either the empirical Kostiakov–Lewis equation or the quasianalytical Parlange equation. The model was validated against field data collected from irrigation events monitored on a commercial laser leveled contour layout consisting of five basins.