Incorporating infiltration in the two-dimensional ANUGA model for surface irrigation simulation

Abstract

Improving irrigation efficiency on farms is crucial in securing a sustainable future for irrigators as well as the environment, especially in water scarce regions such as Australia. More efficient irrigation designs are increasingly being investigated using irrigation simulation models but there is a dearth of readily available two-dimensional (2D) models for investigating surface water flow within irrigation bays. This paper adapted the 2D ANUGA open source model to simulate border and basin irrigation by incorporating an infiltration algorithm based on the modified Kostiakov equation. The algorithm was successfully incorporated in ANUGA and the adapted model, ANUGA_MK, was tested using eight border and two basin irrigation events. ANUGA_MK performance was benchmarked against the one-dimensional (1D) SISCO irrigation model for border irrigation events, against the 2D B2D basin irrigation model for basin irrigation events and against observed data. ANUGA_MK adequately simulated surface water advance and depth. SISCO’s total infiltration was comparable to that of ANUGA_MK, but its spatio-temporal dynamics differed due to differences in representation of microtopography. For example, the 1D SISCO model did not account for surface depression water storage remaining long after cessation of runoff. Performance of ANUGA_MK was similar to that of B2D in simulating basin irrigation. ANUGA can represent surface water flow on complex surfaces with diverse boundary conditions, and with an appropriate infiltration algorithm, has been adapted as a surface irrigation model that can be used to investigate bay surfaces engineered to improve surface drainage.