High-resolution 2D modelling for simulating and improving the management of border irrigation

The structure of an integrated hydrodynamic modelling framework intended to describe the dynamics of surface irrigation is presented in this work. Specifically, the modelling framework, named IrriSurf2D, is constituted by a combination of three elements i.e. (i) high-resolution topographic data of ground surface, (ii) two-dimensional shallow water equations and (iii) one-dimensional Green-Ampt approach for describing infiltration process. The modelling framework was validated with a real case study where timings of waterfront advance and water depths on the field were monitored during a border irrigation event. The results show that IrriSurf2D was able to reproduce both the timings of waterfront advance and the maximum water depths with high accuracy, i.e. with average RMSE below 2 min and 3 cm, respectively. Model performance was robust and accurate even using literature parameters without a tailored calibration of infiltration and roughness parameters. Details of the digital terrain model, which affect the computational grid resolution, had a strong influence on the description of waterfront propagation: a coarse grid resolution (1 m2) was found inadequate for reproducing reliable timings of waterfront advance and water depths in the field, while with a finer grid (0.01 m2) as modelling input the simulation results appeared properly consistent with the observations. The modeling approach appears promising to describe the dynamics of border irrigation and paves the way for the development of an operational tool for improving the management of surface irrigation.