The use of numerical modelling to assess soil water dynamics in subsurface irrigation

Resumo

Knowledge of soil water dynamics is essential for establishing appropriate methods of irrigation management. Water
dynamics in unsaturated soils is a complex process that can be explained by the Richards equation. As this is a non-linear differential
equation, there is no analytical solution, but requires the use of the fi nite element method, for example, to obtain solutions, where
simulations using numerical modelling make it p ossible to predict the the fl ow of water from the soil. As such, the aim of this study
was to evaluate a 2D numerical model in simulating wate r distribution and wet bulb formation resulting from a subsurface irrigation
system, in addition to validating the generated model. The Pearson correlation coeffi cient (r), the coeffi cient of deter mination (R2
) and
the root-mean-square error (RMSE) were calculated. For each treatment, both during and after irrigation, the model showed a small
relative error, high values for R2
and a positive correlation with the fi eld data. It was concluded that the model is applicable to the design
and management of subsurface irrigation systems, varying the installation depth of the drip tube, the spacing between emitters and the
soil moisture, giving good results for the various simulated scenarios.