COMPARISON BETWEEN A HYDRODYNAMIC FULL MODEL AND A HYDROLOGIC MODEL IN BORDER IRRIGATION

The practice of surface irrigation makes it necessary to have a criterion for the design of surface irrigation, with the aim of achieving more efficient water management in agricultural production. Therefore, we made a comparison between the full hydrodynamic model and the hydrological model in border irrigation. To reduce the variations caused by differences in the infiltrated depth obtained with the Green-Ampt and Richards equations used in hydrological and full hydrodynamic models, we performed the suction parameter adjustment in the wet front of the Green-Ampt equation, thereby reproducing the change of the infiltrated depth obtained with the Richards equation. We did the comparison based on the analysis of the profiles of surface and subsurface flows occurring in irrigation, and the final distribution of the infiltrated depth. There were differences between the elements analyzed, attributable to the use of an equation of overall momentum in the full hydrodynamic model. Differences in flow profiles influence the final distribution of the infiltrated depth and therefore the optimal irrigation flow. Thus, by analyzing their behavior in texture triangle soils, where it is appropriate to apply border irrigation, we observed that the difference between optimal irrigation flow provided by the hydrological model and the full hydrodynamic model grows with the increasing content of clay in the soil.