Resumo

YANG, Dejun; ZHANG, Tuqiao; ZHANG, Kefeng  e  LEI, Shaogang. Extending the integrated Richards Equation method to new boundary conditions: model description and validation. Agrociencia [online]. 2015, vol.49, n.7, pp.723-737. ISSN 2521-9766.

There is a need for developing an accurate and simple method, which can be widely used in agro-hydrological models. The Integrated Richards Equation method is a good and simple method to simulate cyclic movement of water in the soil-atmosphere system. However, this method still has some unsolved problems and it is needed for further development if used in agro-hydrological simulation. In this study, the Integrated Richards Equation method was further developed for the agro-hydrological simulation by introducing the commonly used soil hydraulic functions, top and lower boundary conditions. Infiltration numerical experiments and a lab evaporation experiment were used for the validation of the model's capabilities of modelling infiltration and evaporation, respectively. A field evaporation experiment, which was conducted from 27 April to 21 November in 1971, at Big Ground field, Wellesbourne, UK, was used for in-site validation. Soil samples from four replicate plots were taken at 5 cm increments to a depth of 45 cm at regular intervals throughout the experiment. In total, 10 measurements of soil water content down the profile for ten different times were taken during the experiment. Numerical infiltration experiments showed that the proposed method could give good predictions for two contrasting soils, loamy sand and clay loam, under unsteady intense rainfall conditions. The results were in line with those from the complex numerical scheme of FEM. Good results were also obtained in testing the method for evaporation from coarse sand, but the method under-predicted the amount of evaporation from fine sand. The results of testing against data from the field experiment show that the predicted soil water content was in good agreement with the measured values down the soil profile, but not for the soil close to the surface. This indicates that the proposed method performed well in agro-hydrological simulations on agricultural bare soils under different complex conditions at the upper boundary. Thus the method could be applied in agro-hydrological simulations.

Palavras-chave : Evaporation; agro-hydrological simulation; infiltration; Integrated Richards Equation; runoff; soil water content.

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