Modelling infiltration and redistribution of water in a Fluvisol

• Published in: Revista de ciências agrárias Vol. 25; no. 3-4
• Main Authors: Neves, R, Chambel-Leitao, P, Fernando, R.M, Leitao, P.C, Cameira, M.R
• Format: Journal Article
• Language: Portuguese
• Published: 01.07.2002
• Subjects: FLUVISOL; FLUVISOLES; FLUVISOLS; INFILTRACIÓN; INFILTRATION; MODELOS DE SIMULACIÓN; MODÈLE DE SIMULATION; POROSITÉ DU SOL; PROPIEDADES HIDRÁULICAS DEL SUELO; PROPRIÉTÉ HYDRAULIQUE DU SOL; SIMULATION MODELS; SISTEMA POROSO DEL SUELO; SOIL HYDRAULIC PROPERTIES; SOIL PORE SYSTEM
• ISSN: 0871-018X

Agriculture, integrated management of water, environmental planning or the study of terrestrial ecology are activities requiring information on soil water circulation and on fertilizers and pesticides transport and transformations. The soil is the physical entity where significant processes occur. Soil sciences supply the basic knowledge required by integrated studies involving biological and/or chemical processes. Models describe the relations between the state variables through a set of interdepent evolution equations, being interdisciplinary in nature. The structure of the evolution equations is the same in any system where a fluid mediates transport and so is the structure of the numerical tools required to solve them. A mathematical model involves 4 aspects: (i) a set of evolution equations, (ii) numerical algorithms, (iii) informatics support and (IV) data to specify parameters, initial and boundary conditions. Equations differ through the production and destruction terms, but requirements to describe space and time distributions are common to any problem involving transport phenomena. Most of the complexity of numerical algorithms is due to transport, which can be shared between very different applications if algorithms and informatics are conveniently organised. In this communication it is described the model MOHID and results of its application in the study of processes of infiltration in situations with and without macropores. This model was initially developed for the simulation of circulation of superficial water and biogeochemical processes in those systems. The simulation of circulation and transport in soil makes use of the algorithms and informatics developed for those applications (three-dimensional), which have been complemented with specific developments for process in the soil. The results of the model are compared with field data collected by Cameira (1999) and with results of another model (HYDRUS), which constitutes an international reference in the modelling of circulation of soil water. It was shown that infiltration can be simulated using a 1D formulation, as far as macropore effect is taken into account (in this case increasing hydraulic conductivity). It is also shown that three-dimensional effects are important during drying process if horizontal gradients are relevant