Analytical approach predicting water bidirectional transfers. Application to micro and furrow irrigation
Résumé
This paper presents an analytical or semi analytical method predicting water bidirectional transfers in a soil under different irrigation systems, and more especially for the micro and furrow irrigation system. The method developed in this article solves the Richards` equation thanks to the Green`s function. This equation is solved under some assumptions allowing its linearization. The Green`s function is a well known method to solve partial differential equation (PDE) with constant coefficients in simple geometries and general boundary conditions. The particularity of the method is to approach Richards` equation in real irrigation contexts by superposing simple solutions which can be treated by Green`s function method. The aims of this work are both to proposed analytical and explicit forms of water content in the soil and to treat in a simple and operative way scenarios of irrigation (unspecified furrow shapes in the case of furrow irrigation, heterogeneous initial conditions, taking into account of precipitation events and plant uptakes, etc~). It allows also the evaluation of the coefficients of the solute transfers equation which depend on the soil water content. This equation can then be solved with the same approach developed for water transfers. We present here the main principles of the model, the first results and the possibilities of further improvements.