[A mathematical model for the description of water movements in layered soils]
1998
Santini, A. | Romano, N. (Naples Univ., Portici (Italy). Dipartimento di Ingegneria Agraria e Agronomia del Territorio) | Brunone, B. (Perugia Univ. (Italy). Istituto Interfacolta' di Idraulica)
A mathematical model for describing water movement in layered porous media under transient, unsaturated flow conditions is presented. Attention is focused on developing a numerical algorithm to evaluate the interlayer conductivities. Setting up a regular space grid by placing two nodes at a symmetrical distance from the interface between two different soil layers, the algorithm is based on the equality of fluxes entering and exiting from the interface and on the continuity of the soil-water pressure potential across it. The pressure potential-based form of Richards' equation governing the flow process was solved numerically by an implicit finite-difference method, using a Crank-Nicolson scheme. Time step was internally controlled and taken as avariable in order to better monitor the evolution of the flow of water during tie. To check the model, numerical results were compared with the analytical solution by Srivastava and Yeh (1991) regarding ideal two-layer soils. Furthermore, model predictions were compared with soil water potential and water content values measured during a transient field experiment. The model provides an accurate definition of local hydraulic characteristics of the flow field and it enables the dynamics of transient processes into soil to be followed with details
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