THREE- DIMENSIONAL UNSTEADY SEEPAGE ANALYSIS IN VARIABLY SATURATED POROUS MEDIA

Abstract

Three dimensional seepage problems through variably-saturated porous media under transient conditions play an important role in many practical situations in water resources engineering (such as flow through dams, seepage from canals and drains, moisture advance in root zone, ... etc.). In this thesis, general reviews for the different approaches, which may be used to estimate the hydraulic conductivity in the unsaturated zone was carried out. Also the different approaches that may be used to solve the governing partial differential equation for the flow in variably saturated porous media is discussed. Three- Dimensional numerical model based on the "Residual Flow Procedure" using the Galerkin-finite element method is used employing isoparametric hexahedron element that simulates the physical geometry of the transient flow in variably-saturated porous media. The non-linear 'pressure- hydraulic . conductivity' relationship that is used in this study to estimate the hydraulic conductivity in the unsaturated zone is discussed in details The numerical model is developed to run on PC computer. The model is capable to handle the transient flow through confined and unconfined seepage problems. The developed numerical model was compared to four different solved problems found in the literature which verified the finite- element solutions and computer program integrity The first problem was solved using numerical and experimental models, the second and third problem was solved using closed form solutions and I numerical models, and the fourth problem was solved using numerical and experimental models. The developed numerical model shows satisfactory comparisons

against the closed form, numerical, and laboratory results. Two applications of the computer program are then given, demonstrating the versatility of the finite- element solution of the variably- saturated flow equation for simulating complex physical geomerties as well as a variety of boundary conditions.