  In this paper we prove the existence of weak solutions to degenerate
parabolic systems arising from the fully coupled moisture movement, solute
transport of dissolved species and heat transfer through porous materials.
Physically relevant mixed Dirichlet-Neumann boundary conditions and initial
conditions are considered. Existence of a global weak solution of the problem
is proved by means of semidiscretization in time, proving necessary uniform
estimates and by passing to the limit from discrete approximations.
Degeneration occurs in the nonlinear transport coefficients which are not
assumed to be bounded below and above by positive constants. Degeneracies in
transport coefficients are overcome by proving suitable a-priori
$L^{\infty}$-estimates based on De Giorgi and Moser iteration technique.
