Coupled governing differential equations for both moisture transfer and heat flow are introduced. The approach adopted is based on the total potential for liquid flow being composed of the temperature potential
the elevation and the capillary potential. Besides
a simplified governing equation with heat source is given. The solutions of a semi-infinite unsaturated porous medium subjected to a plane heat source with variable strength with time on its free surface are studied. The numerical integral methods for calculating the unsteady temperature field
volumetric water content field are studied. The evolutions of temperature and moisture content are given under the conditions of constant and variable heat strengths; and the gravitational influences are also analyzed.