To ascertain the vertical distribution of the matric suction in unsaturated soil by a source term’s 1D steady flow,a general solution was found with Gardner model.In addition,two particular solutions under the conditions of no source term and constant source term were also obtained,and the vertical distribution of the matric suction in unsaturated silt soil was analyzed under different surface flux boundary conditions and by different source terms.The results showed that the matric suction in unsaturated silt soil,when adopting constant source term,could be controlled with a specific discharge from the surface,a source term,a soil saturated infiltration coefficient and others.Under hydrostatic conditions,the matric suction and the distance from water table had a linear relationship.However,the relationship was non linear in non hydrostatic conditions.The specific discharge,when applying the constant source terms in the same direction of water flow,increased from the groundwater level to surface.Under the condition of evaporation,the matric suction by a constant source term was less than that with no source term at the same surface flow rate,whereas the result was the reverse when in the infiltration conditions.
