The approach of the Green and Ampt (1911) for describing water entry into unsaturated porous media was critically appraised .Theoritical revision was made of a previous mathematical approach, to give it complete rigor in describing   water flow for rectangulary abrupt water content profile. Rigorous rederivation of this equation yielded a straightforward and complete interpretation of the suction head at the wet front t_w. The suction head t_w at the wet front is given as the integral of the suction-head- t dependent hydraulic conductivity function K (t) with the upper limit of the integral being the suction head t₀ at the initial water content q₀. Furthermore, t_w is shown to be a constant of the flow process even when G-A rectangular abruptness does not hold. The equation is shown to be the hydraulic conductivity K (q₁) of the wet region behind the wet front which is a function of the constant averaged water content of the wet region. For experimental data of cumulative infiltration with time, both the G-A and two –term Philip equation were fitted by nonlinear regression. The G-A equation gave better fitting than Philip equation for certain soil texture, but both equations gave a very well fitting (%1error). G-A parameter K₁ gave a very good agreement with the measure hydraulic conductivity for all soil studied. The other parameter t_w was calculated from the fitted parameter a  and show values correlated to soil texture in expected .Abruptnen of soil water transient profile was tested using soil moisture probes-GS3.