Many GCM land surface schemes were recently developed in order to take into account the physical processes of soil water flow by resolving Darcy equation. But numerical resolution of the Darcy equation requires care because of its high degree of non-linearity. This paper presents a sensitivity experiment of the numerically computed surface fluxes to the vertical soil resolution. It is shown that too coarse resolutions drastically affects the ability of the scheme to give physically based representations of moisture and energy fluxes. ¿ 2000 American Geophysical Union