The present invention relates to a unitary absorbent structure and method thereof wherein said unitary absorbent structure comprises an absorbent core (5) and/or an acquisition (2) and dispersion (3) layer, said absorbent core (5) and/or an acquisition (2) and dispersion (3) layer comprising at least one non-woven fibrous substrate layer (23) having a void volume suitable to be penetrated by super absorbent particles, characterized in that said super absorbent particles are dispersed in the substrate layer (23) according to a size distribution gradient along the depth direction or z-direction of said absorbent core (5) and/or acquisition (2) and dispersion (3) layers.
