The invention relates to a process of hydroentangling a fibrous web (N) including of positioning the web on a porous moving support (10) in translatory movement or in rotation about an axis, and of treating at least one side of the web by means of a plurality of streams of water arranged in a row perpendicular to the direction of movement of the web, characterized in that the row includes streams with a first cross-section (14A) and at least streams with a second cross-section (24A) different from the first. The invention also relates to a process including treatment of the web by means of a plurality of streams of water arranged in at least two rows perpendicular to the direction of movement of the web. The rows include streams with a first cross-section (14, 16, 17, 18, 19) and at least streams with a second cross-section (24, 26, 27, 28, 29, 39) different from the first cross-section, at least one row including streams the spacing of which is not constant. This process may be applied to produce webs the state of the surface of which varies.