The present invention relates to a water movement device comprising a flexible wall (1) placed in water close to the surface, substantially vertically in a static rest state, made up of optionally perforated (5) massive unit blocks (4) assembled to one another in strings by cables (2, 3) on which said blocks (1) are threaded or on which said blocks are crimped, said cables comprising: a series of cables (2) disposed vertically (ZZ') side by side, parallel to one another, and a second series of cables (3) disposed horizontally (XX') one above another and in parallel, and said vertical cables (2) being suspended or tensioned at their top ends and/or respectively tensioned or moored at their bottom ends, and said blocks including empty orifices (5) passing through them between the front and rear faces (1-1, 1-2) of said wall (1), and/or empty spaces (7) between said blocks, such that said orifices (5) and/or empty spaces between said blocks (7), if any, confer overall porosity on said wall lying in the range 5% to 75%, preferably 20% to 45%, of the area of the vertical section of said wall.