Problem with "warping" of LEGO water
This image of the same model shows that the whole set sits on a frame of bricks. In the inside, you could place bricks underneath wherever necessary to attach the water plates (not only 1x... but maybe 2x10, or several 2x4 in a row). They are invisible, so color and type don't matter. If this row of bricks reaches from one side of the frame to the other, it can shift to allow the longitudinal waves but it cannot curl up transversal(ly?).