2D side-scrolling water method

Is there any good way of making a (possibly low-res) water from the side like this:

(Orientation wise, not necessarily photo-realism)

https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTbwVRGjxxCiQv9-PlEB2S6ABNDxmBwyRh3g_1rxbZBHfjxZY1-

I was thinking of making a shader-pass over a low-resolution render target, but that seems kinda… intense to program. Plus its waay over current knowlege of GLSL.