An even more dramatic effect can be achieved by capturing the shot when there is light rain or drizzle. The overcast sky will take care of the exposure issue, and the rain will make the rocks and other landscape elements glisten and “pop”. Try setting your aperture at f/22 and leave the shutter open even longer, this can be over 10 seconds, to get the silky, flowing water effect. If you pick the aperture priority mode then your camera will leave the shutter open as long as it takes to get the right exposure for your image. You can also try experimenting by using black & white mode or another filter, depending on what settings your camera has in place.
To create the opposite effect i.e. the landscape appears to be moving and the water is still, set your shutter to 1/60 and pan the water. This may take a few trial runs before you get the effect that you want but it will be worth it for a really stunning final image.