Flowing and falling water are high on the list among my favorite subjects,...providing many year-round photographic opportunities.
A low ISO/ASA setting and a cloudy day are your best possible scenarios and will yield excellent results if you want the falls to "veil" or to appear cotton-like.
The farther you are away from the falls though, the more difficult it will be to get a shutter speed slow enough to blur the action. (To clarify this point,...Next time you are driving along a stretch of highway, look at the road surface next to your vehicle,...then look at the other side of the highway,...then at the distant landscape. You will immediately notice the difference in the perceived degree of motion as the distance from your point of reference increases.)
I prefer to shoot small waterfalls on tiny creeks. This gets you close to your subjects,...so close in fact that you sometimes have to worry about water splashing on the front of your lens. Not only does this solve the distance dilemma,…but sometimes it’s just fun to get your feet wet.
As to your camera settings:
With your camera,…I would try a full-manual exposure with the ISO set at 100.
If the weather cooperates and you have some overcast, set your shutter to 1/8 second. Meter the brightest portion of the rapids and set your aperture to 1/2 stop over what your camera meter recommends. (My own tests have proven that vociferous rapids will over-expose and blow out when you exceed that parameter.) Then, recompose and take a shot at that setting and examine the result.
If you want more blur, try 1/4 second,...or all the way down to a full second or more,...which is quite possible at ASA 100 on a cloudy day. (Just make the appropriate adjustments to your lens aperture setting as the shutter speed gets slower.)
If the sun is bright,...try to find some shaded area in which to shoot. Keep in mind though that shaded sunlight is “cool”, and will produce a blue tinge to the water and any other highlight. If you really know your camera, you can set your white balance to correct this.