any tips?

 

There is a big difference between DoF and sharpness,
you got the first but not the second.

The key is too high and that is partly responsible for the
lack of details, try tonal taming (will help with high key).

To my taste, the 15s were way too long. Next time try 8s.

Let's see if we can use terms that average people can understand...

(I find that the) exposure is fine, and appears to represent the light at that time of day.

You used a tripod. Good. You used f/32. Bad. The problem with smaller apertures is you get distortion, that can lead to an appearance of blurriness. Given your proximity to the stones, you're going to have to settle for f/11 or f/14 and less DoF (depth of field) if you want anything to be sharp.

FWIW, I've been bit by this, too. Happens to most of us. At least, those of use that make mistakes.

If you have VR on your lens, turn it off. While it's not clear that active VR on a tripod is a Bad Thing, you don't need it. It does not help you.

A 15 second exposure is fine, if that's what you want. 8 seconds is fine. 1.5 seconds is fine. You get different results with each, so explore.

For me, the composition can be improved. You don't need anything at the left of top. This could be improved by having the rocks (from this angle) and the water (and its patterns) filling the frame. We already know it's a man-made waterfall; you don't need to beat us over the head with it. By eliminating the non-rock/non-water parts of the image, our imagination fills in what lies outside the frame, making the environment bigger from our perspective. That's to your benefit as the maker.

Did you try different vantage points? You should.

All that said, find better light. Midday, kinda cloudy. Meh. Or work the image in post to add some drama.

If my English is not understandable I will translate
my thoughts into a picture.

The exposure is not fine and the key is too high, a 
simple mid-tones tweak yields this kind of drama in
the posted image.

ƒ32 will introduce diffraction — as it increases DoF
it will cause loss of sharpness.