I suppose the stream could be more visually appealing if it followed
a more interesting route. I think that, if I were to find an underground
spring somewhere in a cavern, the water would spread out over the
rock rather than carve a deep channel. Sure, it might etch grooves
into the rock, or follow any existing path, but what you're depicting
looks at least a foot down. Plus, your stream seems to barrel in and
out of the cave wall. Is there a tunnel for the water to go through or
something? If so, you might include that with a dotted line. What's the
slope in the cave aside from your trench?

Also, I can see where you intentionally widened the stream the further
it got from the source. While this would probably be pretty accurate on
a large scale, with something so small as this, the stream could be
deeper instead of wider. Would this stream have other sources?

Overall, I can see where what you've done looks nice in those close-ups,
but the stream might benefit from following a different path.

Best of luck, and hope my comments help
Foremost