I am trying to form a landscape around my story, and having a hard time figuring out the landscape. The main content of the story is equating a river to memory, and traveling up the river to revisit a lost memory. Washing in the river removes memory, or at least people believe it does. I was considering having the river reach a canyon at a mountain range, where it comes from a waterfall that is falling from further up in the mountains.
In the story, two people's paths diverge, one getting lost in the river, and the other getting washed away. My initial idea was to have them enter the canyon and one of them go underneath the waterfall, thereby getting sucked underneath. Part of the story will have flashbacks, so the visual of where they are going is important. I want the main character to return to the canyon and remember the river flowing out of it.
A new idea came to me, that they live up in the mountains, at the mouth of the river. It would be a caldera with a large lake feeding a river. However, for this to work, I would want the river to flow into and out of a canyon (they remember the river flowing into the canyon, but when the see the river flowing out they think it is the same thing). With a caldera's walls rising up, does it make sense for a river flowing out to enter a canyon, go down a waterfall, and then flow out of the canyon at the edge of the mountains? Could this be achieved over a short distance (as in maybe the waterfall is just beyond the mouth of the canyon, then the exit is shortly after the waterfall)?
Edit: Additionally, would there be any way to do this without the caldera (having the river enter and exit a canyon with a waterfall separating, over a short distance)?
