Water is tricky, more powerful than you would imagine and pretty much has a mind of it's own. I still don't know that I'm good with it, but I learned a lot creating this creek for a high school production of "The Women of Lockerbie."
Each platform was built up with layers of foam attached together with contact adhesive and then carved down. The creek was carved into the foam and then coated with Jaxan rubberized coating to make it water tight.
I added a chunk of 2x4 to the front of each platform and built up the sides with more jaxan to create the waterfalls in between the levels.
The water was run using a fountain pump from Home Depot. I purchased one that was listed as being good for up to 15 feet. My water was flowing for 12 feet horizontally and three feet vertically. As it turns out it was FAR too strong. On our first test the water came pouring out of the hose and overflowed the "banks" of our creek everywhere. To fix the problem I covered about 3/4 of the intake of the pump with duct tape to limit the amount of water, which made a huge difference, though in the future I will remember how incredibly strong these pumps are and get a smaller one.
After that it was a constant battle and engineering challenge. I would run the pump and have students stationed at all point along the path watching, finding the drips and leaks, figuring out where they were coming from and trying different ways to fix them. the first few times I worked with them we would make as many fixes as possible with the jaxan and then we'd have to wait for it all to dry before running it again. For the last few fixes I bought a couple tubes of quick dry silicone caulk so that we could do multiple rounds of fixes in one after school work session.