Fixing stretched landscape


Just learning to use the landscape editing tools and ran into something that a simple Google search isn’t specific enough to fix! The stretched components of the map not only stretch the material being painted on them, but as I zoom in or out through the editor (or even just moving around the map in the Launcher), the map warps and distorts. As you can see from the image I’ve attached, the stretched material is more than noticeable. But also, the left image is zoomed out, while the right image is zoomed in. On the left, it looks like the river bends, while on the right, it almost goes straight. This is because, as I get closer, some of the landscape shrinks away while other parts become more prevalent.

I know on flat surfaces, I’ve been able to just align them but I don’t seem to have the same option here. Anyone know how to fix this problem or do I have to rebuild on a smaller scale?

Thanks in advanced!