Click "e", "prt scr" and jump at the same time, and you can go over any high walls! You may have to try a few times to get used to it.
When ye're tryin' to get over the waterfall (or any steep slope), hold down the prt sc key on yer keyboard right as ye' near it. The game will freeze for a few milliseconds- that's a good thing- then after a second or two, release the key and ye' should be well over the fall. If not, ye' can try again as sometimes it'll take a second or third try til' the tactic is successful.
I use this motive all the time so it should work for ye' too if used correctly.