The frame and background is a bit boring, but pretty good job otherwise. You cropped the original picture quite nicely. There is a lot of noise on the canal image, so you should maybe add some noise to your waterfall as well, to blend it better. You should maybe try adding some more stuff, from the waterfall image perhaps or something else. Pretty ok so far, thou the frame edge where the waterfall starts could use some minor tweaking, the masking isn't as good as it can be. Watch out especially for the sides.

Really appreciate the comments Widiar. Thank you.

nice job on the water

This one is very neat! Waterfall is perfect.

nice idea -- the water needs to be a bit transparent so the brickwork shows through