The design element/principle for this image is color. Because what really catches your attention about it is all the different colors in the image.

The principle/element could also be harmony, though. Because all of the different color's blend well together and have harmony.
I edited this in photoshop to enhance the colors. 
I made this image with Bomomo. I used the button that makes the lines, and before the lines started to go horizontal, I saved the image.

The design element/principle of this image is lines. I made the colors of the image pretty basic so nothing distracts the viewer from the main point of it; the big vertical lines.

I edited this in photoshop to make the lines appear darker, and I also cropped it.