Wiktionary
vb. (present participle of rainbow English)
Wikipedia
Rainbowing is the process in which a dredging ship propels sand that has been claimed from the ocean floor in a high arc to a particular location. This is used for multiple purposes, ranging from building up a beach to prevent erosion to constructing new islands. The name is derived from the appearance of the arc, which closely resembles a brown-colored rainbow.
This technique was used extensively in the construction of the Palm Islands and The World, Dubai.
Usage examples of "rainbowing".
The noise of their wings made the air vibrate until it was almost impossible to think, but there was a kind of beauty in them, too, their glossy bodies rainbowing as they caught the sun, their swift-beating wings an almost invisible iridescence.
The roofs of silver were merely dark slate, and what he thought were gemstones merely collected dew rainbowing back the dawn.