As long as
you understand what you mean; my concern is that other folks, seeing "irrigation ditch" will think of a ditch which moves water from one place to another, whereas the purpose of a
swale is to hold the water in one place.
"The essentials of swale construction are simple; they are all built on contour or dead level survey lines, and are neither intended nor permitted for water flow. Their function is just to
hold water."
Bill Mollison,
Permaculture A Designers Manual, page 167.
(I'm worried I look like a fussy nit-picker)