It looks like it could be a shortened version of this type of design:
http://www.butterick.com/item/B3418.htm View D
Obviously, your skirt is a lot shorter so that the ruffled tiers overlap slightly, but that pattern is a general construction idea. Maybe instead of top stitching the ruffles onto the base skirt, pin the ruffles to the base upside down (but put right sides of fabric together so the wrong side of the ruffle shows while you sew) then stitch so that afterwards, when the ruffles fall into position (right side out and upside up), the top edges don't show. Sorry if that description's a bit hairy.
It shouldn't be very hard, just tedious with all the gathering of the ruffles.