-Select The edges that you wanna use.
-Go to Select >> Set Selection (To create a Selection Tag)
-Drag and drop that selection tag inside the Relax UV >> Cut selected Edges and tun it On (check box).
-Go to Projection >> Flat.
-Go back to Relax UV >> Apply.
Your object is on a Transparent Plane.
You need to :
1 Generate a geometry for your hair (Flat, square or so).
2 Because your hair has a geometry now, you need to Unchild the hair from your Transparent Plane to Avoid the transparent material to be
applied to the hair.
3 Go to your Compositing Tag >> uncheck Seen by refraction (because of the transparent object).
4 Go to your Compositing Tag>> Exclusion >> add the Water Plane here.