How to get Coordinate axis (x,y) parallele to the orientation axis ?

[anicetDjiemon]

G'day, I am using ArcMap 2.14 or QGIS 2.14.11. I have a map with drains as you can see on the image. I would like the coordinates (x,y) of each point but my origine point (at the corner just below in red on the map) will be (0,0). The x axis should be parallele at the length and y axis parallele to the Width as you can see on the image. Do you know how that could be done? Thanks