Creating a custom CRS for the South African coordinate system (SACRS) in QGIS?

Question

My question relates to creating a custom CRS of the official coordinate system used in South Africa, called SACRS.

The SACRS is a projected coordinate system that must be referenced to BOTH the "Hartebeesthoek94" datum and the "Gauss Conform Coordinate System" (see help guides at the bottom of this post). I seek technical advice on creating this projected coordinate system as a custom CRS.

What should I type in the parameters box in QGIS (proj4 format)?

I am not sure if any of the following coordinate systems are already close (or similar) to the SACRS, but perhaps they are a good starting point for a custom CRS:

• Hartebeesthoek94 / Lo25 [EPSG 2051]
• South African CRS: HBK_NO_25 [ZANGI:ZANGI:HBKNO25]

Background information on the SACRS is available at:

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=13&cad=rja&uact=8&ved=0ahUKEwizmdnHwoXSAhVpLMAKHY3CATUQFghRMAw&url=http%3A%2F%2Fwww.ngi.gov.za%2Findex.php%2Fresources%3Fdownload%3D37%3Athe-south-african-coordinate-reference-system&usg=AFQjCNFywI3HdttJQWFzPXFqtAr4leRdiQ&sig2=mGJdK_hyvRsJXU8-F6w86g

https://ace-notebook.com/An-introduction-to-coordinate-systems-in-south-africa-free-related-pdf.html

Answer 1

One feature characteristic to official SACRS is its axes definition: westing = Y, and southing = X. (+axis=wsu in Proj4 string.) This is the Hartebeesthoek94/LO25 (EPSG:2051) which you can choose.

The other one you also mentioned, ZANGI / HBKNO25 (easting = X and northing= Y) is not official. (And not registered in EPSG code). But it is still widely used. ArcGIS offers only this one.