Additions to the official templates at https://www.hzdr.de/db/Cms?pOid=14247&pNid=435
In Linux, the color palette file HZDR.gpl needs to be saved in the folder ~/.config/inkscape/palettes/.
Afterwards, it will be a selectable palette within inkscape.
Note, that the colors Hellblau 1 and Hellblau 2 are none of the official colors, but match the hue of the official blue tones and are probably acceptable. In the Corporate Design Manual the scientific posters use "lighter blue or gray tones" and served as templates for the additional colors.
Gimp uses the same color palette format as inkscape, therefore you can use the same file HZDR.gpl.
For Gimp 2.8, place the file in ~/.gimp-2.8/palettes/.
Alternatively, you can save the palette at an arbitrary location and import it via the GUI: right-click on the palette menu and select "import palette".