This is an image from the Noaa Satellite. This covers most of South Australia. It is a false colour image to aid interpretation. Lake Gairdner is clearly visable.
Rainfall and Lake Gairdner
Here are the drainage catchments for Australia. The Gairdner catchment (1) is in the Western Plateau Division (XII).
There are no major entry points for rivers and creeks to Lake Gairdner other than from the very North-West tip. Even when it does rain north of the Lake it takes a couple of weeks to get down to where the speed trials are conducted.
And here is the catchment boundaries draped over the satellite image for the Lake Gairdner area.