the humble donga and gbg, page-5

Good question and that prompted a google Frank, this is the best I could find with a quick search....

DONGA
source: http://www.anu.edu.au/ANDC/pubs/ozwords/June_98/3._from_the_centre.htm

The term is a borrowing from South African English, where it means ‘a channel or gully formed by the action of water’. It first appears in Australian English in 1902 (a borrowing during the Boer War?), and it has come to mean ‘a broad shallow often circular depression most commonly found in dry country’. A quotation from 1913 describes an Australian donga: ‘Scattered over the plain for about twelve miles westward of Ooldea, are slight depressions having the appearance of shallow lake beds, where the soil is softer and the low monotonous blue bush gives place to thick rank grasses and clumps of stunted scrub. These ... ‘dongas’ ... watered only in times of heavy rain, must seem a veritable haven of refuge to the animal life of the plains’. In recent years, however, especially in bushwalking contexts, donga appears to have become also a term for ‘thick bush or scrub’. It is not entirely clear how this meaning arose.

More troublesome is a second Australian sense of donga: ‘a makeshift or temporary dwelling’. The term is now widely used in Australia to describe a demountable building. Is this sense an Australian transfer from the South African word? Or from the Australian ‘depression’? It has been assumed so, with the notion of a ‘gully’ or ‘depression’ being extended to ‘any place of shelter’. We know that in Papua New Guinea donga means ‘a house’. The second earliest piece of evidence for ‘a makeshift dwelling’ in Australian English occurs in Through: The Official Journal of Signals 8th Australian Division(Singapore, 1941): ‘The great number of mosquito proof ‘Dongas’ erected on the beach’. Is it possible that the origin of this sense lies in Papua New Guinea rather than in South Africa and the Boer War?

The stumbling block to this argument seems to be a 1900 quotation from Truth(Sydney): ‘And dossed in dongas ev’ry night/Daown [sic] in the old Dermain [sic]!’ It has been assumed that this is the first evidence for the ‘makeshift dwelling’ sense. But were these dongas in the Sydney Domain makeshift dwellings, or were they simply depressions in the ground where a tramp could take shelter? If so, we are perhaps back to WW2 for the origin of donga in the sense ‘a makeshift shelter’.