The only info I have about this photograph is that it was taken in WW1. The badges were a bit too grainy for me to match them up with others that I am familiar with so hoping someone else with more knowledge can assist! Asking on behalf of a friend. Thank you!
Formed in 1914 by the combination of three mounted regiments and disbanded in 1919, the brigade served in the Gallipoli Campaign and the Sinai and Palestine Campaign. The photo looks like it could have been taken in the dry scrubland near the beach where the Australian and New Zealand troops landed.
Plenty of more detailed info on them can be found here.