The purpose for the hose is uncertain: to flush the fixture, or the entire facility?
After having seen this page, a visitor by the name of AG writes in with the following clarification: "Hi there. I stumbled across your picture of the urinal at Khartoum airport. The purpose of the hose is actually to wash your penis before and after you urinate, as Muslims are required to do. Incidentally, I have used this actual urinal (I think there is only one at Khartoum airport) and it was even more rancid than it looks in the picture".