Vauxhall Corsa 1686 Diesel

I was out this morning when my temperature gauge started climbing higher. It never hit the red but when i checked the level it was empty. The alternator belt was slipping so i suspect there is a water pump fault. However since topping it up there seems to be a huge leak when its running, it runs fine the water just seems to be pouring out somewhere behind the engine.

Can anyone give me any idea what could be leaking? I’ve checked the haynes manual but doesn’t show any breakdown of what cooling related components are on that side of the engine.