Answer:
annual rainfall is 700mm.
Step-by-step explanation:
The Vaal River and its tributaries drain about 20% of the Orange-Vaal basin. The source of the main stem is near Breyten (Mpumalanga) at 1770 metres and the main tributaries originate near Harrismith and Bethlehem along the Eastern Escarpment Mountains, where the annual rainfall is 700mm.