Overuse upstream could dry the

New report shows that an increase in farming and town water supply needs in Angola and Namibia is draining

- 

A silent crisis is unfolding in the highlands of central Angola. Here, where miombo forests stretch towards the horizon and rivers thread through deep sands, the Cubango River begins its long journey toward Botswana's Okavango Delta. But not all of it makes it there.

A new report by researcher John Mendelsohn warns that substantial volumes of water are being lost along the way - drawn off by farms, towns and irrigation schemes with almost no oversight or accountability. And the Delta, hundreds of kilometres downstream, is starting to feel the pressure.

"The Delta is so vast and natural that it is easy to become complacent about its protection," writes the report's author, researcher John Mendelsohn. "Yet as magical as it seems, this wetland does not just appear from nowhere."

The water that eventually evaporates or sinks into the Kalahari sands in Botswana has travelled more than 1,000km from the highlands of central Angola and then along the border of Namibia.

What happens to the rivers in Angola and Namibia can threaten the health of the Okavango Delta.