The Okavango ariver's delta in Botswana, a wildlife sanctuary that has so far been able to protect itself from the ravages of human intrusion, is currently under threat from surrounding regions for growing need for water.

The delta, which rises in the Angolan highlands and flows through the deserts of south-west Africa to drain into an inland depression, forms the 16,000 sq km of the Okavango swamps.

Neighbouring Namibia, under the continuous onslaught of a four-year-long draught, has for years been supplicating Botswana for the right to pump water from the river. "We have no choice, our rivers are almost empty,' said Richard Fry of Namibia's water supplies department.

Under a 1973 agreement on utilisation of the river's resources, Namibia has to procure the consent of upstream Angola and downstream Botswana. The Namibians want to build an 250-km long aquaduct from the Okavango to capital Windhoek to draw off 17 million cu m water annually. The yearly flow of the river widely varies between six billion and 15 billion cu m.