Funded by the World Bank and other donors, the Southern African Millennium Ecosystem Assessment (SAMA) is the first in a series of regional checkups of the planet's health launched by the United Nations in June, 2001.

It examined 19 African countries on or below the equator. "Southern Africa, broadly speaking, has a water-scarce south and a water-rich north," said the study.

Bob Scholes, one of the study's authors, told Reuters the water situation was most serious in Kenya, Rwanda, Burundi, South Africa and Malawi.

"A large fraction of the population in rural areas is totally dependent on ground water and it is being used unsustainably almost without exception," he said.

Food insecurity is also a cause for concern though the region's roughly 275 million people grow enough to eat.

"The region as a whole produces enough carbohydrate crops to in principle meet the aggregated minimum needs of its population," the study said.

"In practice, because of distribution inequities, up to 25 percent of the population are undernourished," it said.

Several southern African countries have battled with food shortages in recent years, with drought and an AIDS pandemic which is killing off workers making the situation worse.

PROTEIN PROBLEMS

Scholes said protein deficiency was another problem. "One of the key things to come out of this is that we have documented severe protein deficieny north of the Zambezi (river)," Scholes said.

He said the minimum requirement for healthy development in adults was 52 grammes of protein per day. But overall in the region it has fallen to 49 grammes from 57 in 1976.

"Critically, the countries north of the Zambezi are down to about 42 grammes," he said - a trend related to rising populations which are stripping nitrogen out of the soil through crop production faster than it is being replaced by fertilizers.

Nitrogen is the foundation of protein. To improve the situation the study recommended, among other things, programs to replenish soil nutrients and macroeconomic policies that encourage the success of smallholders.

But the study estimated that "84 percent of the pre-colonial biodiversity is intact in the region" - although many species including the wild dog and cheetah are endangered.