Okavango Delta, Botswana

The Okavango Delta is a large swampy inland delta in northern Botswana near Maun. Most of the Okavango River, which originates in the highlands of east-central Angola, terminates here. The delta has been formed over 2 million years from silt deposits left as the river enters the flat, arid terrain of northern Botswana. The Okavango Delta consists of a maze of meandering channels, often choked with dense masses of papyrus and other aquatic plants, many shallow, water-filled basins and numerous islands, or elevated wooded areas that remain dry during flooding.

The delta covers about 16 000 square km, although up to 22 000 square km may be flooded in high-rainfall years. Water levels and flooding reach a maximum between March and July, after rains near the source of the Okavango increase the volume of the river. About 3 percent of the water in the delta is carried away via the Boteti River and two other channels. This outflow preserves the freshwater ecosystem in the delta by flushing out salts and other minerals that would otherwise collect in the delta. Average temperatures range from about 14° C (57° F) in January to 24° C (75° F) in July. Annual rainfall averages 525mm but varies greatly from year to year.

Part of the eastern delta is included in the Moremi Game Reserve which was founded by the local Batawana people in 1965. Hippopotamuses, crocodiles, buffalo and two kinds of antelope, lechwe and impalas, are common in the delta. Large numbers of other plant-eating animals also migrate there seasonally. Rhinoceroses and elephants were also fairly common but hunting has eliminated the rhinoceros and reduced the elephant population.

Two barrier fences on the southern and western edges of the delta were built to protect the livestock from diseases carried by animals in the north. These fences have disrupted seasonal migrations of wildlife and have caused the deaths of large numbers of migrating animals that could not negotiate the barrier in their path.

Since the 1900s there have been several proposals to use water from the delta for irrigated agriculture, cattle ranching, and industries such as diamond mining. Most of the proposed projects, however, have required more financing than was available. Since the economy of Botswana is focused more on raising livestock than on growing crops, there has also been insufficient interest to proceed with extensive irrigation plans. Moreover, ecologists fear that the development of such plans could permanently damage the delta's delicate ecosystem.

There are more than 500 species of birds, including the African fish eagle, and ibis. Tiger fish, sharp-toothed catfish, barbel, and bream are among the many species of fish. Rapidly growing cattle populations to the south and west of the delta have damaged the wildlife habitat by overgrazing and overburdening the water supply.