Okavango Delta

Okavango Delta or Okavango Swamp, large swampy inland delta in north-western Botswana, one of the world’s largest inland water systems. Most of the Okavango River, which originates in the highlands of central Angola, terminates here. The river and the delta are named after the Okavango people of Namibia; the swamp was visited by David Livingstone in 1849. A protected area, the delta covers 16,835 sq km (6,500 sq mi), although up to about 22,000 sq km (approximately 8,500 sq mi) may be flooded at times of high rainfall. The delta has been forming over 2 million years from silt deposits left as the river enters the flat, arid terrain of northern Botswana.

The Okavango Delta consists of numerous meandering channels, often overgrown with papyrus and other aquatic plants; many shallow, water-filled basins; and islands, or elevated wooded areas that remain dry during flooding. Water levels and flooding reach a maximum between March and July, after rains near the Okavango's source increase the river's volume. About 3 per cent of the water in the delta is carried away via the Boteti River and two other channels; this outflow preserves the delta’s freshwater ecosystem 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. Rainfall averages 525 mm (21 in) annually, 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, lions, cheetahs, and two kinds of antelope—lechwe and impala—are common in the delta. Large numbers of other plant-eating animals also migrate there seasonally. Rhinoceroses and elephants were fairly common at one time, but hunting has eliminated the rhinoceros and reduced the elephant population. There are more than 500 species of birds, including the African fish eagle, ibis, and slaty egret. 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. 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 early 20th century 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. The government is committed to maintaining the tourist potential of the delta, operating on the principle of high cost-low density tourism in order to prevent overexploitation. In 1996, the Okavango Delta system was included in the Ramsar List of Wetlands of International Importance.