As any reader of the Just So Stories knows, it was on the banks of "the great grey-green, greasy Limpopo River, all set about with fever trees" that The Elephant's Child got his long trunk. The Limpopo river arises in the interior of Africa, and flows generally eastwards towards the Indian ocean. It is around 1 600km (1 000 miles) long (or 1 770km /1 100 miles according to another source). The Limpopo is the second largest river in the region, after the 2 200 mile Zambezi river.
The Limpopo river flows in a great arc, first zig-zagging northeast and north, then turning east and finally southeast. At the source in South Africa it is known as the Krokodil (Crocodile) River, until passes through the Hartbeespoort Dam and joins the Marico river, when it becomes the Limpopo.
Then it serves as a border for about 400km, separating South Africa on the southeast bank from Botswana in the northwest. Then it forms 240km of border with Zimbabwe on the north side. Then the river enters Mozambique at the point where South Africa, Zimbabwe and Mozambique meet. After this, there are several rapids as the river falls off Southern Africa's interior escarpment.
The main tributary is the Olifants river (Elephant River), which flows northeast through South Africa, and joins the Limpopo around 210km (130 miles) from the river mouth, in Mozambique. The river finally flows southeast to the sea near Maputo. The port town of Xai-xai is on the river near the mouth. Below the Olifants, the river is permanently navigable to the sea, though a sandbar prevent large ships' access except at high tide.
The waters of the Limpopo are indeed sluggish and silty. Rainfall is seasonal and unreliable. In dry years, the upper parts of the the river flow for 40 days or less. The upper catchment area is arid, in the Kalahari desert, but becomes ever less arid further down the river. The lower reaches are fertile and heavily populated. Floods after the rainy season are an occasional problem in the lower reaches, most notably the catastrophic floods in February 2000.
At the north-eastern corner of South Africa the river touches the greatest conservation area (or game reserve) in South Africa, the Kruger National park. Following agreements with Mozambique and Zimbabwe in 2000, this forms part of the Great Limpopo Transfrontier Park which joins the Kruger park to Zimbabwe's Gonarezhou National Park and Mozambique's Limpopo Park. The big five are found in these parks.
Game found in or near the river include hippopotamus and crocodile; as well as land-dwellers such as elephant, giraffe, lion, hyena and several kinds of buck. However it is the crocodiles and hippos (and to a lesser extent the lions) that pose the greatest danger to illegal immigrants wanting to cross the border into South Africa.
Nearly 14 million people live in the Limpopo river basin, an area of around 413,000 km2. Water demand exceeds supply. Most of the people living in the Limpopo river basin are poor, and starvation and malnutrition are not uncommon during drought or crop failure, particularly in impoverished Mozambique, still recovering from a long and bloody civil war. Ten percent of the population of the river basin are expected to die from AIDS-related illnesses. Dense settlements, mining and industrial activity pollute the lower reaches of the river.
The province of South Africa on the south side is the Limpopo province. It was not always so. Prior to 1994, South Africa had 4 provinces, and the Transvaal reached to the Limpopo river. After the regime change, the country was redivided into 9 provinces, and then the prosaically named Northern Province lay against the river. The provinces with such names were encouraged to find better ones, and the Northern province took their name from the river in February 2002.
Vasco da Gama was the first European to sight the river, when one of his expeditions anchored off the mouth in 1498. Hoverer, there has been human habitation in the region since time immemorial - sites in the Makapans Valley near Mokopane contain Australopithecus fossils from 3.5 million years ago. Other sites provide evidence of stone-age and Iron age habitation near the Limpopo. Some rock paintings further south at Ukhahlamba-Drakensberg are thought to be around 3000 years old, and iron-using farmers are thought to have moved south of the Limpopo river by the 4th or 5th century CE at the latest.
Sources:
http://www.waterforfood.org/BB_Limpopo_River_Basin.asp
Encyclopædia Britannica 2003.