South Africa's geography: a high plateau with a step around it

What the shape is

South Africa occupies the southern tip of the continent, and its coastline runs more than 2,850 kilometres from the desert border with Namibia on the Atlantic side around to the subtropical east.

Like much of Africa south of the Sahara, the country's form is dominated by a high central plateau surrounded by coastal lowlands. The plateau is the interior; the lowlands are a rim around it; and the thing that separates them is the feature that organises everything else.

What the Great Escarpment does

The plateau is rimmed by the Great Escarpment, and in South Africa it is at its highest in the east, where the edge varies between 2,000 and 3,300 metres.

That edge is where the land drops sharply to the coastal plain, and the portion that can properly be called mountains is the stretch forming the international border between KwaZulu-Natal and Lesotho, where the Lesotho Highlands rise as a local high point.

The escarpment has three consequences that recur throughout the rest of this catalogue's articles on South Africa.

It makes the interior high, which changes the climate: the plateau is cooler and drier than its latitude would suggest, and frost is a normal feature of the highveld winter.

It makes movement between the interior and the coast expensive, because everything travelling either way climbs or descends a step of up to three kilometres. Rail and road engineering in South Africa is dominated by that one problem.

One stretch of the step is also an international frontier. Where the escarpment reaches its greatest height, forming the boundary between KwaZulu-Natal and Lesotho, the Lesotho Highlands rise as a local high point, and South Africa's own summit, Mafadi at 3,450 metres, stands on that line. What sits above the escarpment there is a separate sovereign state entirely surrounded by South African territory, so the wettest and highest catchment adjoining the country's driest interior belongs to somebody else, and the water falling on it is the subject of agreements rather than of domestic policy. A country short of water whose best catchment lies across a border it encircles has a permanent diplomatic interest in a small neighbour, and no government has been able to change that.

And it puts the ports and the interior in different worlds. The mineral wealth that built the modern economy is on the plateau. The harbours are below the escarpment. The distance between them is short in kilometres and long in vertical metres.

Why there is so little water

The central plateau contains only two major rivers: the Limpopo, part of which is shared with Zimbabwe, and the Orange, with its tributary the Vaal.

For a country of 1,221,037 square kilometres, that is very little surface water, and its distribution is worse than the count suggests. The Orange rises in the east, where the escarpment is highest and the rainfall greatest, and runs west across progressively drier country to the Atlantic, which means the river passes through the land that needs it most on its way out.

Everything about South African agriculture and industry follows from that scarcity. Where the water is not, the farming is grazing rather than tillage. Where a city sits away from a river, its water arrives by scheme rather than by proximity, and the schemes are large, old and politically consequential.

How the coast varies

The coastline is long, and it is not uniform.

The Atlantic side in the west begins at the Namibian desert border, and the current running up that coast is cold. The consequence is a dry, sometimes almost rainless western seaboard, with fog rather than rain and a vegetation adapted to it.

The eastern side is warm and subtropical, and far wetter, watered by moist air off the Indian Ocean that rises against the escarpment and drops its rain on the seaward slopes.

The coast itself offers few natural harbours for its length, which is a common feature of a continent with a smooth outline, and the ports that exist have therefore been strategically important out of proportion to their number.

What the rainfall gradient means

South African rainfall falls off from east to west, and the gradient is steep enough to change what the land can be used for over a few hundred kilometres.

The eastern seaboard and the escarpment's seaward slopes are the wettest ground, because moist Indian Ocean air rises against the step and drops its water there. Behind the escarpment the plateau receives less, and the further west it goes the less it receives, until the country meets a desert border at the Namibian frontier.

That single gradient does most of the work in South African land use. It sets where crops are possible and where only grazing is, where a farm can be small and where it must be large to be viable, and where settlement is dense and where it is nearly absent. It also means that the country is not short of water uniformly: it has some in one corner and very little across most of its extent, which is a harder problem to manage than uniform scarcity.

The two rivers compound it rather than relieving it. The Orange collects from the wet east and delivers to the dry west, crossing the country's most water-hungry ground on its way to the Atlantic, so the water that exists is largely in transit through the places that need it.

The gradient also divides the plateau into regions. They follow the rainfall more closely than any line on the ground, and their boundaries are vague.

The Highveld is the wettest and most fertile part, in the centre and east at 1,500 to 2,100 metres. It stands highest at the Mpumalanga Drakensberg and slopes down to the south and west, takes between 400 and 1,200 millimetres of rain a year on a largely flat grassland plain, and takes in the whole of the Free State. Much of it is given to commercial farming, and the Gauteng conurbation stands on it as well.

South of the Orange River the plateau continues as the Great Karoo, sparsely populated shrubland. To the north the Karoo grades into Bushmanland, drier still, with saline groundwater and soil that will not farm.

Below the escarpment in the north-east lies the Lowveld, under about 500 metres, running from the Limpopo valley south through Mpumalanga into eastern Eswatini. On the northern border a failed rift valley some 180 million years old cuts into the plateau and wipes out the escarpment locally. The Lowveld is hotter and less intensely cultivated than the Highveld. It was once called fever country, because malaria was endemic across almost all of it.

Along the southern and south-western coast the plain holds the Cape Fold Mountains, parallel ranges folded into an L about 800 kilometres long, with the angle of the L just inland from Cape Town. The coastal plain itself widens from about 60 kilometres in the north-west to more than 250 in the north-east.

What grows where

The combination of altitude, latitude and rainfall gives South Africa an unusual number of distinct biomes for a single country, and they are arranged concentrically rather than in bands.

The interior plateau carries grassland and dry scrub, thinning westward as the rainfall falls away. The Karoo, the semi-arid interior, occupies a large share of the country and supports grazing rather than crops. The eastern seaboard and the escarpment's wet slopes carry subtropical vegetation and forest. The southwestern corner, around the Cape, has a Mediterranean climate and a distinctive shrubland flora found in very few other places.

That last one is the reason South Africa is treated as a biodiversity hotspot with unique biomes, plants and animals. A small corner of a large country holds a flora with a very high proportion of species found nowhere else, and it is small because the climate that supports it exists only where the winter rainfall reaches.

The country has twelve properties on the UNESCO World Heritage List, and the inscriptions run from fossil hominid sites on the interior plateau to the wet eastern parks, which is a fair summary of the range.

What the minerals did to the map

The interior plateau's economic value is underground, and that has arranged the country's settlement against every other geographic incentive.

A plateau with two rivers, low rainfall over most of its extent and a three-kilometre step between it and the sea is not where an economy would ordinarily concentrate. What put it there was the discovery of what the plateau contained, and the response was to build cities, railways and water schemes to reach ground that had none of the usual advantages.

The engineering consequences are permanent. Water is moved uphill and inland in bulk. Bulk exports travel from the interior down the escarpment to the ports, which means the country's freight economics are dominated by a single descent and its reverse. A mine on the highveld and a berth in Durban are connected by a route that has to solve the same problem in both directions.

That arrangement also explains why South African infrastructure is unusually heavy for the continent. A country whose wealth is inland and whose outlets are coastal has to build the link or forgo the wealth, and the link is expensive because of the step.

Where the people are and why

Settlement follows the water and the minerals rather than the coast, which is unusual for a country with 2,850 kilometres of it.

Johannesburg sits inland, on the high plateau, and it is there because that is where the gold was. A city on the highveld has no river, no port and no obvious agricultural hinterland, and it exists because of what was underneath it. Its water comes from schemes reaching back towards the escarpment and beyond.

The coastal cities are ports first: Cape Town in the southwest where the Mediterranean climate is, Durban on the warm eastern coast, Gqeberha and the others along the southern shore. Each sits below the escarpment, connected to the interior by the long climb described above.

What that produces is a country whose economic centre and whose harbours are separated by a mountain step, and whose internal transport therefore matters more than in most economies of comparable size.

What the geography does not explain

Land ownership in South Africa was distributed by statute, and a geography article should say so, because terrain and ownership are frequently read as the same thing here.

The Natives Land Act of 1913 described in the history article restricted black South Africans to 7% of the country, and the 7% was not chosen by rainfall or altitude. Which land is farmable is a fact about the ground. Who was permitted to own it was a decision, and the pattern that decision produced is still visible on any land-use map.

The catalogue records the physical geography and the statute separately, because they are separate things, and reading the second off the first would be wrong in both directions.

What the geography does explain is why the argument is as difficult as it is. In a country where arable, well-watered land is a small fraction of a large territory, and where most of the interior supports grazing rather than crops, redistributing land is not a matter of dividing a uniform resource. The good ground is specific, limited and already in use.