AFRICA is urbanising rapidly; the share of urban residents has increased from 14% in 1950 to about 40% today. By 2030, Africa is set to become majority-urban, by then more than 50% of the population will live in cities and towns.
But there’s a little appreciated trend that has shaped urban growth in Africa, and is acting as a brake on cities’ reaping the benefits of growth. In several African cities, the rate of physical expansion (going by land area) has been faster than that of population growth.
In other words, city growth has been fragmented and sparse. Data from the African Development Bank shows that despite rapid population growth, the rate of expansion of built-up areas is even faster.
In Kigali, for example, the city’s built up area expanded by 18% a year, one of the highest in the world for the time period the data covers. Kampala too, saw physical expansion of 10.6% per year, while population growth, though still quite rapid, was lower at 4.3% a year.[advanced_iframe securitykey=”68f51ed951ec4f22230bb7eb91315944cb08a912″ src=”//datawrapper.dwcdn.net/5af0b/1/” frameborder=”0″ transparency=”true” allowfullscreen=”true” width=”100%” height=”478″]
On the ground, African cities are often developing as a collection of small, disconnected neighborhoods, even as land near the city centre ironically remains undeveloped. For example, in Harare, Zimbabwe, and Maputo, Mozambique, more than 30% of land within five kilometres of the central business district remains unbuilt.
This means that many African cities are actually becoming less, not more dense. The same data from AfDB reveals that between 2000 and 2010, Accra’s density decreased at an average annual rate of nearly 2.5%, while Algiers’ density has decreased by 4.3% per year.
This kind of urban sprawl, if not well managed, decreases the benefits of connectivity within urban areas. Cities are typically engines of a country’s economic growth, because labour productivity is higher in towns than in the rural areas.
But a sprawling city means that distances between neighbourhoods are long and transport costs are high. A resident of Nairobi, on average, can reach no more than 8% of all jobs available in the city within 45 minutes. By contrast, in greater London in 2013, this figure was 21.6%.
Such high rates of urban expansion are also likely to be environmentally unsustainable, AfDB says.
Urban sprawl reduces the supply of ecosystem services available to a city, such as arable land, freshwater and waste absorption. They may also affect hydrologic cycles and vegetation cover.
Sub-Saharan Africa’s urban population is projected to quadruple between 2010 and 2050, from 295 million people to 1.15 billion people. Even at a constant rate of land expansion, the physical area of cities will grow at least four-fold, projections show.
But if land area continues to grow at 1% or 2% per annum, the land area of cities is likely to increase six- or eight-fold, respectively. Incidentally, urban sprawl in Africa is sustained and intensified by an unlikely factor: the presence of the motorcycle taxi, known by various names such as okada, bodaboda, bendskin and moto.