Karachi is one of the world’s fastest growing megacities. In 2010 it housed over 15 million people. It is also Pakistan’s commercial centre and only international port. But however frenetic the pace of commerce in the city, it can’t mask the fact that Pakistan is still one of the world’s poorer countries, where 72 per cent of the population live on under US$2 a day and over half a million under-fives die every year.

With poverty rife and thousands of people flooding in to the city every month, it is unsurprising that Karachi is home to hundreds of informal settlements, known as katchi abadis. Many are marginalised and vulnerable to forced evictions, which are ever more common as part of urban ‘upgrading’.

As a result, Karachi is increasingly demarcated into rich and poor areas. It is, in effect, becoming a city divided.

The problem is acute. In his book Participatory Development, Karachi architect-planner Arif Hasan notes that nearly 24,000 houses and shops were demolished by various government agencies between 1992 and 2007. In the course of that, over 188,000 people were displaced. Not only were they offered no compensation or alternative; the evictions were also carried out by police or paramilitaries.

The trend shows no sign of abating, as commercial interests and affluent individuals vie for city land.

Hasan focused on density because governments tend to justify building high-rise apartments for the relocated poor on the grounds that they are the only way for communities to achieve high densities. The building bylaws reflect this, and prescribe higher maximum densities for high-rise developments.

But as Hasan reveals through case studies of existing settlements and models of potential ones, the logic behind the bylaws is flawed. High-rises are not the only path to high density. Planned settlements with compact individual houses on small plots can comfortably match the maximum density rates for high-rise apartments. In fact, they can even exceed them — and do so without jeopardising the physical and social environment.

In the study, Hasan and his team looked at density in four low- to lower-middle-income settlements. Three are ‘plot’ settlements with small houses; one is an apartment complex.

The team then used computer modelling to redesign each of the four settlements. Their aim was to show how small houses on small plots can, if designed to allow incremental growth, achieve high density that is both comfortable and sustainable over time. Other studies have highlighted incremental growth as key for poorer people, as it allows them to add to their dwellings to accommodate a growing family and have space, if needed, for running a small enterprise.

Better by design: the four settlements remodelled

In remodelling Khuda Ki Basti, a large suburban settlement in Karachi with comparatively low density, Hasan found that roadways and community spaces could be combined in order to increase available space for parks, amenities, businesses and schools. Individual plots could be smaller if residents were allowed to build additional floors on each house. In the remodelled high-density settlement, plots would also be cheaper, falling in price by over 40 per cent.

In Nawalane — one of Karachi’s oldest plot settlements, an ethnically uniform community in the dense inner city — ad hoc development has led to congestion, encroachment on public spaces, and poor lighting and ventilation. Hasan and his team found through remodelling that the site’s residential area could be scaled down and space for amenities increased while maintaining a density close to that of the present settlement and more than twice the maximum allowed by Karachi bylaws.

Paposh Nagar is a government plot scheme dating from 1954 that has been engulfed by urban development. Initially well-planned and spacious, the settlement now has a much higher density. Poorly planned extensions on housing have encroached on its roads and public spaces. In the remodelling exercise, carefully designed and managed incremental growth created a dense but uncongested, pleasant settlement.

Fahad Square, unlike the others, is an apartment complex. Located near the city centre, it houses mainly young white-collar workers, but after a decade of poor maintenance the complex’s upwardly mobile image is starting to tarnish. Apartment blocks are more lucrative for developers than designs that provide a basis for incremental development, because there is more housing for sale immediately after construction. The team discussed this concern with developers and designed two small-plot settlements, based on their proposals, that would represent profitable alternatives to apartments.

The findings by Arif Hasan and his team are important for a number of reasons. One is, as we have seen, that high-rises can be fraught with problems for the poor, whereas small houses that can be incrementally built up to accommodate growing families and entrepreneurial activities are demonstrably preferable. Another is that if such houses also achieve high density, they are workable for crowded cities — and for the nearly billion people who live in informal settlements round the world.

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You can find out more about this study and the four settlements in it throughout this IIED/UNFPA subsite.