Urban flooding: the case of Karachi

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By Arif Hasan

Before 27 August, this monsoon season had brought much less rainfall to Karachi than on previous occasions. Yet, streets turned into rivers, cars and homes were washed away, and over 30 people drowned or were electrocuted.

However, on 27 August we had more rainfall in one day than the past 92 years. Entire settlements were washed out. This has raised two questions. One, despite a lower volume of rainfall, why has Karachi been devastated? And two, was the heavy rainfall of 27 August linked to climate change?

Vast population increase and lack of investment in sewers

Karachi’s storm water drains connect to two seasonal rivers, the Lyari and the Malir. Both rise in the foothills of the Kirthar range and run parallel to each other, 14-20 kilometres apart. Fifty-eight storm water drains (nalas) carry water from their catchment areas to these two rivers. Over 600 smaller drains feed into these nalas.

Before independence in 1947, Karachi’s population was only 450,000; it is now over 15 million. The city’s sewage system mostly consisted of underground earthenware pipes, and sewage biologically treated at the gutter baghicha (gutter garden).

The treated effluent was used for growing vegetables, flowers for religious ceremonies and fruit trees. The gutter garden covered just over 1,000 acres (404.7 hectares).

With Partition and the arrival of around 800,000 migrants from India and the rest of Pakistan between 1947 and 1951, the city was forced to expand. Formal and informal sectors developed far away from the gutter garden.

The Greater Karachi Resettlement Plan of 1958 created two satellite towns some 20 kilometres from Karachi. Sewage treatment plants were planned for but never constructed and their sewage flowed (and still flows) into the sea and/or the nalas.

Informal settlements and informal drains

Due to lack of housing, informal settlements developed along the nalas – into where sewage was discharged. After the mid-1960s formal sectors also began using nalas for disposal. Sludge from sewage clogged the nalas and their tributaries, and during the heavy rains of 1978-79, much of the housing along the nalas was washed away.

After that, informal settlement residents started to informally purchase solid waste from the municipal authorities and compact it along the nala edges to secure them and to create land for their homes. Nala widths decreased substantially from 20-40 meters to less than ten, and four to five metres in some places.

Deterioration of the nalas

Spatially, Karachi is a large city with only two landfill sites, both over 40 kilometres from the eastern edge of the city. Due to the time and costs to get there, garbage increasingly did not reach the landfill sites. Meanwhile, a recycling industry developed, mostly in the informal sector.

Contractors pay the Karachi Metropolitan Cooperation (KMC) officials not to collect the garbage so that recyclable material can be picked from it. The non-recyclable material is then thrown into the nalas or at various informal dumping sites along the natural drainage systems.

By the mid-1990s, most of the nalas were full of compacted solid waste. And to this day children play cricket and football on some of them.

Building over the nalas

With Karachi’s development plans stalled and space pressures for commercial activity, the local government constructed bazaars over the nalas. Meanwhile, the government of Sindh constructed car parking facilities, offices, and hostels on the nalas, and even part of the registry of the Supreme Court of Pakistan.

As space for disposal of solid waste in the nalas reduced over time, solid waste was and is still used for reclaiming land from the sea for both low income and elite housing. Informal developers informally arrange for KMC trucks to deposit their solid waste on the mangrove marshes and hire tractors to compact it.

A major part of Karachi’s most elite settlement – the Defence Society – has been reclaimed from the sea through use of municipal solid waste. In addition, two of Karachi’s major outlets to the sea have been considerably reduced by developing housing for high income groups and a highway. Now, water struggles to flow out into the sea especially during high tides.

Storm water drains

To overcome these problems, in the 1980s and 90s the government of Sindh arranged for old sewage treatment plants to be rehabilitated and new ones constructed along with trunk sewers along the main roads. However, these trunks remain dry because the sewage continues to flow in the storm water drains.

The Orangi Pilot Project Research and Training Institute (OPP-RTI) has long supported communities to develop lane sewers and decided to document the storm water drains. It discovered this problem could only be tackled by cleaning and covering the drains and incrementally building trunks along the nalas. This concept was accepted by the state and is being partially implemented.

Real estate development

But now, another issue has surfaced. In the hilly formations north of the city, massive real estate development is taking place. Much of this development has demolished the geological formations that contained natural drainage channels and water collection depressions.

When it rains, areas south of this region are completely submerged by flood waters. With more developments, the likelihood of flooding will also increase.

Serious institutional issues

The central and provincial governments are controlled by different political parties. They are at constant loggerheads making it impossible for Karachi’s infrastructure problems to be tackled rationally and with sufficient finances. It also makes it impossible to develop a decentralised city government, free from direct provincial control.

Desperate to maintain its vote bank, the federal government brought in the National Disaster Management Authority to de-silt Karachi’s nalas. So far they have removed 30,000 tonnes of solid waste from 42 choking points on three nalas.

However, desilting will once again make the edges of the nalas vulnerable to erosion and destroy an unspecified number of homes – widening just one major nala will require 5,782 houses to be removed.

If the proposal for widening all the nalas to their original width is followed, around 60,000 houses will be affected. So far, a concept for the rehabilitation plan has not been developed even though promised by the government.

Tackling these issues will require a long-term plan for Karachi that is in keeping with the finances available or that can be generated. But this cannot be done without an empowered local government and participation of people living along the nalas.

OPP-RTI’s interaction with those communities found only they knew the points of maximum flooding, the behaviour pattern of the floods and of various smaller drains that had disappeared. But how to bring these communities into the planning and rehabilitation process has not been considered by the government agencies.  

Meanwhile, climate change only adds to the urgency of addressing Karachi’s worsening floods.

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