Karachi, Pakistan’s largest metropolis, received another spell of monsoon rains toward the end of last month. More than 20 people died, majority of them from electrocution.

Different parts of the city such as North Karachi, North Nazimabad, Drigh Road, NIPA, Orangi, Malir, Northern Bypass, and colonies located on either side of one of the city's longest drains, the Gujjar Nala, were inundated with rainwater. Many underpasses were inaccessible as they were completely submerged.

The severe rains caused a breach in Thado Dam, located in the Kirthar mountains, that initially flooded the Super Highway, country's busiest artery that connects Karachi with the rest of Pakistan. Gusty waters then entered into Gadap town and inundated Amir Bux and Usman Khaskheli goths, and later flooded Saadi Town.

This is not the first time Karachi has witnessed urban flooding. Since 2000, it has happened five times, in 2006, 2011, 2012, 2013 and now this year.

The areas most prone to flooding include Sharifabad and Gareeabad in Liaquatabad Town, Nagan, Ghulshan-e-Mayamar, Azizabad, Safoora Goth, Burns Road, Tower, Kharadar, Khada Market and Machar Colony in Lyari, parts of Saddar, Shahrah-e-Faisal, airport, Gulshan-e-Hadeed, Malir, and Shah Faisal Town.

Karachi faces the threat of urban flooding mainly due to unrestrained housing, encroachments on natural waterways, and dumping of solid waste into stormwater drains.

Dr Qamar-uz-Zaman, former director general of the Meteorological Department of Pakistan, tells me if we let people build homes wherever they want without any planning, then we should expect severe urban flooding each time it rains.

According to Dr Zaman, many of the incoming migrants to Karachi are actually climate refugees. Due to lack of rains or other changes in the weather pattern, they are uprooted from their homes in different parts of the country and have no choice but to move to Karachi to find a source of income. Karachi, in fact, hosts the highest number of such migrants compared to any other city in Pakistan.

At the same time, Karachi is not equipped to provide for these incomers. The influx of climate migrants actually ends up worsening the conditions that lead to bigger climate-related problems.

The migrants live in slums that are mostly built on waterways or drains. Data collected by the Sindh Katchi Abadi Authority reveals that there are 5,639 slums in Karachi and majority of them are built alongside drains.

According to the Orangi Pilot Project, Karachi has 41 major drains – most of them stormwater drains – scattered across the city. These drains would normally bring rainwater from across the city to either the Lyari or Malir rivers, which would then drain the water into the Arabian Sea.

As the settlements keep swelling, the drains are encroached and narrowed, blocking the natural water paths. Drains are also choked since they have become sites for solid waste dumping. This is the main cause of urban flooding in Karachi.

Areas of Karachi most vulnerable to flooding

Climate change is only going to amplify the danger. Dr Zaman also tells me that the variability in weather patterns has put Karachi on the hit list. The city is now receiving average rain of four months just in one day. We are simply not prepared for the change in climate.

Given the city’s lack of planning, major urban design flaws and weak regulation, Karachi is simply not prepared for the changing climate. Urban flooding is most likely to become a more serious issue, affecting tens of thousands and millions more indirectly.

Dr Noman Ahmed, head of the Department of Architecture and Planning at the NED University of Engineering and Technology, qualifies urban flooding as failure of urban planning. He points out that there actually hasn’t been a government body over the past five or six years to clean the drains.

He informs me that after the 2012 floods in Karachi, a study was conducted that pointed out all the causes, but the government didn’t pay any attention. He also suggests that every year before the monsoon, at least the drains should be cleaned to mitigate the floods to some extent.

The urban sprawl has also led to a depleted forest cover and green spaces in Karachi. Concrete doesn’t allow for water to be absorbed into the ground and the fast-disappearing mangrove forests and swamplands mean that there is very little that holds water naturally in the city.

While it may take some years for us to know if monsoon patterns have changed for good, what is for sure is that Karachi’s long-standing problem of almost-absent urban planning is the biggest reason for the mini-disaster we saw last month. If Karachi is left abandoned and the climate continues to take a turn for the worst, the disasters will only get bigger.