Disaster management: Rawalpindi’s high-tech flood warning system

The idea is to be able to issue an evacuation alert 60 minutes before a flash flood.

Irin May 28, 2014
A water level gauge at Leh Nulleh near Gawalmandi. PHOTO: IRIN


A dozen children toss a Frisbee around in a park in Rawalpindi’s Gawalmandi neighbourhood, under the shadow of a 30-foot-high tower capped with two loudspeakers. “When the alarm sounds, it means a flood is coming, so we should leave,” one explained.

At a car workshop nearby, Malik Ijaz Faisal said how a flood in 2001 killed his two nephews, Malik Fahad, 16, Malik Zaid, 18, and their friend, Mehmood, 21.

“The water came so fast, we had no time, no chance to save them.”

Rawalpindi received 620mm of rain in 10 hours, and the city’s haphazard network of drains and streams overflowed, inundating areas with upto 30 feet (9.14 meters) of water, killing 74 people.

In an effort to be better prepared in known flood-prone urban areas, the Pakistani authorities are trying to build sophisticated systems to predict and monitor floods, hoping to give locals a few hours warning to get to higher ground.

“In most cases, you can predict floods more than 12 hours ahead of time, and can tell people so they may evacuate,” explained Shehzad Adnan, an expert at the Pakistan Metrological Department (PMD). “But in these flash floods, the delay time is very short, a few hours, so within a short timeframe it is very important to get information to people.”

Faisal’s workshop sits in a bend of the Leh Nullah, a stream meandering through the city that collects water from six tributaries flowing south from the Margalla Hills, about 15km to the north. Even a minor shower here causes the stream to spill its banks.

Testing the water

Six rain gauges and two water level gauges with up to five days of backup power sit in the stream, taking measurements every two minutes. This data is then wirelessly transmitted to a control room at the PMD headquarters in Islamabad.

Data from sensors in Rawalpindi and Islamabad is displayed at the control room in real time. PHOTO: IRIN

There, meteorologists use the information to predict flooding, passing on their forecast to a control room in Rawalpindi. City officials can issue warnings to residents based on what they are seeing. At 10 points in the city’s most flood-prone areas, warning stations can issue instructions to residents to get to higher ground, or leave the area altogether.

“We end up issuing evacuation announcements around three times every year,” said Usman Khalid, standing in front of two screens in the Rawalpindi control room displaying the water levels across the city in near real time.

The idea is to be able to issue an evacuation alert 60 minutes before a flash flood. When he thinks an area is in danger, Khalid picks up a phone on his desk and his voice booms into the homes of residents living within 300m of one of the 10 warning posts he can select.

“People’s responses have not been so positive,” he explained. “No one wants to leave their property behind, so they just stand on bridges or whatever high ground they can find.”

“The water came so fast, we had no time, no chance to save them.”

But the system has helped, like during a flood last year. “It was 2am, and we saw that a flood was going to occur so we sounded an evacuation alarm. People didn’t leave their area, but they woke up and realized what the water level was outside, so many went for higher ground.”

A handful of times, officials have had to enlist the help of police and the army to force people to evacuate. Three or four lives are still lost to floods in the city each year, but it’s a marked improvement from before the system was installed in 2007.

But the millions of dollars to expand such schemes are hard to find, despite evidence of the financial benefits of investing in disaster risk reduction.

The $5.5 million it took to put together Rawalpindi’s early warning system on the Leh Nullah came from a grant by the Japan International Cooperation Agency (JICA).

“We have identified 24 locations across Pakistan, including in urban areas where there is a need for early warning systems,” Azmat Hayat Khan, director of the Remote Sensing & Computer Division at PMD, told IRIN. Pakistan’s National Disaster Management Plan has proposed setting up these systems since 2012, but there is no government funding available.

Such systems would be a step up from more basic pilots based on weather forecasts rather than scientific measurements. 

Published in The Express Tribune, May 29th, 2014.


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