On 17 July 2025, sirens went off along the banks of Nala Lai as its water rose to 22 feet at Kattarian Bridge and 19 feet at Gawalmandi. Homes and shops in Dhok Khaba, Pirwadhai, Amarpura, Sadiqabad, Arya Mohalla and Bohar Bazaar took in two to three feet of water. More than a hundred students were evacuated from a madrasa in Saddar. A cemetery wall collapsed in the cantonment. The district administration declared an emergency, WASA declared its own rain emergency, and Rawalpindi asked the army for help. Six weeks later, on 2 September, it happened again, water climbing to within a foot of the same danger marks.

None of this was unprecedented. It was, in fact, routine, a channel behaving exactly as it has for decades, in a city that keeps building as though it won’t.

What Nala Lai actually is

Nala Lai is a natural, rain-fed stream, not a drain built by any single authority, but a watercourse shaped by the land itself. It gathers runoff from the Margalla Hills and carries it from Islamabad into Rawalpindi before emptying into the Soan River. Its full catchment covers roughly 235 square kilometres across both cities.

Three hill streams, Saidpur Kas, Tanawali Kas and Badrawali Kas, carry Islamabad’s share of that water down to meet the main channel near Kattarian Bridge. From there, inside Rawalpindi, it joins Nikki Lai, Pir Wadhai Kas, Dhok Ratta, and a web of smaller drains, each adding volume as the channel pushes on toward the Soan. It is, in other words, an entire catchment system disguised as a single nullah, and what falls on Margalla in an hour can appear in Rawalpindi’s low-lying streets soon after.

A history that keeps repeating

The channel’s worst-known disaster remains 23 July 2001, when Islamabad recorded roughly 620 millimetres of rain in about ten hours. Nala Lai and its tributaries rose faster than the city could react. Seventy-four people died, close to 400,000 were affected, and around 3,000 homes were destroyed or damaged, with losses running into billions of rupees.

More than two decades on, the pattern has not broken; it has simply repeated itself, almost annually, at a smaller scale, with the same low-lying neighbourhoods, the same sirens, the same evacuations. What has changed is the city around the channel, and that is precisely the problem.

A second front: what happens upstream

Nala Lai’s collapse is not only a story about what has been built inside its own floodway. During one of Rawalpindi’s most severe recent flooding episodes, Rawal Dam, further upstream in Islamabad, reached capacity after heavy rain, and its operators opened the spillways, releasing a large volume of water that, combined with the flow from Nullah Korang, entered the River Soan on the same day Rawalpindi was flooding.

Some Rawalpindi residents and civic groups have since raised a pointed question: whether that release reduced the Soan’s capacity to absorb Nala Lai’s own floodwater at the same time, effectively pushing water back up the channel and into the city’s drainage network. Floodwater from Nala Lai and roughly fifteen connected rainwater drains went on to inundate major commercial and residential areas, including Raja Bazaar, Fawara Chowk, Moti Bazaar, Bara Bazaar, Dingi Khoi Chowk, Jamia Masjid Road, College Road and Naya Mohalla.

That specific claim, that the timing of an upstream dam release affected a downstream city’s ability to drain its own floodwater, is not yet........

© Daily Pakistan