The recent flooding of Islamabad and Rawalpindi was not a meteorological anomaly, but an act of arithmetic—the inevitable result of narrowing natural drainage channels, ignoring urban master plans, and prioritizing real estate over hydrology.
Mohammad Ehsan Leghari
By the afternoon of 2 September, the water had receded from Raja Bazaar. The dewatering pumps went back into storage. A public holiday was declared. Official statements described “record rain” and “unprecedented” monsoon intensity, and the country waited for the next disaster to write itself.
But the rain was not the story.
On the morning of 1 September, Pakistan Meteorological Department gauges recorded 201 millimeters at Shamsabad, 191 at Chaklala, 157 at Golra, and about 150 in a short spell in Sector E-11. Serious rainfall, but nothing close to 23 July 2001, when 620 millimeters fell on Islamabad in ten hours and killed seventy-four people. This time, the sky delivered roughly one-third of that storm — and produced a Nullah Lai gauge reading at Kattarian of about seventy percent of the 2001 peak.
That ratio is the whole diagnosis. The Lai basin now produces near-record floods at moderate rainfall. Something has broken. Something has been broken.
The Nullah That Went Missing
If you want to understand why Islamabad flooded on 1 September, look at a satellite image of Sector E-11.
The natural piedmont stream that carries stormwater from D-12 and E-12 once had an unconstrained width of more than seventy feet. It was, in the most literal sense, the city’s flood insurance policy — a wide, rough, vegetated channel that could absorb whatever the Margallas sent down. Beginning around 2007, that channel was quietly renegotiated. The Pakistan Medical Cooperative Housing Society and adjacent schemes reduced it to fifteen to eighteen feet. A roadway was built over the covered section. Both banks were subdivided into plots and sold. The Capital Development Authority itself signed off on the covering.
The nullah that used to enter E-11 from D-12 was forty feet wide in 2012. By 2026 it was eighteen. A sharp bend was engineered into the reduced channel because a straighter line would have cost a row of plots.
In July 2021, when a localized storm hit these narrowed sectors, the water did what water does when denied its channel. It broke through basement walls. A mother and her child drowned. The CDA claimed it had cancelled the society’s layout plan years earlier. Property sales continued anyway. Statutory easements were not enforced.
In September 2026, the same basements filled again. The city sent teams to demolish encroaching commercial shops in the aftermath — five years too late, as one publication drily noted. The nullah was still eighteen feet wide.
This is not a story about climate change. This is a story about geometry. When you narrow a hundred-foot channel to eighteen feet, the water that used to pass through the channel appears somewhere else. That is not a meteorological event. It is arithmetic.
The Lake That Never Got Built
Constantinos Doxiadis, the Greek architect who designed Islamabad in 1959–60, understood the Potohar plateau in a way his successors have refused to. He laid the city not on a blank sheet but on top of an ecological grid — ravines, seasonal streams, low-lying detention sites, forest belts. Almost half the metropolitan area was reserved for green space or agriculture. Around each 2,100-yard sector, natural drainage was to be preserved. A forest belt was to wrap the Margallas. And in one particular low-lying reach south of the city — a place called Lohi Bher — Doxiadis proposed a lake. He picked the site because the land was already, in effect, a natural detention basin. All the city had to do was formalize what water was already doing.
The CDA never acquired the land.
Two private housing schemes now occupy the site of what should have been Islamabad’s flood-storage reservoir. When the September 2026 monsoon hit, the water that Lohi Bher was supposed to hold had nowhere to go. It flowed downstream into Rawalpindi. Every year, at every gauge reading on Nullah Lai, Rawalpindi pays the price for a lake that was never built.
Multiply that story across the basin. Doxiadis wanted a forest belt on the Margallas; parts of it now hold housing societies. He wanted the ravines within each sector preserved as drainage swales; most have been paved. He wanted Zone 4 kept as a green belt for agro-forestry and water catchment; in a series of amendments culminating in 2010, roughly two hundred square kilometers of it were opened to private housing schemes. The Doxiadis plan itself recommended a comprehensive review every twenty years. Sixty-five years on, no comprehensive revision has been completed. Instead, at least fifty-one piecemeal amendments have chipped away at the ecological grid, each one legalizing a specific development, each one taking a specific bite out of the drainage system, none of them guided by a hydrological model of the basin as a whole.
The plan was not wrong. The plan was right, and it was taken apart. The flood is what the plan looks like after the plan is dismantled.
One Basin, Two Cities
The most important physical fact about the Islamabad–Rawalpindi conurbation is that it is a single hydrological unit. The Lai Nullah basin covers about 235 square kilometers. Roughly 69 percent of the catchment lies within Islamabad and the Margalla Hills National Park. The remaining 31 percent lies within Rawalpindi and its cantonments. Six major tributaries feed the trunk stream. Rain that falls on Islamabad’s paved sectors arrives in Rawalpindi’s mohallahs within hours.
Under any land cover, this asymmetry means Rawalpindi is the receiving end. Under the current land cover, it means Rawalpindi is the sacrifice zone. A composite Flood Vulnerability Index computed for the twin cities over 2000–2023 places Rawalpindi at 0.47 and Islamabad at 0.24; nearly double. That gap has nothing to do with the rain preferring one city over the other. It has to do with the fact that Islamabad has been permitted to raise its runoff coefficient; the fraction of rainfall that becomes surface flow, from roughly 0.15–0.30 under scrub and terraced soil to 0.75–0.90 under concrete and asphalt. In plain language: a landscape that used to absorb seven out of every ten drops now sheds eight out of every ten. The extra water has to go somewhere. It goes to Gawalmandi.
And yet the institutional map does not recognize this basin. The Capital Development Authority governs the federal territory. The Rawalpindi Development Authority, WASA Rawalpindi, the Municipal Corporation, the district administration, two cantonment boards, and Punjab’s urban machinery govern the lower city. Rawal Dam is operated as an Islamabad water-supply asset; which is why activists in Rawalpindi asked pointed questions on 1 September about whether the dam’s spillways were opened in the afternoon in a way that backed water into the Soan and made Lai’s crest worse. There is no single authority with the power to refuse a housing scheme in Islamabad on the grounds that it would raise the peak stage at Kattarian. There is no basin regulator. There is no rule that binds a dam release to the receiving city’s hydrograph.
The two cities are joined by gravity. They are separated by law. Water does not read jurisdictional maps.
The Climate Change Alibi
None of this is to deny that the climate is changing. It is. Attribution science for the 2022 floods in Sindh and Balochistan found five-day rainfall roughly 75 percent more intense than it would have been without about 1.2°C of warming. Short-duration urban storms are expected to intensify further. Any serious flood policy must therefore raise design standards, restore storage, and stop building in harm’s way.
But climate change does not squeeze a hundred-foot nullah to eighteen feet. It does not dump concrete slabs on a Ghauri Town drain. It does not amend Zone 4. It does not leave Lohi Bher unacquired. It does not permit basements below the design flood elevation. It does not fail to desilt Lai between monsoons.
There is a specific rhetorical function to “unprecedented rainfall” and “climate anomaly” as the opening lines of the post-disaster press briefing. The framing converts a foreseeable outcome of institutional decisions into an unforeseeable event beyond decision. It absolves the approving authority, the elected representative, and the developer alike. It sets the terms of every follow-up conversation so that questions about pumping capacity and check dams crowd out questions about layout approvals and nullah covers. It is not incompetent. It is efficient. It works.
Consider what a 1990–2024 remote-sensing study of Islamabad actually found. Continued built-up expansion at recent rates is projected to drive a 41 percent increase in high-risk flood zones by 2030; larger than the 35 percent increase attributable to climate-intensified precipitation. In the twin-city basin, land-use change is a bigger driver of future flood risk than climate change. That fact will not appear in any post-monsoon press briefing. It cuts too close.
The Powerful Do Not Get Wet
The most quietly corrosive feature of Pakistani floodplain governance is not the absence of law. It is the class-differential application of law. Enforcement against katchi abadis and small traders is swift. Enforcement against housing societies, commercial plazas, cantonments and public-sector compounds is slow, contested, and often abandoned.
Two cases capture the pattern. On the shores of Rawal Lake; a protected reservoir within Zone 3, the Pakistan Navy constructed a commercial sailing club without building permits, environmental clearances, or CDA land allotments. In 2020 and 2022, the Islamabad High Court declared the construction illegal and ruled that armed forces entities have no constitutional mandate for real-estate ventures. Demolition was ordered. In September 2026, an IHC division bench set aside the demolition order on procedural grounds. Meanwhile, extensive commercial restaurants like the Monal, La Montana, Gloria Jean’s, operated for years atop Pir Sohawa ridge, inside the Margalla Hills National Park, under contested CDA leases and military land claims. It took a 2024 Supreme Court judgement under Chief Justice Qazi Faez Isa, invoking Article 9’s right to life and a healthy environment, to shut them down.
Both cases involved public-sector actors. Both required years of litigation. Both would have been closed in a week if an informal settlement had built the same structures on the same land.
A senior Rawalpindi official told a national newspaper in 2026 that action against encroachments had been “difficult because of political pressure.” That sentence is the planning system in miniature. Of approximately 250 housing schemes in Islamabad, only 53 have approved layout plans, and only 28 hold formal No Objection Certificates. Approved schemes represent 6.8 percent of the federal territory. The remaining 93 percent operates in varying degrees of non-compliance, unapproved expansion, and master plan violation. The Auditor General has said as much. Nothing changes.
Flood resilience requires the opposite of what this system produces. It requires enforcement that binds the powerful more tightly than the powerless, not less. A resilience policy that cannot say no to a well-connected society cannot protect a working-class mohallah on Lai.
The Water Pockets We Build
Not every flood is caused by an encroached nullah. Some are caused by the roads themselves.
Modern arterial highways in the twin cities — Srinagar Highway, Islamabad Expressway, I.J.P. Road, Murree Road — are frequently built on raised embankments that run perpendicular to the natural slope. They act as linear dams. Transverse culverts are often engineered for two- to five-year storms rather than fifty- or hundred-year events, and are frequently misaligned with the natural routes of Potohar streams. When rain arrives, the water cannot pass through. It piles up on the upstream side of the road. Adjacent neighbourhoods flood. Underpasses become linear reservoirs. Committee Chowk drowns. Stretches of Murree Road disappear under two feet of water. And on at least one reported occasion, water was diverted into adjoining drains to keep Old Airport Road passable for VVIP movement. Development-induced flooding, with a protocol.
Add to this Rawalpindi’s sewerage geometry, in which roughly 35–40 percent of the city has proper sewerage and the rest uses the storm drains as an open sewer. When the monsoon comes, the same undersized, garbage-choked channels must carry both sewage and stormwater. What enters homes is not rainwater. It is contaminated floodwater. Add uncovered manholes — still counted in the hundreds — and you have a landscape in which three feet of standing water can hide a two-metre vertical drop. People do not only lose their belongings. They lose their lives to infrastructure that was designed for someone else’s city.
What Must Change
The technical answers have been on file since the 2003–04 JICA study commissioned after the 2001 disaster. They were restated by the UN-Habitat/NDMA Multi-Hazard Vulnerability and Risk Assessment in 2025. They appear in academic papers, in newspaper editorials, in Supreme Court judgements, and in every Institute of Architects statement. There is no shortage of knowledge. There is a shortage of will.
Five instruments, adopted in sequence, would change the trajectory.
First, constitute a single Lai–Soan Basin Authority with statutory power over CDA, RDA, WASA, cantonments, and dam operators for all matters of stormwater, floodplain, and dam-release timing. One basin, one veto. No approval anywhere in the basin without hydrological sign-off from the basin authority.
Second, complete within twelve months a binding basin hydrological survey — current channel cross-sections, two-dimensional inundation maps for the 100-year storm on 2040 land cover, property-scale hazard overlays — and make the model a public legal instrument. No layout plan, road widening, or underpass is approvable unless the model shows no increase in downstream peak or duration of inundation. Design for the 100-year event, not the 25-year event.
Third, restore rights-of-way. Reconstruct the E-11 and D-12 feeders to the width required by the 100-year hydrograph. Remove slabs on Ghauri Town’s drains. Freeze Lai’s banks by legal notification. Compensation where title is lawful. No delay where title is not.
Fourth, treat green cover as flood infrastructure, not decoration. Statutory canopy and permeable-surface ratios for every sector and society. Ban conversion of notified greens and depressions. Acquire what remains of natural detention sites. Require on-site storage from every new development.
Fifth, rewrite the story that gets told after every monsoon. Official statements should lead with which waterway was blocked, which approval was given, which society remains unregularized, and which design storm the drains were built for — not with a rainfall total offered as an alibi. Publish a standing basin flood-risk register updated after every event. Make the file readable by every citizen who has ever waded home through their own street.
Planning as the Test of the State
Islamabad was sold to the world as a planned city of the future. Rawalpindi was the older city that would be sheltered by that planning. Sixty-five years later, the planned city floods its own sectors because it permitted the destruction of the ecological grid on which the plan stood, and it floods the unplanned city below because water still obeys gravity.
The September 2026 event did not reveal a new problem. It measured, in millimeters and in feet on a gauge, how far land-use practice has travelled from land-use promise. Every one of the pathologies this piece has walked through — the covered nullah, the unacquired lake site, the amended zone, the underpass without an outlet, the sewer masquerading as a stormwater drain, the housing society that cannot be enforced against — was licensed by a decision, taken by a named institution, under a rule that could have refused it.
None of these were inflicted on the twin cities by weather. All of these were installed by planning. The rain, in the strict sense, is not the flood. Planning is the flood. Rain is what reveals it.
The wager of every serious flood policy from here forward should be that Pakistan already knows what to do, has known since 2001, and has refused. What is required is not new knowledge. It is the political authority to apply the knowledge that already exists — and to apply it, for once, against the powerful as well as the poor.
Whether that authority can be constituted before the next monsoon is the question this country’s cities are asking, in two to five feet of standing water, once a year, every year, on schedule.
The rain has been patient. It will not be patient forever.
Read: Motherland Sindh Cannot Be Divided
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The author is Member (Water), Planning and Development Board, Sindh. He draws on the Doxiadis Master Plan documents, the JICA Comprehensive Flood Mitigation Plan (2003–04), the UN-Habitat/NDMA Multi-Hazard Vulnerability and Risk Assessment (2025), multi-decadal land-use change analyses of the twin cities, Islamabad High Court and Supreme Court judgements on Rawal Lake and Margalla Hills encroachments, and contemporaneous reporting on the 1–2 September 2026 event by Dawn, The News, Express Tribune, Geo, and Arab News.
