A study by an engineering firm into the chronic waterlogging at Jorabat and Ninth Mile on National Highway-27 has traced the problem to a specific, fixable cause: a single culvert with no backup drainage route at Jorabat, and a Ninth Mile culvert offering barely three square metres of waterway — nowhere near enough to carry stormwater away from a naturally bowl-shaped stretch of highway during peak monsoon rainfall. The findings, reported by The Assam Tribune, come after a mid-July 2026 flash flood pushed water levels under the Jorabat flyover to three to four feet, forcing the National Highways Authority of India (NHAI) to divert traffic via Digaru and Narengi while restoration crews worked to reopen the highway.
Background
Jorabat sits at one of the most consequential chokepoints in Northeast India's road network — the junction where NH-27 (the Guwahati-Shillong highway) meets NH-37, carrying virtually all road traffic between Assam's capital region and Meghalaya. It is also, awkwardly, split down the middle administratively: the larger, northern part of Jorabat falls under Kamrup Metropolitan district in Assam, while its southern reaches lie in Ri-Bhoi district, Meghalaya. That split matters enormously for a drainage problem, because a drain that starts in one state and empties in another has, in practice, no single agency clearly on the hook for maintaining it end to end.
The flooding itself is not new. Residents and local reporting describe it as a recurring issue spanning more than 15 years, but 2026 has been a particularly severe monsoon. Waterlogging beneath the Jorabat flyover was first reported in early July, then escalated into a full flash flood in mid-July that effectively cut the highway. The Assam Tribune's follow-up reporting frames this as part of a broader pattern across Guwahati this monsoon, where road engineering deficiencies — not just heavy rainfall — are increasingly seen as the aggravating factor turning ordinary monsoon showers into multi-day submersions.
Guwahati's drainage troubles are, in a sense, older than the highway itself. City planning records reviewed by local media show that successive civic bodies have drawn up master plans for the city's drainage network going back to 1960, and that in nearly every case those plans were never fully implemented. A retired PWD engineer quoted in Sentinel Assam's reporting on the issue put it bluntly: pre-monsoon drain-clearing exercises, repeated every year before the rains arrive, amount to a routine that rarely involves the kind of dredging depth needed to actually restore a drain's carrying capacity. The result is a city that spends a recurring, if unquantified, sum every year on flood preparation without ever closing the structural gap that keeps producing floods in the first place.
Key Details
The engineering study, conducted by an outside firm and examined further by experts from IITs and NITs, identifies several distinct, compounding problems rather than a single cause:
- Natural bowl-shaped depression: Both Jorabat and Ninth Mile sit in low-lying terrain that was already prone to pooling water before any road construction — the kind of geography that demands over-engineered, redundant drainage, not the minimum.
- Flyover construction deepened the problem at Jorabat: When the Jorabat flyover was built, the carriageway beneath it was lowered further, according to the study — effectively deepening the natural depression it sits in rather than routing around it.
- Single point of failure: The Jorabat depression depends on one culvert to drain, with no redundant or secondary outflow. If that single culvert is blocked, silted, or simply undersized for a heavy downpour, there is no backup route for the water.
- Undersized waterway at Ninth Mile: The culvert at Ninth Mile offers only around three square metres of waterway — a figure engineers describe as inadequate for the peak stormwater volumes the area actually sees during intense rain events.
- Encroachment and illegal construction: Separately, Kamrup (Metro) district officials have pointed to clogged drains as a direct contributor to the Jorabat waterlogging, and local reporting has documented illegal construction on government land directly on top of the arterial drain — including old RCC slabs blocking flow — which Assam's Water Resource department has since begun clearing between Jorabat and Byrnihat.
- Disputed drain design across the state border: At least one resident, cited in local reporting, has alleged that NHAI's drains on the Meghalaya side of Jorabat were not built to a proper scientific design. Whether or not that specific claim holds up, it captures the deeper structural problem: nobody has published a single, coordinated hydrological plan for a drainage system that crosses a state line.
- Hill-cutting runoff from Meghalaya: Residents and local reporting have repeatedly pointed to hill-cutting on the Meghalaya side of the border — including activity linked to institutional expansion near Jorabat — as a factor that has reduced the hills' natural capacity to retain rainwater, sending larger volumes of surface runoff downhill into Assam during intense spells of rain than the terrain historically saw.
- Culvert height under the flyover: Separate allegations reported in local media point to the height of the culvert under the Jorabat flyover itself as a contributing obstruction, on top of the single-culvert redundancy problem identified in the engineering study — a detail that, if confirmed, would mean the flyover's own construction created a second, independent chokepoint rather than just deepening the existing depression.
The interstate dimension has now reached the level of state governments. Meghalaya Chief Minister Conrad Sangma has proposed setting up a joint expert committee, drawn from both Assam and Meghalaya, specifically to investigate whether water flowing down from the Jorabat side of the border is a meaningful contributor to Guwahati's wider flooding problems. That proposal followed pointed remarks from Assam Chief Minister Himanta Biswa Sarma, who has previously blamed hill-cutting activity linked to the University of Science and Technology, Meghalaya (USTM) for intensifying flash floods that flow down toward Assam. Whether or not a joint committee is formally constituted, the exchange underlines how much of Jorabat's flood behaviour is shaped by land-use decisions made across a state border that Assam's own engineers and administrators have no authority over.
Separately, a longer-term response is already underway a short distance from Jorabat itself. A joint technical team combining specialists from the Netherlands, IIT Guwahati and IIT Roorkee is working on a plan to redirect excess stormwater — including flows originating from the Meghalaya hills — toward Silsako Beel and Deepor Beel, two of Guwahati's natural wetland sinks that have historically absorbed the city's excess water before encroachment and siltation reduced their capacity. That redirection plan is reported to carry an implementation timeline of roughly three years, which — if it proceeds on schedule — would place a genuine structural fix for the wider Guwahati flooding problem, of which Jorabat is one symptom, somewhere around 2028 or 2029, not before.
The stakes for that redirection plan are higher than they might first appear, because the wetlands it targets are themselves in crisis. Deepor Beel, on the southwestern fringe of Guwahati, is Assam's only Ramsar-designated wetland of international importance and has historically functioned as the city's natural stormwater sink, absorbing overflow that would otherwise back up into residential areas. Conservationists and satellite-imagery studies cited in regional reporting estimate the wetland's water-spread area has shrunk by roughly a third from its historical extent, with some assessments putting the decline as steep as from about 4,000 hectares down to a few hundred, driven by unplanned urbanisation, waste dumping and encroachment on the channels that feed it. Silsako Beel, the other target of the redirection plan, has faced similar pressure from city expansion. A plan to route more stormwater toward two wetlands that are themselves shrinking is, in effect, racing against the same encroachment problem that created Jorabat's culvert bottleneck in the first place — which is part of why local commentators treat the redirection plan as necessary but not sufficient on its own.
In response to mounting pressure closer to Jorabat itself, a public meeting was convened bringing together Kamrup (Metro) district administration, Ri-Bhoi district administration, and NHAI officials — a rare instance of the three parties who each control a piece of the problem sitting in the same room. Local commentary, including a Sentinel Assam letter to the editor, has explicitly called for NHAI to commission a scientific survey for Jorabat drainage, a demand the newly surfaced engineering study appears to partially answer, even if it has not yet translated into construction on the ground.
The 2026 monsoon alone produced a clear escalation pattern at Jorabat that illustrates how quickly the single-culvert bottleneck turns manageable rain into a highway closure. Waterlogging beneath the flyover was first reported in early July, with heavy rain on July 8 leaving the service road impassable and forcing vehicles onto the flyover itself. Roughly a week later, continuous rainfall since a Sunday afternoon triggered the more severe flash flood that pushed water to three to four feet under the flyover, prompting NHAI's diversion of traffic via Digaru and Narengi. Local reporting has since described the highway as having "turned into a river," with restoration crews racing to reopen the stretch even as IMD forecasts warned of further rain and the risk of fresh flooding within days. That compressed timeline — two separate flooding events roughly a week apart, each requiring active traffic management — is precisely the pattern the engineering study's single-point-of-failure finding would predict for a depression with no redundant drainage route.
At a Glance
| Factor | Jorabat | Ninth Mile |
|---|---|---|
| Terrain | Natural bowl-shaped depression | Natural bowl-shaped depression |
| Primary drainage | Single culvert, no redundancy | Single culvert, ~3 sq m waterway |
| Compounding factor | Flyover construction lowered carriageway, deepening depression | Rapid urbanization and solid waste reducing waterway capacity |
| Jurisdiction | Split between Kamrup Metropolitan (Assam) and Ri-Bhoi (Meghalaya) | Kamrup Metropolitan, Assam |
| Mid-2026 flood event | 3-4 feet of water under the flyover; NH-27 traffic diverted via Digaru and Narengi | Waterlogging documented alongside Jorabat in the same study |
| Named highway | NH-27 / NH-37 junction | NH-27 corridor |
| Longer-term fix proposed | Joint Assam-Meghalaya expert committee (proposed by CM Sangma) | Netherlands/IIT-Guwahati/IIT-Roorkee stormwater redirection plan, ~3-year timeline |
Local Impact
For commuters and freight operators, Jorabat is not an optional detour — it is the primary road link between Guwahati and Shillong, and by extension a large share of Meghalaya's road traffic to and from the rest of the country. When the flyover floods to three or four feet, as it did in mid-July 2026, NHAI's only option is to push traffic onto longer diversions via Digaru and Narengi, adding significant travel time for private vehicles, buses, and goods trucks alike. Vehicle breakdowns in the standing water compound the congestion further, and businesses along the corridor — from roadside dhabas to transport operators — lose working hours every time the highway effectively closes.
The human cost extends beyond traffic. Residents in low-lying pockets near Jorabat face repeated flooding of homes and shops during a season that, per local reporting patterns, now recurs multiple times each monsoon rather than as a single one-off event. For a stretch of highway carrying interstate traffic, the unresolved question of who is ultimately responsible — Assam's Water Resource department, Meghalaya's Ri-Bhoi administration, or NHAI as the highway's builder and operator — has left residents caught between three sets of officials, each managing only their portion of the problem.
The problem is also not unique to Jorabat and Ninth Mile, which makes the specific engineering diagnosis at these two spots useful well beyond their immediate footprint. Reporting on Guwahati's broader drainage failures has documented similar patterns of road elevation without adequate drainage provision in Hatigaon, Rukminigaon and the Beltola Survey area, and haphazard construction without proper drain allocation in localities including Kahikuchi, Lokhra and Jyotikuchi. Jorabat and Ninth Mile are, in that sense, the most visible and highway-critical instances of a city-wide pattern rather than isolated failures — which is part of why the interstate political attention on this particular stretch matters: whatever accountability framework eventually gets built for Jorabat could plausibly become the template for the rest of the city's flood-prone junctions.
What Happens Next
Assam's Water Resource department has already begun clearing obstructions and illegal encroachments on the arterial drain between Jorabat and Byrnihat, including removal of structures and RCC slabs identified as blocking stormwater flow — a near-term, low-cost fix that does not require new construction. The joint meeting of Kamrup (Metro), Ri-Bhoi, and NHAI officials signals the beginning of coordinated attention, though no public timeline or budget for a permanent re-engineering of the Jorabat culvert system has been announced yet.
Two separate tracks of longer-term action are now visible. The first is political: Meghalaya's proposal for a joint Assam-Meghalaya expert committee to formally assess whether cross-border water flow from Jorabat is worsening Guwahati's flooding would, if constituted, be the first body with an explicit mandate to look at the problem from both sides of the state line at once — addressing the accountability gap the engineering study's findings implicitly point to. The second is technical and considerably larger in scope: the Netherlands-IIT Guwahati-IIT Roorkee plan to redirect stormwater toward Silsako Beel and Deepor Beel over an approximately three-year implementation window, which would address the regional hydrology feeding into spots like Jorabat rather than just the local culvert design.
Given the study's finding that the core issue at Jorabat and Ninth Mile specifically is structural — a single point of failure at Jorabat and an undersized waterway at Ninth Mile — residents and local commentators are pressing for what the Sentinel Assam letter described as an evidence-based hydrological audit followed by accountability for the original drainage design, rather than repeated short-term desilting operations ahead of each monsoon. Whether that translates into an actual redesign — a second culvert, a widened waterway at Ninth Mile, or a jointly funded Assam-Meghalaya drainage authority for the shared stretch — will likely only become clear once the current monsoon season ends and budget planning for 2027 begins. Given Guwahati's own history of drawing up drainage master plans since 1960 without implementing them, the test for this study will be whether its specific, structural findings survive the transition from diagnosis to a funded, executed fix.
For now, the most concrete near-term marker to watch is whether the joint Kamrup (Metro)-Ri-Bhoi-NHAI meeting produces a follow-up with an actual budget line attached, rather than another round of encroachment-clearing ahead of next year's monsoon. The engineering study has done the harder diagnostic work of pinpointing exactly which structures need to change — a second culvert or outflow route at Jorabat, and a widened waterway at Ninth Mile — which narrows the debate considerably from the vaguer "poor drainage" framing that has dominated coverage of Guwahati flooding for years. What it cannot do on its own is compel NHAI, Assam and Meghalaya to jointly fund and execute that fix before the next monsoon arrives.
Frequently Asked Questions
Why does Jorabat flood so badly compared to other parts of Guwahati?
Jorabat sits in a naturally bowl-shaped depression, and the engineering study found that construction of the Jorabat flyover lowered the carriageway further, deepening that depression. Combined with a drainage system that relies on a single culvert with no backup route, even moderate rainfall can overwhelm the area's ability to drain water away.
Is Jorabat in Assam or Meghalaya?
Both. Jorabat straddles the state border, with its larger, northern portion falling under Kamrup Metropolitan district in Assam and its southern portion under Ri-Bhoi district in Meghalaya. This split administrative control is part of why coordinated drainage maintenance has historically been difficult.
What specifically is wrong with the drainage at Ninth Mile?
The study found the culvert at Ninth Mile provides only around three square metres of waterway, which engineers assess as inadequate to carry away peak stormwater volumes during heavy rain, on top of reduced capacity from rapid urbanization and solid waste obstruction.
Who is responsible for fixing the problem?
Responsibility is currently split across at least three bodies: NHAI, which built and maintains the highway and its drainage structures; Assam's Water Resource department, which has been clearing encroachments on the Jorabat-Byrnihat drain; and the district administrations of Kamrup (Metro) in Assam and Ri-Bhoi in Meghalaya. Meghalaya Chief Minister Conrad Sangma has proposed a joint expert committee to examine the cross-border dimension specifically.
How long has this been a problem?
Local reporting describes Jorabat's flooding as a recurring issue spanning more than 15 years, though 2026's monsoon has produced some of the most severe episodes, including a mid-July flash flood that pushed water levels under the flyover to three to four feet. Guwahati's civic bodies have drawn up drainage master plans dating back to 1960 that were never fully implemented.
What was NHAI's response during the mid-July 2026 flooding?
NHAI diverted traffic away from the flooded stretch via Digaru and Narengi while restoration teams worked to reopen NH-27 at Jorabat, according to local reporting at the time.
Is there a longer-term plan to fix Guwahati's flooding, not just Jorabat?
Yes. A joint technical team from the Netherlands, IIT Guwahati and IIT Roorkee is working on a roughly three-year plan to redirect excess stormwater toward Silsako Beel and Deepor Beel, two natural wetlands that historically absorbed the city's excess water. This is separate from, but related to, the specific culvert-level fixes needed at Jorabat and Ninth Mile.
What role does hill-cutting in Meghalaya play in Jorabat's flooding?
Residents and local reporting have linked hill-cutting activity on the Meghalaya side of the border to reduced natural water retention in the hills above Jorabat, which sends larger volumes of surface runoff downhill into Assam during heavy rain than the terrain would naturally handle. Assam Chief Minister Himanta Biswa Sarma has specifically pointed to hill-cutting linked to institutional expansion near the border as a contributing factor.
What is Deepor Beel and why does it matter for this story?
Deepor Beel is Assam's only Ramsar-designated wetland of international importance, located on Guwahati's southwestern fringe, and has historically absorbed the city's excess stormwater. Its water-spread area has shrunk by an estimated one-third or more due to encroachment and urbanisation, which is part of why the Netherlands-IIT Guwahati-IIT Roorkee redirection plan targeting it is seen as necessary but not guaranteed to succeed on its own.
Does this affect travel between Guwahati and Shillong?
Yes. Jorabat is the junction connecting NH-27 and NH-37, making it the primary route between Guwahati and Shillong. Flooding here forces long diversions and has repeatedly disrupted both private and commercial traffic between Assam and Meghalaya.
Sources
The Assam Tribune; Sentinel Assam; Northeast Live TV; Northeast Now (nenow.in); Guwahati Plus; Pratidin Time.
