Bhubaneswar: The weather system over the west-central Bay of Bengal is now entering the critical stage of its journey. The depression has been intensified into a Deep Depression (DD) Tuesday Evening, before making landfall along the north Andhra Pradesh coast, around the Srikakulam–Vizianagaram sector.

But for Odisha, the bigger concern begins after the landfall.

The track indicated by the India Meteorological Department (IMD) shows the system taking a pronounced west-northwestward to northward curve after crossing Andhra Pradesh, carrying a substantial moisture field into southern and western Odisha.

That trajectory changes the nature of the threat.

The immediate coastal concern will be heavy rain and squally weather. But as the system moves inland across Odisha between September 24 and 25, the principal hazard could shift towards rapid river rises, flash flooding and a delayed surge in Mahanadi-basin inflows.

And that is where the latest Central Water Commission (CWC) inflow forecast for Hirakud becomes particularly important.

Deep Depression likely within 24 hours

The system is currently organising over the Bay of Bengal and is expected to strengthen into a Deep Depression, with the landfall phase centred on northern Andhra Pradesh.

The IMD track indicates a progression broadly along:

Date	System position/intensity indicated

Sept 22

Depression, around 25 kt

Sept 23

Deep Depression, around 30 kt

Sept 24

Deep Depression, around 30 kt

Sept 25

Deep Depression/weakening phase inland

The crucial point is that the system does not simply move inland and disappear.

Instead, the forecast track bends towards the interior, taking the circulation and its moisture plume towards southern and western Odisha.

That creates a second-stage hydrological problem for the state.

Landfall in Andhra, but Odisha faces the inland consequence

The core landfall zone is expected to be around Srikakulam, Vizianagaram and adjoining north Andhra Pradesh.

The landfall region will experience the strongest direct effects, including heavy to very heavy rainfall and winds potentially reaching 50–60 kmph, gusting around 70 kmph.

For southern Odisha, however, the Eastern Ghats provide an additional mechanism.

Districts such as Gajapati, Ganjam, Rayagada, Koraput and Malkangiri will remain close to the circulation. Moisture-laden winds encountering the Ghats can produce strong orographic uplift.

That means rainfall does not necessarily decline immediately after landfall.

Instead, parts of southern Odisha could see intense rainfall concentrated over relatively small catchments, creating the possibility of rapid rises in streams and rivers.

Rainfall threat shifts westward

As the system progresses inland, the focus moves towards:

• Kalahandi

• Nuapada

• Balangir

• Sonepur

• Sambalpur

The Depression status hoisted by IMD over these districts indicates 7–11 cm of heavy to very heavy rainfall, with isolated pockets potentially reaching 20 cm.

For these districts, the problem is not simply the amount of rain falling at a particular location.

It is where that rain falls within the river catchment.

Why Western Odisha could see flash floods

The most immediate concern is the Tel River basin.

The projected path takes the depression across or close to the upper catchments around Kalahandi, Nuapada and Balangir.

These areas contain relatively steep terrain and numerous tributaries feeding larger river systems.

Once rainfall becomes sufficiently widespread, the sequence can be rapid:

Heavy rain → soil saturation → rapid surface runoff → tributary rise → main-channel rise → downstream flooding.

This is different from the slower reservoir-driven flooding that can occur several days later.

The Patharla gauge reading of around 35,266 cusecs today provides a useful baseline, but the key issue is how quickly that flow responds once intense rainfall begins across the upper catchment.

The Hatti, Udanti and other tributary systems can respond considerably faster than the larger Mahanadi system.

That makes localized flash flooding a separate risk from the eventual Hirakud inflow problem.

Tel River presents a special problem for Hirakud

There is an important geographical distinction.

The Tel does not enter Hirakud upstream of the dam.

It joins the Mahanadi downstream.

Therefore, Hirakud cannot act as a flood-control barrier for a flash flood generated inside the Tel basin.

If intense rainfall produces a sudden rise in the Tel, that water will move downstream towards the Sonepur–Boudh side of the Mahanadi system, independently of Hirakud's ability to regulate upstream inflows.

This means western Odisha could potentially face two different problems at different times:

1. Rapid flash-flood/river-rise threat from local and tributary rainfall, particularly in the Tel basin.

2. Delayed large inflow surge into Hirakud from the wider upper Mahanadi catchment.

The Hirakud problem

This is perhaps the most important signal in the latest CWC forecast.

The CWC advisory does not indicate that Hirakud will suddenly receive the entire rainfall runoff on September 23 or 24.

Instead, the forecast shows a substantial lag.

Period	CWC inflow signal	Interpretation
Sept 22–25	Around 1,500 m³/sec in the forecast	Relatively low/flat immediate inflow
Sept 26	Rapid rise begins	Upper-basin runoff starts arriving
Sept 27–28	Major surge	Peak inflow phase
Peak forecast	Around 15,500 m³/sec	About 5.47 lakh cusecs

That 48–72-hour delay is critical.

Rainfall occurring across western Odisha and adjoining Chhattisgarh on September 23–25 does not instantly appear at Hirakud.

The water has to move through an enormous river network.

That creates the delayed hydrological pulse visible in the CWC forecast.

Hirakud is already carrying very little absorption space

According to DoWR data, Hirakud is at around 629.97 ft, or approximately 99.81% of capacity.

That changes the management equation considerably.

With the reservoir already close to its operating ceiling, a projected inflow of 15,500 m³/sec cannot simply be absorbed passively.

The key issue therefore becomes pre-emptive reservoir management.

The current period of comparatively low inflow – September 22 to 25 – provides a potential operational window.

If downstream conditions permit, reservoir managers have to assess whether sufficient controlled releases can be created before the major upper-basin inflow arrives.

That does not mean that a particular gate-opening decision is predetermined. Actual releases depend on real-time reservoir level, inflow, downstream river conditions, rainfall, forecasts and the decisions of the dam authorities.

But the CWC hydrograph makes one point clear:

The critical Hirakud inflow window is likely to come after the depression has already weakened over land.

The two flood Timelines: September 23–25 and September 26–28

This system therefore creates two distinct flood-risk windows for Odisha.

September 23–25: Flash-flood clock

The depression's inland movement can produce heavy to very heavy rainfall across:

Kalahandi → Nuapada → Balangir → Sonepur → adjoining western catchments

The immediate concern is rapid runoff and sharp rises in smaller rivers and tributaries.

The Tel basin becomes particularly important because Hirakud cannot regulate water generated downstream of the dam.

September 26–28: Reservoir inflow

The second phase comes later.

Runoff generated over the broader upper Mahanadi catchment begins reaching Hirakud, with the supplied CWC forecast showing a potential peak of approximately 15,500 m³/sec.

That is the point at which reservoir management becomes critical.

The biggest analytical distinction is that a flash flood in western Odisha can occur before the Hirakud inflow surge.

The Tel basin, for instance, can respond within hours to intense rainfall.

What authorities will have to watch

The coming 72 hours therefore require close monitoring of four indicators:

Indicator	Why it matters
Rainfall over Kalahandi–Nuapada–Balangir	Determines flash-runoff potential
Tel/tributary gauge response	Provides earliest indication of local flooding
Upper Mahanadi catchment rainfall in Odisha & Chhattisgarh	Determines eventual Hirakud inflow
Hirakud reservoir level + forecast inflow	Determines the scale and timing of required reservoir operations

The depression itself may weaken rapidly after moving inland. But the water it deposits across the catchments will continue moving for several days.

That is the central concern emerging from the IMD track and the CWC inflow forecast: the weather system may weaken first, while the river response is only beginning, signalling the Government and authorities to watch and take actions needed.
Also Read: EXCLUSIVE|Bhubaneswar-Cuttack Deep Depression Rain Peak Tonight: Why Twin City May Get Its Heaviest Spell When Landfall on Sept 23-24