EXCLUSIVE| Cyclone Arnab Flood Threat: High-Alert For Odisha Reservoirs as Rising Inflow Poise To Trigger Massive Gate Openings!

Bhubaneswar:  Emergency response systems are flashing red across Odisha as Very Severe Cyclonic Storm Arnab closes in. The impending onslaught threatens to transform a calm reservoir landscape into an active flood management crisis. With the storm projected to dump extreme rainfall across major catchments over the next 72 hours, state engineers are preparing for massive, sequential water discharges.

The Odisha Department of water Resources has put reservoir operators on hyper-vigilance. Current numbers show a highly deceptive calm, but predictive modeling warns of massive incoming surges that will force widespread opening of dam gates – most notably at the downstream giant, Hirakud Reservoir.

RESERVOIR INFLOW & GATE STATUS MATRIX (OCTOBER 27, 2026)

• Hirakud Reservoir
• Current Level: 627.50 Feet
• Open Gates Now: 0 / 98 Gates
• Forecasted Peak Inflow: ~12,000 m³/sec (Day 4)
• Upper Indravati Dam
• Current Level: Baseline Low
• Open Gates Now: Closed
• Forecasted Peak Inflow: ~3,200 m³/sec (Day 2)
• Balimela Dam
• Current Level: Baseline Low
• Open Gates Now: Closed
• Forecasted Peak Inflow: ~870 m³/sec (Day 2)
• Upper Kolab Dam
• Current Level: Baseline Low
• Open Gates Now: Closed
• Forecasted Peak Inflow: ~420 m³/sec (Day 2)

The Current State: Silence Before the Storm

As of the evening of October 27, 2026, the state’s massive water storage networks are holding firm, completely shut down against outside flows to optimize storage buffer capacities before heavy downpours begin.

Official data confirms that Hirakud Dam currently has all 98 sluice gates completely closed, maintaining a controlled reservoir water level of 627.50 feet (against its maximum capacity threshold of 630 feet). The current live storage sits at 89.94%, with inflows holding steady at minimal baseline rates under 500 m³/sec.]

Similarly, southern structures – including the Upper Indravati, Upper Kolab, and Balimela dams – report all spillway gates closed, keeping pool levels in a strategic drawdown state to maximize structural safety margins.

The Impending Crisis: How Arnab Will Spike Inflows

The peace will break as Cyclone Arnab hits land on October 28 between Bapatla and Visakhapatnam, near Kakinada, pushing heavy moisture bands deep across southern and western Odisha.

·         The Initial Southern Surge (Day 2 - October 29): Heavy storm bands tracking over Nowrangpur, Malkangiri, and Koraput will bring up to 20 cm of severe rain. This will send localized inflows into Upper Indravati screaming up to ~3,200 m³/sec, alongside a sharp rise to ~870 m³/sec at Balimela.

·         The Hirakud Deluge (Day 4 - October 31): As the cyclonic system breaks down inland, its extreme cloud profile will empty directly over the expansive upper Mahanadi catchment network, dumping a massive rain matrix of 100–150+ mm across multiple drainage grids. Runoff from key channels like Rajim, Simga, and Kotni will consolidate into a huge, slow-moving flood crest. Inflows to Hirakud will climb rapidly over Days 2 and 3, culminating in a prolonged peak plateau of ~12,000 m³/sec on Day 4.

Will Hirakud and Other Dam Gates Open?

Yes, a massive opening of spillway gates is highly likely, beginning sequentially between October 29 and October 31.

Because Hirakud is currently holding a high water profile of 627.50 feet, the reservoir only has roughly 2.5 feet of remaining vertical space before reaching maximum storage limits. It cannot absorb a massive 12,000 m³/sec inflow plateau over multiple days without releasing vast quantities of water downstream.

Engineers at the Odisha State Emergency Operations Centre indicate that a high-volume water release plan will be initiated. Controlled gate operations are expected to roll out in distinct, strategic phases:

1.    Phase 1 Outflows (Southern Dams): Upper Indravati and Balimela are expected to trigger automated gate activations by late October 28 or early October 29 to handle their sharp inflow spikes.

2.    Phase 2 Outflows (Hirakud Control): To avoid severe flooding in the coastal delta region, Hirakud operators will delay large-scale gate activations until localized, downstream rain runoff peaks. Once coastal peaks start subsiding around October 30, Hirakud will systematically open multiple sluice gates to maintain a safe water level.

Mid-Term Outlook and High-Risk Safety Warnings

The structural outlook through early November remains high-alert. While model tracking shows storm inflows tapering back down to safe levels by November 3, the massive volume of water moving through the Mahanadi river system will keep downstream embankments under severe hydrologic pressure for days.

Also Read: EXCLUSIVE EXPLAINER| Cyclone Arnab Wind Speed: IMD marks 155-165 kmph vs JTWC’s 222 kmph – Know the Truth!