Context: Odisha recorded 1,453 mm rainfall between June–September 25, 29% above normal, despite beginning June with a 47% deficit.
- The monsoon was dominated by an unusually large number of atmospheric systems, including 11 systems over the Bay of Bengal; the latest made landfall near Kalingapatnam on September 23.
Why Rainfall Became Excessive
- The IMD had forecast 90% of the Long Period Average (LPA) for India, partly anticipating the development of El Niño, but repeated Bay of Bengal systems overwhelmed this broader seasonal pattern.
- Successive systems brought heavy rainfall with little recovery time, increasing soil saturation, reservoir/storage stress and surface runoff.
- By July 30, about 5.2 lakh people had been affected, rising to another 13.5 lakh by August 27, highlighting the cumulative impact of repeated rainfall.
Major Physical and Hydrological Risks
- At least 60 locations received >100 mm rainfall in 24 hours, swelling rivers and increasing downstream flood risks in districts such as Bhadrak and Jajpur.
- Saturated soils and already-full local storage reduce infiltration capacity, causing subsequent rainfall to convert rapidly into surface runoff and flooding.
- Odisha’s southern highlands face greater risks of landslides and slope failures, while the coastal region is a low-gradient depositional plain with multiple deltas, where drainage into the sea is relatively slow.
- Major rivers requiring close monitoring include the Baitarani, Budhabalanga, Jalaka and Rushikulya, particularly for their peak flood levels after the latest weather system.
Emerging Evidence of Changing Rainfall Pattern
- A May study by Odisha University of Agriculture and Technology, using 1901–2020 data, found that maximum one-day and five-day rainfall bursts are becoming more frequent, even as the number of heavy-rainfall days declines.
- This indicates a shift towards fewer but more intense rainfall episodes, increasing the risk of flash flooding, urban flooding and infrastructure damage.
- Climate change is increasingly associated with more prolonged monsoon withdrawal and intense rainfall events, although individual extreme events involve multiple interacting atmospheric factors.
Disaster Management: Strengths and Gaps
- Odisha has developed a strong reputation for disaster preparedness, evacuation and zero-casualty-oriented disaster management, particularly through advance warnings and coordinated evacuations.
- However, recurrent urban waterlogging in Berhampur and disruption of inter-State highways and railway networks indicate that evacuation capacity has progressed faster than underlying civic infrastructure.
- The CAG’s 2024 observations on deficiencies in drainage design and maintenance highlight the need to strengthen infrastructure alongside emergency response.
- The effectiveness of Odisha’s zero-casualty approach will increasingly depend on whether drainage, flood-control and urban infrastructure can withstand repeated extreme rainfall.
Key Concept: Runoff and Soil Saturation
- Infiltration: Entry of rainfall into the soil; it declines sharply once soil becomes saturated.
- Surface runoff: Rainwater flowing over the land surface when rainfall exceeds infiltration and storage capacity.
- Antecedent soil moisture: Existing soil wetness before a rainfall event; higher antecedent moisture increases flood-generation potential.
- Thus, successive intense rainfall events can produce disproportionately greater flooding even when later rainfall is not substantially higher.
What Odisha Needs to Prioritise
- Shift from preparing for isolated seasonal anomalies towards planning for repeated intense downpours with short recovery intervals.
- Strengthen urban drainage, storm-water management, river-channel capacity and maintenance, alongside evacuation systems.
- Undertake vulnerability-based planning for deltaic coastal areas, hilly landslide-prone regions and urban centres.
- Assess the eventual crop and infrastructure damage and river peak levels to improve future flood-risk modelling and preparedness.
- Build broader socio-economic and infrastructural resilience, rather than relying primarily on evacuation and post-disaster response.
