INCOIS installs second Coastal Flood Monitoring System near Kollam to forecast Kallakkadal swell-surge flooding on Kerala's pre-monsoon coast
Why in News
The Indian National Centre for Ocean Information Services (INCOIS) has installed a second Coastal Flood Monitoring System (CFMS) near Kollam Harbour on Kerala's southwest coast, doubling the country's real-time observation footprint for Kallakkadal — sudden coastal flooding driven by long-period swell waves generated thousands of kilometres away in the southern Indian Ocean. The first CFMS was set up at Vizhinjam; the new Kollam node fills a critical gap along the Kerala arc that bears the brunt of pre-monsoon (February-May) swell surges. The system integrates automatic weather stations with high-frequency pressure sensors in shallow water to capture nearshore wave transformation and centimetre-scale water-level fluctuations as the swells shoal in.
Kallakkadal is now a UNESCO-recognised oceanographic term (adopted 2012, drawn from Malayalam *kallan* 'thief' + *kadal* 'sea') because the surges arrive without the usual cyclone or storm signature visible to coastal residents. They are produced by distant southern Ocean storms that generate long-period swells; these travel ~10,000 km and infragravity components (wave periods 30-300 seconds) carry enormous energy that piles up via the shoaling effect when the swells encounter shallow continental-shelf bathymetry. The hazard is most acute for fishing communities, fish-landing harbours, low-lying coastal settlements and tourism infrastructure in Kerala, Tamil Nadu and parts of southern Karnataka.
Operationally, the Kollam CFMS feeds into INCOIS's Swell Surge Forecast System (commissioned 2020) which already delivers up to seven-day advance warnings, helping district authorities pre-position resources and issue fishing-ban advisories. India's broader ocean-observation grid — tsunami buoys, tide gauges, HF radars and Argo floats — feeds into INCOIS's mandate to provide ocean information and advisory services to coastal stakeholders. The expansion is part of MoES's push to densify hyperlocal coastal hazard observation in an era of intensifying ocean swells linked to changing storm-track climatology.
At a Glance
- Installer
- INCOIS (under MoES) — second CFMS, near Kollam Harbour, Kerala.
- First CFMS location
- Vizhinjam (southern Kerala).
- Phenomenon tracked
- Kallakkadal — swell-surge flooding from distant southern-Indian-Ocean storms.
- Wave periods
- 30-300 seconds (long-period infragravity swells).
- Travel distance
- swells originate ~10,000 km away, reach Kerala in 2-3 days.
- Peak risk season
- pre-monsoon, February-May.
- INCOIS Swell Surge Forecast System (2020) gives 7-day advance warnings.
- INCOIS HQ
- Pragathi Nagar, Hyderabad.
What is Kallakkadal?
Kallakkadal is a coastal flooding phenomenon caused by long-period ocean swells generated by high-energy storms in the southern Indian Ocean, far from where the flooding hits. The term, from Malayalam *kallan* ('thief') + *kadal* ('sea'), captures the suddenness — there is no local warning sign such as a cyclone or onshore wind. UNESCO/IOC formally adopted 'Kallakkadal' in 2012 as the scientific term for this class of swell-surge events. Physics: distant storms transfer wind energy into the ocean; the resulting long-period swells (30-300 s wave periods) travel thousands of kilometres with very little loss because long waves dissipate slowly. On approach, the shoaling effect compresses wave energy as depth decreases, coastal bathymetry focuses it, and water piles up rapidly on shore — flooding harbours, beachside villages and low-lying farmlands. Wave periods between 30 and 300 seconds put Kallakkadal in the infragravity band, distinct from regular wind waves (typical periods 5-20 s).
Coastal Flood Monitoring System (CFMS)
CFMS is a real-time observation network that combines (a) weather stations (wind, pressure, rainfall) with (b) high-frequency pressure sensors deployed in shallow nearshore water to track sub-second pressure fluctuations corresponding to wave height and water-level changes. Together these allow INCOIS to observe how an incoming swell transforms as it crosses the continental shelf — i.e., where on the bathymetric profile energy is amplified, where wave breaking sets up, and how the surge propagates along the coast. Locations: first CFMS at Vizhinjam (near Thiruvananthapuram); second CFMS near Kollam Harbour. The Kollam site is strategically chosen because Kollam Harbour and nearby fish-landing centres are heavily exposed during Kallakkadal events and the bathymetry differs from Vizhinjam's. Outputs feed into INCOIS's Swell Surge Forecast System and the IMD's coastal hazard advisories.
About INCOIS
Indian National Centre for Ocean Information Services (INCOIS) is an autonomous body under the Ministry of Earth Sciences (MoES), headquartered at Pragathi Nagar, Hyderabad. Registered as a society on 3 February 1999 under the AP (Telangana Area) Public Societies Registration Act, 1350 Fasli. Mandate: provide ocean information and advisory services to society, fisheries, shipping, navy, industry, government and the scientific community through sustained ocean observations and modelling. Flagship services: Indian Tsunami Early Warning Centre (designated Regional Tsunami Service Provider for the Indian Ocean by UNESCO/IOC), Ocean State Forecast, Potential Fishing Zone (PFZ) advisories, High Wave alerts, and the Swell Surge Forecast System (2020) that gives 7-day advance Kallakkadal warnings.
Vulnerable regions and impact
India's southwest coast — especially Kerala, parts of Tamil Nadu, southern Karnataka and the Lakshadweep islands — is most vulnerable to Kallakkadal during the pre-monsoon season (February-May), when southern-Indian-Ocean storm activity peaks and the seas off Kerala are relatively calm, making the contrast of incoming swells dramatic. Impact: damage to fishing boats and harbours, inundation of beach hamlets and tourism property, salt-water intrusion in low-lying paddy fields, disruption of fish-landing operations and risk to life for fishermen caught at sea. Densifying CFMS coverage — Vizhinjam first, now Kollam — is part of MoES's plan to shift coastal hazard management from reactive to anticipatory, with district-level pre-positioning of resources triggered by INCOIS forecasts.
Must Remember
- •INCOIS installed the second Coastal Flood Monitoring System (CFMS) near Kollam Harbour, Kerala — first one is at Vizhinjam.
- •CFMS is operated by INCOIS under the Ministry of Earth Sciences (MoES).
- •Kallakkadal is a Malayalam term ('kallan' = thief + 'kadal' = sea) — UNESCO formally adopted it in 2012 as the technical name for these swell-driven surges.
- •Kallakkadal swells are generated ~10,000 km away in the southern Indian Ocean and reach the Kerala coast in 2-3 days.
- •Wave periods of Kallakkadal swells range from 30-300 seconds (long-period infragravity waves).
- •Kerala's southwest coast is most vulnerable during the pre-monsoon season (February-May).
- •INCOIS is headquartered at Pragathi Nagar, Hyderabad; registered as a society on 3 February 1999.
- •INCOIS also runs India's tsunami early warning, Ocean State Forecast and Potential Fishing Zone advisories.
- •INCOIS launched a dedicated Swell Surge Forecast System in 2020 giving 7-day advance warnings.
Static GK
- •INCOIS HQ: Pragathi Nagar, Hyderabad; registered as a society on 3 February 1999.
- •Parent ministry: Ministry of Earth Sciences (MoES).
- •: INCOIS hosts the Indian Tsunami Early Warning Centre — recognised by UNESCO/IOC as a Regional Tsunami Service Provider for the Indian Ocean.
- •: First CFMS at Vizhinjam, Kerala; second CFMS near Kollam Harbour, Kerala.
- •: UNESCO formally adopted 'Kallakkadal' as the technical term in 2012.
- •: INCOIS Swell Surge Forecast System was launched in 2020 with 7-day advance warning capability.
- •Other MoES bodies: IMD (Delhi), IITM (Pune), NCMRWF (Noida), NCPOR (Goa).
Glossary
- Kallakkadal
- Malayalam-origin term (kallan = thief + kadal = sea) adopted by UNESCO in 2012 for sudden swell-driven coastal flooding caused by distant southern-Indian-Ocean storms.
- Swell waves
- Long-period ocean waves generated by distant winds that travel thousands of kilometres with little energy loss.
- Infragravity waves
- Long-period ocean waves with periods of roughly 30-300 seconds, formed through non-linear interactions among shorter wind waves.
- Shoaling effect
- Increase in wave height as a wave moves from deep into shallow water and its energy is compressed vertically.
- Bathymetry
- Underwater topography of the seafloor; controls how wave energy focuses or disperses near the coast.
- CFMS
- Coastal Flood Monitoring System — INCOIS network of weather stations and high-frequency pressure sensors for real-time nearshore wave and water-level monitoring.
- INCOIS
- Indian National Centre for Ocean Information Services, Hyderabad; autonomous body under MoES; operates India's tsunami warning and ocean advisory services.
- MoES
- Ministry of Earth Sciences — parent ministry of IMD, IITM, INCOIS, NCMRWF and NCPOR.
Timeline
- 1999INCOIS registered as a society under MoES, headquartered in Hyderabad.
- 2004Indian Ocean tsunami exposes warning-system gaps; India accelerates ocean-observation expansion.
- 2007Indian Tsunami Early Warning Centre operationalised at INCOIS, Hyderabad.
- 2012UNESCO/IOC formally adopts 'Kallakkadal' as the scientific term for swell-surge floods.
- 2020INCOIS launches the Swell Surge Forecast System with 7-day advance warning.
- 2026Second CFMS commissioned near Kollam Harbour after the first at Vizhinjam.
- →Kallakkadal = 'thief sea' (Malayalam): kallan + kadal — UNESCO 2012.
- →Two CFMS sites in Kerala: V before K — Vizhinjam first, Kollam second.
- →Kallakkadal season = Feb-May (pre-monsoon); swells travel ~10,000 km in 2-3 days.
- →INCOIS = Hyderabad, under MoES — same family as IMD/IITM/NCMRWF.
- →Wave periods: 30-300 seconds = infragravity band.
Exam Angles
Kallakkadal = 'thief sea' (Malayalam): kallan + kadal — UNESCO 2012.
India has roughly 7,500 km of coastline and a coastal population of about 250 million people who are exposed to a layered hazard mix: cyclones, storm surges, tsunamis, sea-level rise and, increasingly, swell-driven flooding such as Kallakkadal. INCOIS, set up in 1999 under MoES, has emerged as India's lead ocean-services agency. The 2026 commissioning of a second Coastal Flood Monitoring System near Kollam Harbour reflects a deliberate strategy of densifying real-time coastal observation, complementing the Swell Surge Forecast System launched in 2020 and the tsunami buoy network expanded after the 2004 Indian Ocean tsunami.
Mains Q · 250wDiscuss the scientific basis of Kallakkadal-type swell surges and evaluate India's institutional response, with reference to INCOIS's Coastal Flood Monitoring System and Swell Surge Forecast System. (250 words)
Flashcard
Q · INCOIS commissioned a second Coastal Flood Monitoring System near Kollam Harbour to track Kallakkadal swell surges — long-period waves born ~10,000 km away in the southern Indian Ocean that flood Keratap to reveal
Connections & Comparisons
- ↔Pairs with STORY 32 (IMD block-level monsoon forecast): both reflect MoES's broader push toward hyperlocal, sensor-driven environmental forecasting for vulnerable communities.
- ↔Connects to the 2004 Indian Ocean tsunami legacy — that disaster catalysed the build-out of INCOIS's tsunami warning capacity at Hyderabad.
- ↔Links to coastal disaster regulation: CRZ notifications, NDMA cyclone guidelines and the State Disaster Management Plans rely on INCOIS advisories.
- ↔Cross-references the climate-change syllabus: shifting southern-ocean storm tracks and intensifying swell climatology are emerging research themes.