Perched at an altitude of nearly 775 metres in the misty hills of Wayanad, the Banasura Sagar Dam holds a rare distinction — it is the largest earthen dam in India and the second largest of its kind in all of Asia. Built across the Karamanthodu, a tributary of the Kabini river, this dam doesn’t just store water for a drought-prone region; it has quietly become one of Kerala’s most photographed landscapes, with jade-green islands rising out of the reservoir like something from a painting.
Quick Facts: Banasura Sagar Dam
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Detail |
Information |
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Official name |
Padinjarathara Dam (Kuttiyadi Augmentation Main Earthen Dam) |
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Popular name |
Banasura Sagar Dam |
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State |
Kerala |
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District |
Wayanad |
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Nearest town |
Padinjarathara, near Kalpetta |
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River |
Karamanthodu (tributary of the Kabini/Kabani river) |
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River basin |
Kabani basin |
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Dam type |
Homogeneous rolled earth-fill dam |
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Height (from foundation) |
38.5 metres (126 ft) |
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Length |
685 metres (approx. 2,247 ft) |
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Full Reservoir Level (FRL) |
EL 775.60 m |
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Storage capacity |
209.25 million cubic metres (169,642 acre-ft) |
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Water spread area |
12.77 sq. km |
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Catchment area |
61.44 sq. km |
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Installed power capacity |
231.75 MW |
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Number of saddle dams |
6 |
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Year commissioned |
2005 (construction began 1979) |
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Owner/operator |
Kerala State Electricity Board (KSEB) |
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Rank in India |
Largest earthen dam |
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Rank in Asia |
Second largest earthen dam |
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Best visiting months |
October to May |
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Nearest city |
Kalpetta (approx. 21 km) |
Where the Dam Gets Its Name
The dam is named after Banasura, the thousand-armed Asura king said to be the son of Mahabali and grandson of Prahlada in Hindu mythology. Local legend holds that the surrounding hills — the second-tallest range in Wayanad — were once his stronghold. This mythological connection is more than folklore; it shapes how the dam is marketed and experienced by visitors, many of whom arrive specifically because of the story behind the name rather than the engineering itself.
The River Behind the Reservoir
Banasura Sagar Dam does not sit on a major river in the way most large Indian dams do. Instead, it impounds the Karamanthodu, a relatively modest hill stream that itself feeds into the Kabini (also spelled Kabani), which eventually merges with the Cauvery system further downstream. This matters for a simple reason: the dam was never designed to tame a massive river’s flow. It was built to trap monsoon runoff from a compact catchment of about 61 sq. km, store it at height, and release it in a controlled way through a canal network.
That distinction explains the dam’s engineering design. Rather than a single concrete gravity structure, the project relies on:
- One main earthen dam at Padinjarathara
- A concrete gravity spillway dam alongside it
- Six saddle dams (Kosani, Kuttiyadi, Nayamoola, Manjoora, and two near Kottagiri) that plug lower ridge points around the reservoir rim
Together, these structures seal off the entire basin so the reservoir can hold its full 209 million cubic metres without water escaping through natural gaps in the surrounding hills.
Why It Was Built: The Kuttiyadi Augmentation Scheme
Work on the Banasurasagar Project began in 1979 as part of the larger Kuttiyadi Augmentation Scheme, a plan devised to solve two connected problems facing this part of Kerala:
- Seasonal water scarcity — Wayanad and neighbouring areas faced acute shortages of irrigation and drinking water during dry months, despite heavy monsoon rainfall.
- Power generation shortfall — The existing Kakkayam hydroelectric project needed a steadier water supply to operate at capacity.
By damming the Karamanthodu at height and channelling water through a canal system, engineers created a reservoir that could feed the Kakkayam power project year-round while also releasing water for irrigation downstream. The dam became fully operational in the mid-2000s, decades after the scheme was first conceived — a timeline typical of large multipurpose water projects in hilly terrain, where saddle dam construction and land acquisition slow progress considerably.
Engineering Scale: What Makes It “Largest”
The “largest earthen dam” title isn’t about height — at 38.5 metres, Banasura Sagar is modest compared to concrete dams elsewhere in India. The scale claim rests on a different measure: the sheer volume of earth, stone, and rubble packed into the structure to hold back water across a wide hill gap.
Key figures that support this ranking:
- Length of roughly 685 metres along the main earthen embankment
- A full reservoir level held at an elevation of 775.60 metres
- Storage capacity exceeding 209 million cubic metres of water
- A water spread area of nearly 13 sq. km once the reservoir is full
This combination of length, height, and storage volume, achieved without a single continuous concrete wall, is what places it ahead of every other earthen dam built in the country.
A Reservoir That Became a Tourist Landmark
Few Indian dams double as scenic attractions the way this one does. When the reservoir filled, it submerged low-lying land around the original riverbed, leaving behind a scattering of hillocks that now sit as green islands surrounded by water on all sides. Boat rides across the reservoir, walking trails along the dam’s crest, and viewpoints overlooking the Banasura hills have turned what was originally a pure irrigation and power project into one of northern Kerala’s most visited sites, drawing well over a lakh of visitors annually.
Points worth knowing before planning a visit:
- The dam is roughly 21 km from Kalpetta town, the usual base for Wayanad travel
- Entry is regulated by KSEB, and boating is typically managed through a separate ticketing counter
- Visibility and water levels are best just after the monsoon, from October onward
- Photography from the top of the dam offers clear views of the reservoir islands and surrounding hill ranges
Environmental and Regional Significance
Beyond tourism, the dam continues to serve its original purpose. It stabilises water availability for irrigation in a district that depends heavily on agriculture, and it supports hydroelectric generation with an installed capacity of 231.75 MW. In recent years, the reservoir has also hosted one of India’s early floating solar power installations, adding a renewable energy layer to a site already generating hydroelectricity — a detail that positions Banasura Sagar as more than a legacy infrastructure project, but as a site still being adapted for newer energy needs.
FAQs
Is Banasura Sagar Dam the same as Banasura Hill?
No. Banasura Hill is the second-tallest peak in Wayanad and forms the scenic backdrop to the dam; the dam itself is a separate earthen structure built at its base.
Can visitors walk across the dam?
Yes, a section of the dam’s crest is open to visitors, offering views over the reservoir islands, though access points and timings are set by KSEB and can vary seasonally.
Why is it called an earthen dam instead of a concrete dam?
It is built primarily from compacted earth, stone, and rubble rather than poured concrete, which is why its “largest” ranking is based on the volume of material used rather than height alone.
Does the dam affect a major river system?
Not directly. It dams the Karamanthodu, a tributary stream, though its downstream effects eventually connect to the wider Kabini river network.
