Which is the Largest Earth Dam in India?

The largest Earth Dam in India is Banasura Sagar Dam which impounds ‘Karamanathodu’ a tributary of Kabini River and is part of major project taken up by the Government Of India in 1979 to support irrigation and domestic needs for water of a region facing scarcity of water during the dry seasons and also to support Kakkayam Dam by supplying water. The Banasura Sagar Dam was commissioned in 2005 and supports Kakkayam Hydroelectric Power Project.

The dam is the largest earth dam in India and the second largest in Asia and is named after ‘Banasura’ – a Hindu mythological figure and son of Bali.

The dam is the most sought after tourist destinations of North Kerala and offers nature in its pristine forms surrounded by lush green landscapes.

Location of Banasura Sagar Dam

The dam lies in Western Ghats region of southern state of Kerala. It is located at a distance of 22 km from the municipal town of Kalpetta which is the head quarter of Wayanad District as well as Vythiri Taluka. Kalpetta is at a distance of 72 km from Kozhikode and about 140 km from Mysore.

The drive from Kalpetta to Banasura Sagar Dam on SH 54 is around 20 km and takes around 50 minutes; through lush green hills, tea estates and sugarcane fields. Even the dam offers a greener view which is otherwise absent in conventional masonry dams.

The dam lies at the foot of Banasura Hill, which is also the highest hill of Western Ghat in Wayanad District.

Technical Details of the Dam

The Banasura Sagar Dam is an earthen dam made from huge piles of stones and boulders. The spillway of the dam consists of four Tainter Gates. Tainter Gates have a cross section looking like a triangle with a curved base. The total spillway discharge capacity of the dam is 208.25 cumecs (cubic meters per second).

The Full Reservoir Level (FRL) of the Banasura Sagar Reservoir is 775.6 mtr (Above MSL i.e. Mean Sea Level) and the minimum draw down level of 754.86 mtr (Above MSL). The reservoir has a water spread area of 12.77 sq km (1277 hectares) and a catchment area of 61.44 sq km (6144 hectares). The maximum storage of the reservoir at full water level is 209 MCM (million cubic meters).

The Banasura Sagar Dam, along with Kakkayam Dam across the Kuttiady River; supports Kuttiady Hydroelectric Project with a total installed capacity of 220 MW. The two reservoirs are inter-connected to each other by a tunnel of length 4.678 mtr. The project has four different functional entities and one under construction.

The following power stations are supported by the waters from the Banasura Sagar Dam and Kakkayam Dam-

1) Kuttiady Old Power House

The Kuttiadi Old Power station has a total installed capacity of 75 MW. It was commissioned on 30^th September 1972 and has three M/S Fuji Electric made Vertical Pelton Turbines of individual capacity 25 MW. The annual generation potential of the station is 268 Million Units.

2) Kuttiady Extension Scheme (KES)

Under this scheme an additional unit of 50 MW was installed nearby the old power house. It consists of a Single Pelton Turbine of 50 MW capacity made by the General Electricals, Canada. The unit was commissioned on 27^th January 2001 and has an annual generation capacity of 75 Million Units.

3) Kuttiady Additional Extension Scheme (KAES)

The Kuttiady Additional Extension Scheme (KAES) was executed by constructing a power house adjacent to the Kuttiady Extension Scheme (KES). It was mainly constructed to counter the spillover during monsoons. A tunnel of 686 mtr long and a penstock of length 2 km were also made under the scheme. The power house has a total capacity of 100 MW with two Vertical Pelton Turbines of individual capacity of 50 MW. The first and second units were commissioned on 11^th Oct. 2010 and 30^th Oct. 2010 respectively and the plant has an annual generation capacity of 223 Million Units.

4) Kuttiady Tail Race Small Hydro Project

This scheme uses the water discharged from the Kuttiady Old Power House and Kuttiady Extension Scheme (KES). It houses three Horizontal Kaplan Turbines of 1.25 MW individual capacity and Boving Fouress make. The first, second and third units were commissioned on 19^th June 2008, 22^nd June 2008 and 23^rd Oct. 2008 respectively. This unit has a total installed capacity of 3.75 MW and an annual generation capacity of 15 Million Units.

5) Kuttiady Small Hydroelectric Project

This is an under construction project aimed at utilizing the tail water of Kuttiady Additional Extension Scheme (KAES) to power two turbines of individual capacity of 1.5 MW.

India’s First Solar Atop Dam

A solar project is installed on the top of the Banasura Sagar Dam by the Kerala State Electricity Board (KSEB); which is fifth such project in Kerala and the second in Wayanad. The project incurring a cost of around INR 4 crores to KSEB and generating five lakh units annually was commissioned in 2016 by the Kerala’s State Power Minister, Kadakampally Surendran.

The project has 1760 panels with individual capacity of 50 KW installed over a 285 meters stretch of the dam’s top road.

Tourism Hotspot

The location of the dam at the foot of a hill in Western Ghats, surrounded by greenery makes it Kerala’s one of the most popular tourist destinations. Trekking on the Banasura Hills and high speed boating in the Banasura reservoir are some of the major attractions of the dam. The reservoir also has many tiny islands covered with greenery which offer a rejuvenating experience away from hectic city life.