Idamalayar Dam
Encyclopedia
The Idamalayar Dam is a multipurpose concrete gravity dam located at Ennakal,
near Bhoothathankettu
, on the Idamalayar River, a tributary of the Periyar River
in Kerala
, South India
. Completed in 1985, with a length of 373 metres (1,223.8 ft), the dam created a multipurpose reservoir
covering 28.3 km² (10.9 sq mi) in the scenic hills of the Western Ghats
.
The reservoir storage is utilized by a hydroelectric power station
which has an
installed capacity
of 75 MW with two units of 37.5 MW capacity, producing an annual energy output of 380 GW·h.
The large reservoir created by the Idamalayar Dam is operated by the Kerala State Electricity Board
to augment its peak power generation
requirements. The dam will benefit the Idamalayar Irrigation
Development Project by diverting water released from the tail race channel of the Idamalayar power station.
at elevation of 2520 metres (8,267.7 ft). The river is a perennial source draining a catchment area of 381 km² (147.1 sq mi) with a topography of high relief. The catchment receives annual rainfall of 6000 millimetres (236.2 in), 90% of which occurs during the monsoon
months of June to September.
The dam is located 81 kilometres (50.3 mi) from Ernakulam in Ernakulam district and 10–12 km (6.2–7.5 ) from the Bhoothathankettu
dam (literal meaning in Malayalam language
: "monster dam") on the Periyar River, which takes its name from local myths attributing its construction to demons who built it with the intention of submerging Thrikkariyoor temple
.
Further, Idamalayar storage is being supplemented from diversion of flows from the Peringalkuthu Reservoir during the monsoon season through the Vachumaram diversion canal constructed during 1997. The water stored in the reservoir is used for energy generation during the monsoon season by adopting a suitable reservoir operational schedule so that the water diverted from the diversion canal is not spilled out.
The storage in the reservoir created behind the high concrete gravity dam is utilized for power generation by diversion through a water conductor system comprising a 1700 metres (5,577.4 ft) long power tunnel, surge shaft and two lines of penstocks connected to the turbines installed in a surface power station for generation of 75 MW of power with two units of 35 MW capacity each.
Instrumentation is provided in the Idamalayar Dam and the observations carried out are analysed regularly to monitor the safety of the structure. However, a rehabilitation project envisaging improving the safety and operational performance of selected structures such as dams, barrages and regulators, which covers 19 projects under the Irrigation Department and 12 projects of the Kerala State Electricity Board, has been approved under the World Bank
funded "Dam Rehabilitation and Improvement Project (DRIP)" to be implemented from January 2011. Idamalayar Dam is one of the projects included in this programme. However, the rehabilitation work on this dam is proposed to be taken up in the second stage.
Apart from power and irrigation benefits, the project situated in scenic forest area also provides recreational benefits of boating in the reservoir, bird watching and trekking.
, which examined this issue, observed that the Idamalayar Dam project has been the "victim of recurring and long inertial periods of labour unrest".
, Common Flameback
, Black Rumped Flameback, Greater Flameback
, Crimson Fronted Barbet
, Malabar Grey Hornbill
, Malabar Trogon
, Dollarbird
, Oriental Dwarf Kingfisher
, Stork Billed Kingfisher
, Common Hawk Cuckoo, Plum Headed Parakeet
, Malabar Parakeet
, White Rumped Needletail, Brown Backed Needletail, Jungle Owlet
, Green Imperial Pigeon
, Emerald Dove
, Pompadour Green Pigeon
, River Tern
, Brahminy Kite
, Hornbill
, Grey Headed Fish, Black Eagle
, Oriental Honey Buzzard
, Rufous Bellied Eagle
, Little Heron, Asian Openbill, Fairy Bluebird, Small Minivet
, Bar-winged Flycatcher-shrike
, Black Naped Monarch
, Asian Paradise Flycatcher White, Blue Rock
, Malabar Whistling Thrush
, Rusty Tailed Flycatcher, White-bellied Blue-flycatcher, Indian Blue Robin
, Chestnut Tailed Starling
, Velvet Fronted Nuthatch
, Great Tit
, Dusky Crag Martin
, Red Rumped Swallow
, Asian Koel
, Yellow Browed Bulbul
, Wynaad Laughing Thrush, Dark Fronted Babbler
, Rufous Babbler
, Yellow Billed Babbler
, Brown Cheeked Fulvetta
, Plain Flowerpecker
, Crimson Backed Sunbird
, and Little Spiderhunter
.
near Bhoothathankettu
Bhoothathankettu
Bhoothathankettu is a dam and tourist spot in Kerala, India. It is situated in the village of Pindimana, about 10 km away from the town of Kothamangalam and 50 km away from the main city of Ernakulam....
, on the Idamalayar River, a tributary of the Periyar River
Periyar River
Periyar is the longest river in the state of Kerala, India, with a length of 244 km. The Periyar is known as the lifeline of Kerala; it is one of the few perennial rivers in the region and provides drinking water for several major towns...
in Kerala
Kerala
or Keralam is an Indian state located on the Malabar coast of south-west India. It was created on 1 November 1956 by the States Reorganisation Act by combining various Malayalam speaking regions....
, South India
South India
South India is the area encompassing India's states of Andhra Pradesh, Karnataka, Kerala and Tamil Nadu as well as the union territories of Lakshadweep and Pondicherry, occupying 19.31% of India's area...
. Completed in 1985, with a length of 373 metres (1,223.8 ft), the dam created a multipurpose reservoir
Reservoir
A reservoir , artificial lake or dam is used to store water.Reservoirs may be created in river valleys by the construction of a dam or may be built by excavation in the ground or by conventional construction techniques such as brickwork or cast concrete.The term reservoir may also be used to...
covering 28.3 km² (10.9 sq mi) in the scenic hills of the Western Ghats
Western Ghats
The Western Ghats, Western Ghauts or the Sahyādri is a mountain range along the western side of India. It runs north to south along the western edge of the Deccan Plateau, and separates the plateau from a narrow coastal plain along the Arabian Sea. The Western Ghats block rainfall to the Deccan...
.
The reservoir storage is utilized by a hydroelectric power station
Hydroelectricity
Hydroelectricity is the term referring to electricity generated by hydropower; the production of electrical power through the use of the gravitational force of falling or flowing water. It is the most widely used form of renewable energy...
which has an
installed capacity
Nameplate capacity
Nameplate capacity, also known as the rated capacity, nominal capacity, installed capacity or maximum effect, refers to the intended technical full–load sustained output of a facility such as a power plant, a chemical plant, fuel plant, metal refinery, mine, and many others.For dispatchable power,...
of 75 MW with two units of 37.5 MW capacity, producing an annual energy output of 380 GW·h.
The large reservoir created by the Idamalayar Dam is operated by the Kerala State Electricity Board
Kerala State Electricity Board
Kerala State Electricity Board is a public sector agency under the Government of Kerala, India, that generates and distributes the electricity supply in the state...
to augment its peak power generation
Peaking power plant
Peaking power plants, also known as peaker plants, and occasionally just "peakers," are power plants that generally run only when there is a high demand, known as peak demand, for electricity.-Peak hours:...
requirements. The dam will benefit the Idamalayar Irrigation
Irrigation
Irrigation may be defined as the science of artificial application of water to the land or soil. It is used to assist in the growing of agricultural crops, maintenance of landscapes, and revegetation of disturbed soils in dry areas and during periods of inadequate rainfall...
Development Project by diverting water released from the tail race channel of the Idamalayar power station.
Geography
The Idamalayar Dam is located on the Idamalayar River, a tributary of the Periyar River in Kerala. Idamalayar River originates in the Anaimalai HillsAnaimalai Hills
The Anaimalai Hills is a range of mountains in the Western Ghats in Tamil Nadu and Kerala states of South India. The name "Anaimalai" derives from the Tamil word 'Ana' meaning elephant and 'Mala' meaning hill, thus Elephant Hill. The highest peak of the Anaimalai Hills is Anamudi, , located in the...
at elevation of 2520 metres (8,267.7 ft). The river is a perennial source draining a catchment area of 381 km² (147.1 sq mi) with a topography of high relief. The catchment receives annual rainfall of 6000 millimetres (236.2 in), 90% of which occurs during the monsoon
Monsoon
Monsoon is traditionally defined as a seasonal reversing wind accompanied by corresponding changes in precipitation, but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with the asymmetric heating of land and sea...
months of June to September.
The dam is located 81 kilometres (50.3 mi) from Ernakulam in Ernakulam district and 10–12 km (6.2–7.5 ) from the Bhoothathankettu
Bhoothathankettu
Bhoothathankettu is a dam and tourist spot in Kerala, India. It is situated in the village of Pindimana, about 10 km away from the town of Kothamangalam and 50 km away from the main city of Ernakulam....
dam (literal meaning in Malayalam language
Malayalam language
Malayalam , is one of the four major Dravidian languages of southern India. It is one of the 22 scheduled languages of India with official language status in the state of Kerala and the union territories of Lakshadweep and Pondicherry. It is spoken by 35.9 million people...
: "monster dam") on the Periyar River, which takes its name from local myths attributing its construction to demons who built it with the intention of submerging Thrikkariyoor temple
Thrikkariyoor temple
Thrikkariyoor Mahadeva Temple is situated 4 km from Kothamangalam.This is considered as the last pratistha of Parasurama. This temple deserves a special mention, as it is believed to have the spirits of Lord Krishna and Lord Shiva. The rites and rituals are based on those of the Arya Dravida...
.
Water resources
Based on detailed hydrological analysis, with observed data supplemented by rainfall-runoff correlation and prediction of low flows during dry months, the mean annual runoff was estimated as about 1,207 million cubic meters (million cubic metres) and that at 95% availability as 730 million cubic metres. Therefore, the live storage in the reservoir was fixed at 1,032.3 million cubic metres. However, subsequent to the commissioning of the project in 1987, availability of the flows was reassessed. It was noted that flows reduced to 1,178 million cubic metres in dry season and reached 4,361 million cubic metres during the monsoon. The total annual flow was assessed as 5,539 million cubic metres. As irrigation requirements are not critical during monsoon season the assessment of dry weather flows is relevant for irrigation.Further, Idamalayar storage is being supplemented from diversion of flows from the Peringalkuthu Reservoir during the monsoon season through the Vachumaram diversion canal constructed during 1997. The water stored in the reservoir is used for energy generation during the monsoon season by adopting a suitable reservoir operational schedule so that the water diverted from the diversion canal is not spilled out.
Structural details
The dam built across the Idamalayar River is a gravity concrete structure with a total height of 102.8 metres (337.3 ft) above the deepest foundation level with a length of 373 metres (1,223.8 ft) at the crest level. The full reservoir level is elevation 169 metres (554.5 ft) and the minimum draw down mevel (MDDL) is 115 metres (377.3 ft). The dam has created a reservoir with a water spread of 28.3 km² (10.9 sq mi). The reservoir has a gross storage capacity of 1,089.0 million cubic metres of which the effective storage is 1,017.8 million cubic metres. The spillway has been designed to pass a design flood discharge of 3012.8 m3/s.The storage in the reservoir created behind the high concrete gravity dam is utilized for power generation by diversion through a water conductor system comprising a 1700 metres (5,577.4 ft) long power tunnel, surge shaft and two lines of penstocks connected to the turbines installed in a surface power station for generation of 75 MW of power with two units of 35 MW capacity each.
Instrumentation is provided in the Idamalayar Dam and the observations carried out are analysed regularly to monitor the safety of the structure. However, a rehabilitation project envisaging improving the safety and operational performance of selected structures such as dams, barrages and regulators, which covers 19 projects under the Irrigation Department and 12 projects of the Kerala State Electricity Board, has been approved under the World Bank
World Bank
The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...
funded "Dam Rehabilitation and Improvement Project (DRIP)" to be implemented from January 2011. Idamalayar Dam is one of the projects included in this programme. However, the rehabilitation work on this dam is proposed to be taken up in the second stage.
Irrigation benefits
Irrigation benefits from the water stored in the Idamalayar Reservoir are proposed by utilizing the tail-race water released from the Idamalayar Power house. For this purpose, the project titled "The Idamalayar Irrigation Project" is under implementation. Under this project, the tail race discharge from the Idamalayar powerhouse is picked up at the barrage constructed across the Periyar River at Bhoothathankettu and diverted through a canal system on the right bank of the barrage. The irrigation benefits envisaged covers an area of 14394 hectares (35,568.3 acre) of wet and dry agricultural lands, out of which the cultivable command area is 13209 hectares (32,640.1 acre). The project is under implementation since 1981. The cost of the project was initially Rs 18.5 crores (about US$ 411.11 million), which as per latest reports of 2007 is stated to be Rs.539.50 crores (US$ 1198.9 million). According to the Annual Plan 2010–2011 of the State Government, substantial work of the main canal, the low level canal and the link canal still needs to be completed to derive full planned benefits of irrigation.Apart from power and irrigation benefits, the project situated in scenic forest area also provides recreational benefits of boating in the reservoir, bird watching and trekking.
Construction delays
The Idamalayar Dam project was started in 1970 and completed after 17 years. In an analysis carried out in 2001 on the reasons for the delay in completion of Hydropower Projects resulting in immense cost overruns in Kerala, it was noted that the Idamalayar project could be commissioned only in 1987 with a time overrun of 9 years and consequent cost over run of 285% resulting in a capital cost of Rs 2.81 per kWh of generation. While technical reasons for the delays were fully documented, the delay highlighted, however, was attributed to the "irrational behaviour of the organized militant labour". A High Level Committee set up by the Government of KeralaGovernment of Kerala
The Government of Kerala is a democratically elected body that governs the State of Kerala, India for a period of 5 years. The state government is headed by the Governor of Kerala as the nominal head of state, with a democratically elected Chief Minister as real head of the executive. The state...
, which examined this issue, observed that the Idamalayar Dam project has been the "victim of recurring and long inertial periods of labour unrest".
Avifauna
In the reservoir area of the Idamalayar Dam, several species of avifauna have been reported. These are: Heart Spotted WoodpeckerWoodpecker
Woodpeckers are near passerine birds of the order Piciformes. They are one subfamily in the family Picidae, which also includes the piculets and wrynecks. They are found worldwide and include about 180 species....
, Common Flameback
Common Flameback
The Common Flameback or Common Goldenback is a species of bird in the Picidae family. It is found in Bangladesh, Brunei, Cambodia, China, India, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Thailand, and Vietnam.-Description and ecology:A medium-sized, golden-backed woodpecker...
, Black Rumped Flameback, Greater Flameback
Greater Flameback
The Greater Flameback, Chrysocolaptes lucidus, also known as Greater Goldenback, Large Golden-backed Woodpecker or Malherbe's Golden-backed Woodpecker, is a woodpecker species...
, Crimson Fronted Barbet
Barbet
American barbets, family Capitonidae, are near passerine birds of the order Piciformes which inhabit humid forests in Central and South America. They are closely related to the toucans....
, Malabar Grey Hornbill
Malabar Grey Hornbill
The Malabar Grey Hornbill, Ocyceros griseus, is a hornbill that is endemic to the Western Ghats and associated hills of southern India. They have a large beak but lack the casque that is prominent in other species of hornbills. They are found mainly in dense forest and around rubber, arecanut or...
, Malabar Trogon
Malabar Trogon
The Malabar Trogon is a species of bird in the trogon family. It is found in the forests of Sri Lanka and peninsular India. In India it is mainly found in the Western Ghats, hill forests of central India and in parts of the Eastern Ghats...
, Dollarbird
Dollarbird
The Oriental Dollarbird , also known as the Dollar Roller, is a bird of the roller family, so named because of the distinctive blue coin-shaped spots on its wings....
, Oriental Dwarf Kingfisher
Kingfisher
Kingfishers are a group of small to medium sized brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species being found in the Old World and Australia...
, Stork Billed Kingfisher
Kingfisher
Kingfishers are a group of small to medium sized brightly coloured birds in the order Coraciiformes. They have a cosmopolitan distribution, with most species being found in the Old World and Australia...
, Common Hawk Cuckoo, Plum Headed Parakeet
Parakeet
Parakeet is a term for any one of a large number of unrelated small to medium sized species of parrot, that generally have long tail feathers...
, Malabar Parakeet
Malabar Parakeet
The Malabar Parakeet also known as the Blue-winged Parakeet, is a species of parakeet endemic to the Western Ghats of southern India. Found in small flocks, they fly rapidly in forest clearings while making screeching calls that differ from those of other parakeet species within their distribution...
, White Rumped Needletail, Brown Backed Needletail, Jungle Owlet
Jungle Owlet
The Jungle Owlet or Barred Jungle Owlet, Glaucidium radiatum, is found in India and the dry zone of Sri Lanka. The species is often found singly, in pairs or small groups and are usually detected by their calls at dawn and dusk...
, Green Imperial Pigeon
Green Imperial Pigeon
The Green Imperial Pigeon is a pigeon which is a widespread resident breeding bird in tropical southern Asia from India east to Indonesia. It has a number of subspecies, of which the distinctive Celebes form, Chestnut-naped Imperial Pigeon .This is a forest species; it builds a stick nest in a...
, Emerald Dove
Emerald Dove
The Common Emerald Dove is a pigeon which is a widespread resident breeding bird in the tropical and sub-tropical parts of the Indian Subcontinent and east through Myanmar, Thailand, Malaysia and Indonesia, to northern and eastern Australia. The dove is also known by the names of Green Dove and...
, Pompadour Green Pigeon
Pompadour Green Pigeon
The Pompadour Green Pigeon is a pigeon in the genus Treron. It is widespread in forests of southern and southeast Asia...
, River Tern
River Tern
The River Tern is a river in Shropshire, England. It rises north-east of Market Drayton in the north of the county. The source of the Tern is considered to be the lake in the grounds of Maer Hall, Staffordshire...
, Brahminy Kite
Brahminy Kite
The Brahminy Kite , also known as the Red-backed Sea-eagle, is a medium-sized bird of prey in the family Accipitridae, which also includes many other diurnal raptors such as eagles, buzzards and harriers. They are found in the Indian subcontinent, Southeast Asia and Australia...
, Hornbill
Hornbill
Hornbills are a family of bird found in tropical and subtropical Africa, Asia and Melanesia. They are characterized by a long, down-curved bill which is frequently brightly-colored and sometimes has a casque on the upper mandible. Both the common English and the scientific name of the family...
, Grey Headed Fish, Black Eagle
Black Eagle
The Black Eagle is a bird of prey. Like all eagles, it is in the family Accipitridae, and is the only member of the genus Ictinaetus. They soar over forests in the hilly regions of tropical Asia and hunt mammals and birds, particularly at their nests...
, Oriental Honey Buzzard
Oriental Honey Buzzard
The Crested Honey Buzzard, Pernis ptilorhynchus, is a bird of prey in the family Accipitridae which also includes many other diurnal raptors such as kites, eagles and harriers...
, Rufous Bellied Eagle
Eagle
Eagles are members of the bird family Accipitridae, and belong to several genera which are not necessarily closely related to each other. Most of the more than 60 species occur in Eurasia and Africa. Outside this area, just two species can be found in the United States and Canada, nine more in...
, Little Heron, Asian Openbill, Fairy Bluebird, Small Minivet
Small Minivet
The Small Minivet, Pericrocotus cinnamomeus is a small passerine bird. This minivet is found in tropical southern Asia from the Indian subcontinent east to Indonesia....
, Bar-winged Flycatcher-shrike
Bar-winged Flycatcher-shrike
The Bar-winged Flycatcher-shrike is a small passerine bird currently placed in the cuckoo-shrike family but possibly closer to the bushshrikes of Africa. It is found in the forests of tropical southern Asia from the Himalayas and hills of the Indian subcontinent east to Indonesia...
, Black Naped Monarch
Monarch
A monarch is the person who heads a monarchy. This is a form of government in which a state or polity is ruled or controlled by an individual who typically inherits the throne by birth and occasionally rules for life or until abdication...
, Asian Paradise Flycatcher White, Blue Rock
Blue Rock
Blue Rock may refer to:* Blue Rock, Ohio, United States* Blue Rock Records, a subsidiary of Mercury Records* Celtic Blue Rock Community Arts Festival, a charity-based festival* Blue Rock , by The Cross* Blues rock, a form of rock music...
, Malabar Whistling Thrush
Malabar Whistling Thrush
The Malabar Whistling Thrush is a whistling thrush in the thrush family Turdidae. They are also known locally by the name of Whistling Schoolboy for the whistling calls that they make at dawn that have a very human quality...
, Rusty Tailed Flycatcher, White-bellied Blue-flycatcher, Indian Blue Robin
Indian Blue Robin
The Indian Blue Robin is a small bird found in South Asia. Formerly considered a thrush, it is now considered one of the Old World flycatchers in the family Muscicapidae. It was earlier also called the Indian Blue Chat. It is migratory, breeding in the forests along the Himalayas in India and...
, Chestnut Tailed Starling
Starling
Starlings are small to medium-sized passerine birds in the family Sturnidae. The name "Sturnidae" comes from the Latin word for starling, sturnus. Many Asian species, particularly the larger ones, are called mynas, and many African species are known as glossy starlings because of their iridescent...
, Velvet Fronted Nuthatch
Nuthatch
The nuthatches are a genus, Sitta, of small passerine birds belonging to the family Sittidae. Characterised by large heads, short tails, and powerful bills and feet, nuthatches advertise their territory using loud, simple songs...
, Great Tit
Great Tit
The Great Tit is a passerine bird in the tit family Paridae. It is a widespread and common species throughout Europe, the Middle East, Central and Northern Asia, and parts of North Africa in any sort of woodland. It is generally resident, and most Great Tits do not migrate except in extremely...
, Dusky Crag Martin
Dusky Crag Martin
The Dusky Crag Martin is a small passerine bird in the swallow family. It is about 13 cm long with a broad body and wings, and a short square tail that has small white patches near the tips of most of its feathers. This martin has sooty-brown upperparts and slightly paler underparts...
, Red Rumped Swallow
Swallow
The swallows and martins are a group of passerine birds in the family Hirundinidae which are characterised by their adaptation to aerial feeding...
, Asian Koel
Asian Koel
The Asian Koel is a member of the cuckoo order of birds, the Cuculiformes. It is found in South Asia, China, and Southeast Asia. It forms a superspecies with the closely related Black-billed and Pacific Koels which are sometimes treated as subspecies...
, Yellow Browed Bulbul
Bulbul
Bulbuls are a family, Pycnonotidae, of medium-sized passerine songbirds. Many forest species are known as greenbuls. The family is distributed across most of Africa and into the Middle East, tropical Asia to Indonesia, and north as far as Japan. A few insular species occur on the tropical islands...
, Wynaad Laughing Thrush, Dark Fronted Babbler
Babbler
Babbler may refer to:* Old World babbler, a large family of mostly Old World passerine birds* Australo-Papuan babbler, passerine birds endemic to Australia-New Guinea* The Babbler, the journal of BirdLife International in Indochina...
, Rufous Babbler
Rufous Babbler
The Rufous Babbler is an Old World babbler endemic to the Western Ghats of southern India. It is dark brown and long tailed, and is usually seen foraging in noisy groups along open hillsides grass or forest.-Description:...
, Yellow Billed Babbler
Babbler
Babbler may refer to:* Old World babbler, a large family of mostly Old World passerine birds* Australo-Papuan babbler, passerine birds endemic to Australia-New Guinea* The Babbler, the journal of BirdLife International in Indochina...
, Brown Cheeked Fulvetta
Fulvetta
Fulvetta is a songbird genus. Originally proposed in 1877, it was recently reestablished for the typical fulvettas, which were long included with their presumed relatives in the Timaliidae genus Alcippe...
, Plain Flowerpecker
Plain Flowerpecker
The Nilgiri Flowerpecker is a tiny bird in the flowerpecker family. Formerly a subspecies of what used to be termed as the Plain Flowerpecker although that name is now reserved for Dicaeum minullum. Like others of the group, it feeds predominantly on nectar and fruits...
, Crimson Backed Sunbird
Sunbird
The sunbirds and spiderhunters are a family, Nectariniidae, of very small passerine birds. There are 132 species in 15 genera. The family is distributed throughout Africa, southern Asia and just reaches northern Australia. Most sunbirds feed largely on nectar, but also take insects and spiders,...
, and Little Spiderhunter
Little Spiderhunter
The Little Spiderhunter is a species of long-billed nectar feeding bird in the Nectariniidae family found in the moist forests of South and Southeast Asia. Unlike typical sunbirds, males and females are very similar in plumage...
.