Idukki Dam

The Idukki Dam, located in Kerala, India, is a 168.91 m (554 ft) tall arch dam. The dam stands between the two mountains - Kuravanmala (839)m and Kurathimala (925)m. It was constructed and is owned by the Kerala State Electricity Board. It supports a 780 MW hydroelectric power station in Moolamattom.

It is built on the Periyar River, in the ravine between the Kuravan and Kurathi Hills in Kerala, India. At 167.68 metres, it is one of the highest arch dams in Asia and third tallest arch dam. It started generating power on 4 October 1975. Technically, the dam type is a concrete double, curvature parabolic, thin arc dam.

This dam was constructed along with two other dams at Cheruthoni and Kulamavu. Together, the three dams have created an artificial lake that is 60 km² in area. The stored water is used to produce electricity at the Moolamattom Power house, which is located inside nearby rocky caves. The Government of Canada aided in the building of the dam with long term loans and grants.

The idea of constructing a dam for power generation was first conceived in 1919. As per history, Shri Kolumban, the head of 'Araya' race during 1922, showed the way to the Malankara Estate Superintendent and his friend Thomas, who were on hunting spree in the forest, the spot of present Arch Dam. He told them of the legend of Kuravan and Kurathi Hills. Mr. Thomas was impressed by the sight of water flow between the mountains and it was his idea that has materialized in the form of Idukki Arch Dam. Sri. W.J.John of Malankara Estate submitted a report to the Government of Travancore in 1932 on the possibility of constructing a dam at Idukki for Power Generation.

In 1947, a preliminary investigation report was prepared and submitted by Sri. P.D. Joseph John, the then Chief Electrical Engineer to the Government of Travancore. It was during 1956 that the Central Water Commission conducted a detailed investigation based on the Government's request. The project report was prepared in 1961 and the Planning Commission accorded sanction for implementing the scheme in 1963 and the preliminary works of the project were started.

The construction of this Dam commenced on 30 April 1969. Storage of water in Idukki reservoir commenced in February, 1973. The inauguration of trial run of the first machine was celebrated on 4 October 1975. Commercial operation of the Power Station was Commissioned on 12 February 1976 by the then Hon. Prime Minister Smt. Indira Gandhi. The Government of Canada aided the Project with long term loans and grants. M/s S.N.C.Inc., Canada, a well-known firm of Consulting Engineers were advising and assisting Project Engineers under the Canadian Aid.

Construction of this Arch Dam and two other dams at Cheruthony and Kulamavu has created an artificial lake of 60 km2 width and the water stored is utilized for production of electricity at the unique Moolamattom Power house, which is located inside the rocky caves.

Features

Idukki Dam is 554 feet tall, constructed between the two mountains - Kuravanmala (839 meters) and Kurathimala (925 meters ). This project is situated in Idukki District and its underground power house is located at Moolamattom which is about 43 km from the dam.

Twice in the past, the shutters had to be opened; during the northeast monsoon (October to December) on both occasions. The first time was in 1981 (when the shutters were repeatedly opened and shut between October 29 and November 13) and the second time was in 1992 (when they were kept open for 12 days from October 12 to 23). On both occasions, the water level in the dam touched the brim only when the storage built up during the southwest monsoon (June to September) was augmented by the inflow received immediately afterwards following heavy downpour early in the northeast monsoon.

Usage 

Power Generation

The Project harnesses a major portion of the power potential of Periyar, the largest river in Kerala, by the creation of a reservoir of 2,000 M.cum (2 Billion Tonnes) capacity, diversion of waters thus impounded through a water conductor system consisting of a power tunnel and two underground pressure shafts to an underground power house situated in Moolamattom. The installed capacity of the Power House is 780MW consisting of 6 Units of Pelton-type turbines with a power generation capacity of 130 MW each. The regulated waters of Periyar falls through a drop of about 669.2 metres (2195 feet) while generating power in the underground power house.

Irrigation

The tail waters flowing to Kudayathurpuzha through tunnel and open channel is diverted for irrigation purposes in the Muvattupuzha Valley.

Tourist destination and attraction

Earlier, there was a blanket ban on public entry in to the dam due to security reasons. Later, it was relaxed opening the dam for public for 10 days during the Onam and the Christmas seasons. The duration has been increased to one month since last year. Cameras and cell phones are not allowed inside the dam area. The entry fee is Rs.10 for adults and Rs.5 for children. The fee for 15-minute boating service for five persons is Rs. 600.

Idukki valley is 121 km away from Kottayam, and is a small hill town surrounded by a spread of beautiful, wooden valleys and meandering streams. Idukki is a well known tourist center in Kerala.

The Idukki Wildlife Sanctuary extends over the Thodupuzha and Udumbanchola taluks of Idukki district, spread over 77 km2 and is about 450 - 748 m above sea level. The Idukki Reservoir formed by three dams - Cheruthoni, Idukki and Kulamavu - extends to 33 km2. One can find Elephants, bisons, sambars deers, wild dogs, jungle cats, tigers, wild boars etc. and variety of Snakes like Cobra, viper, krait and a number of non poisonous snakes in this Sanctuary. The birds of Idukki are Jungle fowl, myna, laughing thrush, black bulbul, peafowl, woodpecker, kingfisher etc.

Kerala Flora and Fauna

Vegetation and animal life of a region form part of the present environment, and they depend on the equilibrium existing amongst the soils, climate, landforms and morphological processes operating in nature today. Physiography is one of the factors which controls the distribution of plant and animal life. The geographical situation, the position of the mountain ranges, the innumerable streams, rivulets, and rivers ensuring a perfect drainage etc., have made Kerala one of the richest types of moist tropical evergreen forest which hold an impressive array of plant and animal life. Kerala with 28.8 per cent of her area under forests comes next to Assam which has the largest area under forests.

The evergreen forests are distributed all over the State, and they grow even up to 1372 m elevation on the Western Ghats. At lower elevation, however, this type merges imperceptibly into the tropical semi-evergreen forests, which is an intermediate type between the wet Evergreen and the Moist Deciduous forests. At higher elevation the wet Evergreen merge into Shola forests and they in turn pass on to mountain grassy lands (lyppan. 1960). Dry type forest are limited to the portions -in the leeward side of the Ghats, and the two main dry localities in the State are the Walayar and Anjanad Valleys in north Kerala.

Five types of forests which are the products of variation in topography, soil and rainfall, have been identified in Kerala (Innes, 1951). They constitute the Deciduous forests of the plains, Evergreen forests of the Ghat slopes, Evergreen Shola forests, Bamboo forests of the Wynad, and the Deciduous forests of the Wynad and Attappadi valley. The Deciduous forests occur along the plains and lower Ghat slope extending upto the hill sides up to 457 m above M.S.L. They are also found along the river banks. The Evergreen forests of the Ghat slopes are seen on the western and eastern slopes of the Western Ghats right from foot hills upto 1220 m a.s.l. The forest growth is magnificent where the rainfall is very heavy, and in some places the rainfall exceeds 7500 mm. The trees are evergreen with abundance of epiphytic orchides, mosses, ferns, rattans, tree ferns, climbing ferns and creepers.

Evergreen Shola forests are noted on all the higher slopes of the Ghats including the Brahmagiri range and also in the highest parts of the Attappadi valley between the altitude of 1067 and 1829 m.a.s.l. Fern and mosses are abundant in these forests but the orchids are poorly represented. Families such as Myrtaceae, Lauraceae, and Styracaceae are dominant. Luxuriant growth of Arundinaria Wightiana Ness, Reed bamboo in this forest is significant. Bamboo forests are found in the marroco belt lying east of the Ghat where the rainfall ranges from 1500 to 2500 mm. The forest stretches from the foot of the Nilgiris on the south to the Brahmagiri on the north. The most dominant species is Bambusa arundinacea wild which is the common bamboo still widely used by tribes for various pur¬poses in their day to day life. The uncultivated swampy lands are dominated by Pandanus Odoratissimus Roxb, Melastoma malabaricum, Linn, and Ligodium. Deciduous forests are found in the Wynad plateau and in the lower portion of Attappadi valley.

Some of the important cultivated crops in Kerala come under certain types of cereals, pulses, oil seed crops, miscellane¬ous crops, ugars, condiments and species, fibre crops and narcotics. Oryza sative Lmn, Rice is the most important cereal crop which is being cultivated in almost all parts of Kerala.

Cocos nucifere Linn, Coconut grows luxuriously in all districts except Palghat where Borassus-fiabellifer Linn, Palmera grows most. Coconut growth is profuse in the coastal region and in the Midlands, and it is the most important among all the oil seed crops and fibre crops in the State.
Artocarpus integrifolia Linn. f., lack, plavu, Mangifera indica Linn, Mango tree, Mavu; Anacardium occidentala Linn, Cashew tree, Parankimavu; Musa sapizntum Linn, Banana, Vazha; Monihot Utllissima Pohl, Tapioca, Ivlarakizhangu; Ipomoea batatas Linn, sweet potato, Mathura Kizhangu and Yams, kachil are some of the important miscellaneous food crops cultivated in the state. Saecharum sp. sugarcane, karimbu is being cultivated in ceitain parts Kerala has been very famous for her condimens and spices since earlier times. Piparnigrum Linn, Pepper, kurumulaku; Zingiber officianalis Rose, Ginger, Inchi; Curcuma longa Linn, Turmeric; puli; and Allium cepa Linn, Onion, Ulli are some of the very important amongst them. Areca catechu Linn, Aracanut, Adakkamarum is one of the important narcotics extensively cultivated all over Kerala.

The forest and hilly regions of Kerala still abound with a large variety of fauna even though the advance of cultivation and deforestation driving them much interior to the forests. Some of the important animals still thrive in the interior forests include Panthera tigris Linnaeus, Tiger, Kaduva; Melursus ussinus shaw, sloth Bear, karadi; Pauthera pardus Linnacus, Leopardi, pu1i; and Elephas nzaximus Linnaeus, Indian Ele¬phant, Ana Boss ganrus H. Smith, Gur, Kattu Pottu is common in north Wynad and Nilambur. Sus cristalus Wagner, will Boar, Kattupanni; Hemitragus hylocrius Oglilby, Nilgiri Tahr, Kattadu; Felis chaus Guldenstaedt, Jungle cat, Kattu poocha; and Cuon alpinns Pallas, Indian wild dog, chennai are seen in interior and foot hilts of the Western ghats in north Kerala. Kattadu is commonly found on the slapes of the Kundaha, the hills surrounding the Attappadi valley and in the sides of the Palghat gap.

Among the Squirrels Ratufu indica Erxluben, Indian Giant squirrels or Malabar squirrels, Annan are generally found in north Kerala. Other types in Kerala include Ratufa macronra Penuant, Grizzlad, Indian squirrel and Funambulus suflineatus Waterhouse, Dusky stripped squirrel. Cervus nuicolor Keer, sambar, Kalaman is the largest of the deer tribe. Axis axis Erxleben, chital, Pulliman is abundant especially in the Nilambur forests. Tragulus meminna Erxleben, Mouse-deer, Kezhaman is widely distributed.

Among the lesser denizens of the jungles monkeys and lemurs are well represented in the Ghat forests. Presbytis johni Fischer, Nilgiri langur, Karin Kurangu: Macaca radiata Geoffroy, Macaque, Vella kurangu, and Loris malabaricus Wroughton, slender Loris, Kuthitevangu are common in the forests. Canis anrens Linnaens, Jackal, Kurukan is a familiar animal rearing over hilly scrubs and low country. Herpestes edwardsi Geoffrey, Indian Grey Mangoose, Kiri is the commonest mangoose found all over the forests and foot hills.

A number of varieties of birds are seen throughout Kerala, and some of them commonly found include Pavo cristatus Linnacus, common Peafowl, Myle; Psittacula cyanocephala Linuacus, Parakeet, Thatta; Gracula religiosa Linnacus, Hill¬Myna, Kattu Myna; Acidotheres tristis Linnaeus, common Myna, Myna; Motacilla maderaspalensis Linnaceus, wood packer, Maramkotthi; Athena brama Temminck, Spotted owlet, Munga; Milvus migraus Boddaert, Pariahkite, Parunthu; Corvus splendeus vieillot, Hougecrow, kakka: Corvus macrorhynchos Wagler, Jungle-crow, Bali-kakka; hrcruius mrrcrocercus Vieillot, king crow, kakka keel, Eudyr,cn,is scolopaceus Linnaeus, Keel; Centropus sineusis Stepheus, Coucal, Uppan; and Motacilla maderaspalensis Gamelin, Waglail, Kokku.

Kerala is rich in fresh water and marine-water fishes. The rivers and back-waters are full of various types of fresh-water fishes. The long coast line of Kerala is a source of different kinds of marine fishes. The people in Kerala generally use varieties of marine and fresh-water fishes. Some of the commonly used fresh water fishes include Etroplus suratensis Bloch, Chromides, karimeen; Ophicephalus marulius Ham, Murrels, Bral; Etropliis maculatus cuv & val, chromides, Pallathi; Alacrone seenghala sykes, cat-fis i, Karatta; Arius dussun2ieri cuv and Val, cat-fish Thedu;--Wallago attu Bleeker. Cat-fish, Attu-vala; D7ugil carinatus cuv & val, Mugil Junna: Mugil belarzak Bleeker, Mugil, Mala; and Mugil cephalus Linn, Mugil, Tirutha.

The marine fishes which are generally used by the people are Thynnus thunnina cuv & val, Tunny-fish, Ayila; Pseudo¬sciaena Coitor Ham, Jewfishes, kora; Engraulis indicus V. Hassett, Clupea, Netholi, Chirocentrus dorab Forsk, Clupea, Muliuva!a; Clupea ilish Ham, Clupea, Paluva; Dussumieria acuta Cuv & val, clupea, chala; Sardinella longiceps cuv & cal, clupca, Nallamathi; Carcharias gangetious Blyth, Shask, Sravu; Late,; Calcarifer Gunther, Sea perches, chempalli; Lactarius deticatulus cuv & val, white fish, Parava; stromateoides cine¬reus Bleeker, Silver promfret Avoli; Sillago sihama Ripp. Sandwhitmg, Mural; Dorosoma nasus Bleeker. Clupea Noonah; and Trygon zugei Mull & Heule, whip Rays, Threndi etc.

Flora and Fauna of Kerala

Most of Kerala, whose native habitat consists of wet evergreen rain forests at lower elevations and highland deciduous and semi-evergreen forests in the east, is subject to a humid tropical climate. However, significant variations in terrain and elevation have resulted in a land whose biodiversity registers as among the world’s most significant.

Most of Kerala's significantly bio-diverse tracts of wilderness lie in the evergreen forests of its easternmost districts; coastal Kerala (along with portions of the east) mostly lies under cultivation and is home to comparatively little wildlife. Despite this, Kerala contains 9,400 km² of natural forests. Out of the approximately 7,500 km² of non-plantation forest cover, there are wild regions of tropical wet evergreen and semi-evergreen forests (lower and middle elevations — 3,470 km²), tropical moist and dry deciduous forests (mid-elevations — 4,100 km² and 100 km², respectively), and montane subtropical and temperate forests (highest elevations — 100 km²). Such forests together cover 24% of Kerala's landmass.

Kerala also hosts two of the world’s Ramsar Convention-listed wetlands: Lake Sasthamkotta and the Vembanad-Kol wetlands are noted as being wetlands of international importance. There are also numerous protected conservation areas, including 1455.4 km² of the vast Nilgiri Biosphere Reserve.

Eastern Kerala’s windward mountains shelter tropical moist forests and tropical dry forests which are generally characteristic of the wider Western Ghats: crowns of giant sonokeling -Indian rosewood, Aanjili (Artocarpus hirsuta), mullumurikku (Erythrina), Cassia, and other trees dominate the canopies of large tracts of virgin forest. Overall, Kerala's forests are home to more than 1,000 species or trees. Smaller flora includes bamboo, wild black pepper, wild cardamom, the calamus rattan palm, and aromatic Vetiver grass.

In turn, the forests play host to such major fauna as Asian Elephant, Bengal Tiger Leopard and Nilgiri Tahr, and Grizzled Giant Squirrel. More remote preserves, including Silent Valley National Park in the Kundali Hills, harbor endangered species such as Lion-tailed , Indian Sloth Bear and Gaur. More common species include Indian Porcupine, Chital, Sambar, Gray Langur, Flying Squirrel, Swamp Lynx, Boar, a variety of catarrhine Old World monkey species, Gray Wolf, Common Palm Cive.

Many reptiles, such as king cobra, viper, python, various turtles and crocodiles are to be found in Kerala — again, disproportionately in the east. Kerala's avifauna include endemics like the Sri Lanka Frogmouth, Oriental Bay Owl, large frugivores like the Great Hornbill and Indian Grey Hornbill, as well as the more widespread birds such as Peafowl, Indian Cormorant, Jungle and Hill Myna, Oriental Darter, Black-hooded Oriole, Greater Racket-tailed and Black Drongoes, Bulbul, species of Kingfisher and Woodpecker, Jungle Fowl, Alexandrine Parakeet, and assorted ducks and migratory birds. Additionally, freshwater fish such as kadu (stinging catfish) and brackishwater species such as Choottachi (orange chromide - valued as an aquarium specimen) also are native to Kerala's lakes and waterways.

Birds in Kerala

Main birds seen in the sanctuaries of Kerela are :
Water fowl, Cuckoo, Owl, Egret, Heron, Water duck, Migratory Siberian Duck, Jungle fowls, Mynas, Laughing thrushes, Black bulbuls, Peafowls, Woodpeckers, Kingfishers, The hornbill, Stork, Raptor, Darter, Cormorant, Grackle, Cluster, Indian rollers, Common snipes, Crow pheasants, Jungle nightjars, Kites, Grey drongos, Malabar trogons, Llarge pied wagtails, Baya sparrows, Grey jungle fowls, Indian hill mynas, Robins, Jungle babblers, Sunbirds, Peacocks, Crimson-throated barbets, Bee-eaters, Shrikes, Fairy bluebirds, Grey-headed fishing eagles, Black winged kites, Night herons, Grey hornbills, Malabar hornbills and more than 253 additional species including migrant birds..

Main flora in the sanctuaries of Kerela are Teak, maruthu, karimaruthi, rosewood, venteak, vengal, chadachi, mazhukanjiram, bamboo, neem, nanjanathi, sandal, dendrocalamus, marythu, vaka, mulluvenka. elavu,manjakadambu pala, vembu, aval etc... and over 1800 flowering plants including 171 grass species, 143 species of orchids etc...

Birds in Kerala

Main birds seen in the sanctuaries of Kerela are :

Water fowl, Cuckoo, Owl, Egret, Heron, Water duck, Migratory Siberian Duck, Jungle fowls, Mynas, Laughing thrushes, Black bulbuls, Peafowls, Woodpeckers, Kingfishers, The hornbill, Stork, Raptor, Darter, Cormorant, Grackle, Cluster, Indian rollers, Common snipes, Crow pheasants, Jungle nightjars, Kites, Grey drongos, Malabar trogons, Llarge pied wagtails, Baya sparrows, Grey jungle fowls, Indian hill mynas, Robins, Jungle babblers, Sunbirds, Peacocks, Crimson-throated barbets, Bee-eaters, Shrikes, Fairy bluebirds, Grey-headed fishing eagles, Black winged kites, Night herons, Grey hornbills, Malabar hornbills and more than 253 additional species including migrant birds..

Main flora in the sanctuaries of Kerela are Teak, maruthu, karimaruthi, rosewood, venteak, vengal, chadachi, mazhukanjiram, bamboo, neem, nanjanathi, sandal, dendrocalamus, marythu, vaka, mulluvenka. elavu,manjakadambu pala, vembu, aval etc... and over 1800 flowering plants including 171 grass species, 143 species of orchids etc...