Western Ghats

Western Ghats (Sahyadri)
Sahya mountains
Range
The Western Ghats at Matheran near Mumbai
Country	India
States	Gujarat, Maharashtra, Goa, Karnataka, Kerala, Tamil Nadu
Cities	Ootacamund, Mahabaleshwar
Highest point	Anamudi
- location	Eravikulam, Idukki, South India, Kerala, India
- elevation	2,695 m (8,842 ft)
Lowest point	Palakkad Gap
- location	Palakkad, Palakkad district, South India, Kerala, India
- elevation	300 m (984 ft)
Length	1,600 km (994 mi), N–S
Width	100 km (62 mi), E–W
Area	60,000 km² (23,166 sq mi)
Biome	forests (30%)
Geology	Basalt, Laterite
Period	Cenozoic
The Western Ghats lie parallel to the west coast of India

The Western Ghats (Kannada ಸಹ್ಯಾದ್ರಿ, Marathi / Konkani- सह्याद्री Sahyadri, Malayalam പശ്ചിമഘട്ടം (സഹ്യപര്‍വ്വതം), Tamil மேற்கு தொடர்ச்சி மலை) also known as the Sahyadri mountains, 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 range starts near the border of Gujarat and Maharashtra, south of the River Tapti, and runs approximately 1600 km through the states of Maharashtra, Goa, Karnataka, Tamil Nadu and Kerala ending at Kanyakumari, at the southern tip of India. About sixty percent of the Western Ghats are located in the state of Karnataka.^[1]

These hills cover 60,000 km² and form the catchment area for a complex of river systems that drain almost 40% of India.^[2] The average elevation is around 1,200 meters.^[3] The area is one of the world’s ten "Hottest biodiversity hotspots" and has over 5000 species of flowering plants, 139 mammal species, 508 bird species and 179 amphibian species. At least 325 globally threatened species occur in the Western Ghats.^[4]

Geology

The Western Ghats are not true mountains, but are the faulted edge of the Deccan Plateau. They are believed to have been formed during the break-up of the super continent of Gondwana some 150 million years ago. Geo-physicists Barren and Harrison from the University of Miami advocate the theory that the west coast of India came into being somewhere around 100 to 80 mya after it broke away from Madagascar. After the break-up, the western coast of India would have appeared as an abrupt cliff some 1,000 metres in height. Soon after its detachment, the peninsular region of the Indian plate drifted over the Réunion hotspot, a volcanic hotspot in the earth's lithosphere near the present day location of Réunion. A huge eruption here some 65 mya is thought to have laid down the Deccan Traps, a vast bed of basalt lava that covers parts of central India. These volcanic upthrusts led to the formation of the northern third of the Western Ghats. Since these uplifts are dome-shaped in nature, the underlying rock is ancient, dating back 200 mya, and can be observed in some parts such as the Nilgiri Hills. Basalt is the predominant rock found in the hills reaching a depth of 3 km (2 mi). Other rock types found are charnockites, granite gneiss, khondalites, leptynites, metamorphic gneisses with detached occurrences of crystalline limestone, iron ore, dolerites and anorthosites. Residual laterite and bauxite ores are also found in the southern hills.

Mountains

The Western Ghats extend from the Satpura Range in the north, go south past Goa, through Karnataka and into Kerala and Tamil Nadu. The major hill range starting from the north is the Sahyadhri (the benevolent mountains) range. This range is home to many hill stations like Matheran,Lonavala-Khandala, Mahabaleshwar, Panchgani,Amboli Ghat,Kudremukh and Kodagu. The range is called Sahyadri in northern Maharashtra and Sahya Parvatam in Kerala. The Biligirirangans southeast of Mysore in Karnataka, meet the Shevaroys (Servarayan range) and Tirumala range farther east, linking the Western Ghats to the Eastern Ghats. In the south the range is known as the Nilagiri malai in Tamil Nadu.

Smaller ranges, including the Cardamom Hills and the Nilgiri Hills, are in northwestern Tamil Nadu. Nilgiri Hills is home to the hill station Ootacamund. In the southern part of the range in the Anaimalai Hills, in western Tamil Nadu and Kerala, Ana Mudi 2,695 metres (8,842 ft) is the highest peak in India, south of the Himalayas. Chembra Peak 2,100 metres (6,890 ft), Banasura Peak 2,073 metres (6,801 ft), Vellarimala 2,200 metres (7,218 ft) and Agasthya mala 1,868 metres (6,129 ft) are also in Kerala. Doddabetta is 2,623 metres (8,606 ft). Mullayanagiri is the highest peak in Karnataka 1,950 metres (6,398 ft). The Western Ghats in Kerala is home to many tea and coffee plantations. The major gaps in the range are the Goa Gap, between the Maharashtra and Karnataka sections, and the Palghat Gap on the Tamil Nadu/Kerala border between the Nilgiri Hills and the Anaimalai Hills.

The northern portion of the narrow coastal plain between the Western Ghats and the Arabian Sea is known as the Konkan Coast or simply Konkan,the central portion is called Kanara and the southern portion is called Malabar region or the Malabar Coast. The foothill region east of the Ghats in Maharashtra is known as Desh, while the eastern foothills of central Karnataka state is known as the Malnad region. The largest city within the mountains is the city of Pune (Poona), in the Desh region on the eastern edge of the range. The Biligirirangan Hills lies at the confluence of the Western and Eastern Ghats.

The mountains intercept the rain-bearing westerly monsoon winds, and are consequently an area of high rainfall, particularly on their western side. The dense forests also contribute to the precipitation of the area by acting as a substrate for condensation of moist rising orographic winds from the sea, and releasing much of the moisture back into the air via transpiration, allowing it to later condense and fall again as rain.

Peaks

Salher, Kalsubai, Mahableshwar, Sonsogor (Goa), Kemmangundi (Karnataka), Mullayanagiri, Kudremukh, Dodda Betta Tamil Nadu, Anai Mudi and Mahendragiri

Lakes and reservoirs

The Western Ghats have several lakes and reservoirs. The most important natural lakes are the Ooty (2500 m altitude, 34.0 ha) in Nilgiris, and the Kodai Kanal (Kodaikanal) (2285 m, 26 ha) and the Berijam in the Palni Hills. All lakes are situated in the state of Tamil Nadu. Two smaller lakes, the Divicolam (6.0 ha) and the Letchmi Elephant (2.0 ha) are in the Munnar High Range, and Lake Yercaud (1340 m, 8 ha) in Shevaroy Hills.

The majority of streams draining the Western Ghats and joining the Rivers Krishna and Cauvery carry water during monsoon months only and have been dammed for hydroelectric and irrigation purposes. The major reservoirs are: Lonavla and Walwahn in Maharashtra; V.V. Sagar, K.R. Sagar and Tungabhadra in the Malnad area of Karnataka; Mettur, Upper Bhawani, Mukurti, Parson's Valley, Porthumund, Avalanche, Emarold, Pykara, Sandynulla and Glenmorgan in Tamil Nadu; and Kundallay and Maddupatty in the High Range of Kerala. Of these the Lonavla, Walwahn, Upper Bhawani, Mukurti, Parson's Valley, Porthumund, Avalanche, Emarold, Pykara, Sandynulla, Glenmorgan, Kundally and Madupatty are important for their commercial and sport fisheries for trout, mahseer and common carp.^[5]

Rivers

The Jog Falls in Karnataka is one of the most spectacular waterfalls in India.

The Western Ghats form one of the three watershed of India, feeding the perennial rivers of India. Important rivers include the Tambaraparani River, Godavari, Krishna, and Kaveri. These rivers flow to the east and drain out into the Bay of Bengal. The west flowing rivers, that drain into the Arabian Sea, are fast-moving, owing to the short distance travelled and steeper gradient. Important rivers include the Mandovi and Zuari. Many of these rivers feed the backwaters of Kerala and Maharashtra. Rivers that flow eastwards of the Ghats drain into the Bay of Bengal. These are comparatively slower moving and eventually merge into larger rivers such as the Kaveri and Krishna. Smaller rivers include the Chittar River, Bhima River, Malaprabha River, Manimuthar River, Kabini River, Kallayi River, Kundali River, Pachaiyar River,Pennar River,Periyar,Kallayi River

Fast running rivers and steep slopes have provided sites for many large hydro-electric projects. There are about major 50 dams along the length of the Western Ghats with the earliest project up in 1900 near Khopoli in Maharashtra.^[6] Most notable of these projects are the Koyna Dam in Maharashtra, the Parambikulam Dam in Kerala, and the Linganmakki Dam in Karnataka. The reservoir behind the Koyna Dam, the Shivajisagar Lake, is one of the largest reservoirs in India with a length of 50 km (31 mi) and depth of 80 m (262 ft).^[7]

During the monsoon season, numerous streams fed by incessant rain drain off the mountain sides leading to numerous and often spectacular waterfalls. Among the most well known is the Jog Falls, Kunchikal Falls, Sivasamudram Falls, and Unchalli Falls. The Jog Falls is the highest natural waterfall in South Asia and is listed among the 1001 natural wonders of the world.^[8] Talakaveri wildlife sanctuary is a critical watershed and the source of the river Kaveri. This region has dense evergreen and semi-evergreen vegetation, with shola-grassland in areas of higher elevation. The steep terrain of the area has resulted in scenic waterfalls along its many mountain streams. Sharavathi and Someshvara Wildlife sanctuaries in Shimoga district are the source of the Tungabhadra River system.

Climate

Annual rainfall along the Western Ghat region.

Climate in the Western Ghats varies with altitudinal gradation and distance from the equator. The climate is humid and tropical in the lower reaches tempered by the proximity to the sea. Elevations of 1,500 m (4,921 ft) and above in the north and 2,000 m (6,562 ft) and above in the south have a more temperate climate. Average annual temperature here are around 15 °C (60 °F). In some parts frost is common, and temperatures touch the freezing point during the winter months. Mean temperature range from 20 °C (68 °F) in the south to 24 °C (75 °F) in the north. It has also been observed that the coldest periods coincide with the wettest.^[9]

During the monsoon season between June and September, the unbroken Western Ghats chain acts as a barrier to the moisture laden clouds. The heavy, eastward-moving rain-bearing clouds are forced to rise and in the process deposit most of their rain on the windward side. Rainfall in this region averages 3,000–4,000 mm (120–160 in) with localised extremes touching 9,000 mm (350 in). The eastern region of the Western Ghats which lie in the rain shadow, receive far less rainfall averaging about 1,000 mm (40 in) bringing the average rainfall figure to 2,500 mm (150 in). Data from rainfall figures reveal that there is no relationship between the total amount of rain received and the spread of the area. Areas to the north in Maharashtra receive the heaviest rainfall, but are followed by long dry spells, while regions closer to the equator receive less annual rainfall, with rain spells lasting almost the entire year.^[9]

Ecoregions

Nilgiri Hills (Tectona grandis) and dipterocarps.

Western Ghats near Rajapalayam

The Western Ghats are home to four tropical and subtropical moist broadleaf forest ecoregions – the North Western Ghats moist deciduous forests, North Western Ghats montane rain forests, South Western Ghats moist deciduous forests, and South Western Ghats montane rain forests.

The northern portion of the range is generally drier than the southern portion, and at lower elevations makes up the North Western Ghats moist deciduous forests ecoregion, with mostly deciduous forests made up predominantly of teak. Above 1,000 meters elevation are the cooler and wetter North Western Ghats montane rain forests, whose evergreen forests are characterized by trees of family Lauraceae.

The evergreen Wayanad forests of Kerala mark the transition zone between the northern and southern ecoregions of the Western Ghats. The southern ecoregions are generally wetter and more species-rich. At lower elevations are the South Western Ghats moist deciduous forests, with Cullenia the characteristic tree genus, accompanied by teak, dipterocarps, and other trees. The moist forests transition to the drier South Deccan Plateau dry deciduous forests, which lie in its rain shadow to the east.

Above 1,000 meters are the South Western Ghats montane rain forests, also cooler and wetter than the surrounding lowland forests, and dominated by evergreen trees, although some montane grasslands and stunted forests can be found at the highest elevations. The South Western Ghats montane rain forests are the most species-rich ecoregion in peninsular India; eighty percent of the flowering plant species of the entire Western Ghats range are found in this ecoregion.

Biome Protection

A view from Ponmudi hills, Trivandrum under Agasthyamalai Biosphere Reserve

Historically the Western Ghats were well-covered in dense forests that provided wild foods and natural habitats for native tribal people. Its inaccessibility made it difficult for people from the plains to cultivate the land and build settlements. After the arrival of the British in the area, large swathes of territory were cleared for agricultural plantations and timber. The forest in the Western Ghats has been severely fragmented due to human activities, especially clear felling for tea, coffee, and teak plantations during 1860 to 1950. Species that are rare, endemic and habitat specialists are more adversely affected and tend to be lost faster than other species. Complex and species rich habitats like the tropical rainforest are much more adversely affected than other habitats. ^[10]

The area is ecologically sensitive to development and was declared an ecological hotspot in 1988 through the efforts of ecologist Norman Myers. Though this area covers barely five percent of India's land, 27% of all species of higher plants in India (4,000 of 15,000 species) are found here. Almost 1,800 of these are endemic to the region. The range is home to at least 84 amphibian species, 16 bird species, seven mammals, and 1,600 flowering plants which are not found elsewhere in the world.

The Government of India established many protected areas including 2 biosphere reserves, 13 National parks to restrict human access, several wildlife sanctuaries to protect specific endangered species and many Reserve Forests, which are all managed by the forest departments of their respective state to preserve some of the ecoregions still undeveloped. Many National Parks were initially Wildlife Sanctuaries. The Nilgiri Biosphere Reserve comprising 5500 km² of the evergreen forests of Nagarahole, deciduous forests of Bandipur National Park and Nugu in Karnataka and adjoining regions of Wayanad and Mudumalai National Park in the states of Kerala and Tamil Nadu forms the largest contiguous protected area in the Western Ghats.^[11] The Western Ghats in Kerala is home to numerous serene hill stations like Munnar, Ponmudi and Waynad. The Silent Valley National Park in Kerala is among the last tracts of virgin tropical evergreen forest in India.^[12]

World Heritage Site

View of the Western Ghats at Keeriparai, Kanyakumari District, near the southern end of the range

In 2006, India applied to the UNESCO MAB for the Western Ghats to be listed as a protected World Heritage Site.^[13] This will be composed of 7 adjoining areas:

1. Agasthyamalai Sub-Cluster (with Five Site Elements) including: The Agasthyamalai Biosphere Reserve 900 km², includes Kalakkad Mundanthurai Tiger Reserve 806 km², in Tamilnadu and Neyyar,^[14] Peppara^[15] and Shendurney^[16] Wildlife Sanctuaries and their adjoining areas of Achencoil,^[17] Thenmala, Konni,^[18] Punalur, Thiruvananthapuram Divisions and Agasthyavanam Special Division in Kerala.^[19]
2. Periyar Sub-Cluster (with Six Site Elements) including: Periyar National Park and nature reserve 777 km², in Kerala, Ranni, Konni and Achankovil Forest Divisions. On the eastern side, lying largely in a rain-shadow area with mostly drier forests, lie the Srivilliputtur Wildlife Sanctuary and reserved forests of the Tirunelveli Forest Division.
3. Anamalai Sub-Cluster (with Seven Site Elements) including: Chinnar Wildlife Sanctuary, Eravikulam National Park 90 km², Indira Gandhi National Park, Grass Hills National Park and Karian Shola National Park are located within the larger Indira Gandhi Wildlife Sanctuary 958 km², and Palani Hills National Park 736.87 km² (PRO) in Tamilnadu and Parambikulam Wildlife Sanctuary 285 km² in Kerala.
4. Nilgiri Sub-Cluster (with Six Site Elements) including: The Nilgiri Biosphere Reserve with Karimpuzha National Park 230 km² (PRO), Silent Valley National Park 89.52 km² and Wayanad Wildlife Sanctuary 344 km² in Kerala, Bandipur National Park 874 km², Mukurthi National Park 78.46 km²,Mudumalai National Park 321 km², New Amarambalam Reserved Forest in Tamilnadu. This sub-cluster constitutes a largely secure forest complex of over 6,000 km², which is one of the most globally significant conservation areas for highly threatened species such as the Asian elephant, tiger and gaur, besides dozens of endangered species in other taxa.
5. Talacauvery Sub-Cluster (with Six Site Elements) including:Brahmagiri Wildlife Sanctuary 181.29 km², Rajiv Gandhi (Nagarhole National Park) 321 km², Pushpagiri Wildlife Sanctuary 92.65 km², Talacauvery Wildlife Sanctuary (105.01 km²) in karnataka and Aralam Reserved Forest in Kerala.
6. Kudremukh Sub-Cluster (with Five Site Elements) including: Kudremukh National Park 600.32 km², Someshwara Wildlife Sanctuary and surrounding Reserved Forests of Someshwara, Agumbe and Balahalli in karnataka.
7. Sahyadri Sub-Cluster (with Four Site Elements) including: Anshi National Park 340 km², Chandoli National Park 317.67 km², Koyna Wildlife Sanctuary and Radhanagri Wildlife Sanctuary in Maharashtra.

Fauna

The Western Ghats are home to thousands of animal species including at least 325 globally threatened species. Many are endemic species, especially in the amphibian and reptilian classes.

• Mammals- There are at least 139 mammal species. A critically endangered mammal of the Western Ghats is the nocturnal Malabar Large-spotted Civet. The arboreal Lion-tailed Macaque is endangered. Only 2500 of this species are remaining.^[20] The largest population of Lion tailed macacque is in Silent Valley National Park. Kudremukh National Park also protects a viable population.^[21]

These hill ranges serve as important wildlife corridors, allowing seasonal migration of endangered Asian Elephants. The Nilgiri Bio-sphere is home to the largest population of Asian Elephants and forms an important Project Elephant and Project Tiger reserve. Brahmagiri and Pushpagiri wildlife sanctuaries are important elephant habitats. Karnataka's Ghat areas hold over six thousand elephants (as of 2004) and ten percent of India's critically endangered tiger population.^[22]

The largest population of India's Tigers outside the Sundarbans is in the unbroken forests bordering Karnataka, Tamil Nadu and Kerala. The largest numbers and herds of vulnerable Gaur are found here with the Bandipur National Park and Nagarahole together holding over five thousand Gaur.^[23] To the west the forests of Kodagu hold sizeable populations of the endangered Nilgiri Langur. Bhadra Wildlife Sanctuary and project tiger reserve in Chikmagalur has large populations of Indian muntjac. Many Asian Elephant, Gaur, Sambar, vulnerable Sloth Bears, Leopard, tiger and Wild Boars dwell in the forests of Kerala.

Bannerghatta National Park and Annekal reserve forest is an important elephant corridor connecting the forests of Tamil Nadu with those of Karnataka. Dandeli and Anshi national parks in Uttara Kannada district are home to the Black Panther and normal variety of leopards and significant populations of Great Indian Hornbill. Bhimgad in Belgaum district is a proposed wildlife sanctuary and is home to the endemic critically endangered Wroughton's freetailed bat. the Krishnapur caves close by are one of only three places in the country where the little-known Theobald's tomb bat is found. Large Lesser False Vampire bats are found in the Talevadi caves.^[24]

• Reptiles- The snake family Uropeltidae of the reptile class is almost entirely restricted to this region.
• Amphibians- The amphibians of the Western Ghats are diverse and unique, with more than 80% of the 179 amphibian species being endemic to the region. Most of the endemic species have their distribution in the rainforests of these mountains.^[25] The endangered Purple frog was discovered in 2003 to be a living fossil. This species of frog is most closely related to species found in the Seychelles. Four new species of Anurans belonging to the genus Rhacophorus, Polypedates, Philautus and Bufo have been described from the Western Ghats. ^[26]
• Fish- 102 species of fish are listed for the Western Ghats water bodies.^[5] Western Ghats streams are home to several brilliantly coloured ornamental fishes like Red line torpedo barb, Red-tailed barb,^[27] Osteobrama bakeri, Günther's catfish and freshwater puffer fish Tetraodon travancoricus, Carinotetraodon imitator and marine forms like Chelonodon patoca (Buchanan-Hamilton,1822);^[28] mahseers such as Malabar mahseer^[29]
• Birds- There are at least 508 bird species. Most of Karnataka's five hundred species of birds [14] are from the Western Ghats region.^[30] Bhadra Wildlife Sanctuary is located at the northern end of the Malabar ranges and the southern tip of the Sahyadri ranges and bird species from both ranges can be seen here.
• Insects- There are roughly 6,000 insect species from Kerala alone.^[31] Of 334 butterfly species recorded from the Western Ghats, 316 species have been reported from the Nilgiri Biosphere Reserve.^[32]
• Molluscs- Seasonal rainfall patterns of the Western Ghats necessitate a period of dormancy for its land snails, resulting in their high abundance and diversity including at least 258 species of gastropods from 57 genera and 24 families.^[33]

Munnar tea gardens.

Notes

References

External links

• Pictures and Images of Sahyadri nature
• Squirrels of the Western Ghats
• Sahyadri forts, old temples & caves
• Pictures and stories on Western Ghats
• Western Ghats travel guide from Wikitravel
• Rivers of Western Ghats
• Pictures of Sahyadri
• Photographs of forts and other in Sahyadri
• Unique tool to share pictures of forts, other prominent places, birds, flowers in Sahyadri
• Sahyadris Gallery
• Western Ghats - Rain forests of India, Video: 4:39

Subfields of physical geography Biogeography · Climatology / Paleoclimatology · Coastal geography · Geomorphology · Glaciology · Hydrology / Hydrography · Landscape ecology · Limnology · Oceanography · Palaeogeography · Pedology · Quaternary science