The Western Ghats or Sahyādri 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 Tapti River, and runs approximately 1600 km through the states of Maharashtra, Goa, Karnataka, Tamil Nadu and Kerala ending at Kanyakumari. These hills cover 160,000 km² (roughly 6% of India’s total geographical area) and form the catchment area for complex riverine drainage systems that drain almost 40% of India. The average elevation is around 1,200-1300 metres. Western Ghats are home to 30% of flora and fauna species found in India.
States and Union Territories under Western Ghats
Western Ghats are spread in six states viz. Gujarat, Maharashtra, Goa, Karnataka, Tamil Nadu, Kerala and two Union Territories viz. Dadra & Nagar Haveli and Pondicherry. The range starts near the border of Gujarat south of Tapti river where foothills of the ranges are occupying the eastern portion of Dadra and Silvassa in D&N. Running around 1600 kilometers down south, it ends at its southern part at Anamudi peak in Kerala. Mahe in Pondicherry is situated on the Malabar coast on the Western Ghats surrounded by Kerala
Western Ghats are known as Sahyadri in northern Maharashtra, Sahya Parvatam in Kerala and Nilagiri Malai in Tamil Nadu. Western Ghats are home to many hill stations like Matheran, Lonavala-Khandala, Mahabaleshwar, Panchgani, Amboli Ghat, Kudremukh and Kodagu.
The extreme northern parts of Western Ghats falls in the Dangs district of Gujarat, known for Dang (Bamboo) forests. The confluence of the Eastern and the Western Ghats is at Biligirirangan Hills in Karnataka. Anamudi 2,695 metres in Kerala the highest peak in Western Ghats. Mullayanagiri is the highest peak in Karnataka 1,950 meters. The smaller ranges of the Western Ghats include the Cardamom Hills and the Nilgiri Hills. Cardamom hills are located in southeast Kerala and southwest Tamil Nadu. They conjoin the Anaimalai Hills to the northwest, the Palni Hills to the northeast and the Agasthyamalai Hills to the south as far as the Ariankavu pass. The crest of the hills forms the boundary between Kerala and Tamil Nadu. Anamudi is also located in Cardamom Hills. The Nilgiri Hills are home to the hill station Ooty.
There are many important passes in Western Ghats such as Tamhini Ghat, Palakkad Gap, Naneghat, Kasara ghat etc.
The northern portion of the narrow coastal plain between the Western Ghats and the Arabian Sea is known as the Konkan Coast, 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 the central Karnataka state is known as Malenadu.
There are two views regarding the Geology of the Western Ghats. One view says the mountains of the Western Ghats are Block Mountains formed due to the down warping of a part of land into the Arabian Sea. Other view says that the mountains of the Western Ghats are not true mountains, but are the faulted edge of the Deccan Plateau. Major rocks found in the region include Basalt, charnockites, granite gneiss, khondalites, leptynites, metamorphic gneisses with detached occurrences of crystalline limestone, iron ore, dolerites and anorthosites.
The rivers that originate in Western Ghats and flow towards west are Periyar, Bharathappuzha, Netravati, Sharavathi, Mandovi etc. The west flowing rivers of Western Ghats are fast-moving, owing to the short distance travelled and steeper gradient. This makes Western Ghats more useful than Eastern Ghats in terms of production of hydroelectricity. The steep gradient makes the Jog Falls on Shravasthi River in Karnataka as one of the most spectacular waterfalls in India. Narmada and Tapti although don’t rise from Western Ghats but flow westwards.
The rivers that originate in Western Ghats and flow towards east include three major rivers viz. Godavari, Krishna and Kaveri, and many smaller / tributary rivers such as Tunga, Bhadra, Bhima, Malaprabha, Ghataprabha, Hemavathi, Kabini. These east flowing rivers are comparatively slower moving and eventually merge into larger rivers such as the Kaveri and Krishna.
In comparison to the eastern side, the western side of the Western Ghats is area of high rainfall because the mountains intercept the rain-bearing westerly monsoon winds. The dense forests also contribute to high orographic precipitation. The climate is humid and tropical in the lower reaches tempered by the proximity to the sea. Elevations of 1,500 m and above in the north and 2,000 m and above in the south have a more temperate climate. Average annual temperature here is around 15 °C. In some parts frost is common, and temperatures touch the freezing point during the winter months. Mean temperature range from 20 °C in the south to 24 °C in the north. It has also been observed that the coldest periods in the south Western Ghats coincide with the wettest.
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. The eastern region of the Western Ghats which lie in the rain shadow, receive far less rainfall averaging about 1,000 mm bringing the average rainfall figure to 2,500 mm.
Due to a sharp contrast in precipitation between western and eastern slopes of the Western Ghats, there is a clear difference between the vegetation of the two sides. Similarly, there is also a clear contrast between the northern and southern Western Ghats. Moreover, the vegetation found on the high hills is also different from the low hills. Thus, there are various different kinds of vegetations found in Western Ghats as follows:
- The western slopes have tropical and subtropical moist broadleaf forests marked predominantly by Rosewood, Mahogany, Cedar etc. These slopes appear green in almost all parts of the year. No time is fixed when these trees would shade their leaves.
- The eastern slopes of the Western Ghats have dry as well as moist deciduous forests marked predominantly by Teak, Sal, Shisham, Sandalwood etc. trees.
- Further, on the northern side of the Wayanad forests; we find dry deciduous forests while on the southern side there are wet deciduous forests. 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. South Western Ghats Montane rain forests are the most species-rich ecoregions in peninsular India. Eighty percent of the flowering plant species of the entire Western Ghats range are found in this ecoregion.
- The areas which are high in elevation are cooler and wetter in the north and so the forests there are called North Western Ghats Montane rain forests. The vegetation here is evergreen characterized by trees of family Lauraceae. Such plants include Litsea glutinosa or Maida lakri in Hindi (a plant of medicinal value), Cinnamomum (Tejpatta) etc.
- There are montane grasslands as well as stunted forests also in the Western Ghats.
- The forest in the Western Ghats has been severely affected 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. The area is ecologically sensitive to development. 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.
Western Ghats is home to India’s two biosphere reserves, 13 National parks, several wildlife sanctuaries and many Reserve Forests. 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. The Silent Valley National Park in Kerala is among the last tracts of virgin tropical evergreen forest in India.
There are two biodiversity hotspots in our country viz. Eastern Himalayas and Western Ghats. Western Ghats are home to over 5000 species of flowering plants, 139 mammal species, 508 bird species and 179 amphibian species, many undiscovered species lives.
Following four species are endemic to Western Ghats.
- Malabar Large-spotted Civet
- Lion-tailed Macaque
- Brown Palm Civet
- Nilgiri Tahr
Malabar Large-spotted Civet is a critically endangered nocturnal mammal. The Lion-tailed Macaque is endangered and is arboreal (lives on trees). Only 2500 members of this species are remaining. The largest population of Lion Tailed Macaque is in Silent Valley National Park. Kudremukh National Park also protects a viable population. Nilgiri tahr is a goat antelope found high up in the mountains of southern India, it is known locally as the ‘Nilgiri ibex’. Its largest population is found within the Eravikulam National Park. Outside breeding seasons, males are found lower down in the best grazing fields, whilst female herds are found on the exposed cliff ledges. It has been classified as Endangered (EN) on the IUCN Red List. The brown palm civet’s distribution extends from the southern tip of Western Ghats in Kalakkad Mundanthurai Tiger Reserve to Castle Rock in Goa to the north. They are nocturnal, and not as rare as previously thought and come under Least Concerned Category.
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.