Western Ghats

Also called: Sahyadri · Topic: Structure and Physiography of India: Himalayas, Plains, Peninsula, Coasts and Islands · NCERT: Class 7, Ch 1 "Geographical Diversity of India"; Class 7, Ch 3 "Climates of India"; Class 11, Ch 2 "Structure and Physiography"; Class 11, Ch 3 "Drainage System"; Class 11, Ch 4 "Climate"; Class 11, Ch 5 "Natural Vegetation"

Meaning

The Western Ghats (also called the Sahyadri) are a long, unbroken chain of steep hills along the western edge of the Peninsula, parallel to the Arabian Sea coast. They run for about 1,600 km through six states [2], average about 1,500 m in height, and get higher from north to south.

They matter because they divide the rivers of the Peninsula: most Peninsular rivers rise here and flow east. They also catch the south-west monsoon, so the slopes facing the wind get very heavy rain while the inner Deccan stays dry. They are a UNESCO World Heritage Site and part of a world biodiversity hotspot.

Explanation

Form and structure: a steep wall on the west, a gentle slope on the east

• The western edge of the Deccan Plateau: the Western Ghats form the western border of the Deccan. They rise as an escarpment (a steep, cliff-like slope) of about 1,000 m or more [5].
• They make one continuous wall. This is the main difference from the Eastern Ghats, which are low and broken into separate blocks.
• Height rises from north to south:
• The northern Sahyadri are lower.
• The southern blocks (Nilgiri, Anaimalai) are the highest.
• Anamudi (also spelled Anaimudi, 2,695 m) in the Anaimalai hills is the highest peak of the Peninsula, which means the highest in India south of the Himalayas.

• Dodabetta (2,637 m) in the Nilgiris is the second highest.

• Extent: about 1,600 km long, covering about 1,40,000 sq km across Gujarat, Maharashtra, Goa, Karnataka, Kerala and Tamil Nadu [2].

• Local names, north to south:

Local name	State(s)
Sahyadri	Maharashtra (also Goa and northern Karnataka)
Nilgiri hills	Karnataka, Tamil Nadu (and Kerala border)
Anaimalai hills	Kerala–Tamil Nadu
Cardamom hills	Kerala–Tamil Nadu
Agasthyamalai hills	southern tip, Kerala–Tamil Nadu

• Nilgiri hills, the meeting point: the Western Ghats and the Eastern Ghats meet at the Nilgiri hills, where Tamil Nadu, Karnataka and Kerala join.

Drainage: why the Ghats act as the Peninsula's water divide

• The Deccan tilts east:
• The plateau is highest along the Western Ghats and slopes gently down towards the Bay of Bengal.

• So the watershed (the line of high ground that divides rivers flowing to different seas) lies close to the west coast.

• The big rivers rise here and flow east to the Bay of Bengal:

• Godavari: rises at Trimbakeshwar (Nashik, Maharashtra).
• Krishna: rises near Mahabaleshwar (Maharashtra).

• Kaveri: rises at Talakaveri in the Brahmagiri hills (Kodagu, Karnataka).

• Short streams flow west:

• These are short, fast streams that rush down the steep western face into the Arabian Sea.
• In the rainy season they drop over the escarpment as monsoon waterfalls.

Climate: heavy rain on one side, rain shadow on the other

• Windward side gets heavy rain:
• The moist south-west monsoon wind blows in from the Arabian Sea and hits the Ghats.

• The wind is pushed up. Rising air cools, its water vapour condenses, and it rains heavily on the windward side (the side facing the wind): 250–400 cm.

• Leeward side stays dry:

• The air crosses the top of the range and comes down the eastern slope.
• Sinking air warms up and keeps its remaining moisture.

• The result is a rain shadow (a dry area on the side of a mountain away from the wind, called the leeward side). Pune, Marathwada and interior Karnataka fall in it and often face drought.

• Gaps let the wind through:

• The Palghat Gap lets south-west monsoon winds pass east.
• So Coimbatore gets some rain even though it lies east of the Ghats.

Ecology: forests, species and protection

• Forests:
• Tropical evergreen and semi-evergreen forests grow on the wet slopes.
• Shola-grassland covers the high tops. Shola forests are small patches of stunted evergreen forest in sheltered valleys, with rolling montane grasslands (high-altitude grasslands) between them.

• Together they work like a sponge: they store rainwater and feed streams.

• Biodiversity hotspot: a region with a very large number of endemic species (species found nowhere else) that has lost much of its original vegetation. The Western Ghats and Sri Lanka together form one hotspot.

• Key species: the lion-tailed macaque (a monkey with a silver-white mane, found only in the Western Ghats), the king cobra, the Nilgiri tahr (a wild mountain goat of the southern Western Ghats) and insectivorous plants (plants that trap insects to get nutrients).
• UNESCO World Heritage Site (2012): 39 component parts in 7 sub-clusters, with a total area of 7,95,315 hectares [2]. The parts are tiger reserves, national parks, wildlife sanctuaries and reserved forests. They are protected under the Wildlife (Protection) Act, 1972, the Indian Forest Act, 1927 and the Forest (Conservation) Act, 1980 [2].

Where it occurs

• Location: the western edge of the Peninsular Plateau, running parallel to the Arabian Sea coast from Gujarat in the north to the southern tip of Kerala–Tamil Nadu [2].
• Peaks:
• Anamudi (2,695 m): Anaimalai hills, Idukki district, Kerala, inside Eravikulam National Park, which is the main home of the Nilgiri tahr.

• Dodabetta (2,637 m): Nilgiri hills, near Ooty (Udhagamandalam), Tamil Nadu.

• Passes and gaps, north to south. A pass or gap is a low break in a mountain chain that lets roads, railways, rivers or winds cross it.

• Thal Ghat (Kasara Ghat): Mumbai–Nashik road and rail.
• Bhor Ghat (Khandala Ghat): Mumbai–Pune road and rail.
• Palghat Gap (Palakkad Gap): 30–40 km wide, between the Nilgiris (north) and the Anaimalai (south). It links Palakkad (Kerala) with Coimbatore (Tamil Nadu).

• Shencottah Gap: between the Cardamom hills and the Agasthyamalai hills. It links Kollam (Kerala) with the Tirunelveli side (Tamil Nadu).

• Protected areas:

• Nilgiri Biosphere Reserve (1986), India's first biosphere reserve. A biosphere reserve is a large protected area with a strictly protected core, while local people live and work in the outer zones.

• Eravikulam National Park (Kerala).

• Rain shadow zones east of the range: Pune, Marathwada and interior Karnataka.

• In the world: together with Sri Lanka, the Western Ghats form one of the world's biodiversity hotspots.

Don't confuse with

• Eastern Ghats: low, broken hills worn down by the Mahanadi, Godavari, Krishna and Kaveri, which cut through them. The Western Ghats are a continuous wall where these rivers rise. Only the Western Ghats are a UNESCO natural site.
• Sahyadri vs the whole range: "Sahyadri" is used as another name for the whole Western Ghats. As a local name, though, it means the northern part (Maharashtra, Goa, northern Karnataka). Nilgiri, Anaimalai, Cardamom and Agasthyamalai are the southern parts.
• Biligirirangan hills: on the Karnataka–Tamil Nadu border. They are counted in the Eastern Ghats and link the two Ghats (BRT Tiger Reserve). The two Ghats actually meet at the Nilgiri hills.
• Narmada–Tapi rift valleys: these rivers flow west because they run in rift valleys (long, narrow valleys formed where land sank between two faults) north of the Deccan. They do not rise in the Western Ghats. The Narmada rises at Amarkantak in the Maikal range.

Prelims Hooks

• Local names, north to south: Sahyadri → Nilgiri → Anaimalai → Cardamom → Agasthyamalai.
• Highest peaks of the Peninsula: Anamudi (2,695 m, Anaimalai hills, Idukki, Kerala, in Eravikulam NP) > Dodabetta (2,637 m, Nilgiris, near Ooty, Tamil Nadu).
• Gaps and passes, north to south: Thal Ghat (Mumbai–Nashik) → Bhor Ghat (Mumbai–Pune) → Palghat Gap (between the Nilgiris and the Anaimalai) → Shencottah Gap (between the Cardamom and Agasthyamalai hills).
• River sources: Godavari at Trimbakeshwar, Krishna near Mahabaleshwar, Kaveri at Talakaveri (Brahmagiri hills). All three flow east to the Bay of Bengal.
• UNESCO World Heritage Site (2012): 39 components in 7 sub-clusters, across 6 states [2].
• Trap: height rises from north to south, not the other way round. The Ghats meet the Eastern Ghats at the Nilgiris, home of the Nilgiri Biosphere Reserve (1986), India's first.

Mains Points

• Relief controls rainfall and water (GS-I, GS-III):
• The Ghats force 250–400 cm of rain onto the windward slope and leave the inner Deccan in rain shadow.
• This explains drought in Marathwada and north interior Karnataka.

• It also explains why the region depends on east-flowing rivers, and why states fight over the waters of the Krishna and the Kaveri.

• Conservation vs development (GS-III):

• The pressures: the range is a UNESCO site and a biodiversity hotspot. Mining, quarrying, hill roads and plantations raise the risk of landslides (Kerala, 2018 and 2024).
• Two reports: an Ecologically Sensitive Area (ESA) is an area where the government limits mining, quarrying and polluting industry. The Gadgil report (WGEEP, 2011) treated the whole Ghats as ecologically sensitive, in three zones. The Kasturirangan report (HLWG, 2013) proposed only about 60,000 sq km, or about 37% of the region, as ESA [3].

• The result: the draft ESA notification was re-issued for the fifth time on 6 July 2022 [4]. States still disagree over villages, mining and plantations, so the final notification is delayed.

• Passes shape connectivity and the economy (GS-I):

• Thal, Bhor and Palghat set the routes of the Mumbai–Nashik, Mumbai–Pune and Kochi–Coimbatore rail and road corridors.
• The Palghat Gap also lets monsoon rain reach Coimbatore, which supports its textile and farming base.

Related concepts

• Deccan Plateau
• Eastern Ghats
• Anamudi
• Dodabetta
• Nilgiri hills
• Palghat Gap
• Thal Ghat and Bhor Ghat
• Nallamala hills

Read more

• The Deccan Plateau and the Western and Eastern Ghats