Western Ghats Biodiversity Hotspot

Location and Extent of the Western Ghats

Western Ghats States: From the Tapi to Kanyakumari

The Western Ghats begin south of the Tapi river and end at the Marunthuvazh Malai at Swamithoppe in Kanyakumari district, at the southern tip of the peninsula. Along this length they form an almost continuous wall between the narrow Western Coastal Plains and the Deccan Plateau. The range passes through six States, from north to south:

• Gujarat: The northernmost stretch, south of the Tapi.
• Maharashtra: The Sahyadri proper, with Mahabaleshwar and the Kas Plateau.
• Goa: A short stretch of the range.
• Karnataka: The Malenadu hills, with Agumbe and Kudremukh.
• Kerala: The Anaimalai and Cardamom hills, with Anaimudi.
• Tamil Nadu: The Nilgiri, Anaimalai and southern hills down to Kanyakumari.

The range carries different local names along its length. It is the Sahyadri in Maharashtra, the Malenadu hills in Karnataka, the Nilgiri hills where Karnataka, Kerala and Tamil Nadu meet, and the Anaimalai and Cardamom hills in Kerala and Tamil Nadu. Its average elevation is about 1,500 m, and the highest ground lies in the south. The northern section rises to between 900 and 1,500 m, the middle section south of Goa falls below 900 m, and the southern section rises to the highest peaks of the peninsula.

Highest Peaks of the Western Ghats: Anaimudi and Dodabetta

Anaimudi (also written Anamudi), at 2,695 m, is the highest peak of the Peninsular plateau. It stands on the Anaimalai hills, in the Idukki and Ernakulam districts of Kerala, inside Eravikulam National Park, and its name means "elephant head" in Malayalam. Dodabetta (also written Doddabetta), the highest peak of the Nilgiri hills, rises to 2,637 m, 9 km from Ooty in Tamil Nadu; its name means "big hill".

The Western Ghats meet the Eastern Ghats at the Nilgiri hills, in the valley of the Moyar river, before the Western Ghats continue south. The two ranges differ in continuity, height and drainage.

The Biligirirangan Hills (also written Biligiriranga; BR Hills) of Chamarajanagar district, on the Karnataka-Tamil Nadu border, sit where the two ranges come close. They form the westernmost edge of the Eastern Ghats and touch the border of the Western Ghats, so animals move between the two ranges through them, and the sanctuary there carries plants and animals of both.

Gaps in the Western Ghats: Goa, Palghat and Shencottah

Three gaps break the chain. The northernmost is the Goa Gap. The Palghat Gap (also called the Palakkad Gap) is the widest and oldest; it is a pass about 30 km wide at about 11°N, between the Nilgiri hills to the north and the Anaimalai hills to the south. The southernmost and narrowest is the Shencottah Gap (also written Sengottai), a mountain pass that, like the Palghat Gap, connects Kerala and Tamil Nadu.

The Palghat Gap matters for climate and transport alike. During the south-west monsoon it lets moisture-laden winds into western Tamil Nadu, so that region gets more rain and milder late-summer temperatures than the rest of the rain-shadow interior. In the other direction, hot winds from Tamil Nadu pass through it and warm the eastern part of Kerala. The Bharathappuzha river flows through the gap, and National Highway 544 and the Jolarpettai-Shoranur and Palakkad-Pollachi railway lines pass through it, making it an important transport corridor between Kerala and Tamil Nadu.

Geology and Formation of the Western Ghats

How the Western Ghats Were Formed: Faulted Edge of the Deccan Plateau

The Western Ghats are not fold mountains like the Himalayas. They are the faulted and eroded western edge of the Deccan Plateau, part of the rigid Peninsular Block, which is made largely of very ancient gneisses and granites and has stood as a rigid block since the Cambrian period, except for part of its western coast, which has sunk beneath the sea. As part of the Indo-Australian Plate, the block has undergone vertical movements and block faulting.

The mountains arose along the west coast during the break-up of the supercontinent of Gondwana, in the late Jurassic and early Cretaceous periods, when India separated from the African continent. Several faults shaped the range, which was later cut into valleys and river gorges. After the break-up, basalt lava built the Deccan Plateau, and the western side was raised. The Western Ghats are therefore older than the Himalayas.

This history explains the shape of the range. Because the western edge stands highest, the western slopes facing the Arabian Sea are steep, while the eastern slopes fall gently into the plateau and are chiselled by rivers flowing east. The coastal strip below the scarp is a submerged coastal plain, narrow because of the submergence, with natural ports such as Marmagao, Mangalore and Cochin (Kochi), and the rivers that cross it form no deltas.

The same history made the range an "evolutionary ecotone", a meeting ground of plant and animal lineages of different origins. India broke away from Gondwana, drifted as an isolated landmass and was then pushed against Eurasia, so the Western Ghats hold species whose ancestors came "out of Africa" alongside others that came "out of Asia", and many that evolved in isolation. The purple frog is one example.

Soils of the Western Ghats: Laterite and Red Soils of the Piedmont Zone

Heavy rain under a hot climate with alternate wet and dry seasons gives the Western Ghats their typical soil, laterite, named from the Latin word later, meaning brick. Laterite forms through intense leaching by heavy rain. It is mostly deep to very deep, acidic (pH below 6.0) and poor in plant nutrients, and it occurs in the southern States and in the Western Ghats region of Maharashtra, among other areas. Under deciduous and evergreen forest it is rich in humus; under sparse vegetation it is poor in humus and easily eroded.

With soil conservation, particularly in the hilly areas of Karnataka, Kerala and Tamil Nadu, laterite is very useful for growing tea and coffee, and red laterite soils in Tamil Nadu and Kerala suit cashew nut. Red and yellow soils, coloured by the diffusion of iron through crystalline and metamorphic rocks, are found along the piedmont zone of the Western Ghats, the belt at the foot of the hills. In the north, the Deccan Trap basalt gives the black soil that covers the plateaus of Maharashtra.

Orographic Rainfall and the Rain-Shadow of the Western Ghats

Monsoon Barrier: Why the Western Slopes Get Heavy Rain

The Western Ghats stand across the path of the Arabian Sea branch of the south-west monsoon, and they turn it into rain by orographic rainfall, rain caused when moist air is forced to rise over high ground. The process runs in a fixed sequence:

1. Moist winds from the Arabian Sea strike the western coast from June.
2. The Western Ghats, 900 to 1,200 m high along this coast, block their path and force the winds up the slopes.
3. As the air rises it cools, and its moisture condenses into cloud.
4. The windward side of the Sahyadri and the Western Coastal Plain receive very heavy rainfall, between 250 cm and 400 cm.
5. After crossing the crest, the winds descend and are heated up, which lowers their humidity.
6. Little rain falls east of the Western Ghats, and this region of low rainfall is the rain-shadow area.

Rainfall on the windward slopes is among the highest in India. The west coast and the Western Ghats receive more than 200 cm a year, and the range as a whole averages about 250 cm. Agumbe in the Malenadu region of Karnataka, called the Cherrapunji of South India, records a mean annual rainfall of about 762 cm, with July the wettest month. At Mahabaleshwar in Maharashtra, 10 to 12 days of continuous rain each July are normal.

Rain-Shadow Deccan and the Dry Tamil Nadu Coast

The rain-shadow explains the dryness of the interior. The southern plateau remains dry from June to September because of its leeward situation behind the Western Ghats, and the vegetation changes accordingly, from evergreen forest on the western slopes to moist deciduous forest on the eastern slopes, dry deciduous forest in the rain-shadow and scrub at the foothills.

The Tamil Nadu coast is dry during the south-west monsoon for two reasons. It lies parallel to the Bay of Bengal branch of the monsoon, which therefore passes along it rather than onto it, and it lies in the rain-shadow of the Arabian Sea branch, behind the Western Ghats. The coast gets its heavy rain later, in October and November, when the north-east monsoon picks up moisture over the Bay of Bengal and causes torrential rainfall over the Tamil Nadu coast.

The Kaveri reflects both monsoons. Its upper catchment in the Western Ghats is fed by the south-west monsoon in summer and its lower catchment by the north-east monsoon in winter, so the river carries water through the year with less fluctuation than other Peninsular rivers.

Rivers That Rise in the Western Ghats

East-Flowing Rivers: Godavari, Krishna and Kaveri

The Western Ghats, running close to the western coast, act as the water divide between the major Peninsular rivers that flow to the Bay of Bengal and the small streams that join the Arabian Sea. Most of the large Peninsular rivers rise here, and the river systems that start in the range drain almost 40 per cent of the land area of India. The three largest are:

• Godavari: The largest Peninsular river system, also called the Dakshin Ganga, rises in the Nasik district of Maharashtra and is 1,465 km long.
• Krishna: The second largest east-flowing Peninsular river rises near Mahabaleshwar in the Sahyadri and is 1,401 km long; the Koyna, the Tungabhadra and the Bhima are its major tributaries.
• Kaveri (Cauvery): It rises in the Brahmagiri hills (1,341 m) of Karnataka, is 800 km long and drains 81,155 square km; the Kabini, the Bhavani and the Amravati are its important tributaries.

Several protected areas lie in the Kaveri basin because its tributaries rise in the Western Ghats. The Kabini rises in Wayanad district of Kerala and flows east into Karnataka past Nagarhole National Park, where the Kabini reservoir separates Nagarhole from Bandipur. The Bhavani rises in the Nilgiris and, with its tributary the Moyar, borders Sathyamangalam Tiger Reserve. Papikonda National Park in Andhra Pradesh, by contrast, lies on the Godavari.

West-Flowing Rivers and Waterfalls: Sharavati, Netravati and Periyar

The rivers that flow west to the Arabian Sea are short and swift, because they drop down the steep scarp across a narrow coastal plain. They form no deltas. Examples include:

• Sharavati: It rises and flows entirely within Karnataka and forms Jog Falls, also called Gerusoppa Falls, where it plunges about 253 m in four cascades in Shivamogga district; it reaches the sea at Honnavar.
• Netravati: It rises in Kudremukh in Chikkamagaluru district of Karnataka and reaches the Arabian Sea south of Mangalore, supplying water to Bantwal and Mangalore.
• Periyar: It drains the forests of Periyar National Park in Kerala, which also feed the Pamba, and flows west to the Arabian Sea.

Streams falling down the steep sides of the range form many waterfalls in the monsoon, and the rivers have been dammed for hydroelectricity and irrigation. Along the Malabar coast, backwaters called kayals are used for fishing and inland navigation.

Forest Types of the Western Ghats

Tropical Evergreen, Semi-Evergreen and Moist Deciduous Forests

Rainfall decides the forests of the Western Ghats. Tropical evergreen forests grow on the western slopes, where the annual rainfall exceeds 200 cm and the mean annual temperature is above 22°C. They are well stratified, with shrubs and creepers near the ground, short trees above them and tall trees reaching 60 m or more. They have no fixed season for shedding leaves, flowering or fruiting, so they stay green all year. Rosewood, mahogany, aini and ebony are among the species of these forests, which also grow in the hills of the north-east and in the Andaman and Nicobar Islands.

Semi-evergreen forests grow in the less rainy parts of the same belt, with a mixture of evergreen and moist deciduous trees such as white cedar, hollock and kail.

The moist deciduous forests grow on the eastern slopes of the Western Ghats, where rainfall is between 100 and 200 cm. These forests, which also grow along the Himalayan foothills, in the north-eastern States and in Odisha, have teak, sal, shisham, hurra, mahua, amla, semul, kusum and sandalwood among their main species. Farther east, in the rain-shadow, dry deciduous forest takes over where annual rainfall is 70 to 100 cm.

The Western Ghats also hold rarer wetland forests. Myristica swamps are freshwater swamp forests made up mainly of species of Myristica, adapted to flooding by stilt roots and knee roots. They survive in Uttara Kannada district of Karnataka, in southern Kerala, in the sacred groves of Goa and at two places in Maharashtra, and UNESCO counts them among the threatened habitats the World Heritage property protects.

Shola-Grassland Mosaic of the Southern Western Ghats

The southern Western Ghats lie within the tropics, yet their vegetation is subtropical on the lower slopes and temperate in the higher regions, where the forests are called sholas in the Nilgiris, the Anaimalai and the Palani hills. A shola is a patch of stunted evergreen forest growing in a valley, separated from the next patch by rolling montane grassland; the two together form the shola-grassland mosaic. Magnolia, laurel, cinchona and wattle are among the trees of economic value in these forests.

Sholas are found in the Nilgiris, the Anaimalai around Anaimudi, the Palani hills, Meghamalai and Agasthyamala in the south, and northwards in Wayanad, Coorg, Baba Budangiri and Kudremukh, with outliers in Goa and in the Satara and Sindhudurg districts of Maharashtra. They are often said to occur above 2,000 m, but they are found at 1,600 m in many hill ranges, such as the Biligirirangan Hills.

Why the grassland stays open has been debated. One view holds that frost lets grass grow but kills tree seedlings on the exposed slopes; the other holds that early herders and shifting cultivators created the grassland by burning. Pollen from bogs in the Nilgiris shows that the mosaic existed 35,000 years ago, long before people could have burned it, which points to a natural origin.

Endemic Flora and Fauna of the Western Ghats

Plant Endemism: 1,273 Flowering Plants Confined to the Western Ghats

The flora of the Western Ghats is rich and highly endemic. An endemic species is one confined to a region and found nowhere else. The Western Ghats have recorded 7,402 species of flowering plants, of which 5,588 are indigenous, 376 are naturalised exotics and 1,438 are cultivated or planted. Of the indigenous species, 2,253 are endemic to India, and 1,273 are confined to the Western Ghats alone. Of the nearly 650 tree species, 352, or 54 per cent, are endemic.

The lower plants are equally distinctive. The range holds 850 to 1,000 species of bryophytes, including 682 mosses (28 per cent endemic) and 280 liverworts (43 per cent endemic), together with 277 species of pteridophytes and 949 species of lichens.

Neelakurinji (Strobilanthes kunthiana), a shrub of the shola forests of Kerala, Karnataka and Tamil Nadu, is the best-known endemic plant. It grows at 1,300 to 2,400 m and flowers in September and October once in 12 years, when whole hillsides turn blue. One population has bloomed on a 12-year cycle documented since 1838; its last mass flowering was in 2018 and the next is due in 2030. Another population bloomed in 1990, 2002 and 2014, on the same 12-year cycle.

Endemic Amphibians, Reptiles, Fishes and Birds

The animals of the Western Ghats are as endemic as the plants, and among the vertebrates amphibians have the highest share of endemic species.

The purple frog (Nasikabatrachus sahyadrensis), described by scientists only in 2003, from Idukki district of Kerala, belongs to an ancient family of frogs and is Near Threatened (IUCN, 2022). It spends most of its life underground, feeding on termites, and comes to the surface only for about two weeks in the monsoon to breed. Its closest living relatives live only in the Seychelles. Whole genera of frogs and toads, such as Indirana, Micrixalus and Nyctibatrachus, are found nowhere else, and new frog species have continued to be discovered in this century.

Among the reptiles, most of the shieldtail snakes (family Uropeltidae) live only in this region. The southern Western Ghats are richest in freshwater fishes, with 13 genera restricted to the range, among them ornamental fishes such as the Denison barb; a regional assessment of 2011 counted 97 freshwater fish species of the Western Ghats as threatened. At least 19 species of birds are endemic, including the rufous-breasted laughingthrush, the Nilgiri wood-pigeon and the Malabar grey hornbill. The great hornbill (Buceros bicornis), the State bird of Kerala, has been listed as Vulnerable on the IUCN Red List since 2018. Among the insects, some 80 per cent of the tiger beetles are endemic.

Flagship Mammals: Lion-Tailed Macaque, Nilgiri Tahr and Malabar Civet

Three mammals stand for the Western Ghats in conservation and in the examination:

• Lion-tailed macaque (Macaca silenus): An Old World monkey endemic to the Western Ghats, with black fur, a silver-grey mane and a lion-like tuft at the tip of its tail. It lives in the upper canopy of tropical evergreen forests and is active only by day. An assessment of 2003 counted 3,000 to 3,500 animals in Tamil Nadu, Kerala and Karnataka, with the northernmost population at Sirsi-Honnavara in Karnataka. It is Endangered (IUCN, 2020).
• Nilgiri tahr (Nilgiritragus hylocrius): A mountain ungulate of the high grasslands and rocky cliffs of the Nilgiri and Anaimalai hills, with the largest population in Eravikulam National Park. Only a few hundred were left by the late twentieth century. The second synchronised survey by the Tamil Nadu and Kerala forest departments, in April 2025, counted 2,655 animals, 1,352 in Kerala and 1,303 in Tamil Nadu. It is Endangered (IUCN, 2008).
• Malabar large-spotted civet (Viverra civettina): A civet known only from the Western Ghats, estimated to number fewer than 250 mature animals and not recorded in surveys carried out between 1990 and 2014. It is Critically Endangered and listed as possibly extinct (IUCN, 2016); whether it is a valid species native to the Western Ghats is itself disputed.

Other endemic mammals include the Nilgiri langur (Semnopithecus johnii), a black langur with a golden-brown mane, Vulnerable (IUCN, 2020), and the Nilgiri marten (Martes gwatkinsii), the only marten native to southern India, with about 1,000 left, Vulnerable (IUCN, 2015). The range also holds large populations of wide-ranging species: The Western Ghats ecoregion has India's largest wild population of the Asian elephant, estimated at 11,000 in eight distinct populations.

At least 325 species on the IUCN Red List of globally threatened species occur in the Western Ghats. By category, 129 are Vulnerable, 145 Endangered and 51 Critically Endangered; by group, UNESCO names 324 of them, 229 plants, 31 mammals, 15 birds, 43 amphibians, five reptiles and one fish.

Protected Areas of the Western Ghats

Nilgiri and Agasthyamala Biosphere Reserves

The Nilgiri Biosphere Reserve, designated in 1986 in Tamil Nadu, Kerala and Karnataka, is the first biosphere reserve of India and the largest contiguous protected area in the Western Ghats. It covers about 5,520 square km, from the eastern part of Kodagu district to Erode district in the east and to the Palghat Gap in the south, at elevations of 80 to 2,600 m. Its protected areas include:

• Tamil Nadu: Mudumalai National Park, Mukurthi National Park and Sathyamangalam Tiger Reserve.
• Karnataka: Nagarhole National Park and Bandipur National Park.
• Kerala: Silent Valley National Park, and the Aralam, Wayanad and Karimpuzha Wildlife Sanctuaries.

The reserve is home to tribal groups such as the Toda, Kota, Irula, Kurumba and Paniya. Mukurthi National Park, in the western Nilgiris, was created to protect the Nilgiri tahr and is characterised by montane grassland and sholas.

The Agasthyamala Biosphere Reserve (also written Agasthyamalai), designated in 2001, lies at the southernmost end of the Western Ghats in Kerala and Tamil Nadu. It covers about 3,500 square km, 1,828 square km in Kerala and the rest in Tamil Nadu, and includes the Neyyar, Peppara and Shendurney Wildlife Sanctuaries and the Kalakad Mundanthurai Tiger Reserve (also written Kalakkad). It holds about 2,000 varieties of medicinal plants and is home to the Kani (Kanikkaran) tribe. It joined the UNESCO World Network of Biosphere Reserves in 2016.

National Parks and Tiger Reserves: Silent Valley, Eravikulam and Periyar

The main national parks and tiger reserves of the range are:

• Silent Valley National Park (Kerala): One of the last undisturbed tracts of the South Western Ghats montane rain forests and tropical moist evergreen forest, in the Nilgiri hills. Plans for a hydroelectric dam on the Kunthipuzha river led to the Save Silent Valley movement of the 1970s, which ended in the cancellation of the project and the creation of the national park.
• Eravikulam National Park (Kerala): Established in 1978 as Kerala's first national park, it is a rolling grassland plateau at about 2,000 m with sholas, holding Anaimudi and the largest population of the Nilgiri tahr.
• Periyar (Kerala): An elephant and tiger reserve of 925 square km in Idukki and Pathanamthitta districts.
• Mudumalai (Tamil Nadu): A national park of the Nilgiris on the borders of Karnataka and Kerala, declared a tiger reserve in 2007.
• Kudremukh (Karnataka): A national park named after a mountain, Kudremukha, where the Netravati rises.

Sathyamangalam: Corridor Between the Western and Eastern Ghats

Sathyamangalam Tiger Reserve, in Erode district of Tamil Nadu, straddles both the Western Ghats and the Eastern Ghats. It was declared a wildlife sanctuary in 2008, enlarged in 2011, and an area of 1,408.6 square km was notified as a tiger reserve in 2013. It is a wildlife corridor between the two ranges within the Nilgiri Biosphere Reserve and a genetic link between the protected areas it adjoins, among them Mudumalai and Bandipur National Parks, the Sigur Plateau and the Biligiriranga Swamy Temple Wildlife Sanctuary. Its tigers rose from 25 in 2011 to 80 in 2018.

UNESCO World Heritage Site: 39 Components in Seven Sub-Clusters

The Western Ghats were inscribed on the World Heritage List in 2012 under criterion (ix), for the speciation that followed the break-up of Gondwana, and criterion (x), for their exceptional plant and animal diversity and endemism. The property is serial: Its 39 component parts, grouped into seven sub-clusters in four States, belong to one biogeographic province and survive as isolated remnants of forest that was once continuous. One component, the Kas Plateau, a volcanic plateau west of Satara in the Sahyadri sub-cluster, is covered with seasonal wildflowers from August to early October.

Protection of the property rests on Indian law. At inscription in 2012 the components were owned by the State and protected under the Wildlife (Protection) Act, 1972, the Indian Forest Act, 1927, and the Forest (Conservation) Act, 1980, under the Forest Department and the Chief Wildlife Warden. About 40 per cent of the property lies outside the formal protected-area system, mostly in Reserved Forests. A Western Ghats Natural Heritage Management Committee under the then Ministry of Environment and Forests was set up to coordinate the components across the States, and the livelihood rights of local communities are governed by the Forest Rights Act, 2006, with their participation through Village Ecodevelopment Committees.

Western Ghats and Sri Lanka Biodiversity Hotspot

Hotspot Criteria: 1,500 Endemic Plants and 70 Per Cent Habitat Loss

The idea of the biodiversity hotspot came from Norman Myers, who wrote about it in 1988 and 1990; the criteria were revised in 2000. A region rich in species qualifies only if it passes two strict thresholds:

• Endemism: It must contain at least 1,500 species of vascular plants as endemics, more than 0.5 per cent of the world's total.
• Threat: It must have lost at least 70 per cent of its primary vegetation.

Thirty-six regions qualify today. Together they hold nearly 60 per cent of the world's species of plants, birds, mammals, reptiles and amphibians on just 2.4 per cent of the planet's surface. South Asia has three of them, the Himalaya, Indo-Burma, and the Western Ghats and Sri Lanka. India has parts of four hotspots, because the Sundaland hotspot reaches the Nicobar Islands.

The range holds nearly 30 per cent of all the species of flora and fauna found in India and is counted, with Sri Lanka, among the world's eight "hottest hotspots" of biological diversity.

Threats to the Western Ghats and the Committees on Their Protection

The threats come from long use of the land. Large tracts were cleared for plantations and timber after British rule was established, which fragmented the forests, and non-native species spread at the cost of rare endemic ones. The fauna is further threatened by overexploitation, illicit grazing, mining, poaching and introduced species.

The Western Ghats Ecology Expert Panel, appointed by the Union Ministry of Environment and Forests and chaired by Madhav Gadgil, submitted its report on 31 August 2011; it proposed Ecologically Sensitive Areas in three zones of sensitivity. The High Level Working Group under K. Kasturirangan, which reported in April 2013, proposed to bring 37 per cent of the Western Ghats under Ecologically Sensitive Area zones, against the 64 per cent of the Gadgil report. The Gadgil and Kasturirangan reports remain the two reference points of the debate on how much of the range to protect.

Landslides in the Western Ghats and the Himalayas

Why Landslides Are More Frequent in the Himalayas Than in the Western Ghats

Landslides strike both mountain systems, but for different reasons and with different frequency. The Himalayas are young, weak and flexible in their geological structure, unlike the rigid and stable Peninsular Block. They are still subject to endogenic and exogenic forces that produce faults, folds and thrust planes, they are dissected by fast-flowing rivers in their youthful stage, and the accumulation and release of stress along the Himalayan arc causes frequent earthquakes. Every Himalayan State falls in the high landslide vulnerability zone, and the young, highly unstable mountain areas fall in the very high zone.

The Western Ghats are older and stable, so their landslides depend far more on rain. High-rainfall regions with steep slopes in the Western Ghats and the Nilgiris fall in the very high vulnerability zone, while the rain-shadow areas of the Western and Eastern Ghats and the Deccan Plateau, with less rain, fall in the moderate to low zone and see only occasional landslides. Laterite, the leached soil of these slopes, is prone to erosion and degradation because of its position on the landscape.

Landslides in both regions occur mostly in the monsoon, and human activity raises the risk in both. Cutting down forests, building infrastructure without following approved methods, and putting up so many buildings that they block the natural flow of water have made landslides more likely in Himachal Pradesh, Uttarakhand, Sikkim, Arunachal Pradesh and the Western Ghats alike, and areas of intense construction of roads and dams are placed in the very high zone.

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