Physiography of Northeast India: Plateaus, Mountains, Hills and Plains
Northeast India is the easternmost region of the Indian subcontinent and is characterized by remarkable geographical diversity. The region has a complex physiography consisting of high mountains, hills, plateaus, valleys, plains, rivers, forests and wetlands. Its varied relief and geological structure have created diverse physical and ecological environments.
For geographical study, the physiography of Northeast India can broadly be divided into three major regions:
Plateau Region
Mountain and Hill Region
Plain Region
These physiographic divisions play an important role in determining the climate, drainage, vegetation, agriculture, settlement patterns and economic activities of Northeast India.
Geographical Location of Northeast India
Northeast India occupies the northeastern corner of India and is connected with the rest of the country through a narrow corridor in the west. The region is bounded by hills and mountains on its northern, eastern and southern sides.
The northeastern region is generally located between approximately 22°N and 29°30′N latitudes and 89°46′E and 97°25′E longitudes.
The region covers an area of approximately 2.62 lakh square kilometres and includes the eight traditional northeastern states:
Assam
Arunachal Pradesh
Meghalaya
Nagaland
Manipur
Mizoram
Tripura
Sikkim
The region lies mainly within the tropical and subtropical climatic belts, although high-altitude areas of Arunachal Pradesh experience much colder climatic conditions.
Major Physiographic Features of Northeast India
The physiography of Northeast India is highly varied. The region contains:
High Himalayan mountains
Patkai and Purvanchal hills
Meghalaya Plateau
Karbi Plateau
Brahmaputra Plain
Barak Plain
Manipur Plain
Tripura Plain
Deep river valleys and gorges
Extensive forests and wetlands
Numerous rivers and tributaries
The region is surrounded by mountains and hills on three sides, while its western side provides a relatively narrow opening towards the plains of India and Bangladesh.
The difficult terrain, heavy rainfall, dense forests, frequent floods, landslides, earthquakes and limited accessibility have historically contributed to the relative geographical isolation of many parts of Northeast India.
Physiographic Divisions of Northeast India
The major physiographic divisions of Northeast India are:
1. Plateau Region
Meghalaya Plateau
Karbi Plateau
2. Mountain and Hill Region
Arunachal Himalaya
Patkai-Purvanchal Hill Region
3. Plain Region
Brahmaputra Plain
Barak Plain
Manipur Plain
Tripura Plain
1. Plateau Region of Northeast India
The plateau region forms an important geological and physiographic unit of Northeast India. The Meghalaya Plateau and Karbi Plateau are generally regarded as detached or uplifted extensions of the ancient Peninsular Indian shield.
The Meghalaya Plateau is separated from the main Peninsular Plateau by the alluvial plains of northern India and Bangladesh. The region is composed largely of ancient crystalline rocks and has been deeply dissected by rivers and streams.
The two principal plateau areas are:
Meghalaya Plateau
Karbi Plateau
1.1 Meghalaya Plateau
The Meghalaya Plateau occupies much of Meghalaya and is one of the most important physiographic features of Northeast India.
It is bordered by the Brahmaputra Valley to the north and the Sylhet Plain of Bangladesh to the south. The southern edge of the plateau rises relatively abruptly from the plains of Bangladesh.
The plateau is deeply dissected by numerous south-flowing rivers and streams. These rivers have created spectacular gorges, waterfalls and deeply incised valleys along the southern slopes.
Major Ranges of the Meghalaya Plateau
Important ranges include:
Garo Hills
Khasi Hills
Jaintia Hills
Tura Range
Shillong Range
The central part of the plateau contains relatively high uplands, while its western and eastern portions are more deeply dissected and eroded.
Important Peaks
Nokrek Peak in the Garo Hills rises to approximately 1,412 metres and is one of the highest points of the Garo Hills.
Shillong Peak, located in the Khasi Hills, reaches approximately 1,965 metres and is the highest point of Meghalaya.
The western Garo Hills and eastern Jaintia Hills have been extensively dissected by streams. Towards the northern plains, the plateau gradually descends through hills, terraces and isolated uplands.
Importance of the Meghalaya Plateau
The Meghalaya Plateau is important for:
Forest resources
Waterfalls and rivers
Biodiversity
Agriculture
Tourism
Mineral resources
Hydroelectric potential
1.2 Karbi Plateau
The Karbi Plateau, also known as the Karbi Anglong Plateau, is located in central Assam. It is a detached upland separated from the Meghalaya Plateau by the valleys of rivers such as the Kopili and Dhansiri.
The plateau is surrounded by important river systems and merges gradually with the surrounding plains.
The Karbi Anglong hills contain numerous ridges, valleys and isolated peaks. The terrain is characterized by undulating uplands, forested hills and deeply dissected valleys.
Drainage of the Karbi Plateau
Important rivers draining the region include:
Kopili
Dhansiri
Jamuna
Diphu
The rivers have played an important role in dissecting the plateau and creating valleys and embayments.
The surrounding plains and terraces also support agriculture and tea cultivation in parts of central Assam.
2. Mountain and Hill Region of Northeast India
The mountain and hill region is the most extensive physiographic unit of Northeast India.
It extends from the Eastern Himalaya in Arunachal Pradesh and bends southward and southwestward through the Patkai and Purvanchal hill systems.
This mountain system forms a broad arc along the northern, eastern and southern boundaries of Northeast India.
The major divisions are:
Arunachal Himalaya
Patkai-Purvanchal Hills
2.1 Arunachal Himalaya
The Arunachal Himalaya forms the eastern continuation of the Himalayan mountain system.
It occupies much of northern Arunachal Pradesh and extends from the Bhutan border towards the eastern part of the state.
The Himalayan ranges continue eastward towards the great mountain knot near Namcha Barwa, after which the mountain system bends southward and connects with the ranges of the eastern hills.
The Arunachal Himalaya contains some of the highest and most spectacular mountains in Northeast India.
Important Peaks of the Arunachal Himalaya
Some important high peaks include:
Kangto – approximately 7,060 metres
Gorichen – approximately 6,488 metres
Namcha Barwa – 7,782 metres, located in Tibet near the eastern Himalayan bend
The mountains are characterized by steep slopes, deep valleys, gorges, glaciers and high-altitude landscapes.
2.1.1 Lesser Himalayan Region
The Lesser Himalayan region of Arunachal Pradesh consists of a complex network of hills and mountain ranges.
The terrain rises progressively from the lower valleys towards the higher Himalayan ranges. Deep river valleys and gorges have divided the mountain landscape into numerous ridges and isolated uplands.
The region receives heavy rainfall, particularly along the southern slopes, resulting in dense forests and rich biodiversity.
Important Uplands
Two notable upland areas are:
Bomdila
Apatani Plateau
The Apatani Plateau is particularly important because of its distinctive agricultural system and long-established human settlements.
At higher elevations, glacial and periglacial features occur, including deposits of transported rocks, boulders and sediments.
2.1.2 Great Himalayan Zone
The Great Himalayan Zone represents the high-altitude mountainous belt of Arunachal Pradesh.
It is characterized by:
Very high elevations
Snow-covered peaks
Steep slopes
Rocky terrain
Glaciers
Deep valleys
Sparse vegetation at higher elevations
The Great Himalaya forms a major part of the mountain system along the northern frontier of Arunachal Pradesh.
The increasing altitude creates significant variations in climate and vegetation, ranging from subtropical forests at lower elevations to alpine and high-altitude environments.
2.2 Patkai-Purvanchal Hill Region
The Patkai-Purvanchal Hill Region forms the eastern and southeastern mountain system of Northeast India.
It begins in the eastern part of Arunachal Pradesh and continues southward through Nagaland, Manipur and Mizoram, with associated hill systems extending towards Tripura and the Barak Valley region.
The eastern mountain system is associated with the complex tectonic and geological structure of the Indo-Myanmar ranges.
Major Hill Systems
Important ranges and hill systems include:
Patkai Range
Naga Hills
Manipur Hills
Mizo Hills
Barail Range
North Cachar Hills
These ranges generally have a north-south or northeast-southwest orientation.
Patkai Range
The Patkai Range forms an important mountain barrier along the eastern side of Northeast India.
It extends through parts of Arunachal Pradesh and Nagaland and continues towards Myanmar.
The mountains are characterized by steep slopes, dense forests and narrow valleys.
The Patkai system is an important geographical divide and forms part of the mountainous boundary between India and Myanmar.
Naga Hills
The Naga Hills occupy much of Nagaland and adjoining areas.
The hills are characterized by rugged terrain, steep slopes and narrow valleys. The ranges gradually merge with other hill systems towards Manipur and Assam.
Mount Saramati, with an elevation of approximately 3,826 metres, is the highest peak of Nagaland and is located along the India-Myanmar border.
Barail Range
The Barail Range is an important hill system of southern Assam and adjoining areas.
It extends through the Dima Hasao region and forms an important watershed between the Brahmaputra and Barak river systems.
The range is characterized by forested ridges, steep slopes and numerous valleys.
The Barail Range is geographically significant because it forms a transition between the hill systems of Northeast India and the plains of Assam.
3. Plain Region of Northeast India
The plains form another major physiographic division of Northeast India.
The principal plains are:
Brahmaputra Plain
Barak Plain
Manipur Plain
Tripura Plain
These plains are generally associated with river deposition, intermontane basins and piedmont environments.
3.1 Brahmaputra Plain
The Brahmaputra Plain is the largest and most important plain of Northeast India.
It occupies a long, narrow valley extending across Assam.
The plain is bounded by:
Bhutan and Arunachal Himalaya in the north
Patkai and adjoining hills in the east
Naga Hills, Karbi Plateau and Meghalaya Plateau in the south
The plains of West Bengal and Bangladesh towards the west
The Brahmaputra River flows through the centre of the plain and is joined by numerous tributaries.
Major Tributaries
Important tributaries include:
Subansiri
Jia-Bharali
Manas
Beki
Dhansiri
Kopili
Burhi Dihing
Dikhow
Disang
The Brahmaputra Plain is characterized by fertile alluvial soils, river islands, wetlands, sandbars and floodplains.
Majuli
Majuli, located in the Brahmaputra River system of Assam, is one of the world's best-known river islands and is an important cultural landscape of Assam.
3.2 Barak Plain
The Barak Plain lies in southern Assam and forms the principal plain region of the Barak Valley.
It is surrounded by hills on several sides:
North – North Cachar Hills
East – Manipur Hills
South – Mizoram Hills
West – Bangladesh
The Barak River and its tributaries drain this plain.
The valley gradually merges with the Sylhet Plain of Bangladesh towards the west.
The Barak Plain is an important agricultural and settlement region of southern Assam.
3.3 Manipur Plain
The Manipur Plain, also known as the Imphal Valley or Manipur Valley, is an important intermontane basin surrounded by hills.
The basin is largely enclosed by the surrounding hill ranges of Manipur.
The valley has a relatively level surface and is drained by several rivers.
Important Rivers of the Manipur Plain
Major rivers include:
Imphal River
Iril River
Thoubal River
Nambul River
Khuga River
The valley also contains wetlands and lakes.
Loktak Lake
Loktak Lake is the largest freshwater lake in Northeast India and is one of the most important geographical features of Manipur.
The lake is famous for its floating phumdis, which are masses of vegetation, soil and organic matter.
3.4 Tripura Plain
The Tripura Plain is a piedmont and alluvial plain associated with the hill systems of Tripura and the adjoining plains of Bangladesh.
The hill ranges of Tripura generally run in a north-south direction, separated by intervening valleys.
The western portion of the state contains broader lowland areas, while the eastern part is dominated by parallel hill ranges.
Important Rivers
The major rivers associated with the Tripura plain and surrounding areas include:
Gomati
Manu
Khowai
Haora
Feni
The valleys between the hill ranges provide suitable areas for agriculture and settlement.
Major Physiographic Features of Northeast India at a Glance
| Physiographic Region | Major Features | Important Areas |
|---|---|---|
| Plateau Region | Ancient crystalline uplands | Meghalaya Plateau, Karbi Plateau |
| Himalayan Region | High mountains, glaciers, deep valleys | Arunachal Pradesh |
| Patkai-Purvanchal Region | Rugged hills and mountain ranges | Nagaland, Manipur, Mizoram |
| Brahmaputra Plain | Extensive alluvial plain | Assam |
| Barak Plain | Valley and alluvial plain | Southern Assam |
| Manipur Plain | Intermontane basin | Manipur |
| Tripura Plain | Piedmont and alluvial plain | Tripura |
Physiography of Northeast India: Important Rivers
The drainage system of Northeast India is dominated by the Brahmaputra and Barak river systems.
Brahmaputra River System
The Brahmaputra is one of the major rivers of Asia. It flows through Tibet, Arunachal Pradesh and Assam before entering Bangladesh.
Its extensive network of tributaries drains much of the northern and central parts of Northeast India.
Barak River System
The Barak River originates in Manipur and flows through southern Assam before entering Bangladesh, where its distributaries form part of the Surma-Meghna river system.
Other Important Rivers
Some important rivers associated with the region include:
Subansiri
Manas
Dhansiri
Kopili
Jia-Bharali
Burhi Dihing
Imphal
Iril
Thoubal
Gomati
Feni
Geological and Geographical Significance of Northeast India
The physiography of Northeast India is closely related to its geological history and tectonic setting.
The region lies near the junction of major geological structures, including the Himalayan mountain system and the Indo-Myanmar ranges.
Consequently, Northeast India is one of the most seismically active regions of India.
The young and tectonically active mountains are vulnerable to:
Earthquakes
Landslides
Soil erosion
Floods
River-bank erosion
The combination of high rainfall, steep slopes, young geological formations and intense river erosion makes the region particularly sensitive to natural hazards.
Physiography and Biodiversity of Northeast India
The highly varied physiography of Northeast India has produced exceptional biological diversity.
The region contains:
Tropical forests
Subtropical forests
Temperate forests
Alpine vegetation
Grasslands
Wetlands
Riverine ecosystems
Mountain ecosystems
The variation in altitude, temperature, rainfall and soil conditions creates numerous ecological niches.
The region is therefore recognized as one of India's most important biodiversity-rich areas.
Importance of Physiography in Northeast India
The physical geography of Northeast India directly influences human activities and economic development.
Agriculture
The plains and river valleys provide fertile land for agriculture, while hill regions support terrace cultivation, shifting cultivation and horticulture.
Tea Cultivation
The Brahmaputra Valley and surrounding uplands provide favourable conditions for tea cultivation, making Assam one of the world's major tea-producing regions.
Forestry
The extensive mountain and plateau regions support valuable forest resources and diverse wildlife.
Hydropower
The steep gradients of rivers descending from the Himalaya and surrounding hills provide considerable hydroelectric potential.
Tourism
Mountains, waterfalls, caves, lakes, forests and river landscapes provide significant opportunities for tourism.
Conclusion
The physiography of Northeast India is characterized by extraordinary diversity. The region can broadly be divided into the Plateau Region, Mountain and Hill Region, and Plain Region.
The Meghalaya and Karbi plateaus form important upland areas, while the Arunachal Himalaya represents the eastern extension of the Himalayan mountain system. The Patkai-Purvanchal hills form a major mountainous arc through the eastern and southern parts of the region.
The Brahmaputra, Barak, Manipur and Tripura plains provide relatively level and fertile areas between the surrounding mountains and hills.
This remarkable combination of mountains, plateaus, valleys, plains and rivers has shaped the climate, drainage, biodiversity, agriculture, settlement and economic activities of Northeast India.
Therefore, understanding the physiographic divisions of Northeast India is essential for studying its geography, environment, natural resources and regional development.
Frequently Asked Questions (FAQs)
1. What are the major physiographic divisions of Northeast India?
Northeast India can broadly be divided into three major physiographic regions: Plateau Region, Mountain and Hill Region, and Plain Region.
2. What are the major plateaus of Northeast India?
The two major plateau regions are the Meghalaya Plateau and Karbi Plateau.
3. What are the major mountain regions of Northeast India?
The major mountain regions are the Arunachal Himalaya and Patkai-Purvanchal Hill Region.
4. What are the major plains of Northeast India?
The major plains are the Brahmaputra Plain, Barak Plain, Manipur Plain and Tripura Plain.
5. Which is the largest plain in Northeast India?
The Brahmaputra Plain is the largest and most extensive plain of Northeast India.
6. Which is the highest peak of Meghalaya?
Shillong Peak, with an elevation of approximately 1,965 metres, is the highest point of Meghalaya.
7. Which is the highest peak of Nagaland?
Mount Saramati, approximately 3,826 metres high, is the highest peak of Nagaland.
8. Which river flows through the Brahmaputra Plain?
The Brahmaputra River flows through the Brahmaputra Plain and is joined by numerous tributaries.
9. What is the importance of the Barail Range?
The Barail Range is an important hill system that forms a major watershed between the Brahmaputra and Barak river systems.
10. Why is Northeast India prone to earthquakes?
Northeast India is located in a tectonically active zone associated with the Himalayan and Indo-Myanmar mountain systems, making it highly vulnerable to earthquakes.