India exhibits a great variation in topography, landscape, climate, soil types, geology, vegetation and demographic character from one part of the country to another. Indian climate vary from place to place due to variation in altitude, temperature, rainfall and other parameters. This module highlights the geoecological regions of India with their characteristics.

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GEO-ECOLOGICAL ZONES OF INDIA
by
Prof. A. Balasubramanian
Centre for Advanced Studies in Earth Science
University of Mysore
Mysore-6

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Ecological conditions of India:
India exhibits a great variation in topography,
landscape, climate, soil types, geology,
vegetation and demographic character from one
part of the country to another. Indian climate
vary from place to place due to variation in
altitude, temperature, rainfall and other
parameters.

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The climatic characteristics range from
continental to oceanic, from extreme hot to
severe cold, from extremely wet to dry desert
type. Geological formations have wide
variations from Archaean, volcanic extrusive,
igneous and sedimentary metamorphic to
younger sedimentary and quaternary alluvium.
The country exhibits a variety of soil types.

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Due to diversity of parent rock materials,
variation in climatic condition and soil forming
processes, soil type varies from place to place.
Alluvium is the common soil type found in
riverine plains and coastal plains.
Raised areas of older alluvial soils are often
lateritic.
Red soil dominates the interior areas of tropical
climate with mild rainfall. Black soil is
common in Deccan plateau.

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Mountain slopes and remote islands are mostly
covered with thin soils.
Sandy soils are found in the semi-deserts and
deserts.
Mixed red and brown soils are common in other
parts of India.
Natural vegetations vary widely from one
region to another.
The tropical rainforest is found in Kerala.

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The subtropical moist evergreen forest
dominates the northeastern uplands. The
deciduous vegetation is found in the east central
part.
The sub-humid to semi-arid types of vegetation,
shrub and grassland are common in the interior
parts.
The arid xerophytes are found in Rajasthan.
Mangrove forests are common in river deltas.

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The Himalayan highlands are having temperate,
alpine and sub-alpine vegetations.
Physical features vary greatly from vast plains,
extensive plateau, dissected hills, small islands
to great mountain chains.
Bounded on the north by the Himalayas and on
the other three sides by seas and ocean, India is
having a variety of landscape.

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India exhibits a variety of physical features
ranging from plains, plateau, and islands to
some of the highest peaks of the world like K2,
Kanchenjunga, Nanda Devi, Kamet, Nanga
Parvat and others.
India is having seven major physiographic
units.

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These are
(a) Northern Mountains;
(b) Great Plains;
(c) Central Highlands;
(d) Peninsular Plateaus;
(e) East Coast;
(f) West Coast and
(g) Islands.

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Physical regions, their altitudinal zones and
coverage are depicted in this Table.
Major Altitudinal zones.
Regions Altitude
(metres)
Area
(Sq Km)
Percentage
Plains < 300m 1,435,576 43.66
Plateau 300-1,000m 1,092,893 33.24
Hills 300-2,000m 486,349 14.80
Mountains 2,000-
>6,000m
272,959 8.30
Total 3,287,782 100.00

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Northern mountains
Along the northern border of the country, this
physiographic division appears as a gigantic
crescent with the convex side towards the north
Indian plain. From the foothills, the land rises
abruptly northwards to over 8,000m within a
short distance of 150 km.
Towards the north, it merges gently with the
edge of the Tibetan plateau.

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The terrain is characterized by a series of
mountain chains with snowcapped summits,
longitudinal valleys and rolling foothills.
The gigantic Great Himalayan range is 2,400
km long and 250-400 km wide with a mean
elevation of 6,000m.
This mountain region is subdivided into three
segments, namely,
(i)Western Himalaya;
(ii) Central Himalaya, and

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(iii) Eastern Himalaya.
Garhwal, Kumaun and Jammu & Kashmir
mountains are included in the Western
Himalaya.
The Central Himalaya covers the mountains of
Nepal.
The ranges of Arunachal Pradesh, Darjeeling
and Bhutan make up the Eastern Himalaya.

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The northeastern ranges on Nagaland-Myanmar
border strike north-south through Myanmar in
an arc bulging towards the west.
Beyond the Western Himalaya lie the
northwestern ranges stretching over
Afghanistan and Pakistan.

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Great Plains
The great plains are one of the largest and most
densely populated alluvial plains of the world,
stretching along the foot of the Himalayas,
fanning out at both ends to include the humid
Bengal Basin in the east and the arid
Marusthali in the west.
Built by the Indus, the Ganga and the
Brahmaputra River systems, this vast plain is
one of the recent landform units.

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Depth of alluvium ranges from 100 to 4,000m.
The plain is divided into three sub-divisions
viz., western plain, northern plain and eastern
plain.
The western plain is divided into two provinces
- (i) Marusthali and
(ii) Rajasthan Bagar.
The former is a region of moving sands and
deficient rainfall while the later is a steppe land
drained by the Luni River.

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The northern plain is divided into four
provinces:
(i) Punjab plain,
(ii) Ganga-Yamuna doab,
(iii) Rohilkhand plain and
(iv) Avadh plain.
Punjab plain is remarkably fertile.
The Bari doab between Beas and the Ravi
rivers and the Bist doab between the Beas and
the Sutluj rivers deserve special mention.

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The Ganga-Yamuna doab is by far the best
known fertile tract.
Further east is the low lying Rohilkhand and
Avadh plains.
The eastern plain is divided into four parts:
(i) North Bihar plain,
(ii) South Bihar plain,
(iii) Bengal Basin and (iv) Assam plain.

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Here the thickness of quaternary alluvium is
around 1,000m.
Central highlands
The central highland forms a wide belt of hilly
country bordered on the west by the Aravalli
and on the south by the Satpura range.
It separates the Great Plains from the
peninsular plateau.

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It is divided into two sub-divisions, viz.,
(i) North Central Highland, and
(ii) South Central Highland which are further
sub-divided into eight physiographic provinces,
viz., Aravalli range, East Rajasthan Uplands,
Madhya Bharat Pathar and Bundelkhand
uplands belonging to the northern part; and the
Malwa plateau, Vindhyan scarpland, Vindhya
ranges and Narmada valley belong to the
southern part.

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Peninsular plateau
The peninsular plateau constitutes the largest
and the oldest physiographic division of India.
It is triangular in shape - one arm extends from
Kanyakumari on the south up to the Rajmahal
hills on the northeast.
Two other sides run along the Satpura hills on
the north and the Sahyadri on the west.

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It comprises of five subdivisions, viz.,
(i) Western Hills,
(ii) North Deccan,
(iii) South Deccan,
(iv) Eastern Plateau and
(v) Eastern Hills.
The Western Hills are popularly known as the
Western Ghats or Sahyadri. It is divided into
three parts - the North Sahyadri, the Central
Sahyadri and the South Sahyadri.

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The North Sahyadri is composed of horizontal
sheets of lava.
A typical trap landscape has developed which
viewed from the east appears as steps.
Palghat gap lies between the central and the
southern Sahyadri and it appears to be a rift
valley.

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Three ranges of South Sahyadri radiate in three
different directions from
Anai Mudi peak (2,695m),
the Anai Malai to the north,
the Palni to the northeast and
the Ealmalai (Cardamom hills) to the south.
The Eastern plateau has a much more
diversified topography than the Deccan plateau.

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It comprises of five provinces - Baghelkhand
plateau, Chhotanagpur plateau, Garhjat hills,
Mahanadi basin, and Dandakaranya.
Geologically Meghalaya plateau is a part of this
subdivision.
The Eastern hills are a coastal range popularly
known as the Eastern Ghats. Due to denudation,
nowhere do the Eastern Ghats exhibit their true
mountain character.

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The Tamil Nadu upland is a fairly wide belt of
undulating land lying at the foot of the Eastern
Ghats. Its highest peak is Doda Beta (2,637m).
The North Deccan comprises of two
physiographic provinces, viz., Satpura range
and the Maharashtra plateau. The Satpura
consists of three hill groups. The western group
is known as Rajpipla hills. The central part is
the Mahadeo hills.

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The eastern part is known as the Maikala range.
Basaltic lava with younger trap formations
mark the Maharashtra plateau over which flow
the rivers of Godavari, Bhima and Krishna.
The South Deccan comprises of Telengana
plateau and Karnataka plateau.

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East Coast
The east coastal plain is wider than its western
counterpart.
It is 100 to 130 km wide at Tamil Nadu and
Andhra Pradesh.
The Utkal coastal plain merges with the vast
Bengal plain at Chilika lagoon in Orissa and
Pulicat lagoon in Andhra Pradesh-Tamil Nadu
border.
Both are important lagoons.

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The Mahanadi delta in Orissa, Ganga delta in
Bengal, Godavari-Krishna delta in Andhra
Pradesh and Cauvery delta in Tamil Nadu are
highly fertile deltaic plains.
The Adam's bridge, a submerged reef connects
the two necks of India and Sri Lanka.

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West Coast
Both the Great and the Little Rann are dark
silty plains with saline patches.
From north to south, the western coast bas been
divided into Kachchh peninsula, Kathiawar
peninsula, Gujarat plain, Konkan coast,
Karnataka coast and Kerala plain (Malabar
Coast).
The northern part of Kathiawar peninsula is a
rolling upward.

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The central part consists of residual hills
including the Girnar (1,117m).
Oceanic islands
The Andaman and Nicobar group of islands in
the Bay of Bengal forms a north-south trending
arcuate chain of unsubmerged peaks. It is
composed of 265 islands covering a cumulative
area of 8,090 sq km.

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These islands stretch from latitudes 14° N to 6°
30' N in two distinct groups - the Andaman
chain on the north separated by the Ten Degree
Channel from the Nicobar group on the south.
The Lakshadweep group of islands in the
Arabian Sea is an assemblage of 25 small
islands between latitudes 11 ° 45' N and 8° N.

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India’s climatic regions:
India's agroclimatic regions classified into 6
major categories. They are
1. Tropical Rainy zones
2. Tropical Humid zones
3. Tropical wet and Dry zones
4. Tropical Dry zones
5. Arid and Semi-arid zones
6. Sub Tropical temperate zones with short
humid summer.

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The sub tropical temperate zones with short
humid summer are confined to the entire state
of Jammu and Kashmir, Parts of Punjab and
Haryana states, in the north.
The Arid and Semi Arid zones are located over
the entire state of Rajasthan, Parts of Punjab,
Haryana and Gujarat states, in the northwest.

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The tropical dry zones are located over the west
central India cover in parts of Rajasthan,
Gujarat, Madhya Pradesh, Maharashtra and
Andhra Pradesh states.
The tropical wet and dry zones are located over
the central India and most of the regions in the
Peninsular India. Parts of Uttar Pradesh,
Madhya Pradesh, Andhra Pradesh, Maharashtra,
Karnataka and Tamil Nadu states have these
climatic zones.

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The Tropical humid zones are located over the
eastern India and the coastal belts of Goa,
Karnataka and Kerala states. Parts of the areas
in Uttar Pradesh, Bihar, Orissa and West Bengal
states are covered by this agro-climatic zones.
The tropical rainy zones are confined to the
North eastern parts of India covering,
Arunachal Pradesh, Assam, Meghalaya,
Mizoram and Manipur.

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The climate of India is mainly controlled by its
geographic location, geomorphic conditions,
temperature, rainfall and wind patterns.
Regional classifications of India :
Due to variation of natural environment
agricultural practices as well as agricultural
produces vary from one part of the country to
another.

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For systematic agricultural development and
identification of homogeneous regions several
scholars attempted to divide India into
geographical regions.
The notable works are
S.P. Chatterjee (1956),
D. Thorner (1956),
M.S. Randhawa (1958),
L. D. Stamp (1958),

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O.H.K. Spate (1960),
Ramchandran (1963),
F. Siddiqui (1967),
P. Sengupta (1968) and
R.I. Singh (1971).
In 1964, the Planning Commission divided the
country into fifteen regions and sixty-one sub-
regions.

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The classification was based on a variety of
criteria like topography, altitude, geological set
up, soil types, climate - especially rainfall and
temperature, pattern of land utilization,
intensity of irrigation and cropping pattern.
The objective of demarcating the regions was to
identify homogenous units for resource
development.

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Thus geographical cum agricultural regions of
India got systematically identified.
Taking into account the classification by the
Planning Commission the map on geo-
ecological regions has been prepared.

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Geo-ecological regions :
The following major regions have been
identified:
I.Western Himalaya - It covers Jammu &
Kashmir, Himachal Pradesh and Uttarakband.
Prominent crops are maize and fruits.
2.Eastern Himalaya - Sikkim, Himalayan West
Bengal, Arunachal Pradesh, foothills of north
Assam belong to this zone. Prominent crops are
maize, tea, rice and fruits.

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3.Northeastern Hills - Meghalaya, Nagaland,
Mizoram, Manipur, part of south Assam
(Cachar Hills) and Tripura are the concerned
areas. Major crops are rice, tea, fruits and
maize.
4.Brahmaputra, Tista and Barak valley -
Brahmaputra and Barak plains in Assam, plains
of Jalpaiguri and Kochbihar districts of West
Bengal. Important crops are tea and rice.

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5.Lower Ganga Plain - .It is the West Bengal
Plain. Predominant crop is rice.
6.Middle Ganga Plain - Bihar and eastern Uttar
Pradesh form this region. Predominant crops
are rice and wheat.
7.Upper Ganga Plain - The western Uttar
Pradesh forms this region. Prominent crops are
rice, wheat and sugarcane.

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8.Trans-Ganga Plain -
This region covers Punjab, Haryana, Delhi,
Ganganagar and Hanumangarh districts of
Rajasthan. Predominant crop is wheat.
9.Eastern Plateau & Hills - Jharkhand, Puruliya
and adjoining areas of West Bengal,
Chhattisgarh, interiors of Orissa, eastern parts
of Maharashtra, Shadol district of Madhya
Pradesh belong to this region.

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Predominant crops are millets and rice.
10.Central Plateau & Hills - The eastern
Madhya Pradesh, the eastern Rajasthan and
southwestern Uttar Pradesh form this region.
Predominant crops are millets, pulses and
wheat.

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11.Western Plateau & Hills - The southwestern
Madhya Pradesh and black soil area of
Maharashtra belong to this region. Predominant
crops are cotton and millets.
12.Southern Plateau & Hills - Interiors of the
states of Andhra Pradesh, Karnataka and Tamil
Nadu belong to this region. Predominant crops
are millets, cotton and groundnut.

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13.East Coast Plains and Hills - Coastal Orissa,
coastal Andhra Pradesh, coastal Tamil Nadu
and adjoining dissected hills of the Eastern
Ghats constitute this region. Predominant crop
is rice.
14.West Coast Plains & Ghats - The Konkan
and Malabar coasts and adjoining Western
Ghats form this agro-region. Predominant crops
are rice and coconut.

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15.Gujarat Plains and Hills- Gujarat and union
territories of Daman & Diu form this region.
Predominant crops are cotton and oilseeds.
16.Western Dry Areas - The western & west
central parts of Rajasthan form this region.
Predominant crops are millets.
17.Islands - Andaman & Nicobar Islands and
Lakshadweep belong to this region.
Predominant crops are coconut and rice.