India can be divided into three main topographic regions; the Himalayan
mountain system, on the north; the Northern Plains, drained by the Indus, Ganges, and
Brahmaputra rivers in north-central India; and Peninsular India, in the south.
The HIMALAYAS form parts of India's borders with Pakistan, Afghanistan, and Tibet in the
west and with Nepal, Bhutan, and Tibet in the east. The region is topographically complex
and divided into prominent elongated valleys and mountain ranges. The highest mountains
are in the KARAKORAM RANGE, where more than 30 other peaks rise above 7,300 m (24,000 ft).
South of the Karakoram are the Great Himalayas, a range with extensive areas over 5,500 m
(18,000 ft); sandwiched between the two major ranges is the narrow valley of the Upper
Indus River. Southwest of the Great Himalayas and between them and the lower front ranges
of the mountain system is the 160-km (100-mi) long Vale of Kashmir, which is located on
the upper Jhelum River and focuses on the town of SRINAGAR. To the east, the mountains
form most of Sikkim and Arunachal Pradesh.
The Northern Plains are part of a vast lowland extending across the subcontinent from
Pakistan in the west to Bangladesh (formerly East Pakistan) in the east. The plains are
bordered on the north by the foothills of the Himalayas; south of the Bramaputra basin are
the Khasi Hills and Shillong Plateau; and south of the Indo-Gangetic Plain rise the
uplands of Peninsular India. In India, this lowland has a length of about 1,600 km (1,000
mi) from east to west and a width of about 320 km (200 mi). It is drained in the west by
the Beas and Sutlej rivers, which are tributaries of the Indus; in the east by the
Brahmaputra; and in the rest of India by the Ganges and its many tributaries and
distributaries. The Northern Plains are floored by alluvial deposits derived mainly from
the Himalayas and deposited over the lowland by the major rivers.
Peninsular India is geologically the oldest part of India. Ancient crystalline and
metamorphic rocks underlie most of the region, but basaltic lavas (igneous rocks) cover
parts of the DECCAN PLATEAU. Topographically, the surface of the peninsula is tilted down
toward the east and north, forming a belt of prominent uplands along the western edge.
These uplands, reaching more than 2,500 m (8,200 ft), include the Western Ghats (see
GHATS) and the Nilgiri Hills. The northern edge of the peninsula, although lower, is also
prominent and rises south of the Northern Plains to form the Aravalli Range in the west
and the jungle-covered Chota Nagpur Plateau in the east. Only a very narrow coastal plain
lies between the Western Ghats and the Arabian Sea; more extensive plains, including the
deltas of the Cauveri, Krishna, Mahanadi, and Damodar rivers, line the east coast.
Soils
The four principal soil types in India are mountain (or immature) soils, alluvial soils,
regur soils, and red soils. Mountain soils are found in upland areas too steep for regular
soil development; they range in texture from sandy in the drier Aravallis to clays in the
wetter Himalayas. Alluvial soils cover the broad floodplains of the Indo-Gangetic valley
and the Brahmaputra basin, the smaller river valleys and deltas of the peninsula, and the
coastal lowlands; these soils, ranging from sandy loams to clays, are generally fertile,
but are sometimes saline when improperly irrigated. The regur soils are rich, fertile
black soils found in the sections of the peninsula covered with basaltic lavas and also in
some eastern and southern regions. Red soils, which cover most of the peninsula, are less
fertile, as are patches of nutrient-deficient lateritic soils.
Climate
The Rajasthan Desert in northwestern India has a semiarid climate, but the majority of
India has a tropical monsoonal climate associated with a wind reversal between summer and
winter. In summer low-pressure areas develop over the subcontinent as the land heats up,
and summer monsoon winds are drawn onto the land from the surrounding seas. These
moisture-laden winds release heavy rainfall when they reach the coast or are forced to
rise over mountains; summers (mid-June to mid-September) are accordingly wet and hot, with
temperatures between 27 deg and 32 deg C (81 deg and 90 deg F). In winter high pressures
build over the land; winds then blow predominantly from the land to the sea, and winter in
India (mid-December to mid-March) is predominantly dry and cool, with temperatures
averaging 21 deg C (70 deg F). Two transitional seasons occur before and after the summer
rains. A hot and dry pre-monsoonal season lasts from mid-March to mid-June and is
associated with temperatures between 38 deg and 43 deg C (100 deg and 110 deg F). A
transitional post monsoonal season occurs as the monsoons retreat (mid-September to
mid-December) and is associated with light and sporadic rainfall and temperatures around
25 deg C (77 deg F). Cooler, more temperate conditions prevail in the Himalayas and
decrease with altitude.
Precipitation ranges from almost zero in the THAR desert to 10,870 mm (428 in) annually in
the Shillong Plateau, which is one of the wettest places in the world. Rainfall is
generally heaviest in coastal and highland areas and diminishes inland. Amounts vary
widely from year to year, especially in inland areas, and dry years often cause widespread
crop failures. Crop damage may also occur on a smaller scale in parts of eastern India
when "nor-westers" and Bay of Bengal cyclones strike the land, most often in May
and early June, in the form of tornadoes, whirlwinds, hailstorms, and heavy downpours.
Drainage
The principal river in India is the GANGES (Ganga), which rises in the Himalayas and flows
across the Northern Plains in a broad, meandering course to reach the sea at the Bay of
Bengal. Most of the Ganges reaches the sea through multiple distributaries in Bangladesh;
its principal distributary in India is the Hooghly River, which flows through Calcutta.
The major tributaries of the Ganges are the BRAHMAPUTRA, which joins the Ganges near its
mouth in Bangladesh, and the YAMUNA, Gogra, Gandak, and Kosi rivers. In northern India the
major drainage basin is that of the INDUS River; although most of this basin lies in
Pakistan, the headwaters of the Indus and two of its major tributaries, the SUTLEJ and the
Beas, are partly in India and are used heavily for irrigation. The principal rivers of
Peninsular India are the Chambal, Son, Mahanadi, Godavari, Krishna, Cauveri, Narmada, and
Tapi. Principal lakes include the Chilka, Kolleru, Pulicat, Lonar, Pushkar, and Wular. A
coastal swamp, the Sundarban, fringes the Ganges delta. The Rann of Kutch is a saline
swamp in northwestern India and southern Pakistan, off the Arabian Sea coast.
The annual regime of river flow in India is controlled by climatic conditions. Rivers
flowing from the Himalayas experience two high-water seasons, one in early summer caused
by snow melt in the mountains, and one in late summer caused by runoff from monsoonal
rains. Other rivers experience high waters only during the monsoon, followed by periods of
diminished flow, when many of the smaller rivers run dry. To counteract this marked
periodicity of river flow, groundwater wells and tube wells are widely used for irrigation
in the Northern Plains and peninsular delta regions; and many dams have been built on the
major rivers to regulate river flow and distribute water for an intricate system of
irrigation canals.
Vegetation and Animal Life
Seven vegetation regions are found in continental India, although the natural cover has
been modified by several millennia of human occupation. In the western Himalayas
vegetation changes with altitude from temperate deciduous forests at low elevations
through coniferous forests to Alpine vegetation above the tree line. The eastern Himalayas
have more extensive deciduous forest cover. In northeastern India, east of Bangladesh,
vegetation cover ranges from tropical evergreen in the wet lowlands to temperate deciduous
forest in drier and cooler areas. The semiarid Punjab-Rajasthan-Gujarat region mainly
supports scrub vegetation cover. In the heavily cultivated Ganges Plain, islands of
deciduous trees and tuft grasses remain among the agricultural fields. The peninsular
uplands support tropical monsoonal deciduous and scrub forest, while the wetter slopes of
the Western Ghats support a tropical monsoonal deciduous forest, with an evergreen cover
in some areas.
India's fauna includes about 500 species of mammals and more than 2,000 species of birds.
The elephant, Indian bison, rhinoceros, and tiger live mainly in the wet, forested
regions; the Himalayan markhor (ibex) and lion live in the Gir forest. Seven national
parks, 135 wild life sanctuaries, and 24 zoological parks are concerned with conservation
of wildlife.
Resources
India has a rich and varied mineral-resource base. Coal and iron ore are abundant and
located close to each other in the Chota Nagpur Plateau in the eastern peninsula.
Manganese, lignite, copper, bauxite, kyanite, fire clays, mica, and limestone are found in
large quantities. Petroleum occurs offshore from Bombay and in Assam and Gujarat, but is
not present in large amounts.
India also has vast land resources. Of the total land area, 20.5% is under forest; 41.6%
is sown with crops; 7.6% is left fallow; 3.9% is in permanent pasture; and 1.5% supports
permanent crops such as tea and fruit trees. Irrigation is of great importance to Indian
farmers. India has the potential to irrigate 1.07 million sq km (410,000 sq mi), but only
43% of this land is currently irrigated. Canals from the major rivers provide water to
40.9% of the irrigated area; wells provide water for 40.7%; and tanks provide water to
11.4%.
