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The
country's rivers are classified as Himalayan, peninsular,
coastal, and inland-drainage basin rivers. Himalayan
rivers are snow fed and maintain a high to medium
rate of flow throughout the year. The heavy annual
average rainfall levels in the Himalayan catchment
areas further add to their rates of flow. During the
monsoon months of June to September, the catchment
areas are prone to flooding. The volume of the rain-fed
peninsular rivers also increases. Coastal streams,
especially in the west, are short and episodic. Rivers
of the inland system, centered in western Rajasthan
state, are few and frequently disappear in years of
scant rainfall. The majority of the South Asia's major
rivers flow through broad, shallow valleys and drain
into the Bay of Bengal.
The
Ganga River basin, India's largest, includes approximately
25 percent of the nation's area; it is bounded by
the Himalayas in the north and the Vindhya Range to
the south. The Ganga has its source in the glaciers
of the Greater Himalayas, which form the frontier
between India and Tibet in northwestern Uttar Pradesh.
Many Indians believe that the legendary source of
the Ganga, and several other important Asian rivers,
lies in the sacred Mapam Yumco Lake (known to the
Indians as Manasarowar Lake) of western Tibet located
approximately 75 kilometers northeast of the India-China-Nepal
tripoint. In the northern part of the Ganga River
basin, practically all of the tributaries of the Ganga
are perennial streams. However, in the southern part,
located in the states of Rajasthan and Madhya Pradesh,
many of the tributaries are not perennial.
The Brahmaputra has the greatest volume
of water of all the rivers in India because of heavy
annual rainfall levels in its catchment basin. At
Dibrugarh the annual rainfall averages 2,800 millimeters,
and at Shillong it averages 2,430 millimeters. Rising
in Tibet, the Brahmaputra flows south into Arunachal
Pradesh after breaking through the Great Himalayan
Range and dropping rapidly in elevation. It continues
to fall through gorges impassable by man in Arunachal
Pradesh until finally entering the Assam Valley where
it meanders westward on its way to joining the Ganga
in Bangladesh.
The Mahanadi, rising in the state
of Madhya Pradesh, is an important river in the state
of Orissa. In the upper drainage basin of the Mahanadi,
which is centered on the Chhattisgarh Plain, periodic
droughts contrast with the situation in the delta
region where floods may damage the crops in what is
known as the rice bowl of Orissa. Hirakud Dam, constructed
in the middle reaches of the Mahanadi, has helped
in alleviating these adverse effects by creating a
reservoir.
The source of the Godavari is northeast
of Bombay (Mumbai in the local Marathi language) in
the state of Maharashtra, and the river follows a
southeasterly course for 1,400 kilometers to its mouth
on the Andhra Pradesh coast. The Godavari River basin
area is second in size only to the Ganga; its delta
on the east coast is also one of the country's main
rice-growing areas. It is known as the "Ganga
of the South," but its discharge, despite the
large catchment area, is moderate because of the medium
levels of annual rainfall, for example, about 700
millimeters at Nasik and 1,000 millimeters at Nizamabad.
The Krishna rises in the Western Ghats
and flows east into the Bay of Bengal. It has a poor
flow because of low levels of rainfall in its catchment
area--660 millimeters annually at Pune. Despite its
low discharge, the Krishna is the third longest river
in India.
The source of the Kaveri is in the
state of Karnataka, and the river flows southeastward.
The waters of the river have been a source of irrigation
since antiquity; in the early 1990s, an estimated
95 percent of the Kaveri was diverted for agricultural
use before emptying into the Bay of Bengal. The delta
of the Kaveri is so mature that the main river has
almost lost its link with the sea, as the Kollidam,
the distributary of the Kaveri, bears most of the
flow.
The Narmada and the Tapti are the
only major rivers that flow into the Arabian Sea.
The Narmada rises in Madhya Pradesh and crosses the
state, passing swiftly through a narrow valley between
the Vindhya Range and spurs of the Satpura Range.
It flows into the Gulf of Khambhat (or Cambay). The
shorter Tapti follows a generally parallel course,
between eighty kilometers and 160 kilometers to the
south of the Narmada, flowing through the states of
Maharashtra and Gujarat on its way into the Gulf of
Khambhat.
Harnessing
the waters of the major rivers that flow from the
Himalayas is an issue of great concern in Nepal, India,
and Bangladesh. Issues of flood control, drought prevention,
hydroelectric power generation, job creation, and
environmental quality--but also traditional lifestyles
and cultural continuities--are at stake as these countries
grapple with the political realities, both domestic
and international, of altering the flow of the Ganga
and Brahmaputra. Although India, Nepal, and Bangladesh
seek to alleviate problems through cooperation over
Himalayan rivers, irrigation projects altering the
flow of Punjab-area rivers are likely to continue
to be an irritant between India and Pakistan--countries
between which cooperation is less likely to occur--in
the second half of the 1990s. Internally, large dam
projects, such as one on the Narmada River, are also
controversial.
