NepalThe River System
Figure 5. Topography and Drainage
Nepal can be divided into three major river systems
from east
to west: the Kosi River, the Narayani River (India's
Gandak River),
and the Karnali River
(see
fig. 5). All ultimately become
major
tributaries of the Ganges River in northern India. After
plunging
through deep gorges, these rivers deposit their heavy
sediments and
debris on the plains, thereby nurturing them and renewing
their
alluvial soil fertility. Once they reach the Tarai Region,
they
often overflow their banks onto wide floodplains during
the summer
monsoon season, periodically shifting their courses.
Besides
providing fertile alluvial soil, the backbone of the
agrarian
economy, these rivers present great possibilities for
hydroelectric
and irrigation development. India managed to exploit this
resource
by building massive dams on the Kosi and Narayani rivers
inside the
Nepal border, known, respectively, as the Kosi and Gandak
projects
(see Energy
, ch. 3). None of these river systems, however,
support
any significant commercial navigation facility. Rather,
the deep
gorges formed by the rivers represent immense obstacles to
establishing the broad transport and communication
networks needed
to develop an integrated national economy. As a result,
the economy
in Nepal has remained fragmented. Because Nepal's rivers
have not
been harnessed for transportation, most settlements in the
Hill and
Mountain regions remain isolated from each other. As of
1991,
trails remained the primary transportation routes in the
hills.
The eastern part of the country is drained by the Kosi
River,
which has seven tributaries. It is locally known as the
Sapt Kosi,
which means seven Kosi rivers (Tamur, Likhu Khola, Dudh,
Sun,
Indrawati, Tama, and Arun). The principal tributary is the
Arun,
which rises about 150 kilometers inside the Tibetan
Plateau. The
Narayani River drains the central part of Nepal and also
has seven
major tributaries (Daraudi, Seti, Madi, Kali, Marsyandi,
Budhi, and
Trisuli). The Kali, which flows between the Dhaulagiri
Himal and
the Annapurna Himal (Himal is the Nepali variation of the
Sanskrit
word Himalaya), is the main river of this drainage
system.
The river system draining the western part of Nepal is the
Karnali.
Its three immediate tributaries are the Bheri, Seti, and
Karnali
rivers, the latter being the major one. The Maha Kali,
which also
is known as the Kali and which flows along the Nepal-India
border
on the west side, and the Rapti River also are considered
tributaries of the Karnali.
Data as of September 1991
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