1. 2nd
International Conference on Emerging Trends in Engineering & Technology, April 12-13, 2013
College of Engineering, Teerthanker Mahaveer University.
River Kosi, Sorrow of India: An overview
Mohd Danish1
, Priyank Gupta1
, Dr. Javed Alam2
, Prof. Mohd. Muzammil3
The Kosi River which is one of the largest tributaries of the river Ganges is infamous for floods, thus causes huge
losses in terms of both life and property. India, after Bangladesh, is the second in the world in loss due to floods,
thus accounting for one-fifth of the deaths due to floods, globally. The Kosi River is considered as the sorrow of
Bihar. It is one of the two major tributaries of the river Ganges(the other river being Gandak) draining the plains of
north Bihar. Despite a long history of flood control management in the basin for more than 5 decades, this River
continues to bring a lot of misery through extensive flooding. Meandering is another bizarre behaviour of this river
which have shifted laterally about 112 km westward in the last 250 years. Due to this, the river which previously
flowed near Purnea in the 18th century is now flowing to the west of Saharsa. The meandering behaviour of the Kosi
River has wasted an area of about 1,295 Sq. Km of land in Nepal and about 7,770 Sq. Km of land in Bihar, resulting
in sand deposition. This wasted land was considered as the garden of Bihar and it was renowned for its rice-field and
orchards. In the course of shifting it has wiped out many towns and villages inflicting heavy losses of human, cattle
life and property. The present paper presents an overview of the behaviour of River Kosi and its shifting pattern in
its total reach with a focus on the structural and non-structural works carried out in this connection so far.
Keywords: Kosi River, The Ganges, Watershed, Meandering
1. Introduction
India is seventh largest country with geographical area
32,87,263 km2
(2.45% of the World’s land resources)
and the second most populous country with over 1.2
billion people (17.5 % of the World’s population) and it
holds 4% of the world’s fresh water resources [1].
Rivers in India are not only considered as a source of
water but also it has been worshipped from centuries.
The major river systems in India are Indus,
Brahmaputra, Ganga, Yamuna, Narmada, Tapti,
Godavari, Krishna, Cauvery and Mahanadi. The Ganges
is the second largest river in the world in terms of water
discharge and the Ganga-Brahmaputra river system
forms the largest delta in the world, known as
Sunderban. These are two of the various reasons for
which Indian rivers are famous in the World. The
Ganges has many tributaries and Kosi River is one of
them. Kosi river has been the centre of attraction for
India for several years due to various reasons, primarily,
due to floods. Several researches have been done to
control this river and several techniques have also been
proposed and implemented but the Kosi has continued
to haunt common people every year.
1. M. Tech. Student, Department of Civil Engineering,
Aligarh Muslim University, Aligarh, India. Email:
erdanish.amu@gmail.com , Email: priyank9092@gmail.com
2. Associate Professor, Department of Civil Engineering,
Aligarh Muslim University, Aligarh, India. Email:
javed_alig2000@yahoo.co.in , mob: +91-9837169427
3. Professor, Department of Civil Engineering, Aligarh
Muslim University, Aligarh, India.
Nayak [2] has studied the sediment management in Kosi
to control the river. Sinha et. al. [3] studied the flooding
problem in the Kosi river basin and presents an in-depth
analysis of flood hydrology. They also integrated the
hydrological analysis with a GIS-based flood risk
mapping in parts of the basin.
2. Origin of Kosi River
The Kosi River flows between the boundary of Nepal
and India and it is one of the largest tributaries of the
Ganges. The river along with its tributaries drains a total
area of 69,300 km2
up to its confluence with the Ganges
in India. This also includes parts of Tibet, Mount
Everest region and the eastern third of Nepal. The river
basin is surrounded by the ridges separating it from the
Brahmaputra in the north, the Gandak in the west, the
Mahanadi in the east and the Ganges in the south. Fig. 1
shows the satellite view of the Kosi River showing its
origin from Nepal flowing into India along its path.
3. Problems caused by the Kosi River
Kosi River has caused many problems to the common
people and to the country morale. These are discussed in
the following sections.
3.1. Meandering of River
A river that winds a course not in a straight line but in a
sinusoidal pattern is called a meandering river. Its
continued action of secondary flow developed on the
river bends that cause further erosion on the outer bank
and deposition on the inner bank. The meandering
action increases the length of the river and tends to

2. 2nd
International Conference on Emerging Trends in Engineering & Technology, April 12-13, 2013
College of Engineering, Teerthanker Mahaveer University.
change its slope. Geometric features of meandering is
shown in fig. 2
Fig. 1 Satellite view of the Kosi River (source: Google
Map)
The Kosi River have shifted laterally about 112 km
westward in the last 250 years. Due to this, the river
which previously flowed near Purnea in the 18th century
is now flowing to the west of Saharsa. The meandering
behaviour of the Kosi River has wasted an area of about
1,295 Sq. Km of land in Nepal and about 7,770 Sq. Km
of land in Bihar, resulting in sand deposition.
3.1.1.Theory of meandering
Several theories have been postulated to define the
reason of meandering of rivers, they are summarised as
follows:
3.1.1.1. Earth’s rotation theory
Gilbert [4] and Neu [5] concluded that the shifting of
river is mainly due the rotation of the earth but Quraishy
[6] has found that the tendency of the stream to shifting
of rivers to either left or right may be due to the erosion
of the bank material whereas the force due to earth’s
rotation is very small to cause this shifting
3.1.1.2. Disturbance theories
According to this theory [7], the disturbance caused by
various factors in a straight channel travels downstream
in such a way that it induce change in the flow pattern of
the river.
Fig. 2 Geometric features of a Meander (source:
http://hydrotopics.wordpress.com/2010/10/05/how-
and-why-rivers-meander/).
3.1.1.3. Helicoidal-flow theories
Many investigators have found by various studies that
the meandering of the river is a result of helicoidal flow
or secondary flow.
3.1.1.4. Excess energy theory
Several investigators have postulated that the energy
content of the river is responsible for the meandering
pattern of the river. Inglis [8] states that “meandering is
nature’s way of damping out excess energy during a
wide range of varying flow conditions, the pattern
depending upon the grade of material, the relation
between the discharge and charge and the rate of change
of discharge and charge”.
It may be concluded here that meander results from the
processes of erosion and deposition in alluvial rivers but
there is no explanation as to why meanders also form on
glaciers in the absence of sediment.
3.1.2. Lateral migration
Some alluvial streams have been observed to undergo
lateral migration over a period of years. In general,
larger streams seem to have larger rates of migration.
Such changes have been found to occur in Yellow River
in China and Kosi River in India. Table 1 gives the
average rates of migration of the Kosi River from 1736
to 1950. The flow pattern of Kosi River during different
period of years (as shown in fig. 3) clearly indicates the
westward movement of the river. In this region, ground
also has a transverse slope towards the west. Thus it
may also be concluded that the westward movement
may be due to the prevalent transverse slope of the

3. 2nd
International Conference on Emerging Trends in Engineering & Technology, April 12-13, 2013
College of Engineering, Teerthanker Mahaveer University.
country. Neil and John [9] studied the shifting of Kosi
River and concluded that its shifting is unidirectional.
When alluvial channels flow at right angles to the
contours, they have the greatest possible slopes. Hence,
if they continue to flow in this manner they may have
the greater tendency to erode and enlarge their channels
thereby relatively free from the problem of lateral
migration [10].
Table: 1 Average Rates of Migration of the Kosi
River [11]
Year
Period of
Movement in
years
Approx.
distance moved
in km
Rate
(km/yr)
1736-
1770
34 10.8 0.32
1770-
1823
53 9.3 0.18
1823-
1856
33 6.1 0.18
1856-
1883
27 12.9 0.48
1883-
1907
24 18.5 0.77
1907-
1922
15 10.9 0.73
1922-
1933
11 29.0 2.63
1933-
1950
17 17.7 1.04
Fig. 3 Different Course of Kosi river (source: Gole
and Chitale 1966)
The Kosi River has shifted laterally about 112 km
westward in the last 250 years which is one of the major
problems caused by this river. A satellite picture
showing various migrations undergone by the Kosi is
given in fig. 4.
Fig. 4 satellite picture showing various migrations
undergone by the Kosi (source:
ponce.tv/kosi_river_india.html)
3.1.3. Cutoffs
The meanders in an alluvial stream move gradually
towards the downstream, during this there is a gradual
increment in the length of the meanders which causes
lateral movement to the meanders that can be checked
by increased frictional losses and bank resistance. When
the bend and the bank resistance becomes too large for
continued stretching of loop it becomes easier for the
flow to cut across the neck than to flow along the bend
which results in a cutoff as shown in fig. 5.
3.2. Floods
Flood is the main cause of misery for the people of India
in general and for Bihar in particular. On August 18
2008, Kosi River burst out after heavy rainfall and
flooded half of Bihar, wiping out villages, farms and
leaving millions of people homeless or dead. The impact
of flood on the people of Bihar after August 2008 flood
is shown in Fig. 6.

4. 2nd
International Conference on Emerging Trends in Engineering & Technology, April 12-13, 2013
College of Engineering, Teerthanker Mahaveer University.
Fig. 5 Aerial view of a cutoff (source:
ponce.tv/kosi_river_india.html)
The New York Times reported that it is the worst flood
in the area in 50 years, prompting Prime Minister Dr.
Manmohan Singh to declare a “National Calamity” on
28 August. The Government earmarked $230 million in
aid for the region. The Indian Army, National Disaster
Response Force (NDRF) and NGOs operated the biggest
flood rescue operation in India in more than 50 years.
Fig. 7 Impact of flood (source: www.ssvk.org)
Death tolls rose from Indian Flood as more than 65
people had been killed in monsoon rains. Villagers ate
raw rice and flour mixed with polluted water in Bihar,
amid hunger and diseases. Supal District was worst hit
by floods and surging water swamped 1000 km2
of farm
lands, destroying wheat and paddycrops.
4. River of Sorrow
The two rivers in Asia, which are known as the rivers of
sorrow are namely Huang Ho in China and Kosi in
India, both are called as sorrow of China and sorrow of
India respectively. Both the rivers are named as “River
of Sorrow” because they had caused widespread human
suffering in the past. At present, the Kosi and the
Yellow River have nothing in common. The Yellow
River is already completely controlled and hence it does
not pose any threat to people. The Kosi still remains
totally unregulated. At present, the embankments built
on both sides of the Kosi temporarily helped to control
this river. It is feared that very soon the Kosi would
abandon its present course triggering off a new cycle of
damages and destructions. After such incident, the Kosi
might not anymore be only the sorrow of Bihar. It could
be the sorrow of the West Bengal and Bangladesh apart
from the terrible havoc the Kosi floods could be playing
with the safety of people in south-eastern Nepal.
5. Conclusion
The nexus of Bihar flood is the Kosi River’s immense
alluvial fan, extending some 180 Km from the river’s
exit from the Himalayas and foothills in Nepal, down to
its confluence with the Ganges in Bihar. The laws of
geology and physics cause rivers to course back and
forth across such fans. The .Problems posed by the Kosi
are due to meandering and its westward shifting and can
be controlled by constructing a dam on the upstream i.e.
in Nepal so that a controlled volume can be released
downstream.
References
[1] Govt. of India, Ministry of Water Resources, “River
Basin Atlas of India”, October 2012.
[2] Nayak J. N., “Sediment Management of the Kosi River
in Nepal”, IAHS Publ. no. 236, July 1996.
[3] Sinha R. et. al. “Flood Risk Analysis in the Kosi River
Basin, North Bihar Using Multi-Parametric Approach
of Analytical Hierarchy Process (AHP)”, J. Indian Soc.
Remote Sens. vol. 36, p.293–307, December 2008.
[4] Gilbert G.K. “The sufficiency of terrestrial rotation for
the deflection of streams”, Nat. Acad. Of Sci., Vol. 3,
1884.
[5] Neu, H.A. “Transverse Flow in a river Due to Earth’s
Rotation”, JHD, Proc. ASCE, Vol. 93, No. HY-5,
September 1967.

5. 2nd
International Conference on Emerging Trends in Engineering & Technology, April 12-13, 2013
College of Engineering, Teerthanker Mahaveer University.
[6] Quraishy, M.S. “River Meandering and Earth’s
Rotation”, Current Science, October 1943.
[7] Garde R.J., Ranga Raju K.G. “Mechanics of Sediment
Transportation and Alluvial Streams Problems”, Third
Edition, New age International Publisher, 2000.
[8] Inglis, C.C. “The Behaviour and Control of rivers and
Canals (with Aid of models)”, pt. I, CWINRS,
Research Publication No. 13, 1949.
[9] Neil A. W John A. D, “Shifting of the Kosi River,
northern India”,v 15 no. 3, p. 204-207, March 1987.
[10] Lane E.W. “Studies on the Problem of the Control of
the Kosi River”, Cyclostyled Memoranda USBR No. 1
and 2, July and August 1954.
[11] Gole, C.V. and S.V. Chitale “Inland Delta Building
activity of Kosi River”, JHD Proc. ASCE, Vol.92, No.
HY-2, March 1966.