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| OPINION |
The Sorrow Of Bihar : Kosi River By Dr. AB Thapa There are two rivers
in Asia, which were known in the past
as the rivers of sorrow. The Huang Ho
River in China , which is also called the Yellow River, was
known as the “Sorrow of China”.
Similarly, the Kosi River that flows from
Nepal to India was known as the “ Sorrow
of Bihar”. Both these two rivers were
named “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, as a result, it
does not anymore pose threat to people. The
Kosi still remains totally unregulated. At
present, the embankments built on both sides of
the Kosi few decades back have 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
southeastern Nepal. In the Past The Kosi river known as the river of sorrow
of the Bihar shifted from east to west over 12O km in the last 200 years. In the past
about 8000 sq. km. of lands had been laid waste because of the sand deposit. In course of
shifting, many towns and villages were wiped out, and heavy losses of property, cattle,
and human life were inflicted. Fortunately, the embankments built few decades ago
temporarily helped to check the lateral shifting of the Kosi. But at present the detention
basin upstream of the barrage at Hanumannagar is almost full of sediments. Soon the
embankments would be ineffective to control the Kosi floods. The Kosi river is now on the verge of
shifting to the east far away from its present course. The peoples of Nepal and India are
heading for a natural disaster of an unprecedented scale. But it appears that only
very few in Nepal and India have realized the extent of this danger. It
would be unfortunate if the Kosi swing to the east takes the life and property of millions
in South Asia by surprise while the governments of Nepal and
India would merely be silent spectator. Rise in Kosi River Bed
Level The Kosi River brings
every year an enormous quantity of sediments
from its catchments in the mountains. Sir
Claude Inglis an expert on Kosi had
attributed the shift of the Kosi River
channel to excessive sand load carried by
the river. Leopold and Maddock considering
Kosi behavior had stated that a braided
stream will tend to shift laterally at a
rate dependent on the rate of accumulation
of material being deposited. As one course
becomes higher than possible adjacent paths,
the river would shift. Data published in the
American Society of Civil Engineering in
March, 1966 indicate that in the period between
1938 and 1957 every year on an
average about 100 million cubic meters of
sediments used to be deposited on the
Kosi River bed. The maximum such deposition
was around Nirmali in India not far
away from the Hanumannagar. There was very big
change in sediment deposition pattern immediately
after the completion of the Kosi barrage
in 1963. The results of the Kosi River
channel study for post barrage period
have been published by V.C. Galgali,
Central Water and Power Research Station, Pune
(India), and Gohain & Prakash of Roorke University.
All the past studies confirm that the
Kosi River bed just upstream of the
barrage has significantly aggraded due
to sediment deposition. On account of ponding,
sediment deposition had occurred, flattening the
bed gradient. The bed slope of the
river in the pond area was abut 0.61 m per
km in the year 1956 prior to construction
of the barrage, which became flatter to
about 0.42 m per km in the year 1969,
ie in six years of the functioning
of the barrage. Studies were made to determine
the sediment deposition based on post
flood 1963 and 1970 surveys These studies
indicated that about 35 million cu.m. sediments
had deposited in the pond length
of about 10 km upstream of the barrage,
giving an average depth of about 0.4
m in about 8 years with a rate of
bed level rise at about 0.05 m per annum. Alarming Situation Few years after the
commissioning of the Kosi barrage there was
a big flood in 1968. A discharge of about
25,000 cumecs was recorded. The flood at that
time did not pose any serious threat. At
present the conditions might be altogether
different. It is said that whenever the
discharge exceeds 9,000 cumecs , which is fairly
common, the whole area between the embankments
is submerged. Such observations raise the fear
that a flood similar to 1968 flood in
magnitude could prove to be catastrophic. It
should be further remembered that the 1968
Kosi flood is not exceptionally rare. A
flood of this magnitude has already been
observed twice within the last 50 years.
Fortunately in course of the last 35 years
the maximum flood discharge of the Kosi
River has not exceeded 16,000 cumecs. Embankments Would be
Ineffective Embankments built a few
decades ago temporarily helped to check
the lateral shifting of the Kosi.
The detention basin upstream of the
Kosi barrage near Hanumannagar is
going to be very soon full. After
that the embankments would be ineffective
to prevent the lateral shifting of
the Kosi. It is predicted that the
Kosi would again take its 1732
course. The farthest position of the new course
of the Kosi is expected to be
about 120 km away from its present
course. The swing of the Kosi river to
the east could be sudden and almost
unexpected because nobody yet exactly knows
when it is going to happen. The people
would be completely taken by surprise. So
the loss of life could be very high.
In a similar type of 1938 flood incident
of the Yellow River in China the number
of people killed alone was about
half a million. It does not need to
be further explained that such shifting
of the Kosi to the east would be a
biggest disaster for the whole
region. Generally, the flood damages are
temporary in nature but the Kosi flood damages
would be widespread and also permanent in
nature. Mr. Shilling Feld an expert on Kosi,
has warned a longtime ago that the
eastward movement of the Kosi will be
in one big swing accompanied
with great loss of life and property. Resolving the Flood
Problem Provision of dams in the drainage area with
very big storage volume is the only lasting solution to the Kosi flood problem. It is the
opinion of the renowned experts and scientists involved on the Kosi study in the past. We
can draw such lesson from the past experience of China also. It can be concluded that
there are not any substitutes for the large storage dams to control the Kosi floods. Thus,
our only recourse is storage dam. The storage dams should be provided in time.
Unfortunately, some peoples in Nepal and India have misgivings about the Kosi dams. Such
misgivings are unfounded and they are often the result of present global disenchantment
with the high dams particularly for the generation of hydroelectricity. In case of the
Kosi dams this type of notion is completely misplaced. The life and property of too many
peoples in Nepal and India would be at great risk if the Kosi dams are not built in time. Learning to Live with
the Floods Some people in Nepal
and India have misgivings about storage
dams. They regard that we should learn to
live with the floods, therefore, it is not
necessary to build storage dams to
control the floods. The core issues often
raised against the flood control
embankments and dams in Kosi drainage area
do not appear to be realistic. Some
subscribe to the principle that the Kosi should
get back its original route to the
Ganga. One would certainly be at a great
loss to determine the original route of
the Kosi to the Ganga. The Kosi
route had shifted from east to west
over a distance of 120 kms in
the last 200 years. In almost all the
cases when there is surplus water in the
river, flooding results. It is a well known
phenomenon in hydraulic engineering.. The Elbe
and Rhine floods reported few years back in our
newspapers come under this category. The Yantze River
floods are also of similar nature. The flood
damages are not permanent in nature. Some
people try to attribute future Kosi
floods also to this type of
hydraulic phenomenon. Unfortunately, the Kosi flood
feared to wipe out in future
vast area of densely populated
lands in our region is altogether
different in nature. Unlike the above mentioned
floods in Europe and China, the Kosi
flood damages would be virtually permanent in
nature. The 1997 Indo-Nepal
Study Agreement In 1997 an agreement was signed between
Nepal and India to carry out feasibility studies of the Sun-Kosi project and the Kosi
project along with a navigation canal linking Nepal with the seaport. This agreement is a
substantial modification to the earlier understanding reached between the Prime ministers
of Nepal and India that covered only the Kosi high dam. The modification was made based on
the findings of Nepal explained to Indian side in the meeting. There is a very close
interrelationship between the Sun-Kosi and the Kosi projects. This interrelationship
required the inclusion of the Sun-Kosi dam project in the Kosi development. Even a simple
analysis of both these projects clearly illustrates the following points that help to
explain why the Sun-Kosi project should be built first, and as a
result, the feasibility study of the
Sun-Kosi Project had to be completed as
soon as possible. (a) The diversion of the Sun-Kosi river at Kurule is
the most important project of Nepal for agriculture development in near future. . It
can be said based on the Karnali feasibility
study that North Bihar would be getting
for free about 65% of the
water diverted from the Sun-Kosi reservoir for
irrigation in Nepal's Eastern Terai as
return flow. Moreover, the stored Sun-Kosi water diverted
in surplus to the need for irrigation in Nepal for generation of
power would also be freely available to irrigate vast area of lands in North
Bihar. This very important project would be precluded forever after the
completion of the construction of the Kosi high dam project. Fortunately, the Kosi
high dam project can be built even after the completion of the construction of the
Sun-Kosi high dam project. (b) The Kosi high dam along with a navigation canal to
link Nepal with seaport is a very big project. Needless to explain that navigation canal
would be extremely important for future development of Nepal as well as
North Bihar. It will take long time to implement this project. But the Kosi river is
on the verge of shifting to the east. The Sun-Kosi dam project could
control the Kosi floods in the interim period till the Kosi high dam is completed.
(c) Very serious downstream degradation problems could be expected to
arise after the completion of storage dam projects. It is due to release of clear
water from the reservoir in big quantity. Such acute degradation problem was observed in
Boulder dam of the USA. The river bed in the 77 mile canyon reach had been lowered between
6 and 14 feet. Owing to the exposure of rock ledges the river became stable. However, at
about 130 kilometers away, the riverbed rose by six metres necessitating the
construction of very expensive flood control structures. Similar phenomenon could be
expected after the completion of the Kosi high dam also. The Sun-Kosi high dam built to
control the floods in the interim period could help to reduce downstream degradation. It
could also help to determine with greater accuracy the volume of flood regulation storage. In Conclusion Mr. F.A. Shilling Feld, a
renowned expert on Kosi study, had made a
chilling forecast a long time ago “ The
westward movement of the Kosi oscillation (in
the past) is slow and is in a
series of steps, each of which is
attended with damage to property of temporary
nature. The eastward movement (in future) of
the oscillation will probably be accompanied
with great loss of life and property.”
It is hoped that the governments of Nepal
and India would take up the Kosi development
matters seriously. (Dr. Thapa writes on water
resources) |
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