Opinion (Spotlight Weekly)

Kosi Challenge And Planning Commission

By AB Thapa

The Kosi development has already emerged as the biggest challenge facing our country. Unfortunately we are not yet fully aware of it. The Kosi River is posing serious threat to life and property of millions in Nepal and India. Luckily this river can also provide a great opportunity for swift development of our country. Even after the partial completion of the Kosi development Nepal might be able within the next 10 to 12 years to supply abundant water to irrigate all the year round about 300,000 ha lands in our Eastern Terai, and also to generate about 5, 000 million KWh electricity at a rate of only about US $ 1/100 per KWh. After the full Kosi development, Nepal and Calcutta seaport would be directly linked by a canal waterway to be used for the transportation. Such waterway would open up new vistas of opportunities for rapid expansion of Nepal’s industry and commerce sector.

Past Sufferings of Nepalese

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 have been laid waste as a result 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.

All the elderly people living in the Saptari district not far away from the Kosi river would not have much difficulty to recall that some 50 years ago the channel of the Kosi river flowing across the Sunsari district from north to south was gradually shifting laterally from east to the west. The river was already quite close to Hanumannagar. It is reported that by that time the Kosi. River debouching into the Terai plain at Chatra and joining the Ganges River near Kursella in India had already laid waste about 500 square miles of lands in Nepal alone. People living in the eastern part of the Saptari district were panic stricken. They were leaving their ancestral homes in thousands to find shelter at safe places far away from their villages carrying with them whatever few things they could take with them. The headquarter of the Saptari district at Hanumannagar was swiftly moved to Rajbirag which was at a safe distance away from the Kosi River. Fortunately the shifting of the Kosi River course to the west was held in check by the embankments built on either side of the river some 50 years ago. Now all those who are involved in the Kosi River study are saying that the embankments built to protect the life and property of millions in India and Nepal might have already outlived their usefulness. What is going to happen the next? Every common man would be expecting to get an answer. Perhaps it is even more important to know why the Kosi River changes its course.

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.

Lack of Awareness

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 hardly anyone in Nepal appears to be concerned. Even the institutions like the ICIMOD noted for their role in studies of the environmental problems and water resources of Nepal have not yet realized the extent of this danger. There is absolutely no mention about it in the recently prepared water resources strategy report that has led great emphasis on water induced disaster mitigation. 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 National Planning Commission and other concerned government agencies would merely be silent spectator.

If the Kosi River changed it course to the east, the flood-affected area of the Kosi in the past estimated at about 8,000 sq. km could again be laid bare with sand deposits within a certain period by the combined effect of the Kosi floods that bring big quantity of sediments and the shifting of the main river course from one channel to another. The changing of the river course is the distinguishing feature of breaded rivers like the Kosi.

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.

National Planning Commission

So far the National Planning Commission appears to be completely unaware of the Kosi flood problems. Very recently Planning Commission even endorsed a plan to invite private developers to build the Dudh-Kosi storage dam project and the Lower Arun project. These two projects would have virtually precluded the plan to build storage dams to control the Kosi River. At present the top echelon of the National Planning Commission is composed of some of those persons who were at one time or other deeply involved in the study of the Nepal’s water resources. Everybody is expecting that from now on the National Planning Commission would be able to fulfill effectively its role to coordinate and if necessary even to guide various ministries and institutions in the implementations of the Kosi development plans.

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. This very important project for Nepal would be precluded for ever 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. It will take very 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 Needles, about 130 kilometers away, the river bed rose by 6 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 our National Planning Commission would take up the Kosi development matters seriously.