Bihar’s Chief Minister And Kosi Problems

By DR. AB THAPA

Just sometimes back Bihar’s Chief Minister Mr. Nitish Kumar had spoken to Nepalese journalists about the close relationship that exists between the peoples of Bihar and Nepal which dates back to ancient period. Surely Nepalese people are very much touched by the warmth of his statement. In the interview with the Nepalese journalists he did not fail to mention about the Kosi flood problems. As a person solely involved to prepare the basic documents from the side of our Government “ Planning Kosi High Dam Project”, “ Kosi Canal Navigation”, “ Sun-Kosi Dam Project”, and in leading the Nepalese team in finalization of the 1997 Kosi Study Agreement with the Government of India I would like to draw the attention of the Government of Bihar to the following matters of the utmost concern to the peoples of Bihar and Nepal.

Kosi Flood Problem

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. 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 only few in Nepal and India appear to be concerned. Even the international agencies noted for their active role in studies of the environmental problems and water resources have not yet realized the extent of this danger. It would be unfortunate if the Kosi swings to the east taking the lives and properties of millions in South Asia by surprise while all of us will 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 Hanumannagar. There was very big change in sediment deposition pattern immediately after the completion of the Kosi barrage in 1963.

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 poundage, 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 a bed level rise at a rate of about 0.05 m per annum. in the pond length of about 10 km upstream of the barrage.

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.

Scale of Devastation

All the past and present studies and the very recent observations indicate that the Kosi is quickly turning into a hanging river and we are heading for an unprecedented flood disaster. Such flood disaster would not be just one time event. Like the Yellow river floods disaster in China in the past, the ferocious floods of Kosi would also be frequently hitting particularly the North Bihar wiping out towns and villages, and laying vast area of lands bare with sand deposits. The eastern and the southern boundaries of the flood-affected area could extend up to Mahananda river and the Ganges respectively. India 's railway and roadway linkages with her northeast states could also be severed. In a similar type of China 's Yellow river 's latest flooding in 1938 the number of persons killed alone was about half a million. After this flooding big storage dams were built to control the Yellow river floods. The river is now completely regulated. There are no more flood damages. It is stated in CHINA DAILY (October 16, 1998) that the Yellow river dams have helped to save flood damages as of now of about US $ 50 billions.

1997 Kosi Study Agreement

In course of the discussions to finalize the 1997 Kosi Study Agreement, the leader of the Indian team, Chairman, Central Water Commission of the Govt. of India, had expressed off the record that from now on they are fully convinced of the fact that the biggest benefit to accrue from the Kosi development would be the flood control Until that time the Indian Government was seen to be drifting away from the facts that it is absolutely indispensable to provide storage dams in the basin to prevent the Kosi flood disaster. The Indian Government was saying that the Kosi flood control problem has already been resolved after the completion of the construction of embankments on both sides of the Kosi River.

Immediate Intervention

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. However, the storage dams should be provided in time.

The Kosi Dam Project is expected to be perhaps the largest in the whole world in terms of the height of the dam and the total installed capacity of the power station if this project is to be planned to accrue benefits to the desired extent. We should beware of unintentional give-away in Kosi development. The optimum Kosi development should not be compromised. A less than optimum dam could preclude optimum development of the Kosi Dam Project for all time. As a result, it is going to take a very long time even to complete the detailed study of such a giant Kosi Dam Project. No wonder it took China more than 20 years just to complete the detailed study of the Three Gorges Project which can be considered to be more or less on a par with the proposed Kosi Dam Project in size and also in volume of investment.

The imminent danger of the Kosi floods to be triggered off by the sudden change of its course is too great to be ignored. Luckily, the implementation of the relatively small Sun-Kosi Storage Dam Project at the earliest could provide effective shield from the threat of the Kosi floods for about next 40 to 50 years. If future studies confirmed that there is room for doubt about the capacity of the Sun-Kosi Storage Reservoir alone to control the Kosi floods, we could also think of implementing the small Tamar-1 Storage Dam Project side by side with the Sun-Kosi Dam Project. Thus, we need not rush to implement in very near future the mammoth Kosi Dam Project which has been considered to be indispensable for the safety of life and property of millions in our region.

Sun-Kosi Irrigation Benefits to Bihar

Irrigation benefits to be accrued to Bihar from the use of the water diverted from the Sun-Kosi reservoir would be greater than such benefits to Nepal even if Bihar would be getting it for free. The feasibility study of the Karnali (Chisapani ) High Dam project carried out under the aegis of the World Bank provides a great deal of information on irrigation planning. They can be applied for planning irrigation from the Sun-Kosi Dam project. It can be said based on the Karnali feasibility study that India would be getting for free as return flow about 65% of the water diverted from the Sun-Kosi reservoir for irrigation in Nepal's Eastern Terai. Only about 35% of the diverted flow would be effectively used for irrigation in Nepal. Thus about 65% would return via surface and groundwater. Of the 65% returning, 15% could enter into deep subsurface aquifer, leaving 50% for return as surface water and shallow groundwater. The return flow from the Nepal Terai would drain back into innumerable small streams flowing from our country into India. They can easily be tapped in the Indian territory for irrigation. The canals provided to divert such surface return flow for irrigation could also be used to deliver underground return flow by providing tubewells for abstracting such underground water.

During winter season the ambient temperature is too low in our Terai as well as in North Bihar for the cultivation of crops like the paddy that requires application of maximum amount of water for irrigation. Usually crops like the wheat are grown that are less susceptible to low temperature. In case of wheat the water requirement is less than half of the paddy. The water diverted into Terai from the Sun-Kosi reservoir during winter season for the generation of electricity would thus be far in excess of our need for irrigation in Eastern Terai, and, as a result, such excess water would be freely available in Northern Bihar for bringing a vast area of lands under irrigated agriculture.

There can be a great deal of variations in cropping patterns adopted by the farmers in Nepal Terai and Bihar. It is often due to considerable differences in meteorological conditions. As a result, even for the same type of crops the maximum stress period for irrigation could advance ahead or go behind within a certain time range. The spreading of the peak water requirement for irrigation over a longer period would certainly help to increase the area of lands going to be irrigated in North-Bihar by the surplus Sun-Kosi water flowing out from Nepal across the border into India.

In Conclusion

It is very clear that the Sun-Kosi dam project should come ahead of the Kosi project, and sooner the Sun-Kosi project is completed the better it would be for millions of peoples in India and Nepal . The peoples of Nepal and India who have already sensed the danger of future Kosi floods would be very grateful if we decided to launch immediately the plan to undertake the construction of the Sun-Kosi Dam Project. Such move could be made, without waiting for the completion of the detailed feasibility report, primarily based on a swiftly prepared interim report. Such interim report updated from time to time as the feasibility study progresses could be used for preliminary discussions with the donor agencies, buyers of electricity and other concerned agencies.

(Dr. Thapa writes on water resources)