Opinion (Spotlight Weekly)

Debates On Saptakoshi Dam

By Dr. AB Thapa

It is heartening to learn that our country’s NGOs have started to take interest in Kosi High Dam Project. Unfortunately none of the NGOs are yet seen to be concerned about the disastrous consequences for our country, if our government allowed the foreign private developer to implement the West Seti High Dam Project without sorting out with India the downstream benefit issues and problem of submersion of a vast area of the Western Terai resulting from Saryu Canal, which is an extension of the West Seti High Dam Project. Nepal’s decision to allow private developer to build the West Seti High Dam without thoroughly examining the design of the dam could precipitate an unprecedented horrific disaster in our region. Private developer has proposed to build 195-meter high concrete faced rock filled dam ( CFRD) , which would be perhaps the highest dam of this type in the whole world. So far there is only one dam in the world close to the proposed West Seti Dam in height. It is the Aguamilpa dam with a height of 185.5 meters built in Mexico That dam has already developed serious technical problems.

It is reported in local newspapers that an NGO in Sunsari District “Mechi-Kali Media Society” had organized an interaction program to discuss possible merits and demerits of the Kosi High Dam. Needless to mention that such debates are extremely important for proper evaluation of any type of project. Thus “Mechi-Kali Media Society” has done a very good job. People in Eastern Nepal have a big stake in the Kosi Project. They should be correctly informed about true benefits as well as the harms the project would do to them..

Development Dilemma

Where ever we build big storage dam in Nepal, large area of populated lands are submerged. It cannot be avoided. It indeed is a great disadvantage in building storage dam. Mr. Paul D. Terrell, JR. from Bechtel International of the USA, who served as the leader of Advisor Team to the Karnali High Dam Project has rightly said in his article published in a local journal HIMAL: “ When you think of land as a commodity used by people, Nepal does not have too much of it. Snowfields and glaciers are not habitable, and much of the country is too steep and mountainous for terracing by the hill farmers. The only resource guaranteed to increase is the human population. The land is increasingly crowded even as the country struggles for self-sufficiency.” Mr. Terrell explains that Nepal would be facing dilemma because on the one hand, reservoir space is needed to harness the water; on the other, land covered by the most economic reservoir, in terms of large storage volume for small volume of dam, is the same precious flat land needed for agriculture. Unfortunately we are forced to build storage dams to regulate the Kosi River because life and property of millions in India and Nepal would be at great risk if these dams are not built in time. It is true that originally the Kosi Dam Project was conceived to save people in India from floods. It is not difficult to be convinced that people in Nepal too are already in great danger. Some of the speakers participating in the interaction program had compared dreadful effect of submergence by Kosi reservoir with recent Asian Tsunami Disaster that took the life of about 150,000 peoples in South and South-East Asian countries. Unfortunately only very few people know the disastrous consequences for Nepal and India if the Kosi dams are not built in time. We should not be surprised that the death-toll in the Kosi flood disaster in Nepal and India triggered by change in course of the Kosi would be comparable to similar Huango River flood disasters. These two rivers are regarded similar to one another in terms of ferocity to floods. In the past China used to be frequently hit by disastrous Huangho floods. It is reported in technical journals that the death toll in the latest Huangho flood that hit China in 1938 was about 500,000 (half million). Huangho flood problem was completely resolved after building storage dams to control that river. It would be prudent to hold debates to discuss this aspect of the Kosi problems also.

Cause of Kosi Danger

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 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. 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.

What Do Experts Say?

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.

Soon Kosi Disaster Could Strike

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 the 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, had warned a long time ago that the eastward movement of the Kosi would be in one big swing accompanied with great loss of life and property.

Resolving Kosi 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 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.

The 1997 Kosi Dams Study Agreement between Nepal and India emanated from the understandings that the Kosi River poses a grave threat to peoples of both India and Nepal. Now, there is a great need for wider participation of various agencies, institutions, individual experts particularly those operating in Nepal in the process to conduct the proposed Kosi study. It need not be stressed that the Kosi development is going to be a big engineering challenge. That apart, it is equally a big challenge to economists, industrialists, agriculture and transport planners who would be finding that the Kosi development would be opening up new vistas of opportunities for Nepal’s rapid socio-economic development.

(Dr. Thapa writes on water resources)