In the present case, Nepal's northern boundary has been shown as the Brahmaputra river, and that of Bangladesh near Kushtia as the Jamuna! The proposed Yarlung-Tsangpo Dam is located on the mid-northern Nepalese boundary with Tibet (China).

In fact, the proposed dam is going to be at Namcha Barwa in the eastern Tibetan plateau, having no link whatsoever with Nepal's international border with China. Having said so, the following piece may give the current situation on the proposed dam.

The Tsangpo-Brahmaputra river
The Tsangpo River originating in the western Tibetan plateau runs east then, bending acutely around a mountain knot called the Namcha Barwa, enters northeast Arunachal Pradesh as Siang, flowing south for a brief stretch, and then flows southwest into the Assam valley as the Brahmaputra.

In its upper part, the river system passes through one of the longest and deepest canyons in the world. It enters Bangladesh near Rajibpur Upazila in Kurigram district and flows south retaining this name, but as it departs its old course as the Old Brhamaputra near Dewanganj (Jamalpur) it is known as the Jamuna.

Owing to the extremely active geodynamic condition of the terrain, characterized by frequent earthquakes, even a slight interference with the ecological-geological balance can initiate an enormous environmental change. It is in this set-up that a giant dam, expected to be the biggest plant ever made in the world, is to be constructed near the Namcha Barwa by the Chinese, within a few years.

It is expected that the dam will generate 40 million kilowatts per hour of hydroelectricity (double the Three Gorges Dam over the Yangtse) once its 26 turbines begin operation. The electricity produced could be exported to India, Bangladesh and Myanmar. In China, the diverted water would irrigate the northwestern part of the Gobi desert in Xinjiang and Gansu provinces of the country, aiming at crop production, and ease overpopulation in the east.

The dam
The Chinese Academy of Engineering Physics asserts "we can certainly accomplish this project with nuclear explosives." Its chief planner, Professor Chen Chuanyu, described the plan to drill a 15 km tunnel through the Himalayas to divert the water before the U-turn (at Namcha Barwa) and direct it to the end of the bend.

This would shorten the approximately 3,000 meters altitude drop, from 100 km to just 15 km. The hydropower potential could be used to pump water to northwest China over 800 km away. This multi-billion dollar project is scheduled to begin in 2009.

The environmental and socio-economic consequences of this dam, and the diversion of water to northwestern China, are multiple and far reaching, not only for the Tibet region but also for India and Bangladesh.

India and Bangladesh would be at the mercy of China for release of adequate amount of water during the dry season (as has happened to Bangladesh with the Farakka dam on the Ganges), and for protection from floods during the rainy season. Precipitation in northern India (particularly in Assam-Meghalaya region) and Bangladesh is very high (80%) during the monsoonal months of June to December, and low (2%) during the remaining months of the year.

China, in her own interests, could withhold water for power generation and irrigation during the dry season and release water during the rainy season, with catastrophic consequences for the lower-riparian countries. Further, this whole region would be starved of nutrient-rich sediments that enrich the soil, but which would be held up in the reservoir instead of reaching the downstream GBM delta.

Further, if the Tsangpo project is implemented a large part of the RLP of India would become redundant, and perhaps the most serious environmental disaster could ensue as this area is located in a highly active earthquake prone zone where breaching of the dam could cause devastating floods both in China and Indo - Bangladesh.

However, Chinese scientists hold that this dam would alleviate floods and erosion in the Brahmaputra. But this makes little sense, since flooding could actually get worse due to relentless silting which, will be accelerated by the slowing down (reduced velocity) of the river flow.

It may be noted that flooding normally happens not as much because of snow-melt waters in the Tsango section, but more from the monsoon rains from the southern side of the Himalayas carried down by the tributaries.

On the other hand, Assam uses little water for irrigation purposes, and there is no commercial navigation in this section of the Brahmaputra in India. Therefore, Assam's economy might not be affected in any marked way, but the economy of Bangladesh would be affected very badly because its agriculture and inland water transportation are very much dependent upon the sustainable flow of the Brahmaputra. Bangladesh has reasons to be concerned about the Chinese design about the Tsangpo.

In view of the above, there are still options for a solution by the concerned countries by taking the matter to the negotiating table. If a river water treaty could be signed between India and Pakistan despite their hostile relationship, in the early 1960s, a similar agreement can be negotiated between China, India and Bangladesh in order to ensure an environment friendly solution as well as sustainable futuristic regional development of the co-riparian countries.

Dr. K. M. Elahi is Professor and Chairman, Dept. of Environmental Science, Stamford University.