200 billion annual flow is equal, on an average, to about 6,000 cubic metres of water per second. This is equal to the recorded low discharge of the Brahmaputra at Sirajganj in the month of April/May. The low flow discharge in the month of December, January, February and March is of the order of 3,000 to 5,000 cubic metres per second. It means that the Brahmaputra will have no flow in the river channel from December to April. In plain language it is clear that the Brahmaputra basin will turn into a desert with direct and peripheral adverse effects in the entire Padma and lower Meghna basins. The average withdrawal of 6,000 cubic metres per second is obviously expected to increase in the dry months in China which will aggravate the crisis as seasons in China and Bangladesh virtually coincide.

On the average the Brahmaputra contributes to more than 50 percent of the flow of all the rivers combined including the Ganges in Bangladesh. The runoff that will be generated in the Brahmaputra basin between China and Bangladesh will occur during the rainy season and will pass as flood flow with no contribution to the low flow as it will also be equally deprived of the low flow supply from China. The runoff that will be generated within Bangladesh is of the order of 8 percent which is comparatively insignificant. This 8 percent runoff is generated only during the rainy season and will flow through the channel as flood flow with a little or no contribution to the dry season flow.

The data used for the analysis may be updated and analysed and low flow studies may be further refined and revised. But still it would mean that the Brahmaputra channel will remain high and dry for nearly six months (Dec-May) of the year which will turn a major portion of the country into a dry desert. It is unimaginable and the result will be devastating and catastrophic. In the world standard a major international river like the Brahmaputra becoming dry is unthinkable. Obviously there will be adverse effects on agriculture, water supply, fishery, navigation, forestry and environment.

The Padma basin will suffer from low flow, with consequence of siltation and deposition of sediments and the lower Meghna basin will suffer from saline water intrusion, also siltation. As a result of the drastic withdrawal of waters from the Brahmaputra, river channels will be silted up and deposition of sediments will occur. This will severely increase flood and navigation problems. At present the massive upland flow through the lower Meghna keeps saline water intrusion pushed by the coast. Salinity intrusion survey was conducted by BWDB with UNFAO/SF hydrological survey in Bangladesh in the sixties in the SW region. Though saline water intrusion penetrated many kilometers upstream through the river channels in Khulna area, salinity stayed by the coast in Barisal and further east.

With withdrawal of 6,000 cubic metres of water per second (which is equal to 200,000 cubic feet per second) in the dry months, saline water intrusion through the lower Meghna channel and its branches, tributaries and distributaries and a maze of channels criss-crossing the coastal areas, is apprehended to be drastically increased. Though without a future real-life survey, it is difficult to determine and forecast how far precisely will the harmful saline water travel upstream, we may reasonably assume that up to Chandpur, even further upstream may be affected by harmful saline water intrusion. It will obviously seriously affect agriculture, fishery, drinking water, navigation, irrigation, forestry, ground water and overall environment of a vast area.

In addition, there will be adverse effects on the minor river system on both banks of the Brahmaputra distributaries and many connecting rivers, like the old Brahmaputra, Dhaleswari, Kaliganga, Sitalakhaya, Balu, Buriganga in the east and river Bangali, Karatoya in the west will turn dry. Hundreds of thousands of low lift pump irrigation projects of BADC and private enterprises will be drastically affected, in many places they will turn virtually non-existent. For that matter major irrigation projects like Chandpur, Meghna-Dhonagoda, Barisal, Dhaka, Demra and other medium and small irrigation projects on both banks will be affected.

For dry conditions in the Brahmaputra, more or less the whole country will be seriously affected hydrologically, ecologically, environmentally and economically. The active deltaic region will be affected by saline water intrusion while depletion of ground water levels will make shallow tubewells and drinking water tubewells and drugwells dry. Flora and fauna of the Sundarbans, including the famous Royal Bengal Tigers, will be severely affected.

The writer has the experience of river flow and salinity intrusion study in the SW region of Bangladesh in association with FAO/UNSF hydrological survey in the sixties. In late sixties and early seventies about 12,000 km2 of land was seriously affected by salinity intrusion through the river channels for drastic withdrawal of the waters of the Ganges upstream in the dry season. The effect might be more severe now as we learn from different sources, including alarming media concerns about the region. The above observations are based upon the writer's studies on rivers, their discharge and sedimentation, saline water intrusion etc. Some papers related to rivers, discharge and sedimentation were published in the proceedings of the several Annual Conventions of the Institute of Engineers and in the print media.

During his work with BWDB, Planning Commission, World Bank in Washington DC and elsewhere as a consultant the writer had gained experiences on rivers, high and low flow, flood control, irrigation dam design and construction, water supply and water development. Some notable names in the field of rivers', flood control, irrigation and water development and environment are former Professor of BUET, Dr. H.R. Khan and Dr. Ainun Nishat and Prof. MR Biswas of BAU and former PSC Member and Engineer M.A. Matin, former Director, BWDB, who can offer expert opinion on this matter of vital national importance.

The possibility of the Brahmaputra being dead is like a kind of death knell for the entire river system and may be a major catastrophy for Bangladesh. This impending man-made artificial multi-dimensional crisis must not happen. The Brahmaputra being a major international river there must be equitable sharing of waters among the riparian countries if such situation occurs. In any international river no unilateral intervention is acceptable. Any probable future dispute which may arise should be resolved by mature and amicable negotiations between the riparian countries co-inhabiting the common river basin.

The writer is a professor of civil engineering in the World University of Bangladesh, Dhaka.