DHAKA, Oct 28 - Prof Ainun Nishat, a towering figure in the area of water resources management and climate change adaptation in Bangladesh, who is also a key member of the Climate Change Negotiation Team of Bangladesh at the United Nations Climate Change Conferences, is of the opinion that dredging of the Brahmaputra, which is known as the Jamuna in Bangladesh, will remain an impractical proposition if the other components to manage the river are not worked out.
Dredging is an ancillary work, the other components are much more important, he asserted.
Also a former Vice Chancellor of the private sector BRAC University, Dhaka, Prof Nishat, who is presently serving the BRAC University as a Professor Emeritus in its Centre for Climate Change and Environmental Research (C3ER), was a member of the Indo-Bangladesh Joint River Commission and played a vital role in the Ganges Water Treaty Negotiations finalised in 1996.
Talking to this correspondent here, Prof Nishat said if the other components are not worked out, the dredged portion of the river would be filled up by the river itself within two years� time. One needs to do the mathematical modelling, physical modelling, etc, taking into consideration all the aspects like the technical and social ones in this
connection. And, for that purpose, data of at least 30 years concerning the river are to be studied scrupulously, he asserted.
Geologically, the Brahmaputra and the Jamuna are �very very young� rivers and hence they must be handled carefully. One should not dare to tinker with these rivers. The Jamuna is carrying one billion tones of sediment every year in Bangladesh. �We can train this river to make it flow through a narrow course. But, at the same time, we need to go for watershed management, riverbank protection, etc, keeping in mind that the river wants to have a meandering channel,� said Prof Nishat.
A river wants to keep a balance in its trajectory in keeping with its bed level and sediment load. In the aftermath of the 1950 earthquake, the slope of the Brahmaputra went up and thus its sediment load also increased. The Brahmaputra needs the sediment to do the balancing act.
It is pertinent to mention here that braiding in the course of a river occurs when it gets a steep slope and its sediment load also becomes high. In the case of the Brahmaputra or the Jamuna, these are their intrinsic characteristics. Moreover, a river does not want to flow in a straight line, said Professor Nishat emphatically.
The Brahmaputra is changing its geomorphology over the past 60 years. It can possibly be attributed to the 1950 quake, when its bed rose by two metres in Guwahati. Depth and width of a river are interchanging. Its slope determines its energy. The sediment load of a river is also important in determining its flow pattern. Prior to the 1950 earthquake, on an average, the Brahmaputra was around four to five kilometres wide. But now, it is 14 to 15 km wide at places, maintained the expert.
On top of all these, this is also a fact that if a river is given the freedom, it becomes wide. Till 1965, the Brahmaputra was managed for navigational purpose. But after 1965, nobody is managing this river. And since then, the river started widening. Till 1987, the Jamuna was about four-km wide at Bhuyanpur, though in the upstream area of Sirajganj it was around 12 km wide. Now, the river is controlled and it is about 12 km wide at Sirajganj and 4.8 km wide at the Bangabandhu Setu point in Bangladesh, the noted water resources expert said.
