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Channelising Brahmaputra can tackle erosion

By AJit patowary

GUWAHATI, June 18 � A concept paper drafted for development and application of sustainable river management options for the Brahmaputra as part of a European Commission (EU)-sponsored project, laid stress on channelising the Brahmaputra to mitigate bank erosion and reclaim new land, basing on comprehensive analysis. It has also proposed gradual reduction in the braiding tendency of the river by adopting new training measures.

Prof Wolfgang Albert Flugel of Friedrich-Schiller University, Germany and Prof Nayan Sharma of the IIT, Rorkee have drafted this concept paper. The project concept was developed by both Prof Flugel (not Slugel as was mentioned on an earlier occasion) and Prof Sharma as the second part of the European Commission-sponsored BRAHMATWINN project, carried out between June 2006 and December 2009.

It has significantly laid stress on taking into consideration the impact of climate change on the hydrological and hydraulic dynamics of the Brahmaputra river while developing mitigation management strategies regarding the process of flooding and bank erosion.

From respective studies carried out in the BRAHMTWINN project, it is evident that rising temperatures and changing precipitation pattern will likely impact river basin water balances and related discharge volumes in terms of surface runoff, interflow, groundwater recharge and seepage to the river. This will affect the generation of floods during the summer monsoon season and low flow during the dry winter respectively, observed Prof Flugel and Prof Sharma.

It needs mention here that Chief Minister Tarun Gogoi said at a recent press conference that the core group of experts proposed by the State Government in its bid to solve the problems of flood and erosion, would include both Prof Flugel and Prof Sharma, besides others.

Along the Brahmaputra River, more than 4, 200 square kilometers of productive farm land in Assam were eroded within the last 40 years, about 0.9 million people, mainly poor smallholders and their families, lost their land and were left homeless and in poverty. By losing their land they also lost their social identity and backup within the rural community.

Total economic losses directly and indirectly caused by bank erosion, although difficult to quantify in their economic and social impacts in detail, were estimated in the range of billions of Euro.

Consequent sedimentation of the leached sand along its banks and within the riverbed is destroying farmland and hampers the navigability of the river.

The strategy suggested by Prof Flugel and Prof Sharma includes measures like assessment of the natural river system and modeling analysis and then integrating them with the complementing socio-economic analysis to address the full range of the complex components of the problem. This is expected to provide enhanced insight into their economic evaluation.

It calls for application of an holistic approach that integrates various disciplines, methods and approaches from natural, engineering and socio-economic sciences, the interfacing of the hydrologic water balance model (J2000) developed by German partner team the with the hydraulic model developed by the Indian partner team respectively.

Reclamation of new land from the Brahmaputra River stretch will be the focus of the implementation phase of the project after successful implementation of the hydraulic river training structures in the pilot areas. They will be replicated along the river stretches. Experiences from the Ganges River indicate that annual reclamation of new land can range between 20 square km to 50 square km.

Synergetic integration of land management options, i.e. bamboo afforestation is expected to establish a continuous and sustainable supply of building material to ensure maintenance and enhancement of bamboo fences and submerged vanes, along with new technique of jack jetty system, in a long-term perspective.

The hydraulic river training measures are designed to protect against bank erosion and to concentrate river flow thus triggering the channelization of the river and deepening its bed.

The latter process will establish a navigable river channel with sufficient depth to be used by cargo vessels with a capacity of up to 1800 metric tonnes. Shifting large quantities of transported loads from the road to the Brahmaputra River will considerably reduce the traffic pressure and maintenance demand of the road system. Consequently road maintenance will improve, and, eventually, significant funds will be released for supporting the river restoration activities, said Prof Flugel and Prof Sharma.

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