GUWAHATI, Feb 8 – Stress should be laid now also on predicting erosion. If erosion in an area can be predicted, it will become easier to tackle the phenomenon. This was the observation made by Asian Development Bank (ADB) consultant for the $ 150 million Assam Integrated Flood and Riverbank Erosion Risk Management Project (AIFRERMP) Knut Oberhagemann. He was addressing a press conference here on Friday.
He said that the average width of the Brahmaputra was 6 km in an area of 3,870 square kilometres (sq km) between 1912 and 1928. The river attained an average width of 7.5 km in an area of 4,850 sq km between 1963 and 1975. During 2006, it was found by the North East Space Application Centre that the river had attained an average width of 9 km in an area of 6,080 sq km.
The system of the Brahmaputra is a complicated one. It has many tributaries and it carries a lot of sand and silt. The river carries most of its silt load to its confluence point, but the sand load it receives settles down at places making the river course irregular. There is a need to assess the sand load carried by the rivers of the State, he said.
He reminded the newspersons that the Assam Plains was built by the sediments coming from the Himalayas, while answering a question on trapping the silt carried by the Assam rivers. It would not be possible to control the entire silt coming to the rivers. However, treatment of the upper catchments of the rivers may be tried with, he maintained.
On the revetments proposed under the AIFRERMP to stabilise the Brahmaputra bank in Dibrugarh, Bonkowal and Palasbari reaches, besides other structural and non-structural measures to manage flood and erosion, he said that revetments were considered better in matter of efficacy compared to the spurs. “We are proposing revetments, not spurs, to protect the existing bank line without opting for interfering with the river system,” he said.
He admitted the fact that the revetments always have a tendency to draw the deep channel towards them. But, he was quick to assert that the rivers were deeper at the spur heads, as, the spurs were angular in their directions.
The structural measures proposed under the AIFRERM also include—embankment renovation and facilities associated with it and also with riverbank protection measures. On the other hand, the non-structural measures proposed under the project include, among others, quality infrastructure with the improved management accompanied with accountability mechanisms.
The embankments proposed under the project would be built for multiple uses like roads and platforms. The total population sought to be benefited directly with the project in Dibrugarh, Golaghat (Bonkowal–upstream of Kaziranga) and Kamrup (Palasbari) districts in phase one is 8,70,000 and the land area directly benefiting with it is 95,000 hectares in the three districts, said the ADB consultant.
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