July 20: The Assam soil conservation department has chalked out a plan to arrest soil erosion by taking up silt-trapping measures in the hills surrounding the city.

The department pointed out that any measure initiated for the improvement of the drainage system in the plains would be a futile exercise unless erosion in the hills was tackled immediately.

Emphasising the need for a holistic and multi-disciplinary approach for soil and water conservation, the department maintained that once the slopes are stabilised, silt deposition would be automatically controlled to a great extent.

This would contribute a lot towards ending flash floods in the city.

In his Rs 9.514-crore project, divisional officer of south bank soil conservation department J. Malakar stated that according to the conservation plan, steep gradients had to be broken first with the help of silt retention dams, spillways and other mechanical measures.

For the lower reaches, the department proposed treatment like water-harvesting ponds, silt pits, percolation tanks, diversion drains and others, which would ultimately be connected to the drainage system in the plains.

“The naked hills of Guwahati point to the advent of man-made disasters like killer landslides, artificial floods and waterlogging. After every downpour, the surface run-off attains erosive velocity and the drains and low-lying areas get silted. As a result, the streets get waterlogged,” Malakar said in his report.

“The recurring flash floods damage high-cost intensive infrastructure like the drainage system, roads, buildings and so on,” he added.

He said the vulnerable streams could be protected with RCC drop spillways, silt retention dams on the slopes and with slit pits in the foothills. The structures will be constructed after detailed levelling is done at appropriate points to trap silt and run-off water in the hills themselves.

Based on various soil and water conservation models, the department has drawn up the design of the different conservation structures.

The report highlighted the fact that due to unplanned construction of buildings in the hills, the alignment of roads was seldom appropriate.

Therefore, to protect these roads, scientific channelling of drains supplemented with silt trapping measures was a must.

The report concluded that once the slit generated in the hills after every downpour could be trapped in the hills themselves, the city’s drainage system would be saved, which would go a long way in solving the flash floods problem.

The reports also suggested that to implement the project, a multi-disciplinary team, comprising representatives of the civic authorities, the Guwahati Metropolitan Development Authority (GMDA) and the Guwahati Municipal Corporation, the environment and forest department, PWD (roads), Assam State Electricity Board, should be formed.

The team will ensure better management and necessary convergence with the department of soil conservation as the nodal department.

The department is now awaiting statutory clearance from the concerned department for implementing the project.

The annual physical and financial requirements of the project will have to be determined before it can implemented.

The yearly requirements will be divided into four quarters and the implementation schedule will be phased out according to the quarterly requirements.

Of the total project cost of Rs 9.514 crore, the requirement for the first year is estimated at Rs 4.757 crore. The second and third year will require Rs 2.854 crore and Rs. 1.903 crore respectively.

It was mentioned that as the project is expected to be completed by 2005-06, maintenance would be required only from the fourth year of implementation.

The department also proposed that the state and the central calamity relief funds would maintain some of the schemes.

The department was of the view that user-groups would have to be formed among the hill dwellers so that the assets created could be ultimately handed over to them. The groups will maintain the assets.