Soil vulnerability study report suggests ‘standard building code’ for Kolkata

Kolkata: In the wake of several multi-storied buildings tilting in the city, a research report on soil vulnerability in Kolkata has called for a standard building code to maintain the load bearing capacity of the surface while warning against lifting of groundwater.

A report ‘Kolkata: The City on the Cradle’, compiled by geologist Sujib Kar along with other researchers, highlighted the changing nature of the city’s surface. It divided the city into five zones which ranged from least to most vulnerable. The report said that more than 40 per cent of the landscape of Kolkata and 35 per cent of Howrah are under the most vulnerable area. The prolonged process of urbanisation is leading to rapid change in landscape.

In the more vulnerable zone are areas such as Sobhabazar, Udyanbati, Dakhineshwar, Burrabazar. It includes areas near the Babughat. The vulnerable zone comprises Garden Reach and Bata Ganga areas, besides Manicktala, Bidhannagar area and nearer to Nabanna, Kona highway and towards Domjur in Howrah. In less vulnerable zones are areas Tollygunge Adi Ganga area, Kalighat, areas nearer to Shyambazar, Sealdah and Dunlop area.

The report concluded that Kolkata is degrading rapidly due to the continuous process of “unwise” growth and development. It suggested that eco-friendly development plans should instead be taken up. Further, any developmental aspects related to geomorphological conditions of the area should be managed seriously.

Lifting of ground water must be stopped so that its fluctuation level can be minimised. Presently, due to continuous fluctuation, the diagonal flow of subsurface water from the surrounding areas is increasing rapidly. This is creating vacuum spaces below Kolkata’s surface and causing urban slumping in spaces.

The report called for a standard building code to maintain the load bearing capacity of the surface. Also, no construction should be allowed in Kolkata which is not suitable to the soil of the city.

The report said the lithological condition of the city is not suitable for huge growth and development on the surface since below the uppermost layer, is an imbalanced fragile textural layer. The city is losing vast amounts of sediment along with movement of sub surface water and groundwater.