An accurate mapping of the city using Airborne Laser Terrain Mapping (ALTM) technology will help a great deal in flood risk management and flood mitigation, said K.R. Srinivasan, former Chief Hydrographer, Government of India.
Mr. Srinivasan, who headed the Indian Naval Hydrographic Department, was also part of the demarcating authority for the Coastal Regulation Zone (CRZ) notification.
Pointing out that the abuse of marshlands with dumping of debris was a matter of concern, he said such man-made obstructions hampered the natural flow of floodwater into the sea and resulted in large-scale flooding.
Chennai needs to be mapped with ALTM technology using a helicopter or even a drone, he suggested.
The three-dimensional pictures would help in understanding the terrain and identifying the route of floodwater flow.
Master plan
“It would enable the civic body to take measures to remove obstructions and plan flood mitigation. A master plan can be chalked out about the areas to be reclaimed and creation of new channels to drain water using this technology,” Mr. Srinivasan said.
While satellite images are available on the internet, this technology would ensure that more accurate details are recorded.
Using accurate details of ALTM technology that can map the city from even 400 metre high, Mr. Srinivasan said the civic body would be able to predict the extent of flooding in the areas closer to rivers and the coast during monsoon.
Precautionary measures such as evacuating people from flood-prone low level areas could be planned in advance of any natural disaster.
“We need such mapping even to lay drainage pipeline networks,” he added.
CRZ notifications
Coastal Regulation Zone notifications were grossly violated in the city with rapid development allowed closer to the sea in areas up to Mahabalipuram along East Coast Road, he observed. There was a need to educate the fishing community too about CRZ.
He also stressed on the need to notify River Regulation Zone to regulate development close to Adyar river and water bodies.
More trees must be planted along the river bund to prevent erosion and protect the Adyar river from silting.
Mr. Srinivasan is now the vice-president of Indian Maritime Foundation.
Three dimensional pictures can help in understanding the terrain and routes of floodwater flow
