CHENNAI: A multi- institutional effort is underway to prepare a digital flood map for Chennai, that would act as a guide for emergency response teams and district administration, to act before there is any loss of life or substantial property damage. During the 2015 December floods, though heavy rains were expected, there was no clarity on how much it would rain and the areas facing inundation risks.
To avoid such a situation from recurring, premier institutions including IIT Bombay and Madras, Indian Meteorological Department (IMD), Central Water Commission, Indian Institute of Sciences, Bengaluru, and Institute of Remote Sensing (IRS) are working on a digital flood map or atlas. It would provide six hours’ cumulative rainfall forecast 24 hours in advance and identify flood-prone spots.
The map would also be able to estimate the areas that are likely to be inundated, with the help of scenarios such as 10 cms rain, 20 cms rain etc. IIT Bombay, which has developed an advanced climate forecasting model, will run the tool based on data from all other institutions, to prepare the final flood map. This would be handed over to the Chennai Corporation, sources told Express.
Experts at IIT Madras are doing the ground survey and installing sensors across the city. The data thus generated will be integrated with a web-GIS based interactive tool for simulating water level in rivers and resulting flood inundation, based on which warnings and alerts could be issued to specific vulnerable spots.
IRS director SS Ramakrishnan told Express that the institute has already conducted flood risk mapping for the city and its suburbs using ‘airborne laser terrain mapping technology’. Detailed topographic maps of very high accuracy and digital elevation model have been generated. Using this, about 25 thematic maps have been developed and along with thematic data, would help recoginise and enumerate the features influencing a waterbody.
“The complete dataset has been given to IIT Bombay. Besides, details of the complete network of stormwater drains and river-connectivity have also been shared,” he said.
Sources said the system may not be ready before this monsoon, which is only 45 days away. However, this monsoon would be used as an opportunity to validate and calibrate the system.