The Brihanmumbai Municipal Corporation (BMC) will install an automatic flood warning system for Mumbai by the monsoon
of 2006. At a recent meeting, the BMC decided to test the system in 25 flood-prone spots in the city and figured that its core components would cost approximately Rs 50 lakhs, a senior official said.

The system will consist of electronic rain gauges rigged to send alarm signals to a central control room in the event of a rise in the water level. If the system is found effective, the control room will be enhanced to send out flood warnings to public transport undertakings such as the railways and the BEST. Mumbai's system should be able to warn citizens half an hour before a flood such as 26/7 occurs, the BMC has estimated.

While the BMC has been mulling over a flood-warning system since 26/7, the meeting is a concrete step in that direction. In this regard, the BMC has appointed IIT Bombay as consultant for the warning system.

Apart from designing the system, the institute will identify about 25 sites to install the electronic rain gauges. Most sites may likely be in the suburbs, the worst-hit by the 26/7 floods. The institute will also peg the water level at which the electronic rain gauges should send warnings.

The rain gauges measure rainfall by accumulating rainwater. When it rains at a certain level above expectation, the gauges send out a warning to the control room which relays it to the general public. The electronic rain gauges will have to be imported at an estimated cost of Rs 2 lakhs each, and their supporting IT infrastructure will cost extra.

Similar systems are already in use abroad. Thirteen eastern states in the USA have about 1,300 electronic rain gauges. China has installed water-level and rainfall gauges at 70 locations along the flood-prone Yangtze river.

Contact: kgupta@iitb.ac.in