Ministry of Defence (MoD) has given permission to Brihanmumbai Municipal Corporation to conduct contour mapping of the city. The Madhav Chitale Committee after studying the 26th July deluge of 2005 emphasized the importance contour maps during flood rescue operations. The recommendations of Chitale Committee will be followed now. The contour maps will help BMC in planning a ‘flood modelling’ system. This flood modelling system will help the civic body to predict and plan for major flood situations in the future. Flood modelling is a system accepted worldwide in predicting floods. It helps in developing an online real-time system with the help of geographical information on low-lying and steep areas. Two private firms, from Mumbai, and ORG from Gurgaon will do the contour mapping exercise.

Flood modelling system can’t be planned without the help of contour maps. Contour maps show points of elevation (height) of valleys and hills, and the steepness of slopes by using a curve connecting points. Low-flying aerial photographs are required for contour mapping. These photographs are taken from a height of 1,000 metres, with a high resolution of 1 is to 50. The distance between two points on each curve is 20 cm. These maps are adequately detailed to enable the plotting of minor storm water drains, river tributaries and even every manhole on the maps. 

Initially the proposal for contour mapping was rejected by the MoD due to security reasons. MoD stressed that low-flying aerial photography is essential for contour mapping. This act will be done by private firms. Hence it will pose a security threat as several low-lying areas which would be photographed for mapping would include sensitive defense zones. The MoD has imposed 13 conditions for the sake of the security of the country. High risk areas like the naval base, Mumbai Port Trust, the Bhabha Atomic Research Centre and the international airport will not be included in the final maps.  

The firms will begin their wok in next few days. Additional Municipal Commissioner R A Rajeev said, “The base maps will be ready by next year and so will the contour maps. We are trying to meet the target of monsoon 2009.” Officials added that the representative from the MOD will be present when photographs are being taken. They will scan all the low-flying aerial photographs and the contour maps and only after their approval will the civic administration be handed over the final maps.