USE OF RUBBER SHEET OPERATIONS IN DISASTER MANAGEMENT PROGRAMMES: A CASE STUDY USING KVR 3000 DATA OF SOUTH MUMBAI, INDIA

Floods are devastating resulting in the loss of property worth millions and the lives of many. There is a worldwide understanding of the importance of creating a database on the land (urban or rural) for the assessment and analysis of hazards:

1. General Topology of the area should be understood using any of the Land Use Maps available.

2. This map should be digitized and various features (natural and manmade) in space that are related to flood and disaster management as well as cartographic information should be integrated using unprojected maps. Population, infrastructure and topography are some of the intricate features which also should be incorporated. The variables could be textural features like drainage pipes, buildings, hospitals, dams etc and continuous variables like topography, rivers etc.

3. Huge number of maps containing cartographic information is incapable of being analyzed since they don’t have a proper projection. To tackle this problem such maps can be georeferenced and their information can be used for creating, at first a landuse map and then a space use map (map that stores information about the various objects like buildings and other structures), on which spatial integration and analysis for emergency services can be carried out.

In this paper the third issue regarding the accuracy of georeferencing of the maps is tackled. As a casestudy the KVR 3000 image of South Bombay has been georeferenced using Linear and quadratic Transformations serperately and the accuracy of each has been compared. For comparison 30 Ground Control Points have been chosen from the South Mumbai (18.083°, 72.836°) imagery. The latitude and longitude readings were acquired using a GARMIN 12 GPS. The resolution of the satellite imagery chosen is 2 meters. The software used for georeferencing is IDRISI Kilimanjaro. The accuracy analysis has been carried out by two methods:

1. Comparison of the RMS error found by Linear and Quadratic transformations.

2. Comparison of coordinates of certain places on the georeferenced imagery other than the Ground Control Points to the actual Ground Data acquired by GPS.

By performing both the accuracy analysis tests it was proved that georeferencing using Quadratic Transformation yields a more accurate result than Linear Transformations in this case study.