Large Scale Ortho Photographs and GIS Supported Disaster Managemnt for Post-Tsunami Rehabilitation M.Stalin Dy. Director Survey of India, Chennai, India Email: mstalinsoi@yahoo.com S.S.Ramakrishnan IRS, Anna University, Chennai B.Nagarajan Survey of India , Dehradun S.Sanjeevi Dept. of Geology, Anna University The recent tsunami which has caused a greater devastation in Sumatra, Andaman-Nicobar islands, Sri Lanka, East Coast of India and even far away region like Samalia Coast has opened up a new chapter in tsunami disaster in Indian Ocean. These tsunami have caused greater devastation in the islands and the continents occurring in and close proximities to the source of triggering events and at times even the far away continental margins and the coastal zones depending upon the magnitude of the triggering earthquakes and the dynamism of such tsunamis. However the disaster vulnerability equally depends on the geological setting, geomorphology and the geometry of the coasts which stand exposed to such tsunamis. In this context, the recent Sumatra Tsunami that occurred on 26th December, 2004 has opened up a new chapter in the tsunami vulnerability assessment in South Asia/Indian Ocean region. Although there was no scarcity of tsunami relief materials which were pumped in by various organizations, the post-tsunami relief operations could have been implemented in a better manner if organized and integrated database at the grass root level were available. The Enormity of the data and inter-relationships demand that they must be GIS supported to facilitate easy manipulation, quick retrieval and varied query processing. This paper presents a GIS approach to identify / classify the villages based on the extent of damage using a TDI (Tsunami Disaster Index) In the GIS, a large scale spatial database was created from post-tsunami ortho rectified photos for the administrative divisions of the villages, residential areas, road networks, water features and plantations, etc. Non-spatial databases were created for each of the damage classes. The non-spatial databases were linked to the spatial database in Oracle environment. Programs were developed in Oracle 8i for handling each of the databases and to answer the relevant queries. One of the salient features of the GIS is that each of the damage classes taken for study is assumed an index showing the degree of damage in that village by assigning values in 0-5 Scale in a realistic way. A composite Tsunami-Disaster Index (TDI) was formulated after assigning the proper weightages to the various indices of the damage classes. Through this TDI, villages have been categorized based on their degree of damage. A planning module was also developed which can list the village in the order of priority for post-tsunami relief operations in the particular district. Out of the villages in Cuddalore District of Tamil Nadu taken for the study, Devanampattinam village was found to be the most damaged village in the district (TDI=5), which needs to be given top priority while performing post-tsunami relief operations. This disaster index based approach may be applied to other districts of Tamil Nadu and Pondicherry coasts.