Estimating built-up risk from multi-natural hazards: A case study of Northern coastal plains of Tamil Nadu

Abstract

The Tamil Nadu state of India possesses a vast coastline of 1076 ​km and is highly vulnerable to many climate change-induced natural hazards. It is essential to evaluate the elements at risk to the coastal hazards and map their spatial variations for the densely populated Tamil Nadu coast. Most of the disaster risk studies had concentrated much on delineating hazard-prone regions based on the overall analysis of multiple parameters. For the first time, this study estimated the risk for built-up areas at the micro-administrative level for the northern coastal plains of Tamil Nadu. The built-up areas in the coastal stretch (within 40 ​m from MSL) were delineated and categorised based on their density and structure. Also, we conducted a focus group survey from the deprived communities in the study area. Our result shows that out of 1848 sq. km. built-up area in the study region, 127 sq. km. fall under the very high category of the impacts of six significant natural hazards: cyclones, storm surges, Tsunami, floods, earthquakes, and shoreline erosion. Our results show that the built-up areas in Chennai, Pondicherry, Karaikal, and towns/villages of Cuddalore and Nagapattinam are at very high to high multi-hazard risks. Since the present study focuses on the built-up damage at the micro-level, the results can be upscaled and used for local and state-level planning strategies.