Source and Causes of 2015 Great Pluvial Flood of Chennai, Tamil Nadu and its Surroundings

Abstract

ABSTRACT A catastrophic heavy downpour was recorded in the month of November-December 2015 which devastated wealth, lives, disturbed the livelihood and regular activity of common man of Chennai city and its surroundings. Indian Metrological Department (IMD), Chennai warned the people in Chennai in advance about the atmospheric depression developed in the Indian Ocean region and moving towards Tamil Nadu coast. The Numerical Weather Modeling (NWM) retrieved parameters such as temperature and Zenith Total Delay (ZTD) along with the ISC earthquake catalog were analysed for the root cause of this phenomena and found a relation between the onset of the atmospheric weather change and the swarms of 8th to 9th November 2015 in the Indian Ocean region and associated thermal radiation. These swarms are generally associated with the submarine volcanic activity which released the thermal radiation from ocean floor that caused the ocean water to warm and evaporate. The consequence of incessant rainfall and the weather condition deviated from the normal climate and monsoon pattern. Thus, the abnormal and distinct weather condition that prevailed during the period has been triggered by the swarms in the north Sumatra oceanic region and the resultant effect was the great pluvial flood disaster in Chennai and its surroundings in November-December 2015.