Application of Solute Transport Modeling to Study Tsunami Induced Aquifer Salinity in India

Abstract

Natural processes such as flooding, earthquakes, tsunami, sea water intrusion and rock-water interaction processes will all result in deterioration of groundwater quality. One such natural catastrophic event, in the form of a massive tsunami occur red on December 26, 2004, triggered by a 9.2 magnitude earthquake off the west coast of Sumatra, killed more than 2,50,000 people and displaced thousands in countries around the Indian Ocean. Extensive damage is not only to the life and property but also for deterioration of groundwater quality in coastal regions. Study of processes of salinization of groundwater by tsunami and the time that it might take for the natural recharge processes to flush this salinity is of great importance. The study area includes a portion of Kalpakkam region situated in the Kancheepuram District of Tamil Nadu state in southern India. A groundwater model was developed to simulate the groundwater flow and solute concentration in the study area. Finite element code FEFLOW 5.2 was used for this purpose. The model was used to simulate groundwater flow and solute transport for a period of two years from January 2005 to January 2007. The results indicate that tsunami-induced salinity in this aquifer system would be flushed out with normal annual rainfall by the year 2008-09. The post audit results also confirms that the model have been calibrated and simulated with high accuracy. The present work has demonstrated the application of groundwater modeling to understand the process of salinisation of groundwater resources by tsunami. It has also helped to determine the time that it would take for remediation of the aquifer system by rain fall recharge.

Keywords: Tsunami, inundation, salinisation, solute transport, sandy aquifer, southern India