Impacts of the 2004 Tsunami and Subsequent Water Restorations Actions in Sri Lanka

On December 26 2004, a 9.3Mw earthquake (United States Geological Survey Earthquake Information Network) off the south coast of Sumatra generated tsunami waves that left over 230,000 people dead or missing from Asia to Africa. Hundreds of thousands of homes were destroyed resulting in a humanitarian crisis in the hardest hit countries. Lack of preparation for this unprecedented catastrophic event delayed responses that could have met immediate needs to provide shelter, food and water to the nearly 1.7 million people who were displaced. In addition to widespread loss of life and property, the tsunami also caused extensive contamination of coastal aquifers across southern Asia that may have long-term implications for water availability and security to a large number of people in coastal communities that rely on groundwater as the primary source of potable water. Seawater filled domestic open dug wells and also entered the aquifers via direct infiltration during the first flooding waves and later as ponded seawater infiltrated through the permeable sands that are typical of coastal aquifers. In Sri Lanka alone, it was estimated that over 40,000 drinking water wells were either destroyed or contaminated. Data collected immediately after the tsunami showed drastic increases in salinity. In this paper, we present the effects of the tsunami and the observations to evaluate science and technology needs to develop strategies and decision tools for recovery of water quality and management of coastal aquifers in Sri Lanka for long-term sustainability. The lessons learned and the knowledge generated will be of use in other coastal aquifers in Asia affected by the tsunami and decision making to recover the water quality in other coastal regions with potential threats of tsunamis.