2010: Tsunami Impacts and Rehabilitation of Groundwater Supply: Lessons Learned from Eastern Sri Lanka

Villholth, K.G., P. Jeyakumar, P.H. Amerasinghe, A.S.P. Manamperi, M. Vithanage, R.R. Goswami, and C.R. Panabokke, "2: Tsunami impacts and rehabilitation of groundwater supply: Lessons learned from Eastern Sri Lanka, " In: Jha, M.K. (Ed.): Natural and Anthropogenic Disasters: Vulnerability, Preparedness and Mitigation, Capital Publishing Company, New Delhi, India and Springer, Dordrecht, The Netherlands, pp. 82 - 99. ISBN: 978-90-481-2497-8.

Huge devastation and human tragedy followed the December 26, 2004 tsunami in the Indian Ocean. The death toll from the earthquake, the tsunamis and the resultant floods totals to over 180,000 people in fourteen countries with tens of thousands reported missing, and over one million left homeless.

After Indonesia, Sri Lanka was the second-hardest hit, with an estimated death toll of 35,000 people. Of immediate concern after the catastrophic event was the destruction of the traditional water supply system in the rural and semi-urban areas of the coastal belt, which for 80% of the population was based on groundwater, mostly drawn from private shallow open wells (Leclerc et al., 2008). Practically all wells within the reach of the flooding waves (up to a couple of kilometers inland) were inundated and filled with saltwater and contaminated with solid matter (sediment and waste), pathogens and other unknown chemicals, leaving the water unfit for drinking (Fig. 1a). Figure 1b shows the devastation of the 2004 Tsunami in a representative coastal town on the eastern coast of Sri Lanka.

The density of wells in these areas is high, with practically each household having its own well (Fig. 2). (2008) found a well density up to 600 per km2. The local villagers reported that the water level reached close to the top of the coconut palm trees shown in the figure (approximately 5 m). Over one thousand lives were lost at this particular site. (2005) and (2005) estimated that the tsunami waves contaminated more than 50,000 wells in coastal Sri Lanka. This initial figure is highly underestimated, however, as the present research found, based on well statistics and flooding patterns, that approximately 18,000 wells were affected in an area representing only 3% of the affected coast line in Sri Lanka (Villholth et al., 2009). This suggests that the total number of affected wells is more in the range of half a million. The total number of people, mostly living in poor coastal rural areas, affected by the disruption of their water supply from wells could be in the range of 2.5 million. Approximately 75% of the coastline of Sri Lanka was impacted by the tsunami. Fig. 1 Tsunami impact on open well and the general devastation of the coastal area in east Sri Lanka (Courtesy a: Scott Tylor and Jayantha Obeysekera Fig. 2 Tsunami-impact site on the east coast of Sri Lanka (Courtesy: Scott Tylor and Jayantha Obeyseckera).


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