Tsunami impacts and rehabilitation of groundwater supply: Lessons learned from Eastern Sri Lanka

This case study reviews the outcomes and experiences gained from comprehensive research and support work in Sri Lanka related to the impacts on groundwater and the destruction and rehabilitation of the local water supply systems after the December 26, 2004 Indian Ocean tsunami. An overriding problem was the flooding of 75% of the highly populated coastal areas of Sri Lanka, and the saltwater entry into soils, groundwater, and open wells, the latter traditionally the backbone of local water supply. The salinity imprints of the tsunami on groundwater and water supply were detectable up to 1.5 years after the tsunami. The primary remediating agent of groundwater salinity was found to be the natural rainfall and ambient groundwater flow and not the intensive pumping campaigns conducted in the aftermath of the event. Immediate relief and interim alternative solutions were provided from a host of actors who should be commended for an immense and effective effort that ensured an uninterrupted supply of freshwater to the great number of affected coastal communities. Apparent shortcomings in the water supply rehabilitation were related to a focus on salinity rather than pathogenic contamination, and towards well water cleaning rather than on primary information and consultation/involvement of affected populations. Recommendations for addressing similar flooding events from a water security point of view are given including reference to a set of guidelines developed as part of this work for the cleaning and rehabilitation of drinking water wells and groundwater protection after
saltwater flooding events.