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The Sumatra Tsunami has affected many fresh groundwater resources in the low-lying coastal zones in the north-eastern part of the Indian Ocean (Gulf of Bengal). Figure 3 1 gives a sketch of possible impacts on freshwater resources in coastal aquifers. Questions can be asked about how serious the impacts of the floods on fresh groundwater resources are; about how harmful they are from a drinking water point of view; and about how long it takes before the contaminated freshwater resources are clean again for consumption.
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Factors of importance are:
• Disturbance and reduction of the freshwater lens by the subsurface pressure wave.
• Local geometry of the inundated areas.
• Duration of sea water standing on the land.
• Leaching of salts from the soil.
• Local weather conditions during the coming months.
Schematic representation of the possible effects of the Sumatra Tsunami on coastal groundwater systems: upconing of brackish groundwater under abstraction wells, intrusion of brackish or saline water from ponds, fingering of brackish water from pools, reduction in freshwater volume due to shoreline retreat, etc.