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Impacts of the 2004 tsunami on groundwater resources in Sri Lanka
Author(s) -
Illangasekare Tissa,
Tyler Scott W.,
Clement T. Prabhakar,
Villholth Karen G.,
Perera A. P. G. R. L.,
Obeysekera Jayantha,
Gunatilaka Ananda,
Panabokke C. R.,
Hyndman David W.,
Cunningham Kevin J.,
Kaluarachchi Jagath J.,
Yeh William W.G.,
van Genuchten Martinus T.,
Jensen Karsten
Publication year - 2006
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2006wr004876
Subject(s) - aquifer , groundwater recharge , groundwater , seawater , hydrology (agriculture) , geology , saltwater intrusion , water resources , salinity , infiltration (hvac) , environmental science , oceanography , geography , ecology , geotechnical engineering , meteorology , biology
The 26 December 2004 tsunami caused widespread destruction and contamination of coastal aquifers across southern Asia. 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 is estimated that over 40,000 drinking water wells were either destroyed or contaminated. From February through September 2005, a team of United States, Sri Lankan, and Danish water resource scientists and engineers surveyed the coastal groundwater resources of Sri Lanka to develop an understanding of the impacts of the tsunami and to provide recommendations for the future of coastal water resources in south Asia. In the tsunami‐affected areas, seawater was found to have infiltrated and mixed with fresh groundwater lenses as indicated by the elevated groundwater salinity levels. Seawater infiltrated through the shallow vadose zone as well as entered aquifers directly through flooded open wells. Our preliminary transport analysis demonstrates that the intruded seawater has vertically mixed in the aquifers because of both forced and free convection. Widespread pumping of wells to remove seawater was effective in some areas, but overpumping has led to upconing of the saltwater interface and rising salinity. We estimate that groundwater recharge from several monsoon seasons will reduce salinity of many sandy Sri Lankan coastal aquifers. However, the continued sustainability of these small and fragile aquifers for potable water will be difficult because of the rapid growth of human activities that results in more intensive groundwater pumping and increased pollution. Long‐term sustainability of coastal aquifers is also impacted by the decrease in sand replenishment of the beaches due to sand mining and erosion.