Groundwater management after a largescale inundation event: 2004 Sri Lanka tsunami case study

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Groundwater management after a large-scale
inundation event 2004 Sri Lanka tsunami case
study
T. Prabhakar Clement, PhD., P.E. Feagin Chair
Professor, Department of Civil EngineeringAuburn
University
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Acknowledgements
Hard-working students of a hardly-working
professor who keeps chasing those research
dollars! Rohit Goswami, PhD CandidateMatthew
Hogan, MS CandidateLinzy Brakefield, MS
CandidateDr. Sushil Kanel, Post-doc fellowDr.
Elena Abarca, Fulbright Post-doc Fellow Dr.
Matthew SimpsonCiaren Harmon, Honors
student2005 NSF tsunami impact assessment panel
Drs Illangasekare, Obeysekera and Villholth
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The National Science Foundation team
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Where is Sri Lanka?
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Where is Sri Lanka?
Iraq!
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What happened on Dec 24, 2004?
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Formation of mid ocean ridges and trenches
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Damage

• Before and After Gleebruk Village, Indonesia

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• West coast of Sri Lanka (Kalutara) Before

Digital Globe Quickbird Image
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• West coast of Sri Lanka (Kalutara) During

Digital Globe, Satellite Images
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• West coast of Sri Lanka (Kalutara) After First
  Wave

Digital Globe, Satellite Image
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Indian ocean
Open dug wells
Illangasekare et al. (2006) Impacts of the 2004
Tsunami on Groundwater Resources in Sri Lanka,
WRR.
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Saltwater storage in lagoons and depressions
Auburn
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Saltwater contamination sources after a tsunami
invasion event (conceptual model)
Source-1 Saltwater discharged through vadose
zone Source-2 SW discharged via wells Source-3
SW discharged from inland ponds and depression
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Experimental Study of Source-3
Source-1 Saltwater discharged through vadose
zone Source-2 SW discharged via wells Source-3
SW discharged from inland ponds and depression
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Simulation of saltwater discharge from lagoons
and depressions (source-3)
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Dynamics of a sinking dense plumefrom a point
(source-3)Experiment 1 (High flow)
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Field evidence for (stable system)
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Dynamics of a sinking dense plume from a point
(source-3) Experiment 2 (medium gradient)
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Dynamics of a sinking dense plume from a point
(source-3) Experiment 3 (low flow)
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Effects of flow
Medium flow
Low flow
High flow
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Convection ratio ? Free convection/Forced
convection For values much greater than
unity, forced convection will dominate and the
plume is stable. For values less than unity,
free convection will dominate and plume is
unstable
Analysis of plume stability
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Study sources-1 2
Source-1 Saltwater discharged through vadose
zone Source-2 SW discharged via wells Source-3
SW discharged from inland ponds and depression
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Sources 1 2
Tsunami water
Open Well
FW Flow
Ocean water
Auburn
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Implications

• After the tsunami event, the saltwater discharged
  via open dug wells would have moved rather
  rapidly. Therefore, pumping open wells
  immediately after the disaster may not be the
  optimal management strategy
• However, removal of few well volumes at a later
  period can reduce residual bleeding of salt mass
  stored in open wells
• Care must taken in disposing the salt water
  extracted from contaminated wells

Illangasekare, T., S W. Tyler, T.P. Clement et
al., Impacts of the 2004 Tsunami on GW
Resources in Sri Lanka, Water Resources Research,
v.42 (5), p.1-9, 2006.
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Implications

• Tsunami water is expected to remain above the
  regional saltwater wedge, hence can be tracked
  for a long period
• Increasing the recharge will help flush the
  tsunami-impacted saline groundwater
• An effective long-term approach to manage these
  sites is to promote recharge (natural or
  artificial recharge) by managing storm water
  runoff

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Questions?
Thanks!