Interaction between canal water and groundwater in the UdaWalawe irrigation system:hydrochemistry and isotopes<br />Mauro ...
Outline<br />Approach<br />Study area: geology and sampling points<br />Sampling results and analysis<br />Discussion, con...
Approach<br />Isotope study; part of a larger research project<br />Objectives<br />Understand  determining factorsof grou...
Study area: Uda Walawe irrigation system<br />Average Temp 28°C<br />Humidity 77%<br />ETpot 1988 mm<br />Rain 1979 mm<br ...
Uda Walawe irrigation system < 400 km2<br />Source: L. Rajasooriyar, 2003<br />
Sub-basins and sampling points<br /><ul><li>Two sub-basins
Uda Walawe
Ridiyagama
Three sampling rounds
Tube wells / boreholes
Shallow dug wells
Canals
Chemical analysis
Ion specific electrodes, ion chromatography, titration, spectrophotometry
Isotope analysis</li></ul>Source: MCCM .Prado, 2002<br />
Results - I<br /><ul><li>Small sample size for isotope analysis
Combining with data from hydrochemical study (fluoride)
Variation between surface and groundwater in terms of physical and chemical features</li></ul>Source: Created by Eline Boe...
Results - II<br /><ul><li>Contrast between surface and groundwater
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Interaction between canal water and groundwater in the uda walawe irrigation system hydrochemistry and isotopes

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Interaction between canal water and groundwater in the Uda Walawe irrigation system:hydrochemistry and isotopes
Mauro Prado, Kevin Hiscock, Lorraine Rajasooriyar, Eline Boelee

Universities of East Anglia , Jaffna & International Water Management Institute

Presented at Session C "Innovation and Technologies" of International Symposium 2010, Ruhuna University, Sri Lanka
November 16, 2010

Published in: Education, Technology
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Interaction between canal water and groundwater in the uda walawe irrigation system hydrochemistry and isotopes

  1. 1. Interaction between canal water and groundwater in the UdaWalawe irrigation system:hydrochemistry and isotopes<br />Mauro Prado, Kevin Hiscock, <br />Lorraine Rajasooriyar, Eline Boelee<br />Universities of East Anglia , Jaffna<br />&<br />International Water Management Institute<br />Presented at Session C “Innovation and Technologies” of International Symposium 2010, Ruhuna University, Sri Lanka <br />November 16, 2010<br />
  2. 2. Outline<br />Approach<br />Study area: geology and sampling points<br />Sampling results and analysis<br />Discussion, conclusions and recommendations<br />
  3. 3. Approach<br />Isotope study; part of a larger research project<br />Objectives<br />Understand determining factorsof groundwater quality<br />Interactions between surface waters and groundwater<br />Consequences for management<br />Mapping<br />Water infrastructure, geology, land use<br />Results<br />Sampling<br />Analysis<br />
  4. 4. Study area: Uda Walawe irrigation system<br />Average Temp 28°C<br />Humidity 77%<br />ETpot 1988 mm<br />Rain 1979 mm<br />Etpot:Potential Evapotranspiration<br />Source: IWMI, 2002<br />
  5. 5. Uda Walawe irrigation system < 400 km2<br />Source: L. Rajasooriyar, 2003<br />
  6. 6. Sub-basins and sampling points<br /><ul><li>Two sub-basins
  7. 7. Uda Walawe
  8. 8. Ridiyagama
  9. 9. Three sampling rounds
  10. 10. Tube wells / boreholes
  11. 11. Shallow dug wells
  12. 12. Canals
  13. 13. Chemical analysis
  14. 14. Ion specific electrodes, ion chromatography, titration, spectrophotometry
  15. 15. Isotope analysis</li></ul>Source: MCCM .Prado, 2002<br />
  16. 16. Results - I<br /><ul><li>Small sample size for isotope analysis
  17. 17. Combining with data from hydrochemical study (fluoride)
  18. 18. Variation between surface and groundwater in terms of physical and chemical features</li></ul>Source: Created by Eline Boelee for the purpose of this presentation<br />
  19. 19. Results - II<br /><ul><li>Contrast between surface and groundwater
  20. 20. More pronounced for deeper groundwater</li></ul>Source: Created by Eline Boelee for the purpose of this presentation<br />
  21. 21. Results - III<br /><ul><li>Trend towards enrichment in heavier isotopes towards coast</li></ul>Source: Created by Eline Boelee for the purpose of this presentation<br />
  22. 22. Results - IV<br /><ul><li>Trend towards enrichment – possible explanations
  23. 23. Surface water: increasing evaporation
  24. 24. Groundwater:
  25. 25. Enrichment in discharge areas close to the sea
  26. 26. Lower rainfall in south
  27. 27. Influence sea spray
  28. 28. Mapping various data to understand better</li></li></ul><li>Uda Walawe land use<br />Source: L.Rajasooriyar, 2003<br />
  29. 29. Uda Walawe geology<br />A<br />hjhgjkhsjkhg<br />Source: L.Rajasooriyar, 2003<br />B<br />Geosutur<br />
  30. 30. Uda Walawe groundwater flow<br />Source: L.Rajasooriyar, 2003<br />
  31. 31. Uda Walawe fluoride<br />Source: L.Rajasooriyar, 2003<br />
  32. 32. Uda Walawe fluoride related to canal recharge<br />Source: L.Rajasooriyar, 2003<br />
  33. 33. Discussion<br /><ul><li>Groundwater is recharged from paddy fields, unlined canals and tanks
  34. 34. Isotope analysis limited in sample size
  35. 35. Results in line with those from hydrochemical analysis
  36. 36. Important implications for groundwater quality and drinking water supply
  37. 37. No quantification of surface – groundwater interactions
  38. 38. Actual situation may have evolved…</li></li></ul><li>Conclusion<br /><ul><li>Groundwater recharge dilutes contaminants, e.g. fluoride
  39. 39. Shallow wells are preferred sources of drinking water
  40. 40. Recharge = seepage = leakage?
  41. 41. Lower irrigation efficiency?
  42. 42. Integrated approach required for efficient and equitable management of surface and groundwater in UdaWalawe</li></li></ul><li>Related Publications<br />Rajasooriyar L (2003). A study of the hydrochemistry of the UdaWalaweBasin, Sri Lanka, and the factors that influence groundwater quality. Ph.D. thesis, University of East Anglia, UK<br /> <br />Prado MCCM (2002).Contribution of irrigation canal water to aquifers in South Sri Lanka. M.Sc. Thesis, University of East Anglia, UK<br />
  43. 43. Thank you!<br />For more information please visit:<br />University of East Anglia - www.uea.ac.uk<br />University of Jaffna - www.jfn.ac.lk/<br />IWMI - www.iwmi.org<br />
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