Groundwater

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Groundwater. Our hidden asset

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Groundwater

  1. 1. Class: Special lecture II for Regular Course 5th grade students Oct. 9th (WED) 15:35-16:20 National University of Malaysia Groundwater (Our Hidden Asset) Wan Zuhairi Wan Yaacob (Assoc. Prof, PhD) Faculty of Science and Technology National University of Malaysia 43600 Bangi, Selangor, MALAYSIA. 28-Jan-14 1
  2. 2. Content: • • • • • National University of Malaysia What is Groundwater Groundwater as a resource Groundwater and Geotechnical Problems Groundwater movement in soil Conclusion 28-Jan-14 2
  3. 3. National University of Malaysia What is Groundwater? 28-Jan-14 3
  4. 4. Two Types of Water National University of Malaysia Unsaturated Water table Saturated Hydrogeology (Groundwater) Subsurface water 28-Jan-14 Hydrology (Surface water) 4
  5. 5. Groundwater National University of Malaysia • Groundwater is a water that is found underground and is stored in the pore spaces (between grains) of porous geologic formation called an “aquifer”. • The importance of groundwater is easily overlooked. Water Cycle • Groundwater is a hidden asset, out-of-sight and out-of-mind. 28-Jan-14 5
  6. 6. • • • • • Aquifer (permeable) Aquitard (Impermeable) Artesian well Water table Piezometric surface Groundwater National University of Malaysia Piezometric surface 28-Jan-14 6
  7. 7. National University of Malaysia Groundwater as a Resource 28-Jan-14 7
  8. 8. Groundwater and the world’s freshwater supply National University of Malaysia "...Altogether, (groundwater) aquifers store 97% of the planet's (available) freshwater." 28-Jan-14 8
  9. 9. Water Usage in Large Cities in the World 28-Jan-14 National University of Malaysia 9
  10. 10. National University of Malaysia Water Usage in Malaysia Water use by source Ground water Groundwater utilization by sector 3 Surface water 97 35 60 5 Industrial Groundwater Surface water Agricultural Domestic • Japan (13%) • South Korea (32%) 28-Jan-14 10
  11. 11. “Air Kelantan” Groundwater National University of Malaysia My hometown • Kelantan : 70% of its water source is from groundwater. Production well Privately owned tube well Crystal clear groundwater 28-Jan-14 11
  12. 12. Surface water vs Groundwater National University of Malaysia Slide from Dr. Saim Suratman (NAHRIM, Malaysia) 28-Jan-14 12
  13. 13. SW GW National University of Malaysia SW GW Sg. Langat, Selangor Sg. Jeli, Kelantan Source: Dr Saim Suratman, NAHRIM 28-Jan-14 13
  14. 14. Bank Infiltration National University of Malaysia Fresh Water River Water Type of filtration that works by passing water to be purified for use as drinking water through the banks of a river or lake. 28-Jan-14 14
  15. 15. National University of Malaysia This is what people normally see This is what people should be able to see Groundwater !! Source: Dr Azuhan Mohamed, Groundwater Expert. 28-Jan-14 15
  16. 16. National University of Malaysia 28-Jan-14 16
  17. 17. National University of Malaysia Source: Dr Azuhan Mohamed, Groundwater Expert. 28-Jan-14 17
  18. 18. National University of Malaysia Groundwater and Geotechnical Problems 28-Jan-14 18
  19. 19. 1. Groundwater & Mining National University of Malaysia PENJOM GOLD MINE, MALAYSIA How to manage the influx of groundwater into the open pit mine? Groundwater to mining engineer (eg. Penjom Gold Mine) 28-Jan-14 19
  20. 20. 2. Groundwater & Stability of Dam National University of Malaysia Vaiont Dam, Italy After Before 28-Jan-14 20
  21. 21. National University of Malaysia Vaiont Dam, Italy Trigger factor: the fluctuation of groundwater level Slip surface Water level before Water level after 28-Jan-14 21
  22. 22. National University of Malaysia Trigger factor: the fluctuation of groundwater level Ancient Slip surface Old landslide area Water level before Dam Reservoir Water level after After Before 28-Jan-14 22
  23. 23. Groundwater & Foundation National University of Malaysia Expensive house Problem: The foundation of the house failed, Resulting cracks and unstable foundation. 28-Jan-14 Crack developed under the house and surrounding area 23
  24. 24. National University of Malaysia Groundwater & Foundation Before development Old river (diverted) After development Retaining Wall Fill material Original WT Reason for failure - Fill material = silt + gravel + boulder material - High K values - Channeling (old river) - Higher new water level/high water pressure 28-Jan-14 24
  25. 25. Groundwater & Foundation 28-Jan-14 National University of Malaysia 25
  26. 26. Groundwater & Foundation National University of Malaysia Groundwater Modeling using Visual MODFLOW Pro 28-Jan-14 26
  27. 27. Groundwater Contamination National University of Malaysia Groundwater Remediation at Taman Beringin Landfill site Malaysia Drilling (boreholes) 28-Jan-14 27
  28. 28. Groundwater Contamination National University of Malaysia Groundwater Remediation at Taman Beringin Landfill site Malaysia 28-Jan-14 28
  29. 29. Groundwater Remediation at Taman Beringin Landfill site Malaysia National University of Malaysia Groundwater Modeling using Visual MODFLOW Pro 28-Jan-14 29
  30. 30. National University of Malaysia Groundwater Movement 28-Jan-14 30
  31. 31. National University of Malaysia Hydraulic conductivity A measure of how easily a fluid (e.g., water) can pass through a porous medium (e.g., soils) water Loose soil - easy to flow - difficult to flow - high permeability 28-Jan-14 Dense soil - low permeability 31
  32. 32. Darcy’s Law National University of Malaysia • Darcy’s experiment • Henry Darcy • French engineer • 1856 28-Jan-14 32
  33. 33. National University of Malaysia Darcy’s Law Z = 0 (Datum) Z1, Z2 Elevation of manometer h1, h2 Elevation of fluid ∆𝒍 Distance of manometer V (specific discharge) of cylinder 𝑸 𝒗= 𝑨 E1 𝒗 𝜶 (𝒉 𝟏 − 𝒉 𝟐) 𝒗 𝜶 ∆𝒉 𝒗 𝜶 𝟏/∆𝒍 28-Jan-14 33
  34. 34. National University of Malaysia Darcy’s Law 𝒗 𝜶 − ∆𝒉 𝒗 𝜶 𝟏/∆𝒍 𝒗 𝜶 − ∆𝒉/∆𝒍 𝒗 = −𝒌 ∆𝒉/∆𝒍 𝒗 = −𝒌 𝝏𝒉/𝝏𝒍 E2 If 𝝏𝒉/𝝏𝒍 (constant); 𝒗 𝜶 𝑲 ; 𝑲 = 𝒉𝒚𝒅𝒓𝒂𝒖𝒍𝒊𝒄 𝒄𝒐𝒏𝒅𝒖𝒄𝒕𝒊𝒗𝒊𝒕𝒚 E2  E1 𝑸 = V.A = (−𝒌 𝝏𝒉/𝝏𝒍) . 𝑨 𝑸 = −𝒌 . 𝒊 . 𝑨 -ve sign: the direction of flow is towards the decreasing hydraulic head 28-Jan-14 34
  35. 35. National University of Malaysia Laboratory - Manometer Field - piezometer Borehole / Well 28-Jan-14 35
  36. 36. Example of Darcy’s Law National University of Malaysia • A confined aquifer has a source of recharge. • The discharge, Q = 37500 m3/day • The piezometric head in two wells 1000 m apart is 55 m and 50 m respectively, from a common datum. • The average thickness of the aquifer is 30 m, and the average width is 5 km. 28-Jan-14 36
  37. 37. Calculate: National University of Malaysia (a) Calculate the hydraulic conductivity (K) ? 5 km 28-Jan-14 37
  38. 38. Solution National University of Malaysia Cross-Sectional area (A) = 30(5)(1000) = 15 x 104 m2 Hydraulic gradient (i) = (55-50)/1000 = 5 x 10-3 (No unit / unit less) Q = 37,500 m3/day Darcy’s Law, Q = k.i.A k = Q / i.A = (37500) / (5 x 10-3)(15 x 104 ) = 50 m/day (0.000578703704 m/sec) = 5.79 x 10-4 m/sec 28-Jan-14 38
  39. 39. National University of Malaysia 50 28-Jan-14 39
  40. 40. National University Determination of permeability in the Malaysia of field int xn dx = xn + 1/(n + 1) logex = 2.303 log10 x 𝑄 𝑟2 𝑡 . 𝑙𝑜𝑔10 𝑟1 𝑘 = 2.3 𝜋 (𝑧22 − 𝑧12 )
  41. 41. National University of Malaysia Example: Pumping well Rate = Q Observation well Z1, Z2 r1,r2 𝑄 𝑟2 𝑡 . 𝑙𝑜𝑔10 𝑟1 𝑘 = 2.3 𝜋 (𝑧22 − 𝑧12 ) 28-Jan-14 41
  42. 42. Conclusions National University of Malaysia Groundwater is precious as a clean water resource Groundwater has implication on engineering structures and stabilities Groundwater can pollute – need for better understanding about the groundwater safety Movement of groundwater is govern by Darcy’s Law. 28-Jan-14 42
  43. 43. National University of Malaysia Thank you どうもありがとうございました 28-Jan-14 43

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