This document summarizes a lecture on groundwater given at the National University of Malaysia. The lecture covered the definition of groundwater, its importance as a resource, and how it relates to geotechnical problems and water movement through soil. It also provided examples of groundwater usage, contamination issues, and modeling techniques. The key points were that groundwater stores most of the world's freshwater, is critical for large cities and industries, and its movement is governed by Darcy's Law.

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
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2. Content:
•
•
•
•
•
National University of
Malaysia
What is Groundwater
Groundwater as a resource
Groundwater and Geotechnical Problems
Groundwater movement in soil
Conclusion
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3. National University of
Malaysia
What is Groundwater?
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4. Two Types of Water
National University of
Malaysia
Unsaturated
Water table
Saturated
Hydrogeology (Groundwater)
Subsurface water
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Hydrology (Surface water)
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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.
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6. •
•
•
•
•
Aquifer (permeable)
Aquitard (Impermeable)
Artesian well
Water table
Piezometric surface
Groundwater
National University of
Malaysia
Piezometric surface
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7. National University of
Malaysia
Groundwater as a Resource
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8. Groundwater and the world’s
freshwater supply
National University of
Malaysia
"...Altogether, (groundwater) aquifers store
97% of the planet's (available) freshwater."
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9. Water Usage in Large Cities in the World
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National University of
Malaysia
9

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%)
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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
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12. Surface water vs Groundwater
National University of
Malaysia
Slide from Dr. Saim Suratman (NAHRIM, Malaysia)
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13. SW
GW
National University of
Malaysia
SW
GW
Sg. Langat,
Selangor
Sg. Jeli,
Kelantan
Source: Dr Saim Suratman, NAHRIM
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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.
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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.
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16. National University of
Malaysia
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17. National University of
Malaysia
Source: Dr Azuhan Mohamed, Groundwater Expert.
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18. National University of
Malaysia
Groundwater and Geotechnical
Problems
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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)
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20. 2. Groundwater & Stability of Dam
National University of
Malaysia
Vaiont Dam, Italy
After
Before
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21. National University of
Malaysia
Vaiont Dam, Italy
Trigger factor: the fluctuation of groundwater level
Slip surface
Water level before
Water level after
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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
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23. Groundwater & Foundation
National University of
Malaysia
Expensive house
Problem: The foundation of the house failed,
Resulting cracks and unstable foundation.
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Crack developed under the house and
surrounding area
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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
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25. Groundwater & Foundation
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National University of
Malaysia
25

26. Groundwater & Foundation
National University of
Malaysia
Groundwater Modeling using Visual MODFLOW Pro
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27. Groundwater Contamination
National University of
Malaysia
Groundwater Remediation at Taman Beringin Landfill site Malaysia
Drilling
(boreholes)
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28. Groundwater Contamination
National University of
Malaysia
Groundwater Remediation at Taman Beringin Landfill site Malaysia
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29. Groundwater Remediation at Taman Beringin Landfill site Malaysia
National University of
Malaysia
Groundwater Modeling using Visual MODFLOW Pro
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30. National University of
Malaysia
Groundwater Movement
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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
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Dense soil
- low permeability
31

32. Darcy’s Law
National University of
Malaysia
• Darcy’s
experiment
• Henry Darcy
• French
engineer
• 1856
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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
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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
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35. National University of
Malaysia
Laboratory
- Manometer
Field
- piezometer
Borehole / Well
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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.
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37. Calculate:
National University of
Malaysia
(a) Calculate the hydraulic conductivity (K) ?
5 km
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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
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39. National University of
Malaysia
50
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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. 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 )
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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.
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43. National University of
Malaysia
Thank you
どうもありがとうございました
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