Groundwater. Our hidden asset

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. 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. National University of
Malaysia
What is Groundwater?
28-Jan-14
3

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. 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. •
•
•
•
•
Aquifer (permeable)
Aquitard (Impermeable)
Artesian well
Water table
Piezometric surface
Groundwater
National University of
Malaysia
Piezometric surface
28-Jan-14
6

7. National University of
Malaysia
Groundwater as a Resource
28-Jan-14
7

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. Water Usage in Large Cities in the World
28-Jan-14
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%)
28-Jan-14
10

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. Surface water vs Groundwater
National University of
Malaysia
Slide from Dr. Saim Suratman (NAHRIM, Malaysia)
28-Jan-14
12

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. 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. 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. National University of
Malaysia
28-Jan-14
16

17. National University of
Malaysia
Source: Dr Azuhan Mohamed, Groundwater Expert.
28-Jan-14
17

18. National University of
Malaysia
Groundwater and Geotechnical
Problems
28-Jan-14
18

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. 2. Groundwater & Stability of Dam
National University of
Malaysia
Vaiont Dam, Italy
After
Before
28-Jan-14
20

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. 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. 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. 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. Groundwater & Foundation
28-Jan-14
National University of
Malaysia
25

26. Groundwater & Foundation
National University of
Malaysia
Groundwater Modeling using Visual MODFLOW Pro
28-Jan-14
26

27. Groundwater Contamination
National University of
Malaysia
Groundwater Remediation at Taman Beringin Landfill site Malaysia
Drilling
(boreholes)
28-Jan-14
27

28. Groundwater Contamination
National University of
Malaysia
Groundwater Remediation at Taman Beringin Landfill site Malaysia
28-Jan-14
28

29. Groundwater Remediation at Taman Beringin Landfill site Malaysia
National University of
Malaysia
Groundwater Modeling using Visual MODFLOW Pro
28-Jan-14
29

30. National University of
Malaysia
Groundwater Movement
28-Jan-14
30

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. Darcy’s Law
National University of
Malaysia
• Darcy’s
experiment
• Henry Darcy
• French
engineer
• 1856
28-Jan-14
32

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. 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. National University of
Malaysia
Laboratory
- Manometer
Field
- piezometer
Borehole / Well
28-Jan-14
35

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. Calculate:
National University of
Malaysia
(a) Calculate the hydraulic conductivity (K) ?
5 km
28-Jan-14
37

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. National University of
Malaysia
50
28-Jan-14
39

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 )
28-Jan-14
41

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. National University of
Malaysia
Thank you
どうもありがとうございました
28-Jan-14
43