Assessment of Future Water Resources Sustainability Based ... · Assessment of Future Water Resources Sustainability Based on 4 National Taps of Singapore National University of Singapore

Assessment of Future Water Resources

Sustainability Based on 4 National Taps

of Singapore

National University of Singapore

Faculty of Engineering

Department of Civil & Environmental

Engineering

Supervisor: Dr. Pat Yeh

By: Foo Chiou Looi (A0099005E)

Copyright National University of Singapore

CONTENT

2

1. Introduction

• Water resources situation around the world

• Research motivation

• Methodology

2. Water resources in Singapore

• The first tap: local catchment water

• The second tap: imported water

• The third tap: NEWater

• The fourth tap: desalinated water

• Estimated production costs

• Alternate sources of water

• Potential future water supply

3. Water demand in Singapore

4. Water sustainability


CONTENT

3

5. Estimated future water demand

• Domestic

• Non-domestic

• Estimated future daily demand

6. Estimated future supply

7. Sustainability index

8. Discussion

• Future demand

• Future supply

9. Conclusion


1. WATER RESOURCES SITUATION AROUND THE WORLD

4

Source: Fry, 2006


WATER STRESS INDICES

5

Withdrawal-to-availability ratio, W/Q Classification

< 0.1 No-stress

0.1 < W/Q < 0.2 Low stress

0.2 < W/Q < 0.4 Moderate stress

W/Q > 0.4 High stress

Per capita water availability,

Q/c (m3 c-1 y-1)Classification

> 1700 No-stress

1000 < Q/c < 1700 Moderate stress

Q/c < 1000 High stress

< 500 Extreme stress


WATER RESOURCES SITUATION: ASIA AND SINGAPORE

6

• Asia: lowest per capita availability of fresh water

• Central Asia and parts of Southeast Asia: “high water stress”

• Q/c: 110.9m3/year high water stress

• Mean annual rainfall: 2400mm > global average of 1050mm

• Challenges: limited land space, no natural aquifers and lakes to collect

rainwater

• PUB: Four National Taps


RESEARCH MOTIVATION

7

• Sustainability: “development that meets the needs of the present without

compromising the ability of future generations to meet their own needs”

• Dry weather: increase in water demand, affects catchment volume available

• Second tap: not very stable due to the complexity of the relationship

between Singapore and Malaysia

• Third and fourth taps: higher production costs, energy-intensive


METHODOLOGY

8

• Aim: to assess the sustainability of the water resources in Singapore

• Estimated future supply of each tap

• Focus: processes of NEWater and desalination

• Estimated future demand


2. WATER RESOURCES IN SINGAPORE

LOCAL CATCHMENT

9

• 1857: donation of $13000 from philanthropist Tan Kim Seng for waterworks

• 2015: catchment area covers two-thirds of Singapore’s land surface

• Rainwater is collected in the storm water collection system before it is stored

in the 17 reservoirs

• Reservoir Integration Scheme: reservoirs are connected through a system of

pumps and pipelines

• Excess water collected in one reservoir can be pumped into another

reservoir for storage to reduce wastage

• Current storage > 140 million m3


IMPORTED WATER

10

• 1924: completion of causeway between Singapore and Malaysia

• 1962: “Johor River Water Agreement”

up to 250 million gallons of water per day (mgd) from the Johor River

until 2061

• Cost: 3 sen per 1000 gallons of raw water

• Cost to treat 1000 gallons of raw water: RM 2.40

• 1990: construction of the Linggiu Dam for additional water to be drawn on

top of the 250mgd


NEWATER

11

Plant Year of commissioning Capacity (million imperial

gallons)

Bedok 2002 19.4

Kranji 2002 17

Ulu Pandan 2007 32

Changi 2010 50

Total 118

DESALINATED WATER

Plant Year of commissioning Capacity (million imperial

gallons)

SingSpring 2005 30

Tuaspring 2013 70

Total 100


ESTIMATED PRODUCTION COST OF EACH TAP

12

Tap Production cost (S$/m3)

Local catchments 0.30

Imported water from Malaysia 0.20

NEWater 0.23

Desalinated water 0.45


ALTERNATE SOURCES OF WATER

• Rainwater Harvesting

• Greywater Recycling

“Greywater”: untreated used water which has not come into contact with

toilet waste

• Use of Seawater

13


POTENTIAL FUTURE WATER SUPPLY

VARIABLE SALINITY PLANT (VSP)

14

• Able to tap water from the smaller streams near the shoreline

• During rain: production of clean water from canal water

• Dry weather: seawater desalination

Source: http://www.pub.gov.sg/research/Key_Projects/Pages/Membrane1.aspx

http://www.pub.gov.sg/research/Key_Projects/Pages/Membrane1.aspx


GROUNDWATER

15

WATER FROM INDONESIA

• 1991: agreement to provide 1000mgd of water ($0.01/m3) to Singapore from

Riau in Indonesia via undersea pipelines

• 1992: joint venture created to develop supply of water from Bintan and to

Bintan and neighboring Riau Islands but project came to a halt due to

political uncertainty in Indonesia

• Western and Southern parts of the island: Jurong Formation

• Consultancy services:

Development of groundwater flow model of Jurong Formation

Field Investigation Programme

Validation Study

• Jurong island


3. WATER DEMAND

16

Current per

capita

demand

(litres/day)

Current

population

Current total

domestic

demand

(litres/day)

Current total

non- domestic

demand

(litres/day)

Current total

demand

(litres/day)

Current

total

demand

(mgd)

150.4 5,469,724 822,646,490 1,005,456,821 1,828,103,310 402.1


4. WATER SUSTAINABILITY

• Environment and Water Regulations and Standards

• SEWERAGE AND DRAINAGE ACT

17

Source: http://www.mewr.gov.sg/docs/default-source/default-document-library/grab-our-

research/mewr-kes-2014.pdf

http://www.mewr.gov.sg/docs/default-source/default-document-library/grab-our-research/mewr-kes-2014.pdf


WATER SUSTAINABILITY

18

Source: http://www.mewr.gov.sg/docs/default-source/default-document-library/grab-our-

research/mewr-kes-2014.pdf

http://www.mewr.gov.sg/docs/default-source/default-document-library/grab-our-research/mewr-kes-2014.pdf


5. ESTIMATED FUTURE WATER DEMAND

19

ESTIMATED FUTURE POPULATION

y = 2628.2x2 - 1E+07x + 1E+10R² = 0.9773

0

1,000,000

2,000,000

3,000,000

4,000,000

5,000,000

6,000,000

7,000,000

8,000,000

1990 1995 2000 2005 2010 2015 2020 2025 2030

Population

Years

Past population

Poly. (Past population)


ESTIMATED FUTURE PER CAPITA DEMAND

20

145

150

155

160

165

170

175

1990 1995 2000 2005 2010 2015

Per capita demand (litres/day)

Year

Past per capita demand


ESTIMATED FUTURE DOMESTIC DEMAND

21

𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 × 𝑑𝑎𝑖𝑙𝑦 𝑝𝑒𝑟 𝑐𝑎𝑝𝑖𝑡𝑎 𝑑𝑒𝑚𝑎𝑛𝑑

Year

Estimated

future

population

Estimated future per

capita demand

(litres/day)

Estimated future total

domestic demand

(litres/day)

Estimated future total

domestic demand

(mgd)

2020 6,560,326 146.8 963,055,793 211.8

2030 8,647,599 140.8 1,217,581,955 267.8

2040 11,260,519 134.8 1,517,917,911 333.9

2050 14,399,084 128.8 1,854,602,034 408.0

2060 18,063,296 122.8 2,218,172,695 487.9

2070 22,253,153 116.8 2,599,168,268 571.7


ESTIMATED FUTURE GDP PER CAPITA

22

y = 76.491x2 - 304575x + 3E+08R² = 0.963

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

1990 2000 2010 2020 2030

GDP per capita (S$)

Year

Past GDP percapita

Poly. (Past GDP percapita)


ESTIMATED FUTURE INDUSTRIAL DEMAND

23

Year GDP per capita (S$)

Current total non-

domestic demand

(litres/day)

Amount of

water used

per $1000

(litres)

Estimated future

total industrial

demand

(litres/day)

Estimated

future total

industrial

demand

(mgd)

2014 71,318.00 1,005,456,821 14,098,220

2020 98,332.75 1,386,316,730 304.9

2030 150,471.07 2,121,374,200 466.6

2040 217,907.61 3,072,109,374 675.8

2050 300,642.38 4,238,522,252 932.3

2060 398,675.37 5,620,612,834 1236.4

2070 512,006.58 7,218,381,120 1587.8

𝑠𝑐𝑎𝑙𝑒 × 𝐺𝐷𝑃 𝑝𝑒𝑟 𝑐𝑎𝑝𝑖𝑡𝑎


ESTIMATED FUTURE DAILY DEMAND

24

Year Daily demand (mgd)

2020 516.8

2030 734.5

2040 1009.7

2050 1340.3

2060 1724.3

2070 2159.6


6. ESTIMATED FUTURE SUPPLY

25

• NEWater and desalination: 80% of our water demand by 2060

• 2030: capacity of NEWater plants will increase by more than 160mgd

• Increase capacity of Changi NEWater plant by more than 50mgd over the

next 5–10 years

• New Tuas NEWater factory: initial plant treatment capacity of 25mgd

• Kranji NEWater plant will be expanded by 5mgd


7. SUSTAINABILITY INDEX

26

Water resource sustainability index (SI):

• If water supply > water demand, 𝑆𝐼 =(𝑤𝑎𝑡𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑦−𝑤𝑎𝑡𝑒𝑟 𝑑𝑒𝑚𝑎𝑛𝑑)

𝑤𝑎𝑡𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑦

• If water supply ≤ water demand, 𝑆𝐼 = 0


8. DISCUSSION

27

FUTURE DEMAND

• Actual population dependent on birth/death rates, immigration/emigration

rates

• Future per capita demand may not follow a linear trend; affected by weather

and conservation measures implemented

• GDP: an economic way of forecasting annual growth rate

• Results based on extrapolation: the further the estimated year, the more

uncertainty

Copyright National University of Singapore 28

FUTURE SUPPLY

• Most possible future sources of water supply: local catchment, NEWater and

desalination

• Water import from Malaysia: past unsuccessful negotiations and the

complex relationship between the two countries

• Water import from Indonesia: high construction cost; project delayed for a

long time with no update


DESALINATION: REVERSE OSMOSIS (RO)

29

External pressure

applied on the sea

water

Water flows opposite

to the natural flow

across the membrane

Dissolved salts left

behind the membrane

Source: Ghalavand, Hatamipour, & Rahimi, 2014


FORWARD OSMOSIS (FO)

30

Source: Ghalavand et al., 2014 Source: Ghalavand et al., 2014


TOWARDS SUSTAINABILITY

31

• Increased market share of Seawater Reverse Osmosis (SWRO)

• Efficiency improvements

• Specific power demand in 1980: 10kWh/m3

• Specific power demand now: 3–5kWh/m3, depending on specific conditions

and constrains such as temperature and salinity of seawater

• Renewable energy

Solar energy

Wind energy

Wave energy

Geothermal

energy


NEWATER

32

Source: http://3.bp.blogspot.com/-0QlrgB77c24/UUx2-

HWBgLI/AAAAAAAAACM/TkwmhxUEsEk/s1600/newater+illustration.jpg


9. CONCLUSION

33

• PUB: water supply and sustainability

• Sustainability of the local catchment depends on the weather

• Desalination and NEWater : researches on decreased energy use

• Extrapolation of data: greater uncertainties for results in the further years

• Comparison of the current demand among different countries to have a

better idea of the water demand situation of Singapore

• System dynamics has been widely used in water resources planning and

management

𝑝𝑜𝑝𝑢𝑙𝑎𝑡𝑖𝑜𝑛 × 𝑑𝑎𝑖𝑙𝑦 𝑝𝑒𝑟 𝑐𝑎𝑝𝑖𝑡𝑎 𝑑𝑒𝑚𝑎𝑛𝑑

Thank You

Q&A

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