The document discusses water resources and constraints. It notes that while water covers most of the Earth's surface, only 1% is readily available freshwater. There are limited global freshwater supplies and uneven distribution between regions. Rising population growth and increasing development are driving higher water demand, straining scarce resources further. Countries face water constraints and are responding by increasing supplies through various methods like expanding catchment areas, desalination, water recycling, and international agreements. Conservation efforts are also key to sustainably manage limited water supplies.

1. Chapter 8Water Resources
Water as a scarce resource
- Water is important life on Earth.
- Needed for drinking, cooking, cleaning and much of world’s water supply used in industries
or agriculture.
- Amount of water consumed by people all over the world is increasing but fresh amount of
water available for human use is limited.
- Water shortage = water constraint
- More than one-third of world’s population lives in countries with water constraint.
- These countries need ways to increase supply of water and must use existing supply in best
possible way to meet needs of people.
Reasons for water constraints
1. Limited supply of water
- Water cover 3 quarters of earth surface, saltwater in seas and oceans make up 97%, fresh
water frozen in form of snow and ice make up 2%, 1% for fresh ground water and fresh
surface water readily available for human consumption.
- Fresh water stored in rivers, streams , lakes -> surface water
- Fresh water stored deep underground -> groundwater
- Uneven distribution of fresh water
 Some countries have abundant supply of fresh water while other lack of it.
Eg. Canada has 20% of world’s fresh water, India 10% only but India population 30
times larger than Canada, making situation worse.
 Caused by differences in climate.
Eg. In countries like Africa, frequent lack of rain led to insufficient water supply for
irrigation. This affected agriculture and led to food shortage for people.
- Water pollution
 Even when there is an abundant supply of fresh water in a country, not all is safe for
drinking.
 Some fresh water resources are increasingly being polluted by human activities.
Eg. Lakes and rivers polluted by drinking, fishing, swimming, waste from factories and
household
 Many households and factories carelessly dump waste into rivers and pollute the
waters.
Eg. Lake Baikal in Russia stores 20% of world’s fresh water supply and now heavily
polluted by discharge of waste chemicals from surrounding industries.
2. Rising demand for water
- Rising demand for water increase problem for water constraints
- Causing problem for many countries especially those located in water-scarce region
- Population growth
 Over past 80 years world population tripled and demand increased more than 6 times.

2.  Between now and 2050 , world population expected to increase by 3 billion people and
total supply of fresh water on Earth will have to be shared among more people.
 Problem of water constraint in some countries will worsen.
- Growth for agriculture
 Increasing need to grow more food to feed growing population throughout the world.
 3 quarters of world’s fresh water supply used for watering crops and rearing livestock.
 Large scale irrigation projects are developed to channel water from rivers, lakes,
groundwater sources to farming areas with little rainfall.
- Growth of industries
 Contribute to rise in water consumption as water plays important part in daily
operation of industries
Eg. Water used to clean and cool machines, raw materials in making products like food,
chemicals and paper
- Changes in lifestyle
 Increased the demand of water
 When country more developed, people adopt modern lifestyles and can afford to buy
items to provide more convenience and comfort.
Eg. In most homes of developed countries, there are electrical appliances like washing
machine and air-conditioners.
 Use of electrical appliances increase demand in water.
Responses to Rising demand for water
- If water constraint problems left unchecked, it will lead to other problems like shortage of
food for people around the world.
- Response : increasing price of water , increasing supply of water , conserving water
- Increasing price of water
 In order to control rising demand for water, many countries increase price for water.
 People who do not want to pay more will be encouraged to use less water and price
increase also help reduce rising cost of producing and distributing water.
 Not best way of response because as water price increase , only those who can afford
high prices can use the amount of water they want and the poor will suffer when price
of water increases.
- Increasing the supply of water
 Increase water supply to cope with situation
 Increase supply of water by increasing catchment areas, buying water from other
countries through international agreements, use of technology (Eg. Water recycling ,
desalination)
 Increase catchment areas
Catchment area : area over which rain falls and is collected
Increase in catchment area will increase amount of water collected
Eg. Singapore’s Central Catchment area consist of forests around 4 major
reservoirs – Upper Seletar Reservoir , Upper Peirce Reservoir , Low Peirce
Reservoir , MacRitchie Reservoir

3. Nature reserves often used as catchment areas as forests retain large supply of
fresh water.
Rain water is intercepted by trees and plants and is absorbed by soil layers on
the ground.
The water will eventually be drained into reservoir for storage.
Process –
1. Reservoir
2. Pumping station
3. Raw water mixing chamber
4. Settling tank
5. Sand filters
6. Disinfection
7. Clear water tank
8. Pumping station
9. Service Reservoir
10. Industries and Homes
Water from catchment areas in Singapore goes through treatment process
before it reaches our homes and industries.
Advantage –
1. Help increase amount of rainwater collected in a country
2. Help to keep cost of water treatment down because rain water much
cleaner than water and does not contain salt like sea water.
3. Easier and less costly to purify
4. When more land in country set aside to build water catchment areas, more
forests are conserved and people can enjoy wider range of nature and
recreational areas.
Disadvantage –
1. Setting aside more land for this purpose means less land for other purpose
Eg. Building house, industries, road
2. Problem for countries struggling with land constraint like Singapore
Eg. Singapore half of land area set aside for water catchment areas.
3. Rain is natural event and country has no control over amount of rain that
falls. If drought happens or little rainfall, catchment areas will be ineffective.
 International agreements
Obtain water supply from neighboring countries under international
agreements
International agreement on water – arrangement between 2 or more countries
regarding supply and use of water resources over specific period of time
While signing international agreements , countries discuss and negotiate terms
on buying or sharing water resources
Eg. Bangladesh-India water treaty signed in 1996 for both countries to share
and manage water supply in Ganges River but treaty valid for only 30 years and
reviewed by government every 5 years.

4. Importing water from another country is convenient way of obtaining water
but dependence on another country not best solution in long term because
international agreements do not last forever.
When agreements expire, countries will negotiate terms for new agreement
and countries cannot be certain they will always have enough water to meet
their needs.
 Use of technology
People use technology to create new source of water.
Effectiveness –
1. Very costly and requires large amount of energy
- Continued advancements of membrane may improve efficiency and lower
cost
2. Technology can convert used water or sea water to potable water, people
may not get used to it due to lack of minerals after treatment process
(different taste)
-In Singapore, NEWater is piped into reservoir before water channeled to
homes, factories, schools.
Recycling water (Water Reclamation)
 Used water can be converted into usable water.
 At the start of the recycling or reclamation process, used water is
collected from households and factories and channeled to water
recycling or water reclamation plants to remove impurities.
 End product – recycled water or reclaimed water
 Treated water from plants can be further treated at industrial water
works to produce industrial water.
 Industrial water – supplied to factories for washing and cooling of
machinery
 With use of modern technology, recycling or reclaiming water has
increasingly advanced.
 It is now possible to treat used water in drinkable clean water or
potable water.
Eg. NEWater in Singapore.
 Stages :
1. Microfiltration
Water is passed through a process of microfiltration (hollow fibre)
where large particles are trapped outside the fibre and bacteria are
removed.
2. Reverse Osmosis
Pressure is applied to water to force it through a special membrane.
Micro filtrated water pass through special membrane and become
pure water as very small particles like bacteria and dissolved salts are
removed.
3. UV disinfection & end product
Water disinfected by ultraviolet light radiation to become NEWater.
Desalination

5.  Process of removing salt from sea water
 Commonly used to convert sea water to drinking water in dry regions
of the world or in areas where water supply is contaminated
Eg. Saudi Arabia has world’s largest desalination plant producing 12
million gallons of fresh water each day.
 Methods : distillation , reverse osmosis
 Distillation – water is boiled and water vapor is collected and
condensed into fresh water
 Resembles natural water cycle
 Can be expensive as a lot energy needed to heat up water
 In some parts of world, households carry out small-scale
distillation of water using energy from sun.
 Reverse Osmosis – sea water pumped at high pressure through
special membrane which separate dissolved salts from water
 More recent method
- Conserving water
 Water conservation – careful use of water resources that wastage is kept to minimum
 Supply of clean water from water catchment areas and other sources are limited and
can run out.
 Conservation help reduce risk of future water shortage by encouraging people to use
less water before it’s too late.
 “Prevention is better than cure. “
 Delay need to develop new facilities or upgrade existing facilities to increase water
supply
 Facilities expensive to build , take up land which may need for housing or industries
 Practicing conservation help industries and households to save money through
reduced water bills
 Government has less need to invest more money on water related facilities like
pipelines and water treatment plants
 Money can be channeled to improve other facilities
 Encourage people by educating public through campaigns but not easy task as people
need change lifestyle.
Eg. Used filled sink instead of running tap = 5 mins save 48 litres of water
 Requires cooperation from everyone. If everyone put in a little more effort in reducing
water wastage, will go long way in protecting limited water resource.
Case Study
 Why Singapore have water constraint?
- Physical environment : rivers of Singapore no adequate supply of fresh water to meet needs ,
rainfall high but occasional dry spells are common especially June to October , amount of
rain collected in catchment area not enough to satisfy all water needs
- Loss of water catchment areas – early 20th century more land cleared to make way for
industries and housing but more land set aside for catchment areas also

6.  Growing demand for water
- Growth of Singapore population and industry increase the demand for limited supply of
water.
- Expected to increase further due to Singapore’s works towards being global centre for high-
tech manufacturing industries.
- Industries will need a lot of water to carry out process.
Eg. Water fabrication industry need pure water for cleaning as tiny impurities will cause
defects in wafers manufactured.
- Using water at increasing rate due to change in lifestyle and use of times that provide more
convenience and comfort
Eg. Washing machine, dish washers
 Water as a strategic resource
- Without water , household , industrial , business cannot continue
- Health at risk as human beings need water to survive
- Increase our vulnerability – put us in weak or unfavorable position
 Methods to increase water supply
Water from Local catchment areas
- Local catchment areas collected in reservoir and storm water collection ponds
- Before 1975 , MacRitchie , Lower Peirce , Upper Seletar
- 11 more constructed over years
- Reservoirs created by building dams across river or along coastline
- Storm water collection pond install in some housing estates to collect rainwater and channel
to reservoir
- By 2009 , Singapore from half to two third island plus Marina Reservoir
Imported water
- Buy water from Malaysia
- 2 agreements expire 2011 and 2061
- Not best solution to buy water in long term as agreement expire and can choose to supply or
not
- Should be self-reliant and self-sufficient and obtain water from local source
NEWater
- Produce high grade water using high technology
- Surpass international drinking standards
- Supplied to many wafer fabrication plants , industrial estates , commercial buildings for
direct non-potable use
- Small amount mixed with rain water to households for consumption
Desalination
- Cost of building , operating plant high

7. - Supply 10% of nation’s demand for water
- Similar to reclaimed water process
Polices, campaigns to conserve water supply
- Conservation tax by additional fees above certain amount water used
- “ Save water” campaign , conservation talks in schools , leaflets to households
- Water-rationing exercises where water temporarily cut off to spread awareness
- “ Water efficient homes “ set up exhibitions and use of water-saving devices , conservation
tips
- More than 250 000 households install water saving device
Enough for future?
- Technological advancements enlarge catchment areas, build dams , obtain fresh water from
sea and used water