Hwa Chong Institution
Integrated Humanities 2014 – Sec 2 Geography
Topic: Land & Water Resources
Handout 2: Water Resources
Name: …………………………………………(
)
Date: ………………
Class: ……………
Sections
1. Prelude
2. Reasons for water constraints
a. High Demand
i. Population growth
ii. Increased water use in agriculture
iii. Increased water use in industry
iv. Changing lifestyles leading to higher water use
b. Low Supply
i. Natural limited supply of freshwater
ii. Uneven distribution of freshwater
iii. Pollution of freshwater sources
3. Responses to water constraints
a. Increasing price of water
b. Increasing freshwater supply
i. Managing water catchment areas
ii. International agreements
iii. Use of technology
1. Recycling water
2. Desalination
c. Conserving water
Prelude
In the lesson on land resources, you learnt about “Reasons for” and “Responses to”
water constraints. This handout will the individual explanations for points in the above
two categories, occasionally backed up by current evidences and statistics that you
should memorize.
Structurally, the water topic is very similar to the land topic you did before this. The
difference lies in the emphasis: There’s more to talk about in the “Reasons for water
constraints” segment. Moreover, you need to be very familiar with Singapore as a case
study – questions in the exam may test your knowledge on how Singapore deals with
water constraints, so you have to know the specific policies for that.
The sections below will also talk about “evaluation” in the “Responses to water
constraints” segment. Evaluation is simply asking the question “What are the benefits
and disadvantages of the solution?” You will need to demonstrate a sound awareness of
the possible evaluations to every “solution” you read about.
Read this set of handouts together with your textbook for a complete understanding of
the topics.
Reasons for water constraints
Water constraints refer to the shortage of water available for human activities. Water
constraints occur because of two main reasons: increasing demand for water and the
limited supply of it. Refer to pages 122 – 124 of your textbook.
1. Population growth
a. Population growth contributes to water constraints, as more water is needed
to cater to the activities of the increased number of people.
b. Many regions and countries have experienced rapid population growth in
recent years. Researchers estimate that by 2050, many African countries will
have more than twice the number of people compared to today; Kenya's
population will rise from 44 million to 97 million. Even in economically
developed countries such as Singapore, population growth has been positive from 2006 to 2012, Singapore’s population growth rate has averaged 3.2%.
c. Over the past 80 years, the increase in population has contributed to a sixfold increase in the demand for water. As human population is expected to
increase in the future, this means that the available freshwater supply has to
be shared between more people, thus exacerbating the water constraints in
many countries.
2. Increased water use in agriculture
a. Water constraints are worsened by an increasing demand for water in
agricultural sectors. In the light of the increasing population, there is a need
to grow more food to feed the growing population.
b. Up to ¾ of the world’s freshwater supply is used for watering crops and
rearing livestock. Moreover, irrigation projects that channel water to farming
areas are extremely water-intensive. In Montana, USA, irrigation accounted
for an estimated 97% of all water use in the state.
3. Increased water use in industry
a. Industrial growth also contributes significantly to the rise in demand for
water, as water plays a significant role in the daily operation of industries.
b. Water is used as a raw material for products like food and beverages,
chemicals and paper. Moreover, freshwater is used as cleaning agents in
factories and energy plants as sediments and nitrates from seawater may
damage sensitive machines. An estimated 15% of water use worldwide is
channeled into industry.
4. Changing lifestyles leading to higher water use
a. Affluence and technological advances have led humans to use more water in
our daily lives.
b. Technological advances have brought with them appliances that provide
convenience to our daily lives, such as air-conditioners and refrigerators.
These appliances are extremely water-intensive. As a country and its people
become richer, these appliances have become increasingly common and
affordable. Hence, the demands for water arising from the increased usage of
these appliances worsen our water constraints.
c. [Some fun stats] In Singapore, basic household water requirements have
been estimated at around 151 liters per person daily, much higher than the
global average of 50 liters per person daily, while far lower than the USA’s
average of 573 liters per person daily.
5. Natural limited supply of freshwater
a. There is a very natural limited supply of freshwater that is suitable for man’s
usage. Only 3% of the Earth’s water is freshwater; the other 97% of it is
seawater that is unsuitable for many uses such as drinking, watering crops,
and cleaning industrial machines.
b. Even within this 3% of freshwater, 80% of it is currently inaccessible as it is
frozen in ice caps and glaciers. Another large proportion of the Earth’s
freshwater supply is groundwater, which is water that flows through spaces
between soil and rocks and deposits in oases or underground reservoirs,
which has to be pumped out from deep layers of soil.
c. Thus, there exists a natural limit to the supply of freshwater man can use.
6. Uneven distribution of freshwater
a. At the regional level, the uneven distribution of freshwater results in water
constraints in some areas being more severe than in others.
b. Differences in the distribution of freshwater usually arise due to differences
in climate; some countries that have an equatorial climate with rain all year
round (Brazil, Peru, Southeast Asian countries) may not face severe water
constraints, whereas other countries that have a dry, desert climate (Egypt,
Middle Eastern countries) may face more pressing water shortages.
c. The uneven distribution of freshwater, coupled with differences in
population sizes, will affect the severity of water constraints in two countries
– Canada has 20% of the world’s freshwater supply with a population of 33
million, whereas India has only 10% of the world’s freshwater supply to
support a population of 1.1 billion.
7. Pollution of freshwater sources
a. Man’s activities may pollute our freshwater supplies, thus aggravating
existing water constraints.
b. In Indonesia, for example, improper waste disposal has severely polluted the
Citarum River – the plastic bottles and assorted garbage that float on the
water’s surface precludes its use for other purposes. In less developed
countries, as much as 90% of all wastewater from sewage is discharged,
untreated, into rivers and streams.
c. Deforestation also contributes to water pollution in that soil erosion is far
more prevalent in areas where trees have been cut down – the soil that flows
into freshwater bodies contaminate it and make it unusable for drinking and
other daily uses.
Exam note: There are very few ways that the questions on this segment can vary. Commit all
of the above points to memory and be able to explain the different competing uses of land.
Responses to land scarcity
1. Increasing the price of water
a. Refer to textbook page 125 for the explanation
b. [Ev: Disadvantage] Increasing the price of water will have different
economic impacts on different groups of people. Those who are able to afford
it will continue to use large amounts of water. On the other hand, the poor
may experience greater shortages of water since they are unable to pay the
high prices. This lowers the standard of living for the poor as it forces them to
scale down on water use.
2. Managing water catchment areas
a. Water catchment areas can be used to increase the supply of freshwater. A
water catchment area is an area over which rain falls and is collected. Nature
reserves are often used as catchment areas since trees help store rainwater
that falls in the catchment. For example, Singapore’s water catchment area
comprises Upper and Lower Peirce, Macritchie and Seletar Reservoirs.
Rainwater is intercepted by the trees and then absorbed into the soil. By
flowing through spaces between soil and rock formations, the water
eventually flows into the reservoir for storage.
b. [Ev: Benefit] Using water catchment areas is effective as it obtains
freshwater at a lower cost than other methods – rainwater is cheaper to
purify than salt water, as it does not contain salt and other sediments.
Moreover, building water catchment areas also increases the amount of
dedicated recreational land for people to enjoy, as the forested nature
reserves are not used for other purposes.
c. [Ev: Disadvantages] However, the use of water catchment areas may not be
very viable for countries with small land space, as such countries already
have little land to set aside for these purposes. Small land space also means
that the rainfall that can be collected in these reservoirs is limited.
Furthermore, precipitation may be unpredictable at times, which means that
these reservoirs may eventually dry up in times of droughts – Singapore
experienced a 3-month period of almost no rainfall in 2014, which raised
concerns over water levels in its reservoirs.
d. [Case Studies] Singapore’s catchment areas – refer to page 132 of your
textbook.
3. International agreements
a. Some countries may increase their water supply through international
agreements with other countries with an excess supply of water.
b.
c.
d.
e.
International agreements on water are agreed arrangements between two or
more countries regarding the supply and use of water over a fixed period of
time. This is the case between Singapore and Malaysia, where an existing
water agreement guarantees the sale of water from Malaysia to Singapore.
This agreement expires in 2061.
In other cases, these agreements may be on water bodies (rivers, lakes) that
run across several countries. These include the Nile River in Africa, and
Mekong River in Southeast Asia. Such these agreements on shared water
bodies fulfill two purposes: First, they help regulate the sustainable use of
shared water resources. Second, they form a basis of cooperative
development of the river for commercial and transport purposes.
[Ev: Benefit] This is a convenient way of obtaining additional supplies of
water. Moreover, it legally binds the various parties to the agreement to act in
accordance to the terms set out in the arrangement, so that there is a greater
degree of certainty in water supplies.
[Ev: Limitations] However, international agreements may be unsustainable
in the long term, as some countries may not agree to an extension of the
water agreement if she needs the water herself. For example, a furor erupted
over the water issue when the first Singapore-Malaysia water agreement
expired in 2011. This links to the second limitation of water agreements,
which makes countries vulnerable to the whims of the other parties on whom
they rely on.
[Case Studies] Singapore – Malaysia water agreement, Mekong & Nile Rivers
4. Recycling Water
a. Recycling water refers to converting used water into usable water. Refer to
page 128 for a short explanation of this. Below is a process which you need to
be able to describe in full:
i. Water from households, industries and public areas are sent to
recycling plants to have impurities removed and bacteria
destroyed by UV radiation
ii. This end product is recycled water, which can be consumed or
used just as freshwater can.
iii. If the water is to be used for industrial purposes, it is further
treated at industrial water works – they end up as coolants used to
cool machinery.
b. [Ev: Benefits] Recycling water increases our water supply by allowing us to
yield more water given a certain initial amount – NEWater is able to convert
50% of a water droplet into a clean and new water droplet. We say that its
recyclable water yield is 50%. Hence, this means that for every drop of water,
we are able to obtain two drops of water through the process of recycling.
c. [Ev: Limitations] The high costs of this process are its greatest limitation – a
large amount of capital is needed to construct facilities to recycle water. For
example, the NEWater plant in Bedok cost $6.8 million to construct.
Moreover, drainage systems need to be put in place to direct wastewater to
recycling plants. The odd taste of recycled water is also an issue – this makes
most people averse to consuming recycled water.
d. [Case Studies] NEWater in Singapore
5. Desalination
a. Desalination increases our water supply by converting abundant seawater
into usable pure water. Desalination refers to the process of removing
dissolved salts from seawater, or highly mineralized groundwater.
Desalination can be conducted in two ways; distillation and reverse osmosis –
refer to page 128 of your textbook for a diagrammatic explanation. Below is a
step-by-step explanation of BOTH ways of performing desalination that you
need to commit to memory:
b. Distillation involves:
i. Seawater is heated in machines known as evaporators. The water
vapour is then collected and condensed as pure water.
ii. The incoming seawater is used to cool the condensers in each
evaporator.
iii. This design conserves energy since the heat released when the
water vapour condenses is used to heat the next batch of seawater
(This happens because when water condenses, it
c. Reverse osmosis involves:
i. Seawater is pumped at high pressure through a special membrane
ii. The high pressure forces the water through this membrane –
water molecules pass through the membrane, but salt molecules
get “left behind” as they are too big to pass through the membrane.
d. [Ev: Benefits] Benefits of desalination are that water supply is increased as
seawater, which the world has in abundance, is convertible into usable water.
Moreover, continued advances in technology may increase desalination’s
efficiency, thereby increasing the amount of water that can be obtained
through the process.
e. [Ev: Limitations] However, there are many limitations to desalination.
Distillation requires high amounts of heat, which are produced by burning
fossil fuels. This releases greenhouse gases into the atmosphere, which may
exacerbate global warming. While reverse osmosis does not share this
limitation, it is extremely costly, as much capital needs to be poured into
membrane research to ensure that the water collected is pure, and no
unwanted particles and bacteria pass through. To illustrate the costs of
desalination plants, note that Singapore’s SingSpring Desalination Plant in
Tuas costs $200 million to build. Lastly, improper treatment and disposal of
waste material collected in the desalination process may contribute to
pollution – plans may indiscriminately discard the brine (water with high
concentration of salt) into the sea.
f. [Case Studies] Singapore, Saudi Arabia, USA.
Exam note: Desalination is really the meat of this topic – pay close attention to it and be
ready to describe its benefits and limitations SEPARATELY for different methods i.e. if you’re
being asked about reverse osmosis, don’t say that it contributes to greenhouse gases because
it doesn’t. That’s distillation.
6. Conserving water
a. Conserving water refers to the careful and reduced use of water resources to
ensure minimal wastage: refer to page 130 and 135 on your textbook. Ways
to encourage water conservation include:
i. Educating the public through campaigns
ii. Educating industries through talks and introduction of guidelines
iii. Imposing higher water tariffs on households that exceed a certain
rate of water usage (remember my China example??)
b. [Case Studies] Singapore’s water conservation strategies.
Exam note: As you can tell from its relative length, there isn’t much that can be asked from
this section. However, you need to be aware of SINGAPORE’s water conservation methods, as
questions on the test/exam can be asked on that. You should know our different campaigns
to target different groups of people.