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Chapter One-Introductory Chapter:
Introduction
Floods are a consequence of migration of the boundary between land and
water bodies (Mandych, 2000), and can result in vast damages in a wide range of
aspects. Among the natural disasters, floods are generally considered to constitute the
most severe weather threat and are acknowledged as the most costly natural disaster
facing the world in this modern age (National Flood Insurance Program USA
Government, 2010). To aggravate the problem, floods are accredited as the most
common climate-related disaster in the Asia-Pacific region (United Nation
Environment Program, 1997). This is compounded by Singapore being protected from
most natural disasters, with floods being one of the few that Singapore is not insulated
against. As Minister of Environment and Water Resources Dr Vivian Balakrishnan
puts it "Every time a flood occurs, it will be newsworthy”. (Chanel News Asia 2011)
As such, floods definitely constitute a major problem in flood prone urban Singapore.
Though the magnitude of floods in Singapore are not as high as the magnitude
of floods in other countries, the economic effect and cost of damages on a small
developed largely urban country like Singapore can be much worse than on other
countries, as the areas affected tend to be densely populated, well developed and
generally economically important.
In summary, my paper will delve into the field of flooding, specifically
covering the changes in the flooding phenomena, the viability of conventional flood
prevention methods in world of today, the usefulness of the new flood prevention
methods, and the difficulty in flood prevention.
Rationale
As can be inferred from the Orchard Road being flooded twice, by floods
described as “once every 50 years” by Yacoob Ibrahim, within two years, the canals,
especially the major stamford canal which runs along Orchard Road, are no longer
efficient enough. Given that the canals were once more than efficient enough to
channel away rainwater, floods have gotten worse since the canels were built. As the
world experiences global warming, much of the sea water once trapped in the ice caps
are realeased. Many other sources of water locked in the form of ice will be released
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over time in the future. Thus with the increae in the water circulating the earth, floods
are probably only going to worsen. As such, it is imperitive that the changes in
floods,the possibility of prevention and the unexplored or up to now still unused
means to counter floods be thouroughly researched on.
In addition, though the physical damages caused by the flood were rather little,
they cost the Singapore Government a lot of money due to the inteangible damage
caused by the floods. For example, on July 17th 2010, due to lack of buissness for one
day, damages of reputation of Ochard Road, and damages to goods and vehicle, the
final cost of the damages, both tangible and intangible, totalled up to 12.5 million
dollars (Asia One Buissness News 2010). As Singapore is likely to continue
developing economically to emain competitive in the world, but yet is not going to
grow in terms of size, each area in Singapore is likely to get more economically
important in the future. As such, it is crucial that we look into flood prevention.
With the knowledge severity of the economic damages caused by floods, and
the frequency of floods, the Singapore government has been trying to put a stop to
floods, or at least reduce the damages caused since the early 1970s. However, the
changes humans have made to the environment have changed many natural processes,
resulting in the change of the natural phenomena of flooding. Thus, it is imperative
that both the differences between the floods of the past and the floods of the present
and the changes in flood prevention technology are identified. In addition, it is acutely
essential to ascertain that all the measures that were implemented in the past are still
relevant today.
Another aspect my paper will delve into is the problems in flood prevention. It
is generally agreed that floods have become less severe with the development of new
flood prevention technology over the recent years. However, despite the research and
development conducted in this area, why is technology unable to completely prevent
flooding? What complications are there in flood prevention? As such, my paper will
delve into this area and attempt to provide an answer to this pressing question.
Also, other than the measures implemented in 2010, the drainage system in the
Orchard area have not been improved much for a long period of time. As such, the
drainage in the area relies heavily of the older technology. Dr Vivian Balakrishnan,
Singapore’s Minister for environment and water resources, admitted the need to
assess if weather patterns were changing. "If indeed it has changed, then our planning
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norms will also have to be modified and that's an engineering and technical issue." As
such, it is important that we look into how floods have changed and the viability of
old methods. Thus, my paper will provide a view regarding this pressing problem.
[1.2] Research Questions and Thesis:
Thesis:
The danger of floods has reduced over the recent 30 years due to
improvements in infrastructure and flood prevention technology.
Research Questions:
1. Why is the complete prevention of floods impossible? What are the
difficulties faced in doing so?
2. With reference to the frequency of floods in Singapore and areas in
floods have affected, how have floods changed over the past 30 years?
Why?
3. Are floods in Singapore as dangerous as 30 years ago?
a. Is Singapore prepared for a flood?
[1.3] Research Methodology:
My research will first consist of a thorough analysis of present literature
regarding my topic. This would encompasses literature that include numerical
information that include the location and date of the previous floods within the past 20
years, for example Singapore archives. Using this data, I will chart out areas affected
over the years and compare the areas affected and discharge in the 1990s and 2000s.
Next, I will retrieve government white papers and periodicals. I will then
analyze the changes in flood prevention technology used, especially in the areas
where floods no longer occur.
Finally, my research will delve into interviews with experts in the field,
namely experts on floods preferably one from National Technological University
environmental engineering department and National University of Singpore
geography faculty and ask them for their opinion, especially on assessment of risk.
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[1.4] Limitations and delimitations:
Given that this paper focues on a time period of 1990s to 2011, this paper will
not be able to anticipate technological improvements in the future, thus certain
sections would be rendered obselete in the future. However, the trends in flooding
predicted in this paper will be applicable in the future.
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Chapter Two-Literature Review:
[2.1] Introduction
This chapter seeks to review past literary works with their focus revolving
around floods, specifically addressing what are the causes of floods, what has the
government done and what else can be done. The chapter will start off by defining
key terms which will be used throughout the paper, followed by a general review of
the types of floods and analyse which types are applicable to Singapore. I will then
address the causes of the flooding and review the damages floods can cause.
[2.2] Definitions of key terms
The term “Floods”, though difficult to define precisely, refer to “The unusual
and rapid accumulation or runoff of surface waters from any source.” [USA NFIP
(National Flood Insurance Program) 2010] or “A high water level along a river
channel or on a coast that leads to inundation of land which is normally not
submerged” (Thomas, D. and Goudie, A. (eds) 2000) in the context of my paper.
The term “Flood frequency” is defined as the follows “An analysis using data
from the period of hydrologic records to establish a relationship between discharge
and return period or probability of occurrence as a basis for estimating discharges of
a specific recurrence intervals” (Thomas, D. and Goudie, A. (eds) 2000) More simply
put, flood frequency can be defined as “Refers to a flood level that has a specified per
cent chance of being equalled or exceeded in any given year” (Kansas Water Science
Centre N.D) Essentially, this paper will delve into the change of frequency in years.
The term “Discharge” refers to “rate of overland flow”, which is expressed in
this formula “Rate of production of overland flow=rate of precipitation – rate of
infiltration” (Strahler A.N & Strahler A.R 1978)
[2.3] Identifying floods in Singapore
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The first step in studying any phenomena is to identify it. Thus this subchapter
will look into the types of floods and identify the type of floods plaguing Singapore
and look into the causes and factors behind it.
General types of flood
Floods can be split into 4 general categories by their causes, namely high
rainfall, tide and wave extremes, thawing of ice and structural failure. The high
rainfall category of floods can be further categorised by the speed of onset of the
flood into 2 groups, slow onset floods and flash floods. (Mandych, A.F N.D)
In slow onset floods, runoff from sustained rainfall of medium intensity over
long periods of time, usually more than 2 days, or gradual snow melt (inapplicable to
Singapore due to its being a tropical country) eventually exceed the capacity of a river
or drain’s channel, thus causing it to break its banks and floods the surrounding area.
This type of floods could last for weeks, and occasionally, in extreme situations, even
months. (Pacione M. 1999) Slow onset floods last for long periods of time over large
areas, thus it displaces many people for vast periods of time, creating much
inconvenience. (Strahler A.N and Strahler A.R 1978)However it is considered less
dangerous, as people have a lot of time to put in place preventive measures to prevent
loss of life, disease and physical damage. Also, the slow onset of the flood generally
results in very little property being washed away during the floods, and the slow
moving waters cause less damage as compared to flash floods. As such, they are
deemed as less dangerous. (Chin, O. P. (Ed.). 2009)
Flash floods are a special type of fast onset floods. A flash flood is defined as
the following “... local or rapid increases in discharge … normally associated with
rapid transport of large amounts of water or sediment. They [tend to] be natural, such
as due to sudden rainstorm” (Thomas, D. and Goudie, A. 2000). Simply put, flash
floods are characterized by incredibly fast, unpredictable and raging torrents after
sudden heavy rains (usually tropical thunderstorms) that cause rivers to burst their
banks and drains to overflow. The unpredictability of flash floods and the speed of
onset cause the average rate of mortality, in terms of numbers killed as a proportion of
numbers affected are the highest for flash floods.
A flash flood normally gathers and dissipates within an average of 6 hours, but
could have an onset time of 10 to 20 minutes and last for less than an hour. The main
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factors that usually decide the build-up time of the flood, the discharge, speed the
waters move and the quantity of water involved are as follows: intensity of rainfall,
duration of rainfall, surface conditions, the slope and surface features of the receiving
basin. (Kansas Water Science Research Centre N.D)
Some areas are more susceptible to flash floods than others. In general, areas
with a steep topography (ground is sloped at a high angle) are more susceptible to
flash floods as the steep land surface will funnel runoff into a narrow canyon thus
overloading the area. When the land surface is very steep, floodwaters may accelerate;
causing the flood wave to move downstream very quickly, possibly too fast to allow
escape, thus resulting in loss of life. (Bashir, B.M 2006)
Urban areas are also considerably more susceptible to flash floods as
compared to rural areas. In urban areas, a high percentage of the surface area is
composed of impervious streets, roofs, and parking lots where water is unable to
infiltrate the earth, thus causing runoff to occur very rapidly. (Bashir, B.M 2006)
Analysis of flood types – which may occur in Singapore and why they are so severe
The geographic location of Singapore protects in from wave and tide
extremities as it is surrounded by close by islands like Sumatra and Malaysia,
specifically, the Indonesian Archipelago in the west and south and the Philippines in
the east. Singapore’s protection from extreme tides is clearly highlighted in the 2004
Asian tsunami, where Sumatra took the brunt of the tsunami, leaving Singapore safe.
Thus, it is safe to conclude that it would be highly unlikely that Singapore will get hit
by any extreme waves or tides. However, there is some debate regarding the safety of
Singapore from these extremities in the near future. After the 2004 tsunami, Sumatra
moved about 100 feet (LA Times 2004). At this rate, Singapore might be much less
protected in the near future. However, at the moment, Singapore is still safe from tide
extremities.
Singapore has no large water bodies that run through it. As such, no structures
meant hold back water from moving water sources, such as dams in rivers, have been
built in Singapore. Thus it is impossible for Singapore to be flooded because of dam
failures. However, Singapore relies heavily on its drainage system, which though
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efficient, but still fallible. Thus Singapore could be affected by floods caused by
structural failures.
Most of Singapore’s land has been developed into paved road, or buildings.
The roads are mostly paved with concrete and asphalt though some roads have been
paved with porous asphalt [NAPA (National Asphalt Pavement Association) 2011].
As concrete and asphalt are not porous, thus water is unable to infiltrate the ground.
As a result, the only way water can be channelled away is through the drainage
system. Singapore has limited land space, thus only that much space can be used for
building drains, thus the stress on the drains are very high. As such, flooding in
Singapore is classified as urban floods.
Singapore lies on the equator, thus experiences a tropical climate. As such,
floods in Singapore cannot be caused by the sudden thawing of ice. However, though
Singapore’s tropical climate rules out the possibility of floods caused by thawing of
ice, it causes Singapore to be vulnerable to high rainfall caused floods. Singapore
experiences high rainfall, occasionally reaching 260mm a month, as it is a tropical
country. In addition, rains tend to occur very frequently, about 50% of the days (Asia
for Visitors). Also, the rainwater tends to present itself in extremely large amounts,
the record being 65 mm in an hour (Straits Times 2011). To further aggravate it, the
convective precipitation, or thunderstorms, from cumulus clouds or cumulonimbus
clouds tend to last for a very short period of time, usually averaging less than 30
minutes long. This problem is made worse by Singapore being extremely close to the
equator, thus having a much higher rainfall as a whole, 2342.2mm per year, as
compared to 500 mm/year in London (National Environmental Agency 2007), when
compared to the other countries,.
Thus in summary, Singapore can experience very high rainfall within a day,
which could fall very suddenly, over a short period of time. This could overload
drains in a short period of time, causing floods. From the short onset of floods in
Singapore, we can conclude that the floods that occur in Singapore are urban flash
floods, and to some extent structural failure floods.
16 June 2010 Orchard Floods
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This flood is classified as an urban flash flood. The rain was sudden and lasted
only 2 hours and the floods subsided within 30 minutes of the end of the rain. The
rainfall that fell fell within 9am and 11 am in two intense bursts of rain and was
measured to be 60% of the average rainfall in June (PUB Press Release 2010). The
100 mm of rain that fell within the two hours (about 50mm/hour) caused an overload
of stress on the drainage systems, and exceeded the capacity of some of the smaller
drains, causing them to overflow and flooding to occur.
Orchard Road is a low lying area that lies at the bottom of the Orchard area,
which has a steep topography. This resulted in water flowing from higher areas
around Orchard Road to flow into Orchard Road, bringing along rubbish in its way.
This put even more stress on the drainage system, as the water from the convective
rain converged in Orchard Road, and brought rubbish that clogged up the drains.
As Orchard Road is a highly developed urban area, most of the ground is
covered with concrete, thus the water could not enter the ground, thus increasing
runoff exponentially. This places enormous strain on the drainage system, as it is only
mean of draining the water. As the water level increased, and water from other areas
flowed in, the rubbish and other material (humus, top soil, leaves etc.) flowed in too,
and clogged up the drains, preventing the water from flowing out of Orchard Road.
Thus the discharge continued to increase and the water was unable to either flow out
through drains or infiltrate the ground. This was considered to be one of the most
important reasons for the flood.
[2.4] Impacts of flash floods
This subsection will look into the effects of floods. Most people only know
about the negative effects of floods, or rather damages caused by floods. However,
there are, in fact, positive effects of floods. Floods could support eco systems, restore
soil fertility and even help certain species find and move to a new habitat. After floods
subside, a lot of sediments and nutrients are deposited on the land, thus could be
beneficial to the areas affected, especially for third world countries. For example, in
Bangladesh, floods are considered to be helpful and regarded positively by the people,
unless the magnitude of the flood reaches an abnormally high degree. Despite the
existence of benefits of floods, only the negative impacts of floods will be discussed
in this subsection as much of the positive effects are not applicable to Singapore.
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Floods cause damages in many aspects, ranging from economic and health
aspects to physical aspects. Among all the aspects, the economic aspect affects
Singapore the most, thus, this subsection will focus more on the economic effects.
[2.4.1]The health aspect
One important aspect of the impact of floods is health risk aspect. As water
borne diseases are not really present in Singapore, the physical health aspect is less
important in Singapore. As such, this subsection will discuss the mental health aspect.
Floods appeared to have a special impact on their victims, instilling a fear of the
consequences that often exceed their actual impacts. (Green and Penning-Rowsell
1989) The trauma of being involved in a flood has caused people to develop a phobia
for water. This will eventually lead to vast social problems. In the most extreme
scenarios, floods led to such extreme trauma that people committed suicide. As
Orchard Road is a tourist belt, this problem very serious. If any such cases were to
occur in Singapore’s Orchard Road, Singapore’s tourism will be hit very hard.
[2.4.2] Economic impacts
Due to the physical damage caused by the floods, the economy of the country
affected will definitely suffer (given that the floods have a high discharge). Any
physical damage caused by the floods will cost tax money to repair, thus preventing
upgrading and building work in other parts of the country. This leads to temporary
stagnation of the country. In this evolving world where change is the only constant,
and the world becomes more and more globalised, any time lost doing repair works
will cost the county severely in terms of its competitiveness in the global arena,
causing very severe long term economic damage to the country. In a small country
such as Singapore, where exports is one of our main industries, we cannot afford to
lose out on our competitiveness even for just a moment, or we will be overtaken by
other countries. Given Singapore’s lack of resources, if falls behind other nations, it
will be extremely difficult to make it competitive again, as it is losing already losing
its best resource, its top brains, at an alarming rate
Other than the long term economic impacts caused by the physical damage of
the flood, the area affected by the flood may cause severe short term economic
problems. For example, the flood in Queensland, Australia on 10 January 2011 is
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predicted to cause a drop of half a percentage point in the GDP for Australia (Wayne
Swan, Australia’s Treasurer 2011). The reason behind this problem, is the area
affected, Queensland, is responsible for 19% of the country’s economic output. Loss
of this 19%, will cause a decrease in the GDP.
Queensland is one of the regions in Australia that mine coking coal rather
intensively. The flood made the industry come to a standstill for a long period of time,
losing approximately 600 million Australian dollars a week [Estimate by Michael
Bush, National Australia Bank analyst 2011]. The companies involved in coking coal
mining in Queensland, BHP Billiton Ltd., Rio Tinto Group and Xstrata Plc have made
a loss of a total of A2.6 billion dollars. This drop of profits in a prominent industry of
Queensland caused a drop in the economic output of Australia. Agricultural activity is
present in Queensland. The drop in the supply of crops due to the destruction of the
harvest and lack of usability of farms in the area caused a general price hike in all
food products, causing inflation.
The presence of floods in Orchard Road would cause a loss of infrastructure,
and thus a loss of business. The loss of infrastructure will isolate and the area,
preventing any economic activity. Since Orchard Road lies at the heart of Singapore,
in the CBD (Central Business District) the amount of economic activity occurring
daily is much higher than in other parts of Singapore. When the floods occur and cut
off the economic activities, the losses are relatively higher too.
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Chapter Three-Research Method:
[3.0] Data collection method
To successfully and thoroughly investigate the change of the danger of floods over the
recent 30 years, it is imperative that we consult specialists in the field, as only the
specialists can provide a non-sensationalized, and unbiased point of view. As such, I
will interview an expert in the field of tropical urban flash floods to get expert opinion
on the subject. I will also be employing other qualitative and quantitative methods to
conduct further research on the field. The abovementioned qualitative methods
include newspaper articles, excerpts from the news and books, while the quantitative
methods refer to numerical data on the frequency of floods and maps of areas affected
by floods over the recent 30 years.
The expert, preferably a professor in National University of Singapore’s
Geography faculty, or the National Technological University’s Environmental
Engineering faculty, would help explain the changes in floods over time and provide a
geographical perspective regarding the flood damages. Thus, the interview with the
expert will help explain the preparedness of Singapore for a flood, and an expert, and
accurate point of view regarding the change in flooding damages.
I grouped the questions according to five categories that I wished to divide my
research into, namely; ‘Change of flood intensity’, ‘Effectiveness of measures put in
place’, ‘To what degree is Singapore prepared for a flood’ and ‘Predicting flood
damage in the future’.
[3.1] Critical problems and considerations in data collection
One major problem in conducting this research is that the governmental
agencies, namely the Public Utilities Board, the National Environmental Agency and
the Urban Redevelopment Agency, may not release the data necessary for my
research, for example the exact number and frequency of floods and the exact
discharge. As such, even the experts may not have the data I require.
Also, those who do tend to be working for the governmental agencies, either
as consultants, or as the specialist review panel hired by PUB to review Orchard’s
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flood prevention system last July. These experts may not be able to assist me as my
research paper encroaches into their field of work with the governmental agencies. As
such, the data I can gather may be generic, and undetailed with respect to the statistics.
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Chapter Four- Results and Analysis
[4.0] Introduction – Chapter Four
This chapter will analyze the changes in the discharge intensity and locations
of floods over the recent 20 years, and attempt to provide an explanation for these
changes and discuss the difficulties faced in flood prevention. Following that, this
chapter will also analyze the effectiveness of the measures put in place by the
government since the 1980s, through analysis of the change in frequency of flooding.
Finally, with that information, I will conclude about how the dangers of floods have
changed as technology and infrastructure develops over the recent 30 years. Finally,
this chapter will determine the degree to which Singapore is prepared for a flood.
Difficulties faced in flood prevention
[4.1] Traditional flood prevention methods and its effectiveness
Flood prevention done by the Singapore governments has a tendency to to be
reactive, and is frequently described as problem driven. This is because flood
prevention work is only done when a major flood occurs, in an effort to preventing it
from happening again. These flood management techniques are focused on reducing
the susceptibility of an area to floods through structural intervention.
In 1984, when the Road Drainage Improvement Task Force was introduced,
five key strategies were set up for the Task Force to implement: Raising low-lying
roads, patching up localized depressions, improving drainage facilities, enlarging of
outlet drains and cleaning of drainage facilities (Tan, Y. S et al 2009). In summary,
these methods helped to modify the flood and make it easier to cope with by reducing
peak discharge level, lengthening lag time, and increase output from basin. In
hindsight, these methods were rather sufficient in the short term to combat most
floods that Singapore faced in the previous 30 years by a mixture of reducing the
intensity of the input, increasing the output and increasing the coping capacity.
However, rapid urbanization and sea level rise increases the vulnerability of
Singapore to floods (Zevenbergen, C. et al 2011). Associate Professor Roth, the
deputy head of the Department of Geography in National University of Singapore,
believes that, floods will increase in frequency as “the trend towards more of the
rainfall concentrated in extreme events as a likely outcome of global warming.” As
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the drainage system is forced to keep up with the development of the nation, these
methods are not always feasible.
Singapore is a small country with much use for its lands. More land used for
expanding and enlarging drainage systems equates to less and usable for other
important pursuits, like economic and residential pursuits, which also grows in
importance as the nation-state expands. (PUB 2010) In addition, the drains and dikes
that were created to prevent flooding require money and effort to maintain. With the
likely increase in the discharge in the near future, drainage systems may have to
expand to the stage where they become extremely expensive to maintain. At the
moment, PUB already spends $10 million a year on maintaining 7990 kilometers of
drains and canals (Tan Y. S. et al, 2009). As such, the option of enlarging Singapore’s
drains and improving Singapore’s drainage capacities becomes more and more
unfeasible as time goes by.
The option of raising low-lying roads was also not feasible. As many of the
low-lying areas that often experience flooding are well developed, and either
important to the residential or economic sector of Singapore, the areas cannot be
closed off for a period of time just to raise the roads. The plan of road raising has to
be combined with the upgrading and expansion projects of the areas, so as to reduce
the inconvenience and losses created by the project. As the tide level continues to
increase as vast sources of water like the ice caps are unlocked and released into the
environment, sea level will rise, causing inundation of low lying areas. (Zevenbergen,
C. et al 2011) Areas previously at sea level will soon become low lying areas.
(Fleming, G. 2002) As such, it is neither economical, nor feasible to have all of these
roads raised.
Patching up localized depressions may help to alleviate floods, but not by
much. These localized depressions that can be patched up are small, thus patching
them up do not effectively help to relieve large floods.
The last method of the Road Drainage Improvement Task Force is to clean up
and unblock the drains. This method is completely reactive, and will only work for a
short period of time. Since most of the frequently flooded areas are well traversed by
the people, and the problem of littering has not been solved, the drains will rapidly
become clogged up once more. As such, the only effective strategy that can be
implemented is the continuous and periodic cleaning and maintenance of vast
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drainage system of Singapore. This method may not work, as most of the clogged up
drains are not slowly clogged up over time; they are clogged up rapidly, leaving
authorities little signs that the drain is blocked, and little time to clear up the blockage
before a flash flood occurs. Also, this method is extremely expansive. At its current
status quo, with 990 kilometers of drains and canals and 7000 kilometers of public
roadside drains, Singapore spends approximately $10 million a year to keep drains
clean. (Tan Y. S. et al, 2009) If the drainage system were to further expand, Singapore
would have to spend an even larger sum to clean its drains. As such this is not a very
feasible flood prevention method.
With these three major portions of the Task Force and Singapore
government’s strategies becoming rapidly unfeasible, the government has to look for
new preventive measures if it is to effectively prevent flooding.
However, this is not to say that Singapore’s action up to now have been
ineffective in warding off floods. To the contrary, Singapore’s government’s actions
have reduced the areas susceptible to flooding by almost 3100 hectares. (Tan Y. S. et
al, 2009) However, to combat the floods of the future, Singapore has to change the
tactics it uses for flood prevention.
[4.2] New methods to be implemented
The land constrain in Singapore has led the government to conclude that it
must take an integrated approach towards flood prevention. As such, the flood
prevention has been combined with the ABC (Active, Beautiful, and Clean) waters
master plan. Thus many of its new approaches and installments can achieve more than
just flood prevention.
For example, the marina barrage is intended not just to alleviate flood, but also
to be a source of freshwater for Singapore, and a tourist attraction. (PUB: Marina
Barrage N.D) The barrage stores rainwater for consumption during low tide and nonextreme precipitation. During high tide, or extreme storms, crest gates, or flood gates,
are activated to prevent water from entering the barrage, while pumps are activated to
pump water out. (PUB: Marina Barrage N.D) It also serves as an ideal water body for
water related recreational activity like boating, windsurfing, kayaking and dragon
boating due to the constant tide levels. (PUB: Marina Barrage N.D)
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Another new method implemented is the roof garden/planter box. This is
another flood prevention method employed by the PUB to serve maximum purpose
with minimum land use. The roof garden, or planter box, helps water retention,
allowing some degree of infiltration, instead of runoff from a concrete roof. However,
it also improves the micro-climate and is cheaper to install and maintain than drains.
(PUB 2011)
If Singapore continues to adopt such “land saving”, multipurpose flood
prevention technologies, it will be able to deal with its land constraint problems, and
remain relatively prepared for a flood.
[4.3]Reasons behind Singapore’s government being unable to attain complete
flood protection
Many people believe that to effectively deal with floods it to completely
eradicate floods. As such, the question has been raised more than once by the general
populace: Why have floods not been completely prevented. The answer is that
complete flood prevention is not only impossible, but also goes against all the rules of
flood prevention. (Kumar, 2009) As utopic as complete flood prevention may sound,
setting a design for absolute protection against flooding is both a trap and a delusion.
PUB also admits that Singapore cannot be completely flood free, (PUB 2010)
due to 2 main reasons. Firstly, Singapore is a small country, and not much land can be
devoted to flood prevention systems. If drainage systems were expanded, Singapore
would suffer vastly in terms of opportunity costs. (Tan, Y. S. et al, 2009) Also,
building a high design standard flood prevention system is very costly. As Associate
Professor Roth succinctly puts it, it may be “advisable not to pursue complete
protection which requires a massive investment in engineering systems which may be
too costly.” In addition, when a high design standard is set, maintenance tends to be
more difficult and costly, both in terms of money and manpower. If not properly
maintained, these drains may become susceptible to failure. In fact, many of these
high design standard flood prevention systems may not be able to prevent floods of
lower magnitudes because of these possible failures. (Kumar 2009) For example, the
main cause of the Orchard floods of 2010 was the clogging of the drains servicing the
area. This amply shows how a system which has kept Orchard road flood free for 25
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years (PUB 2011) can succumb to failure due to poor maintenance. In conclusion,
attempting complete flood protection is both costly and impossible to attain.
In addition, for complete prevention of floods requires knowledge of the exact
peak discharge in major storms, which might change over time due to climate change.
Some experts predict that there will be an increase in both the intensity and duration
of monsoons (Kumar, 2009), resulting in increased seasonal flash floods. These
changes may not be predictable, as climate change occurs at a rate with respect to
human activity. As such, the increase in monsoons will not be uniform, thus will not
be predictable.
Having ruled out the possibility of complete flood prevention, Singapore has
to decide on the degree of flood prevention it wishes to adopt. After some debate, the
conclusion was that Singapore would adopt a design norm of one-in-five year storms,
which is a widely adopted standard in flood prevention, for most areas. (Tan, Y. S. et
al, 2009) However, this is one of the many criteria marked out by the Inter-Agency
Drainage Review Committee (IADRC), which was convened by PUB after the 2010
Orchard floods, for change.
The changes can be summarized in the following table taken from the PUB’s
overview
of
the
Singapore
drainage
system
at
http://www.pub.gov.sg/general/documents/overview_drainagemgmt.pdf
[4.4] How have floods changed over the recent 30 years?
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Floods and monsoons have become worse in the past 30 years, and will
become worse in the near future (NASA N.D). This is because temperature has risen
by an average of 1.74 degrees Celsius and is predicted to increase by another 1.5 to
6.1 degree Celsius within the 21st century (Intergovernmental Panel on Climate
Change 2007). Warmer temperatures will cause more evaporation, resulting in an
increase in water vapor in the atmosphere, resulting in more intense storms.
(American Museum of Natural History N.D) Associate Professor Shuy Eng Ban,
agrees with this, suggesting in the interview that climate change and global warming
could result in “more frequent and more intense rainstorm,” and a “raise the sea
level”, which would result in higher tides.
To exacerbate this problem, Professor Roth believes that the rapid
urbanization of Singapore in the past 30 years has resulted in the rapid “replacement
of natural with impermeable surfaces” promoting “fast overland flow”, or Horton
overland flow, instead of “buffering” rainwater through natural soil, increasing storm
runoff.
With concrete or asphalt surface, infiltration is made impossible. As such, the
infiltration capacity will be zero, the only output being the drains. As a result, the
reliance on drains as the primary method of drainage has increased significantly,
resulting in the risk of flooding due to structural failure to increase massively.
However, according to Professor Shuy, PUB has taken note of this, and has
embarked on “a continual program” to improve and upgrade the storm drainage
systems in Singapore, to cope with “more extreme flow events” which will enable
Singapore to be well prepared for this increase in storm magnitude.
As such, given that Singapore has improved its drainage system vastly since
the 1980s, and has reduced the flood prone areas by about 3200 hectares (PUB, M.D)
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Chapter Five- Conclusion
[5.1] Validity of Thesis
Considering that the areas that are susceptible to floods have reduced by about 3200
hectares (refer to Appendix 0 for the map detailing the changes), the flood prevention
methods that were employed by the government have successfully mitigated the
floods by a rather large extent. As such, it is apparent that the dangers of floods have
reduced over the past 30 years as the flood prevention technology and infrastructure
was improved by the Singapore government. This opinion is supported by Professor
Shuy Eng Ban, who stated that flooding in Singapore has certainly been greatly
mitigated in Singapore over the past 30 years.
[5.2] Recommendations
Having already established that the government’s actions have been successful in
mitigating floods, and that hard engineering method that were previously employed
are no longer useable, the question is how will Singapore proceed with flood
prevention in the near future. Some research can be done in the field of establishing
and predicting the future flooding patterns, and planning possible future strategies.
In addition, knowing that complete flood prevention is impossible, and land use in
only likely to increase in the near future, Singapore’s government should look into the
flood return periods of drains.
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Chapter Six- Bibliography
Books
Intergovernmental Panel on Climate Change (2007). Climate change 2007: synthesis
report. IPCC Publication.
Retrieved from http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr.pdf
United Nations (2003). Guidelines on Participatory Planning and Management for
Flood Mitigation and Preparedness. United Nations Publication.
Tan, Y. S., Lee, T. J., & Tan, E.-L. K. (2009). Clean, Green and Blue: Singapore's
Journey Towards Environmental and Water Sustainability. Singapore: ISEAS
Publishing.
Cornwell, D. (1998) Introduction to environmental engineering. Singapore: McGrawHill Book Co
Lancaster, J. W., Preene, M., Marshal, C. T. (2004) Development and flood riskguidance for the construction industry. London: CIRIA
Warner, J. (2011) Flood Planning: The politics of water security. London: I. B. Tauris
& Co Ltd
Burt, N., Watts, J. (Ed.). (1996) Engineering design & environmental impacts. West
Sussex: John Wiley & Sons Ltd
Burke , G., H., Singh, B., R., Theodore, L. (2000) Handbook of environmental
management and technology USA: John Wiley & Sons Ltd
Chin, O. P. (Ed.). (2009). Flood risk management. New York: Nova Science
Publishers, Inc.
Few, R., & Matthies, F. (Ed.). (2006). Flood hazards and health: responding to
present and future risks. London, UK: Earthscan.
Pacione M. (1999). Applied Geography: Principle and Practice Routledge (imprint of
Taylor and Francis Group)
Strahler A.N and Strahler A.R (1978). Modern Physical Geography John Wiley and
Sons
Fleming, G. (Ed.). (2002). Flood risk management. London, UK: Thomas Telford
Publishing.
Tran, P., & Shaw, R. (Ed.). (2010). Integrated river basin management for effective
flood risk reduction. Singapore: Research Publishing Services.
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Thomas, D. and Goudie, A. (2000) The Urban Dictionary Of Physical Geography
Blackwell Publishers Ltd
Ferguson, F. (1975). Architecture, cities and the systems approach. New York:
George Braziller,Inc.
Zevenbergen, C., Cashman, A., Evelpidou, N., Pasche, E., Garvin, S., & Ashely, R.
(Ed.). (2010). Urban flood management. London, UK: Taylor and Francis Group.
Kumar, A. (2009). Handbook of flood management volume II: Flood recovery
innovation and response management. New Delhi, India: Chaman Enterprises.
Kumar, A. (2009). Handbook of flood management volume I: Flood risk simulation,
warning, assessment & mitigation New Delhi, India: SBS Publishers & Distributors
Pvt Ltd
Academic Papers
Marks, J. C., Power, M. E., Parker, M. S., (2000) Flood disturbance, algal
productivity, and interannual variation infood chain length
Retrieved August 15, 2011 from
http://oregonstate.edu/instruction/fw580/pdf/22.%20Disturbance%20and%20Food%2
0Webs.pdf
Bashir, B.M (2006) Flash Floods.
Retrieved on May 14, 2011 from
http://www.unesco-ihe.org/content/download/2120/22025/file/Flash%20floods.pdf
Mandych, A.F (N.D) Classification of Floods
Retrieved June 20, 2011
http://www.eolss.net/Sample-Chapters/C01/E4-06-02-05.pdf
Websites
Ministry of Environment and Water Resources (N.D) Water issues: Drainage
Retrieved June 20, 2011 from
http://www.ifaq.gov.sg/mewr/apps/fcd_faqmain.aspx?qst=2fN7e274RAqY1a7Hv3f3
yifLve7VNcLPX2Hcj%2fD%2bq04gBKrInmqYtSmfG2i%2fWzAqoR1afoC%2b6%
2beRNGQ4V6ryb%2bNt%2bVSUxCRk7%2fwEkhG63E6q3uQ2Uj%2buLOhcGMM
Bz7XCrsVqlHf1g1%2b2iEWsu3%2bYQXAJV02xmD7zaagngfiCZYsnG6eUUxLcns
csv9JI0RtjBQ9RJkfF1FMV%2bTvlGR%2b35OqQNp94x1hH%2fsj5%2fqXgFIl7ioh
usJE1iq4tOiNITP6%2f%2bHl1Bm9tzM2Cuzf%2b3QXDDTnIriCIxfJUwa5Mfe6zqx
8%3d
United Nations Environment Program (many dates)
Retrieved June 10, 2011 from
http://www.unep.org
Tan, T. S.(N.D) Managing stormwater for water resource and flood control
Retrieved August 2, 2011 from
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http://www.slideshare.net/vicmanlapaz/singapore-managing-stormwater-for-waterresource-and-flood-control-presentation
NASA (N.D) Global Warming
Retrived August 15, 2011 from
http://earthobservatory.nasa.gov/Features/GlobalWarming/
Public Utilities Board (many dates) Press Releases
Retrieved June 10, 2011
http://www.pub.gov.sg/mpublications/Pages/PressReleases.aspx
Public Utilities Board (N.D) Annual report 2009
Retrieved August 19, 2011
http://www.pub.gov.sg/mpublications/Lists/AnnualReport/Attachments/4/PUB_AR20
072008.pdf
Public Utilities Board (N.D) Annual report 2009
Retrieved August 19, 2011
http://www.pub.gov.sg/annualreport2009/
Public Utilities Board (N.D) Annual report 2010
Retrieved August 19, 2011
http://www.pub.gov.sg/annualreport2010/wf_Rain-Drain.html
Public Utilities Board (many dates) Standard and References
Retrieved August 19, 2011
http://www.pub.gov.sg/general/drainageworks/StandardSpecifications/Pages/Standard
Specifications.aspx
Public Utilities Board (many dates) Managing flash floods
Retrieved August 19, 2011
http://www.pub.gov.sg/managingflashfloods/Pages/default.aspx
Public Utilities Board (2011) Overview of Singapore’s Drainage Management
Approach
Retrieved August 20, 2011
http://www.pub.gov.sg/general/documents/overview_drainagemgmt.pdf
Public Utilities Board (2011) Marina Barrage
Retrieved August 20, 2011
http://www.pub.gov.sg/Marina/Pages/3-in-1-benefits.aspx
National Environmental Agency (many dates) Weather FAQ
Retrieved June 20, 2011 from
http://app2.nea.gov.sg/weather_faq.aspx#affected
National Asphalt Pavement Association (many dates)
Retrieved June 20, 2010 from
http://www.hotmix.org
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American Museum of Natural History (N.D) Changing Atmosphere
Retrieved August 15, 2011 from
http://www.amnh.org/exhibitions/climatechange/?section=atmosphere&page=intense
_storms
Kansas Water Science Center (N.D) Definition of floods
Retrieved May 10, 2011 from
http://ks.water.usgs.gov/waterwatch/flood/definition.html
Federal Emergency Management Agency (FEMA), U.S. Department of homeland
security (2010). Mitigation
Retrieved August 3, 2011 from
http://www.fema.gov/government/mitigation.shtm
Federal Emergency Management Agency (FEMA), U.S. Department of homeland
security (2010). The National Flood Insurance Program: Floodplain Management
Retrieved August 3, 2011 from
http://www.fema.gov/plan/prevent/floodplain/index.shtm
Kerb, R. (1960) Flood and flood control water resource activities in the United States.
Retrieved August 5, 2011 from
http://www.archive.org/stream/floodsandfloodco007511mbp/floodsandfloodco007511
mbp_djvu.txt
Houston-Galveston Area Council (N.D) Flood management handbook
Retrieved August 2, 2011 from
http://www.h-gac.com/community/water/rfmc/documents/FMH.pdf
Tan, L. Y. (1999). 1978 Singapore floods.
Retrieved August 2, 2011 from
http://infopedia.nl.sg/articles/SIP_780_2004-12-30.html
Vaugham, V. (2010) Orchard Road to be raised
Retrieved May 10, 2011 from
http://www.straitstimes.com/BreakingNews/Singapore/Story/STIStory_593510.html
The Straight Times. (2010) New Kerb to help curb Orchard Road flooding. Retrieved
May 10, 2011 from
http://www.straitstimes.com/BreakingNews/Singapore/Story/STIStory_617854.html
Ramesh, S (2011) An open discussion on floods and climate change
Retrieved June 20, 2011
http://www.todayonline.com/Singapore/EDC110523-0000236/An-open-discussionon-floods-and-climate-change
Asia for Visitors (N.D) Singapore Weather
Retrieved June 15, 2011 from
http://asiaforvisitors.com/singapore/sg-weather.html
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Asia One Business News (2010) PUB: Heavy rain and debris likely cause of Orchard
flood
Retrieved June 20, 2011 from
http://www.asiaone.com/News/AsiaOne+News/Singapore/Story/A1Story20100617222707.html
Asia One Business News (2010) Jul 17 flooding cost insurers more than Orchard
flood
Retrieved June 20, 2011 from
http://www.asiaone.com/Business/News/My+Money/Story/A1Story20100811231567.html
Thomas H. (2004) A Rare Tsunami and a Change in Geography
Los Angeles Times Retrived June 24, 2011 from
http://articles.latimes.com/2004/dec/27/science/sci-tsunami27
Ramesh, S., (2011) Dr Balakrishnan pledges transparent process in climate change
challenge Retrieved August 15, 2011 from
http://www.channelnewsasia.com/stories/singaporelocalnews/view/1130393/1/.html
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Appendix 0: Flood prone areas map
This is a map of the flood prone areas in the late 1970s. Since then, flood prevention
methods set by the government has shrunk the vulnerable areas to this:
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Appendix 1: Interview questions
1) Do you think Singapore will still be prepared for floods if the monsoon season
becomes more extreme in the next 20 years?
2) Do you think that the number of floods and discharge of floods are likely to
increase? If yes, what do you think is causing the change?
3) How prepared do you think Singapore is for a flood in terms of its flood response
systems?
4) Do you believe that the dangers of floods in Singapore have reduced over the past
30 years?
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Appendix 2: Profile of the interviewees
Interviewee 1
Deputy Head and Associate Professor
Matthias Roth
Associate Professor Matthias Roth is the Deputy Head of the
Department of Geography.
Until the end of 2009 he was President of the International
Association for Urban Climate (IAUC) and keeps serving on the
IAUC Board as Immediate Past President.
Matthias holds certification as a meteorological consultant
through the Canadian Meteorological and Oceanographic Society
(CMOS).
In 2009 he was appointed as a member of the University
Taskforce on the new Environmental Studies Program.
He is a member of the editorial board of the Singapore Journal of Tropical Geography.
Within the Department, Matthias is a member of the Tropical Environment Change Group.
Interviewee 2
Dr. E.B Shuy is an Associate Professor in the Division of Environmental & Water
Resources Engineering, School of Civil & Structural Engineering in Nanyang
Technological University. He received his Ph.D from the University of Queensland in
1985. His research interests include the quantity and quality modelling of urban storm
runoff and the sustainable urban drainage systems and management
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Appendix 3: Interview transcipts
Associate Professor Roth
1) Do you think Singapore will still be prepared for floods if the monsoon season becomes
more extreme in the next 20 years?
To my knowledge Sigapore is working towards improving its exposure to floods and become
more prepared. It will likely not be possible to prevent all floods, and it might even be
advisable not to pursue complete protection which requires a massive investement in
engineering systems which may be too costly.
2) Do you think that the number of floods and discharge of floods are likely to increase?? If
yes, what do you think is causing the change?
There is a possibility for floods to increase in frequency, given (i) the trend towards more of
the rainfall concentrated in extreme events as a likely outcome of global warming and (ii)
increasing urbanization associated with the replacement of natural with impermeanle surfaces
which promote fast overland darinage rather than buffering some of the rain in natural soils.
3) How prepared do you think Singapore is for a flood in terms of its flood response systems?
I have no insider knowledge but understand that Singapore is working on improving heavy
rain forecasts and better monitoring of its drainage canals which should bot improve its
prepardeness and hence response.
4) Do you believe that the dangers of floods in Singapore have reduced over the past 30
years?
I don't have the actual data, so cannot comment on this point.
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Associate Professor E.B. Shuy
1) Do you think Singapore will still be prepared for floods if the monsoon season becomes
more extreme in the next 20 years?
PUB has a continual programme to improve and upgrade the storm drainage systems in
Singapore. PUB is also planning to upgrade the standards for design of storm drainage
systems to cope with more extreme flow events. If such plans are implemented successfully,
Singapore should be well prepared for monsoon storms in coming years.
2) Do you think that the number of floods and discharge of floods are likely to increase? If yes,
what do you think is causing the change?
Both the frequency and magnitude of flood discharges are likely to increase in future for two
main reasons. The first is continual land developments as a result of economic and population
growth. Land use changes as a consequence of urbanisation and urban growth will increase
the storm runoff volume and rate even if rainfall patterns do not change. The second is
potential impacts of climate change and global warming, which could results in more frequent
and more intense rainstorm, and raise the sea level, making Singapore more vulnerable to
flooding.
3) How prepared do you think Singapore is for a flood in terms of its flood response systems?
In Singapore, flood response is the responsibility of SCDF. We do not expect prolonged and
deep flooding as experienced in many other places to happen in Singapore, mainly because
of the relatively small catchments and efficient storm drainage systems we have. Hence flood
response in terms of big scale evacuation and relief centres are not likely to be required. PUB
is still expanding its flood level monitoring and warning system via SMS throughout Singapore.
This should be helpful in alerting residents and businesses to take precautions in event there
is a potential flood risk.
4) Do you believe that the dangers of floods in Singapore have reduced over the past 30
years?
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Flooding in Singapore has certainly been greatly mitigated in Singapore over the past 30
years. The future challenge is continual upgrading of the storm drainage systems, and
upgrading design standards to withstand the potential impacts of climate change and sea
level rise.
31