ICUS/INCEDE NEWSLETTER
International Center for Urban Safety Engineering

Institute of Industrial Science
The University of Tokyo

VOLUME 3 NUMBER 1
APRIL -JUNE 2003

International Center for
Urban Safety Engineering

FLOOD DISASTER TRENDS IN ASIA
IN THE LAST 30 YEARS
By
Dushmanta Dutta
Few years before, the Director
General of the United Nations
Environment Program said that war
over water would be a distinct
possibility in the 21st century.
Similar view is reflected by manyother experts from the United
Nations and other internationalorganizations highlighting theseriousness of the problem of water
too little in the 21st century. Anotherequally important and pressing
water issue is Water too much the floods, although that do not leadto a war but kill millions and cause
big hindrance in socio-economic
development. Floods are a constantthreat to life and property. It has been

obser ved that more and more
people have been affected byriverine floods in the recent years.
From 1990 to 1996, there were six
major floods throughout the worldin which the number of fatalities
exceeded 1,000 and 22 floods withlosses exceeding US$1 billion each.
The majority of these recent

Devastating floods in Central Vietnam in November 1999

page 2
disastrous floods have occurred in
Asia. The highest material losses
were recorded in China during the1996 and 1998 floods: about US$30
and 26.5 billion respectively. Is theflood frequency increasing in Asia?
If it is increasing, how rapid is thei n c r e m e n t ? W hy a r e f l o o d sincreasing? These are some of theimportant issues that need to bea d d r e s s e d t o u n d e r s t a n d thegravity of the problem of floods inthe 21st century. This article closely
looks at the flood disaster trend in
Asia in the past three decades andanalyzes the major causes of thechanging characteristics of flood
disasters in Asian countries andtheir consequences.
Floods in Asia
from global perspective
O u t o f ove r 7 , 0 0 0 n a t u r a ldisasters occur red around theworld during the last 30 years,
more than 74% were water related
disasters including floods, drought
and windstorms. Among these,
floods are the most frequent natural
disasters. Floods account for about
33% of all the natural disasters. In
the past 30 years, floods have been
the most catastrophic natural
disaster affecting half of the total
population affected by any natural
disaster, i.e., on average about 80
million people per year and caused
economic damage of over US$11
million annually around the world.
Annual statistics of natural
disasters of the past 30 years showthat number of floods andwindstorms are rapidly increasingaround the world compared to allother disasters. Floods have thehighest increasing rate ofoccurrence. In the last 30 years
a n n u a l f l o o d f r e q u e n cy h a s
doubled. There were on average
about 50 flood events annually in
1970s, it became100 in 1990s, andi n t h e l a s t t h r e e ye a r s i t h a s
increased to about 150 events per
year. Windstorm has been following
a s i m i l a r t r e n d a s t h e s e t wo
disasters are closely related. The
same statistics show that except

An example of damage due to frequent flash floods in Japanl a n d s l i d e s , wh i c h h av e b e e nincreasing at a low rate, no othern a t u r a l d i s a s t e r s ex h i b i t a ny
increasing trend unlike floods andwindstorms in the past three
decades.
Floods occur in most of thecountries around the world. Having
the highest amount of average
rainfall and volume of river water(13,500 km3/year), Asia is the mostfrequently affected continent by
floods. During the past 30 years, total
flood disasters occurred in Asia isthe largest, 40% of the total events,
compared to any other continents:
America (25%), Africa (17%),
Europe (14%) and Oceania (4%).

In terms of casualties, floods aret h e m o s t d eva s t a t i n g a n dwidespread in Asia. 98% of the total
population affected globally byfloods are located in Asia.
Flood Trend in Asia
Almost all the Asian countries
are affected by floods. The regional
distribution of flood events in Asia
shows that South Asia is the mostfrequently affected region by floods(about 39%), followed by Southeast Asia (about 30%) and East
Asia (about 25%). The West Asia
region including Russian Federationis the least affected region (6%).
The floods and windstorm in Asia
in the past 30 years follow a similar

Global statistics of natural disasters in past 30 years: i) ratio ofdifferent natural disasters around the world, ii) percentage ofaffected people by natural disasters, iii) percentage of economic
damage caused by natural disasters, and iv) continental level
distribution of flood disasters and regional distribution in Asia

ICUS/INCEDE Newsletter Vol. 3, No. 1

page 3
180

Drought
160

Number of Events

increasing trend as the global trend.
The frequency of floods in Asia has
doubled during the period of 19781999. The rate of increase of flood
frequency is more prominent in thelast 10 years, especially, the recent
three years statistics show rapid
increase of floods in Asia.

FloodsEarthquake

140

Extreme-temperature
120

Slide
Volcano100

Wild-fire
80

Windstorm

60
40
20

19
75
19
76
19
77
19
78
19
79
19
80
19
81
19
82
19
83
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02

Drought
FloodsEarthquake
Extreme-temperature
FamineSlide
VolcanoWild-firewindstorm

60

Number of Events

50

40

30

20

10

19
75
19
76
19
77
19
78
19
79
19
80
19
81
19
82
19
83
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02

0

Year

Trends of flood disasters in Asia in the last 28 years
compared to other natural disasters
350,000,000

300,000,000

250,000,000

Drought
FloodsEarthquake
Extreme-temperature
Slide
VolcanoWild-fireWindstorm

200,000,000

150,000,000

100,000,000

50,000,000

19
75
19
76
19
77
19
78
19
79
19
80
19
81
19
82
19
83
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02

0

Ye ar

Global trend of number of people affected by natural disasters
in the last 28 years
350,000,000

300,000,000
250,000,000

Drought
FloodsEarthquake
Extreme-temperature
FamineSlide
VolcanoWild-fire

200,000,000
150,000,000

100,000,000
50,000,000

0

19
75
19
76
19
77
19
78
19
79
19
80
19
81
19
82
19
83
19
84
19
85
19
86
19
87
19
88
19
89
19
90
19
91
19
92
19
93
19
94
19
95
19
96
19
97
19
98
19
99
20
00
20
01
20
02

Climate change and floods:
With the rapid increase of extreme
climate events in the past few
years, it is a common understandingthat the major reason of increasing
flood magnitude and frequency inmost of the regions around theworld is the climate change. The
general direction of change inextreme water related events in
Asia is broadly consistent with theclimate scenarios presented by the

Year

Worldwide trends of flood disasters in the last 28 years
compared to other natural disasters

Number of Events

Causes ofincreasing floods in Asia
According to several researchstudies and obser vations, thecauses of growing trends of floods
in Asia can be attributed to mainly
two factors: i) climate change andii) landuse change and surface
degradation.

0

Number of Events

Among the Asian countries,
China is the most frequently
affected country by floods followedby India. The other eight of the top
ten flood affected countries are
Indonesia, Philippines, Bangladesh,Iran, Thailand, Sri Lanka, Vietnam
and Pakistan in descending order.
Except China and Iran, all thesecountries are located in South andSouth-east Asian Regions. The 5year average flood statistics of last
30 years show that flood frequency
is increasing in all these countries.
China shows higher rate of increaseof frequency than India in the last
10 years. Thailand also shows ahigher rate of increase of floodf r e q u e n cy c o m p a r e d t o i t sneighboring countries in the last 15
years. Among these 10 countries,
the rate of increase of flood
frequency was the lowest in Sri
Lanka and the Philippines in the last
15 years.

Year

Trend of number of people affected by natural disasters
in the last 28 years in Asia

ICUS/INCEDE Newsletter Vol. 3, No. 1

page 4I n t e rg ove r n m e n t a l Pa n e l o n
Climate Change (IPCC). The
observed increase in the incidenceof great floods was found to beconsistent with results obtained
from the climate models, and themodel results suggest that the trend
will continue. Although only a few
studies have assessed the effects
of climate change on flooding
frequencies, there are a number ofpossible reasons why, in a warmer
climate, the frequency of floods
increase in any particular region.
Out of that the most related issues
to Asia that have been observedare:i) an increased frequency of
extreme precipitation eventsii ) i n c re a s e d m ag n i t u d e s o f
precipitation events of highintensity
In 1997, some studies showedthat flood discharges in the majorr iv e r b a s i n s i n I n d i a a n dBangladesh (Ganges, Brahmaputra
and Meghna) were estimated toincrease by 6-19%. The statisticsof the flood records of the past few
years also indicated the effects ofclimate change in the flood
frequency in Asia. The averageannual flood events in the past
three years are 1.5 times of that of
1990s and 3 times of 1970s.
Landuse changes and floods:
The effect of climate change alone
is not triggering the high rate ofincrease of flood frequency in Asia.
It can be observed from the timeseries of flood data that they are
not exactly in tune with climatechange-related prognoses, but theyreflect complex responses that may
be due to other non-climatic factors
such as deforestation andurbanization.
Under the pressure of highpopulation growth and economic
development, a great change inlanduse pattern has taken place inmost of the Asian countries in thelast few decades. One of the majorchanges is the deforestation caused

Flood events in different Asian countries in last 28 years

Flood trend in most frequently flood affected 10 countries in Asia
by conversion of forest to agriculturalor inhabitable land. Thailand is agood example of that. Between 1976
and 1989, Thailand lost 28 percent
of its forecast cover. A recent study
at the University of Tokyo has
showed that deforestation has
greatly influenced the changes inrainfall patter ns in Thailand.
Additionally, deforestation also
causes the increase of surface
runoff and thereby increases the
flash floods. In several Asian
countries, where deforestation isvery prominent, increase of flash
floods can be witnessed in the pastfew decades.
The tremendous economic
development and migration of
population to urban centers in mostof the Asian countries in the pastfew decades have caused rapid
urbanization. Urban growth in mostof the Asian countries in the last
three decades is more than 4%.
Nepal shows the highest growthr a t e ( 7 . 5 % ) f o l l owe d by
Bangladesh (5.9%). The
urbanization has not only led toreduction of pervious areas but
also change in catchment use ofmanipulation of water within thechannel (e.g., dams, abstractions,canalization). These factors havedirectly contributed to increase ofurban floods.
Impacts of increased flood
frequency in Asia
Economic losses and humancasualties from flood events have

Percentage of total population affected by floods annuallyin different Asian countries in last 28 years

ICUS/INCEDE Newsletter Vol. 3, No. 1

page 5increased five folds between the
1970s and 1990s in Asia. These
losses largely reflect an increase in
the vulnerability of our society as awhole to extreme events. Althoughpart of the observed upward trend
in losses can be linked to socioeconomic factors, such as
economic developments, population
g rowth, etc., increased flood
frequency attribute more to theo b s e r ve d g r ow t h i n h u m a ncasualties and economic losses in
the past three decades. Although it
is difficult to quantify the effects,
the increasing flood frequency
certainly seem to have adversely
affected many Asian countries. In
the recent years, floods have had
increasingly detrimental anddisr uptive effects on various
aspects of socio-economic
conditions in Asia including: humanhealth (through diseases such as
diarrhea in flooded areas); buildings
and infrastructure; settlements;
coastal areas; financial services(including insurance andreinsurance); transport; watersupply; agriculture and ecosystems.
Conclusions
The statistics of the flood eventsof the past 30 years in Asia clearlyshow an increasing trend of flood
disasters in most of the Asian
countries. Combined effects ofclimatic changes, landuse changes
and urbanization are considered tobe the main reasons of thisincreasing trend. Due to several
devastating flood disasters anddroughts in different parts of theworld in the past few years, extreme
weather and climate events havereceived greater attention. A recent
study of 2002 that analyzed theoutputs of 19 climate models predicts
that very wet summers in the Asianmonsoon region will probably rise up
to five folds increasing the risk offlooding. This is a very serious
concern for Asian countries. Properconsideration of long-term climatechange scenarios in flood risk
management strategies is utmost

important to cope with thei n c r e a s i n g f l o o d f r e q u e n cy.
Population in Asia is expected to
grow by more than 25% in the next
20 years exceeding 4.9 billion by2025, and urban growth is going tocontinue in a similar rate as the past
decade in most of the developing
countries in Asia. Unlessappropriate countermeasures aret a k e n t o e s t a bl i s h b e t t e r
preparedness and prevention offlood disasters, uncontrolled
d ev e l o p m e n t i n d ev e l o p i n g
countries will certainly result inincreased flood damage due to thegreater concentration of population,
most notably the poor, in disasterprone areas. This will make it
difficult to break the vicious cycleof poverty in Asia.
T h e a u t h o r g ra t e f u l l yacknowledges the usefulness of
the International Disaster
Database of Centre for Researchon the Epidemiology of Disasters
in preparing this article.

ICUS participated in IIS Open House
This year, ICUS participated in
the Open House of the Instituteof Industrial Science (IIS) withthe theme Towards safety andsecurity of Mega Cities which
was held during June 5-6, 2003.
The Open House is an importantannual event of IIS held for twodays in the first week of Juneevery year to demonstrate there s e a rc h a n d d e v e l o p m e n t
a c t i v i t i e s o f t h e d i f f e re n tlaboratories and departments of
the institute to the public. OpenHouse saw a large increase in thenumber of visitors this year, withthe total number exceeding
5,100, compared to the past few
y e a rs . A n ew t re n d o f y o u n g
participants from junior high or
high school could be observed.
It was overwhelming to see theinterest of these young people in
the new scientif ic andtechnological developments inthis frontier institute of Japan.

A snapshot from the ICUS booths on the 2nd day of the Open House
The three research divisions of
ICUS prepared their own subthemes for the Open House underthe banner of the main theme anddisplayed their past and present
research activities. ICUS also
arranged a video display of its

international activities carriedout in the last two years. About
200 persons visited ICUS boothin two days. They showed deep
interests in ICUS activities inurban safety and security ofmega cities.

ICUS/INCEDE Newsletter Vol. 3, No. 1

page 6

New Developments in ICUS Staff
Farewell to Dr. Ochi
After serving ICUS as a
Research Associate for a period of
two years from April 2001 to March
2003, Dr. Shiro Ochi has moved to
Kinki University, Nara, Japan tojoin its Faculty of Agriculture as an
Associate Professor. During thisperiod, Dr. Ochi played a very
important role at ICUS andstrongly contributed to the various
activities of the center including its
collaborative research project inThailand. Dr. Ochi is going tocontinue his research activities in
the fields of GIS, remote sensing
and environmental monitoring in the
Kinki University. We wish him all
the best and great success in his
new career in Nara. The newcontact address of Dr. Ochi is:
Faculty of Ag riculture, Kinki
University, 3327-204 Nakamachi,
Nara-City, Nara 631-8505, Japan.
Congratulations to Dr. Dutta
ICUS staff Dr. Dushmanta
Dutta was promoted to Associate
Professor from June 1, 2003. At
ICUS, Dr. Dutta has been involvedin academic and research activities
in the fields of hydrology and water
resources engineering. For the last
few years, he has been mainly
focusing on physically basedmodeling for urban flood risk
management and water resources
analysis. Dr. Dutta is currently
acting as a team leader of acollaborative research project of
ICUS in Thailand on urban flood risk
mapping. We extend our hearty
congratulations to Dr. Dutta.
Welcome to Dr. Endoand Ms. Yoshimura
We are glad to introduce our newcolleagues Dr. Takahiro Endo and
Ms. Miho Yoshimura, who joined
ICUS as Research Associates from
April 1 and June 1, 2003
respectively.
Dr. Endo received his D. Eng.
degree from the Department of Civil
Engineering of the University ofTokyo in March 2003. His researchi n t e r e s t s a r e e nv i r o n m e n t a lmonitoring and modeling with remotesensing. Presently, he is involved indeveloping detection method for
concrete degradation, and estimationof terrestrial ecosystem parameterssuch as biochemical content andcarbon dioxide absor ption ofvegetation using advanced
hyperspectral remote sensing.

We welcome Dr. Endo and Ms.
Yoshimura and wish them great
success.
New Assistantfor ICUS Intl. Symposium
ICUS welcomes Ms. Shravani
Hazarika, who joined ICUS from
June 2003 to assist in the activitiesof the 2nd International Symposiumof ICUS on New Technologies
for Urban Safety of Mega Cities in
Asia . She can be contacted forany matters related to this
symposium by e-mail (icus@iis.utokyo.ac.jp).

Dr. T. Endo, Ms. M. Yoshimura and Ms. S. Hazarika

ICUS ACTIVITY RECORDS* Prof. Y. Yasuoka visited AIT,
Thailand during May 28-31 to

Ms. Yoshimura received her M.
Eng. degree from the Department
of Civil Engineering of the
University of Tokyo in March 2001.
Prior to joining ICUS, she worked
a Research Associate with Prof.
Meguro of ICUS. Her researchinterests include retrof itting
p r o m o t i o n s y s t e m f o r l ow
earthquake-resistant structures inearthquake prone countries.

attend a meeting on MODIS
Satellite Receiving Station.

* Dr. D. Dutta visited AIT from
June 8-17 to start his term as
a Visiting Faculty from ICUS.

Registration for ICUS International Symposium on October 30-31, 2003
The activities of ICUS 2nd
International Symposium in Tokyoon New Technologies for Urban
Safety of Mega Cities in Asia are
p r o g r e s s i n g v e r y we l l . T h edeadline for submission of abstract
was over at the end of June. We

have got a very good response frommany professionals around Asia andEurope. Please note that thedeadline for submission of full paper
and advanced registration is August
31, 2003. The registration form isavailable at the Symposium Website

ICUS/INCEDE Newsletter Vol. 3, No. 1(http://icus.iis.u-tokyo.ac.jp/
isus03). You may also contact the
Symposium Secretariat by e-mail(icus@iis.u-tokyo.ac.jp) for a copyo f t h e r eg i s t r a t i o n f o r m . We
welcome any interested person toattend the symposium.

page 7

ICUS Publishes Two Technical Reports
ICUS has recently published tworepor ts of the ICUS/INCEDE
Technical Report series.
The f irst repor t is ICUS/
INCEDE Repor t 2003-01. It
contains the proceedings of theInternational Symposium on the
New Technologies for the Urban
Safety of Mega Cities in Asia,
which was held in Bangkok,
Thailand on October 28, 2002. It
was jointly organized by ICUS and
the Asian Institute of Technology(AIT), Thailand. The symposium
was very successful in bringing
together a large number ofpar ticipants from different
disciplines including policy makers,planners, engineers and architects
to c r e a t e g r e a t e r awa r e n e s s
towards the issues related to urban
safety. This report contains a totalof 14 technical papers presented in
the symposium by the participantsfrom different countries covering awide range of issues in the areasof new technologies for urban
safety. The report is jointly edited

Visitors to ICUS
During the period of AprilJune, 2003, ICUS received thefollowing visitors.
-Dr. Somnuk Tangtermsirikul,
A s s o c i a t e P r o f e s s o r,
Sirindhorn International

Cover pages of Report 2003-01 and Committee Report 2002-01
by Prof. Sudhir Misra and Dr.
Yoshitaka Kato of ICUS.
The second report is ICUS/
INCEDE Committee Report 200201. It contains the technical papers
and research activity reports of the
Research Committee-39 that was
initiated by ICUS a year ago as apart of its collaborative research
activities with private sectors inI n s t i t u t e o f Te c h n o l o g y,
T h a m m a s a t U n i v e r s i t y,
Thailand (April 14).
- Dr. Cintia Marquetti, Geological
Mining Survey of Argentina,
Argentina (May 22).
- Dr. Kenichi Kurihara, Japan
Mining Engineering Center forInternational Cooperation,areas of urban safety. The reportcontains a great deal of information
about the on-going activities of thisResearch Committee. This reportis available only in Japanese.
Those who are interested toreceive a copy of these reports,
please contact ICUS by e-mail(icus@iis.u-tokyo.ac.jp) or fax(+81-3-5452-6476).
Japan (May 22).
Dr. Masaharu Toyama, Japan
Mining Engineering Center
for I n t e r n a t i o n a l
C o o p e ra t i o n , Ja p a n ( M a y
22).
- Dr. Yoshii Kakimoto, Japan
International Cooperation
Center, Japan (May 22).

Dr. Dutta joins SCE, AIT as a Visiting Faculty
From the beginning of June 2003,
Dr. Dushmanta Dutta of ICUS has
j o i n e d t h e S c h o o l o f C iv i lEngineering (SCE) of AIT as a
Visiting Associate Professor fromthe University of Tokyo. At AIT,
Dr. Dutta will coordinate theactivities of the ICUS Regional
Network Office for Urban Safety(RNUS), which was established at
SCE in October 2002 to work inareas of mutual interests of AITand ICUS. RNUS focuses oncollaborative research activities withdifferent organizations in Asian
countries in the fields of urban safety
e n g i n e e r i n g w i t h a d va n c e dtechnology tools such as numericalmodels, remote sensing,geographical information system,
global positioning system, etc., fordevising appropriate methodologies
for management and maintenance ofurban buildings, infrastructures,
mitigation of urban disasters ande nv i r o n m e n t a l p r o bl e m s f o rsustainable development of Asian
cities with adequate safety andsecurity.
In addition to the activities of
RNUS, Dr. Dutta will be involved
in research and academic
activities at the Water Engineeringand Management program of SCE,
AIT. He can be reached at AITby telephone (+66-2-524-5794) or
fax (+66-2-524-5565) or e-mail(ddutta@ait.ac.th).

ICUS/INCEDE Newsletter Vol. 3, No. 1

page 8
Editor’s Note
In the past few decades, various
problems associated with water are
increasing rapidly. The seriousnessof water related problems wasbrought to the attention of the wholeworld by the 3rd World Water Forum
held in Japan at the beginning of
this year. The main article of thisissue of the ICUS Newsletter showsthat water related extreme events areon rise around the world and thistrend is going to continue due tochange in climatic conditions. Asia
is going to be most severely affectedby water related disasters due to the
combined effects of its high rate of
population growth and urbanization
with climatic changes. The article
shows that flood frequency is
increasing in most of the Asian
countries in the last three decades.

To cope with the increasing problemsof floods in Asia, large scale and longterm mitigation measures are required.
Flood problems have to be addressed
together with other water issues inbasin scale not as a standalone issue
confined within the floodplain. It
requires adaptation of integrated river
basin management policies
incorporating various issues of water.
Transbasin water sharing is anotherimportant aspect to be focused into
for mitigating the problems of water
too much and too little .However,such measures need long-termplanning and high cost. Emphasisshould also be given to short termmeasures for reduction of devastatingconsequences of major floods bytaking proactive strategies of proper
guidelines for floodplains, hazard andrisk mapping, early warning and realtime risk management.

From the beginning of June 2003,
I have joined AIT as a visiting
faculty from ICUS. At AIT, I am
going to be involved in coordinating
the activities of the Regional
Network Office for Urban Safety(RNUS) established jointly by ICUS
a n d A I T l a s t y e a r. T h e m a i n
objective of RNUS is to expand theinternational activities of ICUS bycollaborating in research andsharing information with leading
institutions of Asia for urban safety.
One of the major issues that I would
like to focus on at RNUS is urban
flood risk management. It is ourstrong believe that through mutual
cooperation with AIT and otherinstitutions, ICUS would be able toadequately address the problems andcontribute towards urban safety andsecurity of the region.
(D. Dutta)

International Center for Urban Safety Engineering, ICUS/INCEDE
Institute of Industrial Science, The University of Tokyo
4-6-1 Komaba, Meguro-ku, Tokyo 153-8505, Japan

International Center for
Urban Safety Engineering