Characteristic of Heavy Rainfall Disaster in Central Area of Japan on September
11 to 12, 2000

USHIYAMA Motoyuki*, TAKARA Kaoru**Disaster Prevention Research Institute, Kyoto University, Japan.

1. Introduction
Heavy rainfall occurred in during the Toukai
district around Nagoya City (Central area of Japan)
on 11 to 12 September 2000. Caused by Typhoon
No.14 and a stationary front(Fig. 1), this heavy
rainfall brought great damages to various areas in
Tokai district. This paper report characteristic of
this disaster from a viewpoint of comparison withpast disaster events and disaster informatics.
2. Characteristic of damage
2.1 Outline of damage
The Fire Defense Agency, Ministry of Home
Affairs (at present Ministry of Public Management,
Home Affairs, Posts and Telecommunications),summarized this disaster inflicted on the entire
country as of October 2, 2000, as shown in Table 1.
Aichi Prefecture was damaged to the extent that itcomposed 92% of all the inundated houses in Japan.
An embankment of about 100m was destroyed in the
Shinkawa river in the Nishi Ward of Nagoya City.
Besides this, embankments were destroyed at tenplaces in Aichi Pref., and much flood damage
occurred surrounding Nagoya City and the northernpart of the Chita Peninsula. Floods and debris flows
occurred in the mountainous area of the upper
reaches of the Yahagigawa river. Therefore, a lot ofhouses, roads, telephone lines, and power lines weredamaged, and the villages became isolated one after
the other.
The operation of the Toukaidou Shinkansen was
suspended for about 24 hours from 11 September.
50,000 passengers had to stay in the train overnight.
This suspension time was the longest since the
Shinkansen began running in 1964. Since thiscreated a large social problem, the Ministry ofTransport (at present Ministry Land, Infrastructure
and Transport) directed JR Central to improve therailway system so as to avoid such disasters in the
future.
The National Disaster Act was put in force in 17
cities and towns in Aichi and Gifu Pref. ( Fig. 2)
2.2 Comparison with the heavy rainfall disasters after

1971 in Japan
In Aichi Pref., about 65,000 houses were inundated
in this disaster. There were especially a lot of overfloors which were inundated. This is one of theheaviest inundator damage after 1971. There werenine heavy rainfall disaster events after 1971 inwhich the inundation of 50,000 houses or more wasrecorded in one prefecture. Most recent similardisaster occurred in Saitama Pref. 18 years ago(September 1982) when Typhoon No.18 and astationary front caused the inundation of 60,100
houses (Japan Meteorological Agency, 1999). The
inundation damage of a recent remarkable heavy
rainfall disaster events were rather smaller than thesetwo disasters. In the case of the Kouchi heavy
rainfall disaster in September 1998, eight people diedor missing, 141 houses were ruined or half-ruined,
and 17,300 houses were inundated. In the case of
the Hiroshima heavy rainfall disaster in June 1999,
these factors were 32, 512, and 3827 respectively.
2.3 Past heavy rainfall disaster events in Aichi Pref.
Table 2 shows the major heavy rainfall disasterevents after 1901 in Aichi Pref. Since large-scale
sediment disasters such as those of July 1972 did notoccur this time. This might account for the lesser
damage to humans and housing in the present
instance, though there was much precipitation.
The "Ise bay typhoon" in September 1959 iswell-known as the cause of an especially large
disaster around Aichi Pref. The number of dead or
missing persons was 5,098 throughout the entire
country(Aichi Pref. 3,251, Mie Pref. 1,273), about
830,000 houses were destroyed, and about 360,000
houses inundated. However, most of this damage
was inflicted by the high tide.
Two-day
precipitation was 198 mm at Gifu(Gifu Pref.), 164mm at Nagoya, and 265 mm at Ueno(Mie Pref.) etc.
These values are much smaller than the 600mm
experienced at Nagoya in the present case.
3. Characteristic of Precipitation
3.1 Precipitation before the heavy rainfall
In 2000, Japan's summer precipitation was soslight that concern was expressed regarding a water
shortage. The ratios in relation to the normal
precipitation in the Toukai district of this year werefrom 70% to 100% in April and May, from 100% to120% in June, and 40% or less in July andAugust(JMA, 2000a - 2000e).
The five-day
precipitation from April to September 2000 at
Nagoya Local Meteorological Observatory is shownin Fig. 3. No five-day precipitation exceeded thenormal during this period.
Rainfall was notrecorded from the middle of May to the middle ofJune. In Baiu seasen (June to July), seasonal
precipitation was slightly less than normal; very few
rainfalls had occurred since August. The total
precipitation at Nagoya was only 23 mm (four small
rainfall events) from the beginning of August to
September 10.
3.2 Situation from September 11 to 12
Fig. 4 shows an isohyetal map of the two -day
precipitation from September 11 to 12. This figure
is based on data gathered by the Ministry ofConstruction, Japan Meteorological Agency (JMA)and Aichi Pref. As the figure indicates, heavy
rainfall areas existed among the areas that received
the total precipitation about 600 mm in the southernpart of Mie Pref., the east part of Aichi Pref., andaround Nagoya City. The southern part of Mie Pref.
and the east part of Aichi Pref. are regions thatexperience heavy rainfall, while Nagoya receives
lesser amounts. It is notable that such heavy
rainfalls occurred around Nagoya City in the present
instance. For example, 618 mm was recorded in
two days at the Miyagawa observatory (Miyagawa
Village) in the southern part of Mie Pref. This is1.18 times the normal amount of precipitation in
September (522 mm). On the other hand, thetwo-day precipitation of 567 mm at Nagoya is 2.43
times the normal amount of precipitation in
September (233 mm).
Fig. 5 shows the hourly precipitation andcumulative precipitation at Nagoya and Yarigairi,
which were selected as representative raingauges in
the areas that received the heaviest amounts ofrainfall. The heavy rainfall in the present instanceoccurred within about 24 hours. The first heavy
rainfall occurred in Nagoya between 18:00 and 21:00
on September 11. The second was from 23:00 on
Sep. 11 to 04:00 on Sep. 12th. Rain stopped around
08:00 on Sep. 12. Table 3 shows the precipitation
data gathered at the main observatories.
The
precipitation record of this time can be summarized
as follows: the maximum hourly precipitation isabout 110 mm; 24-hour precipitation is about 500
mm; and the total precipitation is about 600 mm.

3.3 Comparison with past heavy rainfalls

Table 4 shows the historical maximum daily andhourly precipitation in the Toukai district. Daily
precipitation records shown in Table 4 are rather
small compared with records obtained in regard to thepresent event. However, investigating the records ofother precipitation observatories in the district (213
locations), we found three events of more than 500
mm in single day(Table 4). Daily precipitation
regarding the present case was especially heavy inrelation to other in the past about 100 years.
Hourly precipitation (93 mm) slightly exceeded thehistorical maximum value (92 mm) in Nagoya Local
Meteorological Observatory. However, as shown in
Table 4, this can be regarded as comparable to thehistorical maximum over the past 100 years.
Fig. 6 shows the relationship to precipitation andduration (DD relationship) for recent 3 heavy rainfall
events in Tokai district and Japan records. The allrecords of present event were smaller than highest
records of Japan. However, the 1-hour to 5-hour
precipitation is higher than the past two heavy rainfall
events. Characteristic of present event is that a few
hours precipitation was very high.
Frequency analysis by the GEV (generalextreme-value) distribution using annual maximum
daily precipitation data (1901-1999) at Nagoya
showed that 100-year probable precipitation is 229
mm, while the 500-year is 334 mm. This analysis
also indicated that the return period of the daily
precipitation of 428 mm (Sep. 11) is 40137 years.
According to the Aichi Pref. Flood Control Plan
(Aichi Pref. 2000), the 100-year hourly precipitationin the Nagoya district is 98mm, and the 100-year
daily precipitation is 330 mm. It is clear that theheavy rainfall in 2000 greatly exceeded the heavy
storms predicted at Nagoya as based on past data.
4. Information dissemination by the Internet
The information dissemination and informationexchange over the Internet regarding such disasters
had been actively performed since the Fukushima andTochigi heavy rainfall disasters in 1998 (Ushiyama,
1999). We may say that the use of the Internet had
become generalized during the current disaster. In
the past, ctizens and volunteer groups have been the
primary Internet users. However, the information
dissemination by the Local Government wasenhanced in the present instance. Aichi Pref., Gifu
Pref., the Ministry of Construction, etc. createdhomepages in regard to this disaster(Fig. 7). The
URL of the main homepage as of April 2001 isshown below.
The River Bureau, The
Infrastructure and Transport

Ministry

of

Land,

http://www.mlit.go.jp/bosai/disaster/saigaitaiyou/toukaigouutaiyou.htm

Aichi Prefecture
http://www.pref.aichi.jp/kasen/TANTOU/GEKITOKU/SHINGEKI/index.html
Gifu Prefecture
http://www.pref.gifu.jp/s11652/saigai/saigai.htm
http://www.pref.gifu.jp/gib/3_news/0009/3082.htm
The present author (USHIYAMA Motoyuki, DPRI,
Kyoto Univ.)
http://www.disaster-i.net/disaster/20000911/
After the disaster, all of these homepages werecreated within the course of a few days. However,there were differences existed regarding the contentsof these homepages and how quickly they werecreated in terms of their originators.
It isnoteworthy that a newspaper article (Fig. 8) pointed
out that several public offices did not use thehomepages for disaster information dissemination.
Probably this is the first time that such a report was
carried on major newspaper in Japan. We may saythat homepage usage is becoming more widespread
as a way to provide disaster information.
5. Conclusion(1) The principal damage over the entire area ofJapan was as follows: The death toll was 10; thenumber of inundated houses was about 71,300;
ruined or half-ruined houses about 310. The mostdamage occurred in Aichi Pref. The death toll anddamaged houses were few, though the number ofinundated houses was the highest in the last 18 years
in Japan. Especially the percentage of over floor
inundated houses were high (41%).
(2) In the heaviest rainfall area, two -day precipitation
was about 600 mm, 24-hour precipitation was about
550 mm, and maximum hourly precipitation was
about 110 mm. The previous record for daily
precipitation was the highest in the past about 100
years in the Toukai district, while the entire hourly
precipitation was comparative with the historicalmaximum records, which had been recorded several

times in the past about 100 years. Especially a few
hours precipitation was very high.
(3) A lot of disaster information were disseminated on
Internet.
Homepage usage is becoming morewidespread as a way to provide disaster information,
it came to be criticized that the local government
didn't use Homepage.
Acknowledgements
This report was supported in part by a Grant-in-aid
for
Scientific
Research(No.12800012;
Representative: Tujimoto, T.) from the Japanese
Minisroty of Education, Science, Sports, and Culture.
Reference
Aichi Prefecture (2000): Aichi Prefecture FloodControl Plan on 2000 (Japanese), Aichi Prefecture.
Japan Meteorological Agency (1999): Statistics ofMeteorological Disaster (CD-ROM, Japanese), Japan
Meteorological Business Support Center.
Japan Meteorological Agency (2000a): The climate inJapan on Apr. 2000 (Japanese), Kisho, Vol.44, No.4,
pp.26
Japan Meteorological Agency (2000b): The climate
in Japan on May 2000 (Japanese), Kisho, Vol.44,
No.5, pp.26
Japan Meteorological Agency (2000c): The climate inJapan on Jun. 2000 (Japanese), Kisho, Vol.44, No.6,
pp.26
Japan Meteorological Agency (2000d): The climate
in Japan on Jul. 2000 (Japanese), Kisho, Vol.44, No.7,
pp.26
Japan Meteorological Agency (2000e): The climate inJapan on Aug. 2000 (Japanese), Kisho, Vol.44, No.8,
pp.26
USHIYAMA Motoyuki (1999): Heavy rainfall
disaster in Fukushima and Tochigi Prefecture on
August 1998 and Internet (Japanese), Research
Report on Natural Disasters, Supported by theJapanese Ministry of Education, Science, Sports andCulture (Grant No.10400011), pp.43-52, 1999.

Fig. 1 Infrared image of meteorological satellite (GMS) at 19:00 Sep. 11, 2000.
http://www.tkl.iis.u-tokyo.ac.jp/SatIAN/

Table 1 The damage in each prefecture
Damage of buildings (buildings)
Ruined andInundated
half-ruined
Over floor
Under floor

Prefecture

Death
toll

IbarakiTochigi
Gunma
Saitama
Kanagawa
Fukui
Yamanashi
NaganoGifu
Shizuoka
Aichi
Mie
Wakayama
Osaka
Hyogo
Tokushima
Okinawa

1
1
7
1
-

9
1
28
239
2
31
1
1

1
0
3
33
8
0
101
56
108
1
26531
283
45
0
0
3
7

24
40
35
106
39
1
549
148
375
33
38879
2806
992
12
16
28
28

All Japan

10

312

27180

44111

Fig. 2 The municipalities where the National Disaster Act was put in force
A:Shikatsu Town, B:Toyoake City, C:Nishibiwajima Town, D:Toyoyama Town, E:Shinkawa Town, F:Handa
City, G:Kariya City, H:Oobu City, I:Iwakura City, J:Mihama Town, K:Nishiharu Town, L:Kiyosu Town,
M:Jimokuji Town, N:Ooharu Town, O:Higashiura Town, P:Kamiyahagi Town.

Table 2 The heavy rainfall disaster Aichi Prefecture since 1971
Damage of buildings (buildings)
Death
tool
140
27
12
23
13
26
0
75
33
0
3,260

Ruined andhalf-ruined
6,000
Unknown
*
52
*
166
*
13
*
30
*
5
* 6,769177
23
410,636

Inundated
Unknown
Unknown
20,000
1,400
2,000
2,700
52,00090,00017,50880,840116,391

1961/06/23-06/29
1965/09/17
1966/10/12
1971/8/30-8/31
1971/9/26-9/26
1972/7/ 9-7/13
1972/9/14-9/17
1974/7/ 7-7/ 7
1974/7/24-7/25
1975/8/21-8/23
1976/9/ 8-9/14
1979/9/24-9/24
1983/9/26-9/28
1989/9/19-9/20
1991/9/18-9/19

6
1
10
4

3
1
2
5
2
2

103
74
29
67
2
528
315
69
38
2
972
0
2
2
9

74,62351,35020,758
0
34500
0
0
8690
57620
997
101100
24560
9886
12
13415

2000/09/11-12

7

239

65,410Date
1912/09/22-09/23
1921/09/25-09/26
1925/09/11
1926/09/04
1930/07/19
1932/07/01-07/02
1952/07/10-07/11
1953/09/25
1957/08/07
1959/08/14
1959/09/26

66
2
2

Weather condition

Typhoon. Flood tide damage.
Over floor inundated houses were 14.
"Ise bay Typhoon". Flo od tide damage.
Over floor inundated houses were 53,560.
Stationary front.
Typhoon. *1
TyphoonTyphoonStationary front *2
Typhoon and occluded front
Typhoon and stationary front
Low passing along south coast
TyphoonTyphoon and stationary front *3
Typhoon and stationary front
Typhoon and stationary front
Typhoon and stationary front
Typhoon and stationary front
Typhoon and stationary front

150

100

Normal
2000

50

0
4/4
4/18
5/2
5/16
5/30
6/13
6/27
7/11
7/25
8/8
8/22
9/5

5-day precipitation [mm]*:Ruined only
*1 Maximum daily precipitation was 711mm(Tokuyama, Gifu Pref.). It is maximum record in Tokai district.
*2 Heavy debris flow occurred on the Obara Village(East part of Aichi Pref).
*3 Embankments were destroyed in the Nagaragawa river.

Fig. 3 5-day precipitation at Nagoya (Normal year: average from 1961 to 1990)

100

500
400
300

9/13 00100
0
9/12 18

0
9/12 12200

9/12 06

50

Cumulative precipitation [mm]

700
600

9/12 00

9/13 00

9/12 18

9/12 12

9/12 06

0100
09/12 00

200

9/11 1850

9/11 12

400
300

150

9/11 18

500
100

800
Yarigairi
Cumulation

9/11 12600

200

9/11 06150

Hourly precipitation [mm]

800
700

NagoyaCumulation

Cumulative precipitation [mm]2009/11 06

Hourly precipitation [mm]Fig. 4 Isohyetal map of the two-day precipitation from September 11 to 12 in Tokai District

Fig. 5 Hourly and cumulative precipitations at Nagoya and Yarigairi from Sep. 11to 12, 2000.

Table 3 Precipitation data at the main observatories

Precipitation (mm)Maximum
Hourly Sep.11
Sep.12
2-day

Station nameMunicipality, Prefecture
Japan Meteorological Agency
Inabu
Inabu Town, Aichi
70
NagoyaNagoya City, Aichi
93
ToyotaToyota City, Aichi 61
217
Tokai
Tokai City, Aichi
114
Gifu
Gifu City, Gifu
34
Yokkaichi
Yokkaichi City, Mie
36
Tu
Tu City, Mie
25
Ministry of Construction
Kamiyahagi
Kamiyahagi Town, Gifu
65
YarigairiKamiyahagi Town, Gifu
80
Aichi Prefectural Office
Uedagawa
Meitou Ward, Nagoya, Aichi 77
Agiu
Agiu Town, Aichi
80

Maximum
24-hour

222
428
196
492
204
295
284

245
139
413
97
38
67
70

467
567
388
589
242
362
354

438
535

202
278

235
317

437
595

403
552

429
498

127
124

556
622

523
588

557
224
319
284

Table 4 Historical maximum daily and hourly precipitations in the Toukai district
Maximum daily precipitation
Maximum hourly precipitation
Data(mm) Date Period
Data(mm) Date
PeriodObservatory of JMA(Japan Meteorological Agency)
Weather OfficeGifu
260.2 1961/06/26 1883-1999
99.6 1914/07/02 1903-1999
Nagoya240.1 1896/09/09 1891-1999
92.0 1919/07/18 1891-1999
Tu288.2 1959/08/13 1889-1999
118.0 1999/09/04 1916-1999
Irako
337.1 1962/07/02 1947-1999
81.8 1962/07/02 1950-1999
Yokkaichi
271.0 1974/07/25 1966-1999
82.5 1971/07/07 1966-1999
AMeDAS (Automated Meteorological Data Acquisition System)
Tarumi351
1986/08/22 1979-1999
98
1986/08/22 1979-1999
Ibigawa
330
1986/06/17 1979-1999
65
1989/09/07 1979-1999
Kaburayama
319
1981/07/12 1979-1999
79
1981/07/12 1979-1999
Hachiman250
1987/08/08 1979-1999
95
1987/08/08 1979-1999
Kanayama
194
1999/09/21 1979-1999
86
1999/09/21 1979-1999
Hirai
190
1986/06/17 1979-1999
84
1987/07/15 1979-1999
Other observatory
Tokuyama
711
Ibigawa
502
Nishiyokoyama 439
Kuzuhara
430
Mino
420
Shimoda542

1965/9/15
1972/9/16
1907
1976/9/10
1954/9/1
1923

Precipitation(mm)

10000

1000

100

10
1
1972/7 Ohkusa(Obara)
All Japan

10
Duration(hour)100

1965/9 Gongenyama
2000/9 Toukai-shi

Fig. 8Fig. 6 Comparison of DD relationships for heavy
rainfall events in Tokai district.

Fig. 7

The Web page about present heavy

rainfall event by Gifu Prefecture.

The report of Asahi Newspaper in

September 14, 2000