Journal of Natural Disaster Science, Volume 25, Number 2, 2003, pp57-63

Heavy Rainfall Disaster in Eastern Japan Caused
by Typhoon 0206 from July 9 to 12, 2002
Motoyuki USHIYAMADisaster Control Research Center, Graduate School of Engineering, Tohoku University(Received 6. Jan., 2003 and in revised form 8 Dec., 2003)

ABSTRACT
Typhoon 0206 (CHATAAN) struck the Pacific coast of Japan from July 9 to 12, 2002 and caused heavy rainfall in eastern Japan. In Gifu Prefecture, hourly precipitation of 93mm was recorded on July 10 and the total precipitation was more than 500 mm. The highest accumulated precipitation for approximately the last 20 years wasrecorded at several observatories in Iwate Prefecture. This rainfall caused 7 deaths, destroyed 39 houses, andinundated some 9,800 houses. The worst damage was in Higashiyama Town, Iwate Prefecture in which twentyfive percent of all the houses were inundated. Residents of that town had had several previous flood experiences,
but in spite of those experiences, extensive damage occurred because the water level rose faster than in past flooding. In Ogaki City, Gifu Prefecture, the flooding of the Otani River inundated of 550 houses. The existence of afuse plug levee of the Otani River in the vicinity of a residential area was blamed. The real time rainfall information and hazard maps developed recently were not sufficiently made use of as indicated by the results of a questionnaire that surveyed the damaged municipalities.

1. INTRODUCTION
A heavy rainfall disaster occurred in the Japanese archipelago
from July 9 to 12, 2002. Seven people died or were missing, 39
houses collapsed, and 9,785 houses were inundated (Fire andDisaster Management Agency, 2002). The causes of this heavyrainfall were typhoon No.0206 (CHATAAN) and a Bai-u front(rainy season stationary front). The characteristics of this event areFig. 1Route of typhoon 0206.

compared with those of other recent heavy rainfall disasters inJapan.
2. PRECIPITATION CHARACTERISTICS
2.1 Outline of weather conditions
The Japanese archipelago has two rainy seasons. The firstfrom June to July, is caused by the bai-u front. In 2002, this front
appeared around in mid-June. The Japan Meteorological Agency(JMA) announced that the bai-u season had begun in Kyushu on

Fig. 2Surface weather map (21JST, July 9, 2002).

KEY WORDS: heavy rainfall disaster, flood damage, disaster information, Iwate Prefecture, Gifu Prefecture

M. USHIYAMA

2.2 Precipitation distribution
The center of typhoon 0206 did not pass over the landmass of
the Japanese archipelago, but a wide area was hit by the heavy
rainfall caused by the bai-u front and typhoon. The major heavy
rainfall areas were (1) western Gifu Prefecture, (2) eastern
Shizuoka and western Yamanashi Prefecture, and (3) northern
Tochigi and northern Gunma prefecture. Cumulative precipitationof more than 300 mm was recorded from July 10 to 11 (48-hour) inthese areas (Fig. 3). In western Gifu Prefecture, a high of 500 mmof precipitation was recorded.
Figure 4 shows hyetographs of Tarumi (Neo Village, Gifu
Prefecture) and Ichinoseki (Ichinoseki City, Iwate Prefecture).
The highest 48-hour precipitation was recorded at the Tarumi

observatory. Ichinoseki is in the neighborhood of the district mostheavily inundated.
Rain began at Tarumi before dawn on July 10. The highest 1hour precipitation (93mm) was recorded at 1 a.m. on July 10.
There after, a precipitation of more than 20mm was recorded every
hour from between 1 a.m. and noon on July 10. The 48-hour precipitation totaled 506mm. At Ichinoseki, rain began on the morning of July 10. Approximately a rainfall of 10mm per hour wasrecorded from 11 p.m. on July 10 through 08 a.m. on July 11. The
highest 1-hour precipitation (31mm) was recorded at 06 a.m. on
July 11. The 48-hour precipitation totaled 223mm.
2.3 Comparison with historical rainfall records
Precipitation caused by this event was compared with historical rainfall records through the use of AMeDAS observatory (1150stations) data compiled by the JMA for the years 1979 to 2000.
The highest historical 1-, 24-, and 48-hour precipitations respectively were exceeded at 9, 32, and 33 observatories, respectively,
indicative that the number of observatories with revised highest 1hour precipitations was smaller than those with longer observation
times. One of the characteristics of this event was the heavy
cumulative precipitation, as seen from various indexes. Theeffective rainfall and the soil water index (SOI. Okada et al.
2001) are cumulative precipitations which are determined by multiplying past precipitation by a degressive coefficient. Theseindexes are used as warning indicators of sediment and other disasters. The historical highests recorded effective rainfall and SOI
respectively at 30 and 27 observatories in this event.

100600

Tarumi500

40200

201000007/11 12300

07/11 00

6007/10 1240007/10 00

8007/09 12

Hourly precipitation [mm]120600Ichinoseki

Fig. 3

Map: 48-hour precipitation distribution (July 10 to 11).

500

40200

201000007/12 00

30007/11 126007/11 00

40007/10 128007/10 00

Hourly precipitation [mm]

120
100

Cumulative precipitation[mm]June 10, and in Honshu and Shikoku on June 11. The bai-u frontof that was not active from the middle to the end of June, but thesituation changed at the beginning of July. Passage of typhoon
No.0205 near Kyushu from July 3 to 4 activated the front.
Typhoon No.0206 passed Minami-Daito Island on July 8,
moving in a northerly direction. The bai-u front was activated by
the its movement and caused rainfall in west Japan after July 8.
The course of the typhoon changed on the afternoon of July 9, andit passed along the Pacific coast from July 9 to 11 (Figs. 1, 2).

Cumulative precipitation
[mm]

58

Fig. 4 Hourly and cumulative precipitation at Tarumi (GifuPrefecture) and Ichinoseki (Iwate Prefecture).

HEAVY RAINFALL DISASTER IN EASTERN JAPAN CAUSED BY TYPHOON 0206 FROM JULY 9 TO 12, 2002

59

Fig. 5 Observatories with revised highest (1979 to 2000) precipitations.
Box size indicates the difference between the highest and present records.

A distribution map of those observatories that had the highest
revised precipitation is shown in Fig. 5. The 24-hour precipitation
record was exceeded in (1) western Gifu Prefecture, (2) eastern
Shizuoka Prefecture and western Yamanashi Prefecture, (3) northern Tochigi and northern Gunma prefectures, (4) southern Iwate
Prefecture. Areas (1), (2), and (3) which had very heavy rainfall(cumulative precipitation of more than 300mm) were those in 2.2.
In contrast, the 48-hour precipitation, effective precipitation, andSOI highs mainly were exceeded in area (4). That area did nothave heavy rainfall, but the highest historical records were exceed-

ed at many observatories. Area (4) may have been at high risk of aheavy rainfall disaster during this event.
3. DAMAGE CHARACTERISTICS
3.1 Damage outline
The Fire Defense Agency of the Ministry of Home Affairssummarized the effects of this disaster as of July 19, 2002 on theentire country (Table 1). The death toll was low and building damage (ruined and half ruined) slight as compared to other important

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M. USHIYAMA

heavy rainfall disasters in Japan during the past several years,
whereas the number of houses inundated was similar to the numbers in those past events. The greatest inundation damage (3,500houses) occurred in Iwate Prefecture and is the highest amountrecorded in Iwate Prefecture in the last 30 years. Miyagi,Fukushima, and Gifu prefectures also experienced much damage.
3.2 Human damage
Drowning in a river was the cause of the deaths of 5 persons(Aomori, Akita, Miyagi and Oita prefectures).
Two deaths in Kamaishi City, Iwate prefecture were caused
by a sediment disaster. This deaths case had two important problems. First, they were single and aged individuals living in an oldhousing complex. It is difficult to disseminate disaster information
to this type of person, and this is a recent cause for concern
because of Japan s aging society. The second problem is that of an
unexpected disaster . A newspaper (Iwate Newspaper, July 12)
reported that the Kamaishi City office and the city s residents werealerted only to river flooding, not to the risk of a sediment disaster.
Table 1This type disaster here is called an unexpected type disaster .
Such disasters have occurred several times. A recent example wasthe July 1997 Harihara debris flow disaster in Kagoshima
Prefecture (Moriwaki et al. 1998).
3.3 The flood disaster in Ogaki City, Gifu Prefecture
The Ibi River basin in western of Gifu Prefecture sustained
heavy rainfall (24-hour precipitation of more than 500mm) on July
10, (see 2.2). The water level in the downstream section of the Ibi
River rose during the daytime on July 10 because of heavy rainfall.
At the Mangoku water level observatory, the designed high-waterlevel (about the height of the embankment) was exceeded on July
10 from 11 am to 2 pm. The highest level, recorded at 12 pm,
exceeded the designed high-water level value by 0.26m (NationalInstitute for Land and Infrastructure Management, 2002).
No breach of the levees of major rivers occurred during thisflood, but many houses were flooded due to inundation inside alevee and overflow. In Ogaki City, in particular, 551 houses wereinundated (over floor, 327; under floor, 224), the deepest inunda-Damage by prefecture.

HEAVY RAINFALL DISASTER IN EASTERN JAPAN CAUSED BY TYPHOON 0206 FROM JULY 9 TO 12, 2002

Photo 1 Flood damage in Ogaki City, Gifu Prefecture.
Photograph: July 10, 16:00. The fuse plug levee is on theright. Copyright (C) 2002 Asia Air Survey Co., Ltd.

Photo 2

Close-up of the fuse plug levee (Otani River Arai zeki).

61

Photo 3 Flood damage in Higashiyama Town, Iwate Prefecture.
Photograph: the morning of July 11. Provided by theHigashiyama Town office.

Photo 4 Inundated house in Higashiyama Town.
Inundation by over flow in spite of being built on filled
ground (about 1m). The wall was destroyed the river water.
Photos 4, 5, and 6 were taken on July 13 by the author.

tion was recorded in 48 hours, there were some sediment disasters
and channel erosions. Most of the damage done was small scale,no human or building damage occurring in that area.

Fig. 6

Location of Higashiyama Town, Iwate Prefecture.

tion in the residential zone being about 1 m (National Institute forLand and Infrastructure Management, 2002). Most of the damage
occurred in the Arasaki area (Photo 1) due to overflow at the fuseplug levee of the Otani River (Photo 2). Residential land development of a lowland paddy zone resulted in this damage. Local residents were not fully aware of the existence and objective of thefuse plug levee. Local people therefore need to be more thoroughly informed about that type structure.
Upstream of the Ibi River basin where 500 mm of precipita-

3.4 Flood damage in Higashiyama Town, Iwate Prefecture
In southern Iwate Prefecture, a 48-hour precipitation of 200 to300 mm was recorded. This was the highest heavy rainfall in thisarea in the past 20 years (see 2.4). The level of the KitakamiRiver, the principal river in southern Iwate Prefecture, rose on theevening of July 10 because of the heavy rainfall. At no observatory did it exceed the designed-high-water-level, whereas the critical-water-level was exceeded at several water level observatories.
At the Kozenji observatory (Ichinoseki City), the highest waterlevel was the 3rd highest recorded since 1945 (Iwate Office,MLIT, 2002). No levee was breached along the Kitakami River,and inundation damage was negligible, whereas much inundation
damage occurred along its branch rivers.
Higashiyama Town suffered the greatest damage in theKitakami River basin area. This town is located in the basin of theSatetsu River, a branch of the Kitakami River (Fig. 6). There were62

M. USHIYAMA

Photo 5 The Satetsu River in the central area of Higashiyama Town,Iwate Prefecture.

am on July 11, and overflows occurred everywhere in the central
area of Higashiyama Town. Many were inundated, houses and at
6:45 am on July 11, an evacuation order was given. Thirty persons
who failed to escape were rescued by helicopter or boat; fortunately there were no deaths. Results of my field survey showed thatthe inundation depth ranged from 1.5 to 2.0m in the town. Houses
with raised basements for flood defense are situated along theSatetsu River, but even these sustained over-floor inundation(Photo 4).
Residents along the Satetsu River also had some flooding due
to the backwater from the Kitakami River. In past event, flooding
was slow because the water level of the Satetsu River rose slowly,
after that of Kitakami River. In the 2002 event, the increase in thewater level was very rapid due to the heavy rainfall in the Satetsu
River basin. According to several residents, they didn t have time
to remove their household effects before flooding took place.
Thus, there was the possibility of an unexpected type disaster .
4. DISASTER INFORMATION

Photo 6 Central Higashiyama Town.
Inundation in this area was more than 1m deep. The groundis covered with mud from the river. Piles of refuses fromthe flooding can be seen along the road.

Fig. 7 Methods of real-time rainfall data access by municipal public
officials.

2 half-collapsed houses, 382 over-floor inundations, and 195
under-floor inundations (Photo 3). As the number of households inHigashiyama Town is 2,277, 25 percent of all the households
experienced inundation. This municipality suffered the worst
inundation damage in this heavy rainfall event.
The water level of the Satetsu River had rose rapidly after 2

In Japan, the development of rainfall observation and disaster
information dissemination systems has progressed rapidly in recentyears. The JMA and Ministry of Land, Infrastructure andTransportation (MLIT) oversee rainfall measurement at about
4,000 observatories. In addition, individual prefectures recently
have instituted rainfall observation systems. Information fromthese observatories has been disseminated by TV, dedicated terminals, facsimile transmission, telephone, etc. Moreover, real time
disaster information dissemination has been growing; e.g., theInternet provides a new tool for transmitting disaster information.
It has many weather information pages, and disaster-related governmental offices, as well as almost all prefectural offices, havepublished disaster information (disaster warnings, rainfall data,hazard maps, etc.) on their homepages. It is no exaggeration to saythat today is the Internet disaster information age . The effectiveness of these information systems, however, needs further examination.
The disaster discussed here is one of the first events to haveoccurred in this Internet age. Therefore, I investigated by questionnire how to collect and use the heavy rainfall disaster information compiled by local governments. Questionnaire information
was gathered from 230 municipalities in Iwate, Miyagi,Fukushima, Gifu and Mie prefectures. Thirty-two of them had
issued evacuation orders during the heavy rainfall disaster, half ofthem answered that the occurrence of damage was the decisive factor in issuing the evacuation order. Results of the questionnaire
indicated that in spite of the availability of disaster information it
was difficult to issue evacuation order before damage actuallyoccurred. Percentages of rainfall information received in real time
based on responses were rainfall JMA data 92%, Ministry of Land,
Infrastructure and Transportation (MLIT) rainfall and water level
data 72%, prefectural rainfall and water level data 78%. Rainfall
information use at the time of the heavy rainfall event were JMA
data was 74%, MLIT data 38%, and prefectural data 51%. Thesefindings show that it is not always a real time rainfall information
system that is used at the time of an actual disaster. Flood hazard
maps were made in 23 municipalities, but only 13 municipalities
used hazard maps during this event. It is important that the practi-

HEAVY RAINFALL DISASTER IN EASTERN JAPAN CAUSED BY TYPHOON 0206 FROM JULY 9 TO 12, 2002

cality of the use hazard maps be verified.
5. CONCLUSION
The characteristics of this disaster were as follows:(1) In the heavy rainfall disaster in East Japan caused by typhoon
No.0206 (CHATAAN) and the bai-u front, 7 people died orwere missing, 39 houses collapsed, and 9,785 houses wereinundated. It was the worst weather disaster in a 2-year period.
(2) The highest 48-hour precipitation (about 500mm) was recorded in western Gifu Prefecture. Historically the highest 24and 48-hour precipitations, effective-rainfall, and soil-waterindex after 1979 had been recorded mainly in southern Iwate
Prefecture.
(3) The worst damage was in Higashiyama Town, Iwate prefecture where inundation damage was especially severe.
Residents had had several previous flood experiences, thistime they and their household effects could not evacuatedbecause the water level rose much more rapidly than in pastevents.
(4) Dissemination of rainfall disaster information via the Internet
has progressed in recent years. Almost all municipalities areable to use real time rainfall information, as indicated by theresponses to the questionnaire submitted to damaged municipalities. The percentage of municipalities using such information, however, was 74% at the time of the rainfall disaster.
Moreover, only some municipalities utilized hazard maps.

63ACKNOWLEDGMENTS
I thank the staff of the Iwate Office of the Ministry of Land,
Infrastructure and Transportation, Sendai District MeteorologicalObservatory, Higashiyama Town Office, Kawasaki Village Office,Tohoku and Kansai branches of the Japan Weather Association,and Asia Air Survey Co., Ltd for providing the relevant data.
Special thanks are owed to Prof. F. Imamura, Tohoku Univ.,
Assistant Prof. T. Katada, Gunma Univ., Assistant Prof. Y.
Murayama, Tohoku Univ., Mr. K. Yoshida, Iwate PrefecturalUniv. and Dr. S. Koshimura, Disaster Reduction and Human
Renovation Institution for their valuable advice.
REFERENCES
Fire and Disaster Management Agency, 2002: The damage caused bytyphoon No.6 in 2002, http://www.fdma.go.jp/html/infor/140709
taifu6.pdf. (in Japanese)
National Institute for Land and Infrastructure Management, 2002: Theflood damage in Ogaki City caused by typhoon No.6,
http://www.nilim.go.jp/japanese/saigai/h14taihu06/oogaki.pdf (inJapanese)
Iwate Office, Ministry of Land, Infrastructure and Transportation, 2002:
The flood disaster on the Kitakami River, on July 11, 2002. (inJapanese)
Moriwaki. H., Sato. T., Chiba. M., 1998: Report on the Hariharagawa
debris flow disaster on July 10, 1997 in Kagoshima Prefecture, Japan,
Natural Disaster Report, No.35, 36-64. (in Japanese)
Okada. K., Makihara. Y., Shimpo. A., Nagata. K., Kunitsugu. M, Saitoh.
K., 2001: Soil Water Index, Tenki, 48, No.5, 349-356. (in Japanese)