Availability and Limitation of Software Counter-

measures for Heavy Rain Disaster in Sayo Town, Hy-ogo Prefecture in August 2009

Kohji UNO1 and Susumu NAKANO2

1Associate Professor, Kobe City College of Technology (Gakuen-Higashi 8-3, Kobe City, Hyogo 651-2194, Japan)

E-mail:uno@kobe-kosen.ac.jp 2Professor, Research Center for Management of Disaster and Environment, The University of Tokushima

(Minami-johsanjima 2-1, Tokushima City, Tokushima 770-8506, Japan) E-mail:nakano@ce.tokushima-u.ac.jp

On August 9, 2009, Sayo town located in western part of Hyogo Prefecture and border with Okayama Prefecture had serious flood damage by local heavy rainfall due to the approach of typhoon 0909. In this paper, first, the summary of this flood disaster is presented. Especially, we refer to where and how fatal victims lost their lives. In addition, it is examined that how the prevention disaster information was released for residents at that time. Second, from the summary of questionnaire on this disaster which conducted by town office to make a rehabilitation and reconstruction plan, the difference of conscious for flood disaster between residents in 13 districts in Sayo town is clarified. Finally, the improvement of hazard map for flooding distributed by local government is pointed out. From the results of our study, we can see it is important that not only the local government should commit faster and more accurate transmission of in-formation using more than one procedure but also residents should try to have a deep insight against pre-vention disaster information and take early evacuation action. Key Words : Sayo town, typhoon 0909, heavy rain, hazard map, questionnaire, evacuation activity,

weather information for prevention disaster

1. INTRODUCTION

Recently, flood disasters caused by local heavy rain were occurred one after another in many places around Japan. In Hyogo Prefecture, it is no exception, flood disaster of Maruyama River in 2004 and the water ac-cident at water amenity space of Toga River in 2008 are still vivid in our memory.

In July 2009, the heavy rain caused extensive sediment disaster in several places in Chugoku region which is the western part of main land Honshu Island. Due to the climate change such as global warming, it is expected that serious flood disaster will continue to happen in various areas around Japan. Therefore, it is important to extract the problems on disaster prevention and river management. Especially, it is significant that residents are aware of the availability and limitation of software countermeasures for the natural disaster.

In this study, we took the flood disaster by local torrential rain as the example. Study site is Sayo town lo-cated in western part of Hyogo Prefecture and border with Okayama Prefecture (Fig.1). On August 9, 2009, Sayo town had serious flood damage by local heavy rainfall due to the approach of typhoon 0909. These rains triggered deadly flooding and mudslides, especially in Hyogo Prefecture. 28 people were died by the storm and ¥7.1 billion in damage occurred throughout the affected region. Most of fatal victims lost their lives on the way to their safe haven or office.

In this paper, first, the summary of this flood disaster is presented. Especially, we referred to where and how the fatal victims lost their lives. Moreover, it is examined that how the prevention disaster information was released for residents at that time. Third, from the summary of questionnaire on this disaster, the difference of conscious for flood disaster between residents in 13 districts in Sayo town is clarified. Finally, the improve-

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ment of hazard map information for flooding distributed by local government is pointed out. 2. THE OUTLINE OF 0909 TYPHOON DISASTER (1) Brief overview of 0909 typhoon disaster

Typhoon 0909 was the deadliest tropical storm to impact Japan since typhoon 0423 in 2004. This typhoon didn t make landfall, the outer bands of the storm produced torrential rainfall in West Japan. These rains

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JAPAN

KYUSHU SHIKOKU

HONSHU

HOKKAIDOSayo River

Makuyama River

Chikusa River

Shiso City

Tatsuno CityKamigori Town

Sayo Town

Akoh City Aioi City

Mt. Mimuro

Okayama Pref.

The Harima Sea

Sayo

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Watershed boundary Administrative boundary Measure point of water level

Chigusa

Enko-jiHyogo Pref.

Fig.1 Study site (Sayo town)

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triggered deadly flooding and mudslides, especially in Hyogo Prefecture. 28 people were killed by the storm and ¥7.1 billion in damage occurred throughout the af-

fected region. According to the Fire and Disaster Management Agency, a total of 5,602 homes were flooded and 183 were destroyed.

Fig.2 shows the time series of water level and precipitation in the Chikusa and Sayo river basin. This figure also shows the warning stage of water level. Namely, Level 1 corresponds to the water level which flood fighting corps should prepare against flood disaster. Level 2 is advisory for flooding and Level 3 shows the judgmental standard of the means almost brimful water level which is the most serious situation.

In Chigusa which is the most upstream measurement site in the Chikusa River, the xceed Level 4 stage. However, in more down-stream Sayo, the peak of water level was exceeded H.W.L. and the settlement sustained serious flood damage. The amount of daily rainfall was recorded 326.5mm at Sayo, it was new record value. In this measurement site, the record of hourly precipitation was also broken. In Enko-ji located between Sayo and Kamigori, the water level gauge went off the scale due to rapid water level raising. In Kamigori which is the most downstream measurement site, the water level also exceeded Level 4. In Fig.2,

8/9 21:00

Sayo town

Fig.3 Radar map of rainfall (2009/08/09 21:00)

Table 1 Time series of information on evacuation Time Event

8/9 11:50 An advisory of heavy rains and local flooding in the northwestern area of Harima region was issued.

14:15 A warning of heavy rains and local flooding in the northwestern area of Harima region was issued.

19:00 Disaster countermeasures office in Sayo town was set up.

19:58 Water level at Sayo reached 3m. Warning Level 3)

20:10 Alerting information against sediment disaster was provided.

20:40 Water level at Sayo reached 3.8m Warning Level 4)

21:15? 11 people in Makuyama district were washed away by flood on their way to evacuation area.

21:20 An evacuation advisory was issued throughout the town.

21:42 Prefectural government asked the Self-Defense Forces to send members to Sayo town on a disaster relief mission.

21:50 Water level at Sayo reached 5.08m Maximum water level)

8/10 13:52 A warning of local flooding in the northwestern area of Harima region was canceled.

15:45 Alerting information against sediment disaster was canceled.

16:11 A warning of heavy rains in the northwestern area of Harima region was canceled.

16:32 An evacuation advisory was canceled throughout the town.

Table 2 Human suffering by typhoon 0909

Dead Disappeared Seriousinjury

Mildinjury

Sayo town 18 2 0 1

Hyogo pref. 20 2 3 7 Damege ratio of Sayo town (%) 90 100 0 14

Human sufferingItem

Table 3 Property damage by typhoon 0909

completecollapse

Large-scalehalf

Halfcollapse

Inundationabove floor

Inundationunder floor

Partiallydestroyed

Sayo town 134 253 489 162 742 0

Hyogo pref. 160 284 652 339 1489 2 Damege ratio of Sayo town (%) 84 89 75 48 50 0

Property damageItem

Table 4 Information on fatal victims by typhoon 0909 Sex (Age) Distress place Action at that time

Male(54) Out of doors(Near Sayo central hospital)

On the way to the address for deliveryby lightweight truck

Female(86) In doors (flat building)(Near Sayo town office

Standing by at homeShe has a walking problem

Female(81) Out of doors(Near Sayo town office On the way to evacuation by walk

Male(40),Female(32),Male(7), Female(4)

Female(40),Female(16)

Male(9)

Female(47),Female(15)

Male(72) Out of doors(Near Sayo River On the way to home by car

Male(40) * Out of doors(Near Sayo River On the way to evacuation by car

Male(49)*, Female(47)*,Make(14) *

Out of doors(Near Sayo River

On the way to homecoming visit bycar

Male(54) Out of doors(Near Sayo River On the way to home by car

Male(48) Out of doors(Near home in Kouduki district On the way to evacuation by walk

Female(32) * Out of doors(Route 179 On the way to home by car

* non - Sayo town resident

Out of doors(Near town-provided housing inMakuyama district

On the way to evacuation by walk

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we can also see that there is the time lag of rainfall between measurement points. Namely, the heavy rainfall caused by approach of typhoon 0909 was locally and in short period of time. Fig.3 shows the radar map of rainfall at 21:00 August 9, 2009. We can see Sayo town was hit by heavy rain at that time.

Table 1 shows the time series of information on evacuation. A warning of heavy rains and local flooding in the northwestern area of Harima region was issued at 14:15. It was more than 6 hours before the water level reached the peak. In addition, alerting information against sediment disaster was provided at 20:10. Namely, the useful information on evacuation was released normally. However, the residents who distance themselves from flood disaster lost a sense of crisis. Actuary, in our hearing survey, many residents replied I didn't think something like this would happen .

The time of accident was around 21:15, it was guessed from the time stamp of E-mail a girl sent her friend We ll evacuate to elementary school (safe heaven). That's scary! at 21:12. There are opinions that the

transmission of an evacuation advisory was too late, however, it was very difficult to respond successfully in following situation. First, the disaster was happened in the Sunday evening, the town office was closed. Se-cond, town office staffs were also disaster victims, it was very hard to go to the town office at that time. Finally, Sayo town was merged in 2005 and the office staffs might not be apply to unfamiliar situations with poor bump of locality.

Makuyama

Kouduki

Minai

Ishii

HirafukuEkawa

Nagatani

MikadukiNakayasu

Sayo

Kuzaki

Tokusa

Mikawa

Chikusa River

Sayo River

Makuyama River

Chikusa River

N

Q1 : Did your house suffer damege from the flood?

0% 20% 40% 60% 80% 100%

Sayo (107)

Nagatani (24)

Hirafuku (32)

Ishii (14)

Miuchi (5)

Ekawa (33)

Makuyama (26)

Kouduki (84)

Kuzaki (76)

Nakayasu (25)

Tokusa (56)

Mikawa (23)

Mikaduki (57)

Yes No No answer

Fig.4 Districts in Sayo town Fig.5 Questionnaire result (Presence or absence of damege)

Q2 : Did you evacuate then?

0% 20% 40% 60% 80% 100%

Sayo (107)

Nagatani (24)

Hirafuku (32)

Ishii (14)

Miuchi (5)

Ekawa (33)

Makuyama (26)

Kouduki (84)

Kuzaki (76)

Nakayasu (25)

Tokusa (56)

Mikawa (23)

Mikaduki (57)

Yes No No answer

Q3 : Did you hear radio communications for disasterprevention and administration?

0% 20% 40% 60% 80% 100%

Sayo (107)

Nagatani (24)

Hirafuku (32)

Ishii (14)

Miuchi (5)

Ekawa (33)

Makuyama (26)

Kouduki (84)

Kuzaki (76)

Nakayasu (25)

Tokusa (56)

Mikawa (23)

Mikaduki (57)

Yes No No answer

Fig.6 Questionnaire result (Presence or absence of evacuation) Fig.7 Questionnaire result (Capture condition of

the radio communications)

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(2) Summary of disaster damage in Sayo town Table 2 and Table 3 show the human suffering and property damage by typhoon 0909, respectively. It is

clarified Sayo town had a higher proportion of the human and property damage against whole Hyogo Pre-fecture.

Table 4 shows information on fatal victims by typhoon 0909. From this table, we can see some features of fatal victims and their distress in this disaster. First, the range oit was irrespective of age or sex. Second, most of victims lost their lives out of doors. They were on the way to evacuation, coming home and going office by car or walk themselves. However, an 86 woman was died in her flat house. She was a vulnerable person who had Such problems on the judgment of evacuation or treatment of vulnerable people are significant issues which are dealt with immediately. Third, some fatal victims were not local inhabitants. Therefore, they might not be familiar with surrounding geographical features and couldn t avoid the flood damage.

Q4 : Do you have disaster prevention map?

0% 20% 40% 60% 80% 100%

Sayo (107)

Nagatani (24)

Hirafuku (32)

Ishii (14)

Miuchi (5)

Ekawa (33)

Makuyama (26)

Kouduki (84)

Kuzaki (76)

Nakayasu (25)

Tokusa (56)

Mikawa (23)

Mikaduki (57)

Yes.No. But I've ever heard about it. No. I've never seen and heard about it.OthersNo answer

Q5 : What kind of disaster prevention informationdo you know?

0 20 40 60 80 100

Sayo (107)

Nagatani (24)

Hirafuku (32)

Ishii (14)

Miuchi (5)

Ekawa (33)

Makuyama (26)

Kouduki (84)

Kuzaki (76)

Nakayasu (25)

Tokusa (56)

Mikawa (23)

Mikaduki (57)

Quantity of responses (persons) Fig.8 Questionnaire result (Utility of disaster prevention map)

Fig.9 Questionnaire result (Useful information for disaster prevention)

Fig.10 Questionnaire result (Important software countermeasures for disaster prevention)

0% 20% 40% 60% 80% 100%

Meeting about disaster prevention between residents

Emergency drill

Development of disaster prevention map

Cultivation of local voluntary disaster management Organizations

Enhancement of volunteers

Psychological care and health counseling

Livelihood support

Others

No answer

Q6 : Wtat is important software countermeasure for disaster prevention?

0% 20% 40% 60% 80% 100%

Sayo (107)

Nagatani (24)

Hirafuku (32)

Ishii (14)

Miuchi (5)

Ekawa (33)

Makuyama (26)

Kouduki (84)

Kuzaki (76)

Nakayasu (25)

Tokusa (56)

Mikawa (23)

Mikaduki (57)

Quantity of responses (persons)

Heavy rain warning or advisory

Flood warning

Evacuation advisory or order

Alerting information against sediment disaster

Radio communications for disaster prevention and administration

Others

No answer

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3. QUESTIONNAIRE SURVEY (1) Procedure

On November 2009, Sayo town office conducted questionnaire survey to reflect the reconstruction plan. The number of object persons was 1,000. The breakdown was 70 % for the person whose age was over 15 by random sampling, 20% for the person whose house had serious damage by flood disaster and 10 % for female demographic and young adult segment. The response rate was 61.3%. In this study, we made up the results of the answers by districts to examine the difference of the consciousness for disaster prevention and the demand for town administration. The towns of Kozuki, Mikaduki Nanko, and former Sayo were merged into Sayo in 2005. At present, there are 13 districts shown in Fig.4.

(2) Results Fig.5 shows the presence or absence of damage. In most of districts of Sayo River and Makuyama River,

over 70% respondents had any damages. On the other hand, in Chikusa river basin, the disaster victims re-mained under 50%. With all these results, we can see the damages suffered by local heavy rainfall.

Fig.6 shows the presence or absence of evacuation. The districts along the Sayo River - Ishi, Minnai, Kouduki Kuzaki - , 40 % respondents were evacuated , however, these answers were also included the evacuation to upstairs of their house. Therefore, actually, the respondents who evacuated to official evacuation center, such as elementary school and nursery might be fewer than this figure.

Fig.7 shows the answers about capture condition of the radio communications for disaster prevention and administration. In Nakayasu district, all respondents said no evacuation in Fig.6. Hence, it exempted from this

Q7 : Do you want to continue to live in this town in the future?

0% 20% 40% 60% 80% 100%

Sayo (107)

Nagatani (24)

Hirafuku (32)

Ishii (14)

Miuchi (5)

Ekawa (33)

Makuyama (26)

Kouduki (84)

Kuzaki (76)

Nakayasu (25)

Tokusa (56)

Mikawa (23)

Mikaduki (57)

Yes.Yes. But, I'd like to move other place in Sayo town.No. I'd like to move from Sayo town.OthersNo answer

Fig.11 Questionnaire result (inhabitancy orientation)

Nursery

Elementary school

Fig.12 Disaster prevention map and actual flood area

(Hirafuku district)

Elementary school

Nursery

Town office

Fig.13 Disaster prevention map and actual flood area

(Sayo district)

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question. Even the highest score was 60 % in Ishii district, it seems that information propagation by radio communications remained some problems to be solved. In fact, we heard from some residents that it was difficult to understand what someone is saying under the heavy rain, especially for people acting outdoors. These problems are pressing issues, therefore, it is necessary concrete countermeasures are required.

Fig.8 shows the answers about awareness of the disaster prevention map. The disaster map of Sayo town shows the flooded area and sediment disaster hazards. The scale of flood was assumed once in a hundred year, design discharge in Sayo River and Chikusa River at Kuzaki was 890 m3/s and 1,000 m3/s, respectively. From the answers of questionnaire, it is clarified the awareness of disaster prevention map is lacking and it is not fully utilized. The reasons and problems of disaster prevention map is described in the next chapter.

Fig.9 shows the kind of useful information for disaster prevention. Many people tend to point to heavy rain warning or advisory in each district, it seems that residents think the communication of weather information for disaster prevention is more important.

Fig.10 shows the kind of important software countermeasures for disaster prevention. The requests cover a broad range of topics in each district, however, the requests concerning about livelihood support tend to in-crease in serious damage district.

Fig.11 shows the inhabitancy orientation of residents. It seems that most residents in Sayo town continue to stay living in present place or other place in the town. Therefore, administration should provide the services which construct more safety and security of life for residents and support to the growing of local industry. 4. DISCUSSION IMPROVEMEMENT OF DISASTER PREVENTION MAP-

In previous chapter, it is clarified the disaster prevention map has little practical application. In this chapter, we examine the adequacy of information of disaster prevention map in Hirafuku, Sayo, Kuzaki and Makuyama

Nursery

Elementary school

Fig.14 Disaster prevention map and actual flood area

(Kuzaki district)

Nursery Elementary school

X

Community center

Fig.15 Disaster prevention map and actual flood area

(Makuyama district)

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district, respectively. Fig.12 shows the disaster prevention map and actual flood area in Hirafuku district which is located up-

stream of Sayo River. In this district, a nursery and an elementary school were declared safe havens, respec-tively. These buildings didn t submerged in this flood, however, the surrounding land and home were partially under the water, it is expected that the evacuation was difficult for the residents trapped their home. Moreover, it is very hard for vulnerable people to evacuate to the elementary school, because it is located outskirt of central settlement.

Fig.13 shows the disaster prevention map and actual flood area in Sayo district, central the town. In this district, a nursery and an elementary school were also declared safe havens, respectively. These buildings are located at high elevation, they didn t be submerged in the flood. However, they are located in the other side of the river, it is very inconvenience for the resident inhabiting in central shopping district. Moreover, the town office and station were completely submerged, administrative function and life line was completely broken down. Drawing up the design of Business Continuity Plan of local government is pressing issue, they should be moved into action as early as possible.

Fig.14 shows the disaster prevention map and actual flood area in Kuzaki district, the junction of the Sayo River and Chikusa River. Fortunately, despite this district had suffered heavy damage, no one died. In this district, a nursery and an elementary school were declared safe havens, respectively. However, the nursery building was collapsed by hit the flood directly. On the other hand, the elementary school didn t submerge in the flood. It's striking that the individual disaster prevention group made a great contribution to evacuate from the flood disaster. Group leaders stayed in close contact to residents and after the beginning of exposure to water into settlement, the residents refrained from evacuate to official safe havens and went go upstairs.

Fig.15 shows the disaster prevention map and actual flood area in Makuyama district which is located in north-western part of the Sayo town. Unfortunately, this district hadn t suffered flood damage, however, 9 people were swept away on the way to safe haven. In disaster prevention map, the estimated flood area isn t shown. It doesn't mean that Makuyama district has no flood area, but it was just exempt from the flood in-undation analysis. Local government should add an explanation to avoid misunderstanding for users. 5. CONCLUSIONS

In this study, we examined availability and limitation of software countermeasures for heavy rainfall dis-aster in Sayo town, Hyogo Prefecture in August 2009. From the results of our study, we can see it is important that not only the local government should commit faster and more accurate transmission of information using more than one procedure but also residents should try to have a deep insight against prevention disaster in-formation and take early evacuation action. REFERENCES 1) Uno, K., Nakano, S., Umeoka H. and Watanabe K. : Preliminary report of heavy rainfall disaster caused by typhoon No.0909 A

case study of Kuzaki district in Sayo town-, Annual Journal of Hydraulic Engineering, JSCE, Vol.54, pp.865-870, 2010. (In Japanese)

2) Uno, K., Nakano, S. and Kume K. : Availability and limitation of software countermeasures for heavy rainfall disaster in Sayo town, Hyogo Prefecture in August 2009-, Advances in River Engineering, JSCE, Vol.16, pp.489-494, 2010. (In Japanese)

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