communities' disaster preparedness - j-stage
TRANSCRIPT
COMMUNITIES’ DISASTER PREPAREDNESS
PROMOTED EVACUATION: A CASE STUDY OF NAGANO CITY DAMAGED BY THE CHIKUMA
RIVER FLOODS CAUSED BY TYPHOON HAGIBIS
Fuko NAKAI1, Shinichiro NAKAMURA2 and Kensuke TAKENOUCHI3
1Member of JSCE, Assistant Professor, Dept. of Architecture, Civil Engineering, and Industrial Management Engineering, Nagoya Institute of Technology (Gokiso-cho, Showa-ku, Nagoya, Aichi 466-8555, Japan)
Email: [email protected] (Corresponding Author) 2Member of JSCE, Associate Professor, Dept. of Civil and Environmental Engineering, Nagoya University
(Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan) Email: [email protected]
3Member of JSCE, Lecturer, Faculty of Engineering and Design, Kagawa University (Hayashi-machi 2217-20, Takamatsu, Kagawa 761-0396, Japan)
Email: [email protected]
This study examined the evacuation behavior of two communities—Naganuma and Toyono—in Nagano City, Japan, during typhoon Hagibis. Only two casualties were reported, despite the large size of the inun-dated area and significant building damage. We analyzed the relationship between (1) the numerical state-ment of aggregated evacuation behavior, (2) social and hazard circumstances, and (3) the social back-ground, including disaster preparedness plans formulated by the community. The study focused on “the details” of evacuation promotion factors revealed by previous research, rather than “the existence or ab-sence” of such factors. Data were collected from newspaper articles, a post-interview survey conducted by Kansai Television Co. Ltd., minutes from the flood control meetings in the flooded area, and district disaster management plans. The results revealed that the main factors promoting evacuation action differed for the two communities due to their disaster preparedness styles. While Naganuma established a specific (a par-ticular measurement of the water level of the Chikuma River) and socially agreed-upon criterion for evac-uation, Toyono had experienced several inland flooding events. It was found that both communities partic-ipated in the flood control meetings, formed organizations for voluntary disaster mitigation action, and cultivated common awareness regarding “the sign of a dangerous situation” and “what information is im-portant for evacuation.” Key Words : Typhoon Hagibis, flood, evacuation, Nagano, social contexts, disaster preparedness, Dis-
trict Disaster Management Plan
1. INTRODUCTION
Typhoon Hagibis hit eastern Japan in 2019, result-ing in more than 1.8 trillion yen worth of damage. Hagibis arrived in the Izu Peninsula at 7:00 p.m. on October 12, 2019, and set new records for heavy rain-fall in the Kanto, Koshin, and Tohoku regions. The heavy rainfall caused a levee breach with roughly 70 m extent, bringing the water into Hoyasu, Nagano City, along the Chikuma River, the longest and wid-est river in Japan and the third-largest basin area. The floods inundated about 1,500 ha, killed two people, seriously injured two people, and affected 3,878 buildings (1,034 totally destroyed, 354 seriously
damaged, 1,305 half-destroyed, and 1,185 partially destroyed) in Nagano City.
Figure 1 depicts the relationship between building damage and human casualties due to heavy rain or flood damage in the past (gray points), and during Typhoon Hagibis (blue points). The data were ob-tained from a list of disaster reports from 1999 on the Fire and Disaster Management Agency (FDMA) website of the Ministry of Internal Affairs and Com-munications. The unit of one point denotes mainly prefectures following the unit of the disaster report provided by the FDMA. The red point signifies five fatal casualties and 6,909 damaged buildings due to Typhoon Hagibis1); therefore, the ratio of human
Journal of JSCE, Vol. 10, 56-69, 2022 (Originally published in Journal of Japan Society of Civil Engineers, Ser. B1, Vol. 76, No. 1, 424-436, 2020 in Japanese)
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casualties to building damage was lower than in case of other disasters. Consequently, this study assessed evacuation to ascertain how human casualties were minimized despite the severe flooding causing exten-sive damage to buildings.
Previous studies on flood evacuation2)–9) have mainly assessed what prompted or inhibited resi-dents’ evacuation. Some studies employed a ques-tionnaire survey and interviews, including the fol-lowing items that potentially affect evacuation be-havior: the number of stories of their residence build-ings, past disaster experience, viewing hazard maps, evacuation preparation in advance, participation in the community’s voluntary disaster mitigation action, encouraging or advising residents or firefighters to evacuate each other, existence of contact network or residents’ name list at the local community associa-tion, the level of weather and evacuation information, and disaster awareness. In addition, Tanaka et al.10) summarize these disaster cases and classify the com-mon factors that inhibit evacuation into three catego-ries: disaster information, individual attribution, and family or living environment.
However, none of these factors adequately explain every case of evacuation for the following reasons: First, factors that affect the promotion or inhibition of evacuation vary by region and case. For example, in the Anke district of Iwaizumi, Iwate, Japan hit by Ty-phoon Lionrock, the main factor that affected lower human casualties differed for each community6), 9). Second, “disaster experience” can contribute to either promoting or discouraging evacuation10).
The difference in the meaning of each factor could explain their differential effects in each community. In other words, what specific conditions and actions do these factors refer to? For example, “participation in local disaster prevention activities” has been re-ferred to as an evacuation promotion factor in some studies; however, “participation” could imply both passive participation, such as joining the evacuation drill program prepared by the municipality, and ac-tive involvement, such as building consensus with the government about the construction of flood control facilities. Again, the meaning of “participation in lo-cal disaster prevention activities” as a generalized item can differ among respondents and researchers. Therefore, it is vital to probe not only the presence or absence of factors that promote evacuation, but also the content and social contexts of each factor.
In addition, since all existing evacuation activities are not necessarily practical, their contents must be enhanced to improve evacuation practically. There-fore, it is important to understand why the factors vary according to each case and region rather than build a general prediction model of factor-evacuation behavior that can explain all cases.
Therefore, in this study, we focus on the “qualita-tive content” of factors that promote evacuation, ra-ther than the “presence or absence” or the “quantified degree of effects” of such factors. In addition, we clarify the process of interpretation that is omitted when factors are generalized as items. The research setting comprises two communities in Nagano City. By comparing the two communities, we aim to high-light the differences between the cases. 2. MATERIALS AND METHODS
The study focuses on evacuation behaviors in two communities—Naganuma and Toyono—affected by the flooding of the Chikuma River in Nagano City, Nagano Prefecture. Section 3 presents an overview of these communities, including topography, urbani-zation history, and industry. Table 1 shows the list of the data used for the overall analysis below.
Section 4 analyzes people’s behavior during the disaster from the evacuation behavior interviews con-ducted by the Kansai Telecasting Corporation (the Kantele Survey). The survey was conducted on No-vember 6–9, 2019. The survey asked 100 residents (47 from Naganuma, 49 from Toyono, and 4 un-known) from the flooded area of Nagano City about how they obtained disaster information when they evacuated (horizontal evacuation: not staying at home but moving to an emergency evacuation site) and what affected their decision to evacuate.
Section 5 presents the data for each factor: weather information from the Japan Meteorological Agency, precipitation data from the Nagano Meteorological Observatory, information on the Chikuma River and
Fig. 1 Relationship between building damage and human casual-
ties due to past heavy rain or flood and to typhoon Hagibis.
0
20
40
60
80
0 2000 4000 6000 8000 10000Number of buildings damaged (total of buildings totally damaged, half damaged, partially damaged, and inundated above floor level) [buildings]
Num
ber o
f dea
d / m
issi
ng [p
eopl
e]
Excludes extremely large disasters: over 10,000 building damages in one municipality, the Great East Japan Earthquake, and water accidents.
Typhoon Hagibis in Nagano Pref.
Typhoon No. 18 of 2004
in Kumamoto Pref.
Heavy rain from August 19, 2014
in Asaminami Ward, Hiroshima
City, Hiroshima Prefecture
Past heavy rain or floodTyphoon Hagibis
Data source: Disaster information list (1999-2019) of the Fire and Disaster Management Agency, Ministry of Internal Affairs and Communications
57
Asakawa rivers, evacuation information from the municipality of Nagano City, and building data from Zenrin maps.
Section 6 shows the social background and spe-cific details of factors that affect residents’ evacua-tion behavior. We analyzed prior flood experiences and corresponding disaster preparedness actions: the data on past disasters were obtained from Disasters and Weather in Nagano city and the Guidebook for disasters in Toyono. To understand prior disaster pre-paredness, such as consensus and rules made by res-idents, we referred to the minutes of the meetings of the Asakawa River Basin Council, established in 2003, that both communities attended, the District Disaster Management Plan of Naganuma, and the Guidebook for disasters in Toyono.
Section 7 shows the interrelationships between the aggregate evacuation trends, the environment around the residents, and their prior flood experience and preparations. We analyzed the data: individual epi-sodes from newspaper articles and interview notes from the Kantele Survey. We searched for newspaper articles using G-Search20), a database of 150 newspa-pers in Japan, using the keywords: “Nagano City,” “Naganuma,” “Toyono,” “Typhoon No. 19 (Hagi-bis),” “District Disaster Management Plan,” and “ty-phoon.”
Section 8 concludes with how prior flood experi-ence and disaster preparedness contributed to the ac-tual evacuation of the two communities, and the sim-ilarities and differences between them.
The data (episodes from newspaper articles or in-terviews) were not obtained by the authors directly. Therefore, the selection of the interview respondents and articles’ contents was biased according to the judgment of the reporters who conducted the inter-views. However, the bias was not significant. The other survey21) conveyed by the Council for Disaster Mitigation Measures on the Chikuma River and the Saigawa River conducted by the Chikuma River In-formation Room, which is one of the departments of the Ministry of Land, Infrastructure, Transport and Tourism (MLIT), revealed a similar trend in evacua-tion behavior. The evacuation rate (i.e., the rate of people who moved to emergency evacuation sites within the flooded area) in the survey conducted by the council (response rate: 62.4%) was 73%, whereas it was 82% in the Kantele Survey. While the value was slightly higher in the Kantele Survey, it was not far off. Therefore, we believe that the representative-ness of the Kantele Survey was not significantly im-paired in terms of evacuation behavior. However, we treated the newspapers as a case presented by the re-porters, implying that many people may not have be-haved in the same way.
3. TARGET AREA
The Chikuma River’s levees broke in Hoyasu, Na-gano City, Nagano Prefecture (Fig. 2), flooding a wide area, including Naganuma, Toyono, Furusato, and Yanagihara. Naganuma had the most flooded area, followed by Toyono, while Furusato and Yan-agihara were affected by partial flooding. The major-ity of the flooded area was classified as an urbaniza-tion control area, mainly in the Naganuma commu-nity (Fig. 3). Figure 4 depicts a gradual increase in the population and number of households in the Toyono community since the 1970s, including urban-ization promotion areas. However, the population and number of households in the Naganuma commu-nity—where the entire area is designated as an urban-ization control area—has remained constant.
Naganuma is located in the northeastern part of the Zenkoji-daira Temple and is a group of settlements developed on the western bank of the Chikuma River. The village was established over a flat land and flour-ished as a castle town of Naganuma-jo Castle in the past. However, after the dissolution of the Naganuma Feudal Domain (1688), the village developed as a
Table 1 Data used for the analysis.
Item Sources Residents’ evacuation behavior
Post-interview survey (Cabinet Office, Japan)11) Post-interview survey conducted by Kansai Tele-vision Co. Ltd. Newspaper articles
Weather in-formation
JMA Disaster Information XML Database (Japan Meteorological Agency)12)
Precipitation Historical weather data search (Japan Meteoro-logical Agency)13)
River infor-mation
Water information system (Ministry of Land, In-frastructure, Transport and Tourism): Tategahana (No. 304031284416100)14)
Evacuation information
Nagano City official Twitter account (@na-gano_city)
Inundation zone
Estimated inundation stage contour map: Outline of inundation area (Geospatial Information Au-thority of Japan)15)
Buildings ZENRIN buildings point data Past floods and damage
Disasters and Weather in Nagano City (Nagano City)16) Guidebook for disaster in Toyono17) Past floods map (Nagano Prefecture)
Previous disaster pre-paredness action
Reports of distinguished communities of the Dis-trict Disaster Management Plan: Naganuma, Na-gano City (Cabinet Office, Japan) 18) Guidebook for disaster in Toyono17) Minutes of the Asakawa River Basin Council (Nagano Prefecture)19)
58
post town on the Hokkoku Highway. Therefore, the old villages are concentrated along the prefectural road No. 368 (formerly Hokkoku Highway). Na-ganuma is surrounded by the Chikuma and Asakawa rivers and is topographically divided into a natural levee zone along the Chikuma River’s coast and the back marsh. The land was regarded as a paddy field, especially the back wetlands, but areas around the Asakawa River were poorly drained and productivity was low. Consequently, commodity crops were mainly cultivated on the natural levee for a long time. In the Meiji period, the mulberry field was expanded for sericulture, but it was gradually altered to an apple field after about 1910 because of less flooding com-pared to the surrounding areas. In 1966, National Route 18 (Apple Line) was opened, which made it a
tourist park. Residential land use in Akanuma New Town and Omachi Daiei area began in 1971 and 1972, respectively, but the population has not in-creased dramatically.
Toyono is located on a hilly terrain on the north-west side to a flat terrain along the Asakawa River and Torii rivers, where a large part of the population resides. The community had only a few houses before the railway settlement. After the inauguration of the Toyono Station in 1888, the community mainly de-veloped around the station. With the economic up-swing in the apple industry post-war, the community became lively with the station as a base. However, due to the public transportation situation and the in-auguration of National Highway No. 18, the liveli-ness of the community gradually disappeared. The present Toyono station is a suburban station that mainly transports commuters and students. Since the 1970s, the number of households has increased as a result of the construction of public housing and build-ing of housing lots by public corporations. Addition-ally, an industrial park was built to the northeast of Toyono station to attract factories. 4. EVACUATION BEHAVIOR OF THE
TWO COMMUNITIES
This section shows the evacuation behaviors of the two communities using the data on 96 out of 100 re-spondents of the Kantele Survey. (1) Comparison of the temporal changes in the
evacuation rate in each community Of the 79 people who were evacuated horizontally,
76 answered at the time evacuation started: they were included in the temporal changes in the evacuation rate in each community. The evacuation rate shown
Fig. 2 Location of Naganuma and Toyono, Nagano City, Nagano
Prefecture, Chikuma River, and Asakawa River (a branch river of Chikuma River).
Fig. 3 Spatial relationship between the inundated area, Chikuma
River, urbanized promotion area, and controlled urbaniza-tion area.
Fig. 4 Population trend (dotted lines) and number of households
(bars) in Naganuma (brown lines) and Toyono (blue lines).
Nagano Prefecture
Shinano River
Chikuma RiverAsakawa River
Nagano City
Toyono
Naganuma
Yanagihara
Furusato
Urbanization promotion areas
Urbanization control areas
Inundation area due to Typhoon Hagibis in 2019
Target Area
Tategahana Water Level Station
Kuiseke Water Level Station
0
1000
2000
3000
4000
5000
0
2000
4000
6000
8000
10000
12000
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
2019
Households (Naganuma)
Population (Naganuma)
Households (Toyono)
Population (Toyono) number of households
popu
latio
n
59
in Fig. 5 is standardized by the number of evacuees in each community. The first evacuees in Naganuma and Toyono evacuated around 6:00 p.m. and 3:00 p.m. on October 12, respectively; this is before the heavy rain warning was issued in Nagano Prefecture at 3:30 p.m., that is, four hours before the typhoon arrived on the shore. The final evacuees in Naganuma and Toyono went out around 6:00 a.m. on October 13 and 8:00 a.m, respectively. It can be observed that while the number of evacuees gradually increased for both the communities in 17 hours, a rapid increase was recorded just before flooding was confirmed in the Hoyasu, Naganuma community at 1:12 a.m. on Oc-tober 13. The number of evacuees gradually in-creased for both the communities during the 17 hours, with a sharp increase around 1:12 a.m. just be-fore flooding. Those who evacuated around 1:00 may have done so after looking at the flooding. In addi-tion, the evacuation rates in each area crossed at the time of flooding. The reason for this was that while residents in Toyono had been evacuating early, resi-dents living far from the Chikuma River were evacu-ating only after the inundation that had begun in the early morning on October 13; it was later than Na-ganuma. (2) Comparison of the reasons for evacuation
Figure 6 depicts the reasons residents decided to evacuate. Based on the interview transcripts, they were classified into the following five categories: “call of the people in the community (neighbors),” “call of the family members (family),” “self-judg-ment,” “information from government (disaster in-formation),” and “looking at the actual inundation (actual condition).” When the respondents cited mul-tiple reasons—for example, “there was a call from the community and they evacuated in consultation with the family”—both “neighbors” and “family” were counted. Therefore, the amount of data constituting the pie charts does not match the number of respond-ents. The results reveal that both areas have the larg-est number of “neighbors,” as the reason for evacua-tion, with more than half in Naganuma. “Disaster information” and “self-judgment” were relatively major reasons for Toyono than Naganuma.
Figure 7 shows the trends in the Naganuma and Toyono evacuation rates based on the reasons for evacuation. In Toyono, the number of evacuees due to “disaster information” and “self-judgment” in-creased at a relatively early stage, while they were not major reasons in Naganuma. “Neighbors” is steadily increasing throughout the entire period in Naganuma. These results indicate that while both communities were located within the same flooded area, the main factors promoting their evacuation were different.
5. THE EVACUATION ENVIRONMENT
This section illustrates the residents’ evacuation
environment by assessing data corresponding with each factor: weather information from the Japan Me-teorological Agency, precipitation data from the Na-gano Meteorological Observatory, information on the Chikuma and Asakawa rivers, evacuation infor-mation announced by the municipality of Nagano City, and building data from Zenrin maps. (1) Information regarding the weather and rivers
and evacuation from the public sector Figure 8 shows the weather, rivers, and evacuation
information in chronological order from the after-noon of October 12 to the morning of October 13: both communities received the same information from the local government.
The heavy rain emergency warning was an-nounced in the entire area of Nagano Prefecture at 3:30 p.m. on October 12. However, the rainfall mainly affected the upstream areas of the Chikuma River. According to the hourly precipitation [mm/h] of the Nagano Meteorological Observatory, it did not exceed 14 mm/h during the typhoon. Therefore, ra-ther than the description of “it was raining so hard that we couldn’t evacuate,” some people mentioned
Fig. 5 Comparison of the temporal changes in the evacuation rate
in each community.
Fig. 6 Comparison of the reasons for evacuation.
0
20
40
60
80
100
長沼
豊野
N=36
N=40
Evacuation recommendation
along the Chikuma River
18:00Evacuation instruction
along the Chikuma River
23:40
Overflow in Hoyasu, Naganuma
1:12
Levee breach at Hoyasu, Naganuma
around 4 a.m.
Evac
uatio
n ra
te[%
]
Naganuma
Toyono
Naganuma Toyono
53%18%
2%
18%
9%
41%
15%10%
24%
10%
neighbors family self-judgment
disaster information actual condition
60
“we thought we were safe because it wasn’t heavy rain.”
The government issued evacuation recommendations at 6:00 p.m. on October 12, and evacuation instructions at 11:40 p.m. All of these cover a wide range along the
Chikuma River. In addition, the evacuation instruction (emergency) was issued the next day at 0:45 a.m. for the area around Naganuma, and the information about over-flow around Hoyasu in the Naganuma was disseminated around 1:12 a.m. Since the evacuation information was
Fig. 7 Trends in the Naganuma and Toyono evacuation rates based on reasons for evacuation.
Fig. 8 Time series of various types of information and residents’ behaviors on October 12–13, 2019.
0
5
10
15
20
25Naganuma
neighborsfamilyself-judgmentdisaster informationactual condition
0
5
10
15
20
25Toyono
neighborsfamilyself-judgmentdisaster informationactual conditionN
umbe
r of p
eopl
e
-5
0
5
10
15
20
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
11:00
12:00
13:00
14:00
15:00
16:00
17:00
18:00
19:00
20:00
21:00
22:00
23:00
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
8:00
9:00
10:00
11:00
12:00
13:00
Evacuation information
River information (The Asakawa River)
20:23Overflow around Shinonoi Yokota
22:27Overflow around Shinonoishiozaki Shonomiya
1:15Inundation around Hoyasu
Around 0:00Over the evacuation warning water level
Around 4:00Levee breach
1:12Overflow in Hoyasu
0:45Evacuation instruction (emergency) in Akanuma area, etc.
23:40Evacuation instruction (emergency) along the Chikuma River
18:00Evacuation recommendation along the Chikuma River
Around 18:00Call for evacuation at Motomachi
Around 4:00Power outage
16:30The neighborhood association launched disaster headquarters
21:25Dissolution of the disaster headquarters
Around 1:00 Evacuation warning by fire bell
0:00Stop pump drainage
1:19Inland water flooding started
Around 7:00The Chikuma River flood reaches the Asakawa River
Behavior of Toyono residents
Behavior of Naganuma residents
Weather information
After 14:55The leader of the residents association contact with the staff of the Chikuma River Office
After 17:30Call for evacuation among community members
Around 0:00Toyono Nishi Elementary School reaches full capacity with evacuees
Warning water level (5.00 m)
Over the evacuation warning water level (9.10 m)
Over the hazardous water level (9.60 m)
0
5
10
15
20
25-5
0
5
10
15
20
14:55Warning water level at Kuiseke-5
0
5
10
15
20
15:30Heavy rain emergency warning announced in Nagano Pref.
Before 19:00Typhoon landing near the Izu Peninsula
3:20Cancellation of heavy rain emergency warning
0:0010/13
18:0012:006:000:0010/12
6:00 12:00
Precipitation (Nagano)
by AM
EDA
S, JMA
[mm
/h]
Precipitation
The ChikumaRiver water level & information
Wat
er L
evel
at T
ateg
ahan
a[m
]
61
issued before the flooding, there was sufficient time for evacuation. However, there was no information regard-ing the progress after the disaster occurred. Conse-quently, some residents, unaware of the Chikuma River’s levee breach, returned home and encountered flooding.
The Kantele Survey reveals that many residents re-ferred to the Chikuma and Asakawa river information. Residents can access the water-level information sys-tem and real-time camera images set in the two rivers. For Chikuma River, the flood warning information was announced at 5:30 p.m. on October12 and the water level reached the over-the-evacuation warning water level at the Tategahana Water Level Observa-tory around 12:00 a.m. on October 13, and the levee breached in Hoyasu, Naganuma, around 4:00 a.m.. The Asakawa pumping station started drainage to the
Chikuma River from the 12th, but was stopped be-cause the water level exceeded the standard around 0:00 a.m. the next day.
(2) Building damage
Figure 9 depicts the estimated inundation depth of this flood and the distribution of buildings based on Zenrin Tatemono data (GIS-based point data of buildings for residents and offices). The inundation depth was estimated from the elevation data and the outline of the inundation range provided by the Geo-spatial Information Authority of Japan. The buildings were in areas not deeply flooded around the western and northern sides. The number of buildings in the flooded area near Hoyasu was 2,209, while Nagano City reported 4,021. This is about half of our estimate of damaged buildings because the Zenlin building
Fig. 9 Distribution of the inundated area (Typhoon Hagibis in 2019 and Typhoon No. 10 in 1983) and buildings.
Private
Office/Shop
Buildings
Urbanization promotion area
Inundation area in 1983
Estimated inundation depth in 2019
District boundary
Legend
To Nagano
Akanuma
Tsuno
Hoyasu
Omachi
Toyono-cho Toyono
Toyono-cho Ishi
Toyonocho Nango
Toyono-cho Asano
Asakawa pumping station
Naganumapumping station
Toyono-nishi Elementary School (Shelter)
Toyono-higashii Elementary School (Shelter)
Pumping station
Shelter
920
940
960
980
1000
1020
1040
1060
1080
1100
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
豊野 長沼
0-0.5 0.5-1.0 1.0-2.0 2.0-3.0 3.0- 合計
Toyono Naganuma
Total
62
point data included residential houses, but did not in-clude non-residential buildings (barns, garages, etc.).
The number of flooded residential houses was higher in Naganuma, but the proportion of flooded residential houses by inundation depth (Fig. 10) re-veals that the buildings were located in areas with shallow inundation depth. About 40% of Toyono was damaged by 2 m or more of flooding. Therefore, Na-ganuma had a horizontally large impact, while Toyono had a vertically large impact. In Naganuma, some people could escape to the second floor without evacuating their homes; however, in Toyono, peo-ple’s lives would have been threatened if they did not evacuate horizontally.
6. EFFECT OF SOCIAL BACKGROUND ON EVACUATION PROMOTION
This section highlights past flood experiences and
related disaster prevention activities that may have driven the evacuation behavior of residents and pro-vided their details and social contexts. First, we as-sessed past flood experiences based on the records of Nagano Prefecture, Nagano City, and the former Toyono Town. Next, we evaluated the flood control measures in the Asakawa River basin, the community disaster management plan in Naganuma, and the evacuation guidance planning committee in Toyono. (1) Prior flood experiences
This area experiences frequent flooding. In 1742, Chikuma River overflowed and the flood hit Na-ganuma and Toyono with more than 4 m of water level, resulting in 168 casualties and destruction of 300 houses. People call this disaster “Inu-no-mansui” (named after the year of the dog, or “Inu” in Japanese, one of the 12 animals of the Japanese zodiac). The historical disaster records of “Inu-no-mansui” are in My-oshoji Temple in Tsuno and Zenkoji Temple in Akanuma, with their pillars marking the flood water level.
The largest historical flooding since modern flood control measures was that of typhoon No. 10 in Sep-tember 1983. The Tategahana Water Level Observa-tory recorded the maximum water level as 11.13 m, although the flood control water level was planned at 10.75 m. The Chikuma River temporarily overflowed at the Obuse Bridge located on the upper stream left bank. In addition, the flow rate of the Asakawa River exceeded the drainage capacity of the pumping sta-tion; it resulted in inland water flooding over a wide area (range shown by the white-dash line in Fig. 9). Although the area covered by the flood in 1983 is smaller compared to the flooding from Typhoon Hagibis, the same areas were flooded in the
residential zones of Toyono; meanwhile, there was no flooding records in the residential areas in Na-ganuma.
Subsequently, the Asakawa River Comprehensive Inland Water Countermeasure Plan was formulated in 2013 to prevent flooding above floor levels in res-idential areas in cases similar to Typhoon No. 1022). Moreover, comprehensive disaster prevention drills were established in Naganuma since the 1983 flood, which continue to this day. These findings suggest that water damage in 1983 was a benchmark for peo-ple living in the Asakawa River basin.
Since Naganuma is located on the natural levee, residents had relatively little experience with floods. If at all, the area experienced agricultural damage with no human victims and few damage to buildings. Contrarily, Toyono is located in the low plains of the Asakawa River, therefore, residents have been expe-riencing flood from inland water and building dam-age once every few years. The inundation has de-creased since pumping stations were installed in the Asakawa River; however, some public housing com-plex on the western side of Higashimachi were flood-prone zones until about 20 years ago. The Shinano Mainichi Shimbun reported23) on residents who expe-rienced building damage by inundation for three con-secutive years after 1981. It is inferred that the people of Toyono were relatively familiar with floods. (2) Flood control measures in the Asakawa River,
a branch of the Chikuma River The Asakawa River is a medium-sized river that
flows through the urban area of Nagano City to join the Chikuma River. It has a short extension and steep flow and was a ceiling river before the renovation project. The flood that was expected to hit residential
Fig. 10 Number of inundated buildings per estimated inundation
depth.
Private
Office/Shop
Buildings
Urbanization promotion area
Inundation area in 1983
Estimated inundation depth in 2019
District boundary
Legend
To Nagano
Akanuma
Tsuno
Hoyasu
Omachi
Toyono-cho Toyono
Toyono-cho Ishi
Toyonocho Nango
Toyono-cho Asano
Asakawa pumping station
Naganumapumping station
Toyono-nishi Elementary School (Shelter)
Toyono-higashii Elementary School (Shelter)
Pumping station
Shelter
920
940
960
980
1000
1020
1040
1060
1080
1100
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
豊野 長沼
0-0.5 0.5-1.0 1.0-2.0 2.0-3.0 3.0- 合計
Toyono Naganuma
Total
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areas in Nagano City was an urgent issue. Accord-ingly, in 1977, the previous plan for the Asakawa River Dam was initiated, with the safety level of flood control set to 1/100.
However, the plan was temporarily interrupted due to the “Declaration on Dam Objection” by Yasuo Tanaka, governor of Nagano Prefecture in 2001. Sub-sequently, flood control measures, including ponds, forests, water plantations, were discussed as non-dam-based countermeasures with residents, experts, and municipalities, and it was concluded that measures combining “river improvement” and “flood control dam” were optimal. The construction of the Asakawa dam began in 2010 and was completed on March 17, 2017.
The Asakawa River Basin Council is of signifi-cance as it investigates non-dam-related water con-trol measures. It has held 22 meetings over a period of 14 years until 2015. Recruitment of members has continued, per the Nagano Prefecture’s website as of 2020, based on the Guideline for Establishment of Nagano Prefecture River Basin Council. Members comprise residents who have applied and the staff of relevant administrative institutions (Nagano Re-gional Office, Nagano Construction Office, Asakawa River Improvement Office, Nagano City, Obuse Town, etc.). In addition, academic experts participate as advisors. Members are gathered from a wide area within the basin, including the residents of Na-ganuma and Toyono. At the time of its inauguration, the council included 115 residents of the basin and employees of the prefectural and municipal govern-ments24). In 2013, it had 147 members25). Approxi-mately 150 people attend each meeting.
According to the Council’s minutes, the relation-ship between the two rivers has been mentioned on various occasions. For example, in the minutes of the third meeting26), a staff member of Nagano Prefecture mentioned several requests, such as “river improve-ment request,” “drilling of the narrow section of Tategahana,” “improving pumping stations,” etc. In the proposal for council membership recruitment, much interest in the Chikuma River is visible. Since the flood from inland water is very much related to the Chikuma River, members of the basin council have proposed improvement. One of the residents said, “there is nothing we can do about our relation-ship with the Chikuma River if the flood gates are closed. We are requesting to increase the pumping capacity: if the Chikuma River rises, we will not be able to pump up and drain the water of the Asakawa River to the Chikuma River. The problem with the Chikuma River lies not in Tategahana but in the nar-rowing of Sasakura’s sharp curve. Even if we solve that problem, the Iiyama basin will be severely flooded. The problem of Iiyama must be taken into
consideration with the removal of the Nishi-Ohtaki Dam.” Many council participants were familiar with the mechanisms of inland water flooding, combining the upstream and downstream situations of the Chikuma River, and how to operate the pumping sta-tion draining the water from the Asakawa River to the Chikuma River. Therefore, the flood experience and discussions conducted by the council naturally cre-ated a common understanding of the necessary infor-mation other than the state of the neighbor river. (3) Community disaster management plan in Na-
ganuma In Naganuma, the project team for creating the Na-
ganuma Disaster Prevention Map was established in December 201318), 27). In 2014, the community disas-ter management plan was promoted as a disaster pre-vention model project of the Cabinet Office, and the “Naganuma Evacuation Rule Book” was created with reference to the “Evacuation Rule Book in the Event of Floods” of Funado, Itabashi Ward, Tokyo.
The Naganuma Evacuation Rule Book was a plan that considered both floods from the Chikuma River and flood from inland waters28). It includes detailed rules, such as establishing a disaster headquarters with specific standards concerning the water level of the Chikuma River, giving evacuation orders sepa-rately from the city29), and assigning a person in charge of rescue even in normal circumstances30).
The criteria for the establishment of residents’ dis-aster headquarters are (1) “when the water level of the Tategahana Water Level Observatory in the downstream of Chikuma River in the area exceeds 7.4 m, and the water level is expected to increase” or (2) “when inland floods occur in various parts of the Naganuma community.” When the situation meets these criteria, leaders of residents associations (Omachi, Hoyasu, Tsuno, Akanuma) meet at the Na-ganuma assembly place and set up the disaster head-quaters31). In addition, the local welfare officer pre-pares an individual evacuation support plan for those who require special support31). (4) Evacuation planning in Toyono
Although Toyono does not have a Community Disaster Prevention Plan like that of Naganuma, or-ganizational activities that correspond with this plan have been conducted. The Toyono Evacuation Guid-ance Planning Committee, subsidized as One Branch One Model Project (2016–2018) of Nagano City—known as the Disaster Prevention Map of My Home and the Guidebook for disaster in Toyono—were published in 2018. These were prepared on the advice and with the cooperation of Nagano City office, the fire department, police, the River Office of the Hoku-riku Regional Development Bureau of the MILT, and
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Nagano Prefecture. The guidebook advises on how to find evacuation information, correspondence be-tween the water level of the Chikuma River and evac-uation information, location of evacuation facilities, place of assembly of the voluntary disaster mitigation organizations, and how to help people requiring sup-port. The disaster headquarters in Toyono cooperates with the Nagano City Disaster Headquarters, the Toyono Branch Office, the Civil Engineering Office, Toriikawa Fire Department, and Toyono Police Sta-tion. 7. INTERRELATIONSHIPS BETWEEN
EVACUATION BEHAVIOR, ENVIRON-MENT, AND SOCIAL BACKGROUNDS
This section presents the interrelationships be-
tween the aggregate evacuation trends, the respond-ents’ environment, and their prior flood experience and preparation. For this, individual episodes from newspaper articles and interview notes from the Kan-tele Survey have been assessed. (1) Systematic response according to the Commu-
nity Disaster Prevention Plan in Naganuma The characteristic of evacuation in Naganuma is
early action based on the criteria in the community disaster management plan. As presented in Section 6.3, Naganuma had formulated a systematic evacua-tion rule in advance. Therefore, despite Naganuma residents’ comparative lack of experience with floods, they could start evacuation approximately six hours before the inundation during the typhoon. Data sup-port that the operation was successful during this flood.
According to interviews given by the residents as-sociation and the Council of Social Welfare in Na-gano City to Nishida and Bono31), the leader of the residents association contacted the director of the Chikuma River Office after the flood warning infor-mation was issued on October 12 at 2:55 p.m. Since the leader of the residents association have been con-tacting the Chikuma River Office frequently, he asked about the water level of Chikuma River at the Tategahana Observatory by phone on that day, too. Moreover, at 16:30, the water level of the Chikuma River had not yet risen, but it was expected that it would exceed 7 m thereafter. Therefore, the four res-idents association leaders assembled at the Disaster Headquarters before the evacuation recommendation was issued in Nagano City at the leaders’ behest. Around 2:45 p.m., each area contacted the local wel-fare officers by phone and conducted door-to-door visits to support early evacuation for those requiring assistance. Members continued to call neighbors to
evacuate even after the evacuation recommendation was issued at 18:00 on October 12; however, the dis-aster headquarters was dissolved at 21:30 because the water level of Tategahana was forecast to rise to 12.8m after three hours, and they also had to evacuate.
According to the community disaster management plan in Naganuma, the disaster headquarters’ activi-ties include command and coordination, communica-tion, evacuation guidance, rescue and relief, emer-gency rice feeding and water supply, firefighting and flood control, and supporting the needy. The newspa-per articles and the Kantele Survey indicate that the firefighting and flood control group activities and the assistance group triggered the commmunity’s evacu-ation. The actions of these groups were carried out in the majority of the “neighbors,” as shown in Fig. 6.
Hiroshi Yanamisawa, director of Naganuma Resi-dents Association, said, “we just did what we have done in the disaster training; the residents in charge of supporting neighbors called for the evacuation by phone or visits to those who required assistance. There were about 60 people who needed support, in-cluding the elderly people, and each supporter helped them evacuate.32)” Another newspaper article also mentioned that the system was well operated during the crisis because the residential community created pairs of supporters and those who required support from usual days. One resident was in charge of an el-derly couple living next door for two years and picked them up and brought them to the evacuation facility in their small truck. According to the woman who received the support, at least five pairs evacuated together at that time, and she would have been at home if she had not been picked up33). Another resi-dent was also in charge of evacuating an 80-year-old man and his own mother; therefore, they began evac-uating early29). Supporters continued to call neigh-bors who had not come to the evacuation facility until 1:00 a.m. on October 13—just before the flood—and urged those who stayed at home to “go upstairs any-way.” 29)
In addition, there are several descriptions about the firefighters. Multiple residents who evacuated around 1:00 a.m. on the 13th, just before the flooding men-tioned that they heard the “sound of a fire bell” and evacuated. The local firefighters were calling for evacuation with a “fire bell” since 12:00 a.m. on Oc-tober 13 34). The fire bells are a kind of warning sirens installed in fire watchtowers in Omachi, Hoyasu, Tsuno, and Akanuma in the Naganuma community, which are about 6–8 m high. These were banned from use after May 2019 due to their age, but they were useful for ringing the fire bells to inform the residents about fires in the area. In this flood disaster, four fire-fighters in Naganuma rang the fire bells because the danger of levee breach was imminent. Regarding the
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situation at that time, the head of the firefighters said, “I hit the fire bell for the first time in eight years. At around 1:10 a.m., I pounded on it as hard as I could with a wooden hammer for five minutes. I just wanted everyone to hear it. When my right hand got exhausted, I switched to the left hand and then, back to the right hand, repeatedly.” 35) Moreover, around 4:30 p.m. on the 12th, when the Disaster Headquar-ters were established, the firefighters drove the fire engine, calling for evacuation until just before the flood.35) According to the Kantele Survey, some older people in the neighborhood reportedly refused evac-uation. However, mutual help, along with the sound of the fire bell, was still one of the main factors that promoted evacuation. (2) Prior flood experiences and calling each other
to evacuate in Toyono There were calls among neighbors in Toyono, too;
however, it is also important to note that the evacua-tion began early based on weather and river infor-mation.
According to an interview survey36) conducted by the Urban Redesign Studies Unit (hereinafter, the UT Survey), around 3:00 p.m., there was a communica-tion among local residents that they would evacuate at night. In addition, after the evacuation recommen-dation was issued at 6:00 p.m., residents in Mo-tomachi Group 5 began calls for evacuation. After that, around 7:00 p.m., some people reported, “I saw that my parents and the elderly in the area moved to the evacuation place early, and I followed them be-cause I had children.” This indicated that people were gradually evacuating. In addition, at a housing com-plex, transportation was available to the evacuation center voluntary operated by shuttle service from 8:00 p.m. for people requiring assistance until 11:30 p.m. According to the Kantele Survey, these commu-nications resulted in residents evacuating from 5:30 p.m. to 9:00 p.m. on the 12th, even before the evacu-ation recommendation was issued. Respondents re-called, “I received a phone call from a community member and evacuated with an elderly couple of the neighborhood;” “I got an evacuation information from the community contact network around 19:00 on the 12th, then alerted the neighborhood, and evac-uated.” In addition, according to a resident, a disaster headquarters was established on the hill in Hi-gashimachi to manage disaster response. These data supported the fact the organizational communication system was functioning quite well in Toyono.
However, there were several cases of residents evacuating after paying attention to river and weather information. The Kantele Survey reveals that resi-dents’ decision to evacuate was based on the real-time camera at the Chikuma River and information
about the upstream situation. For example, a resident who began evacuating at 7:00 p.m. on the 12th, which was relatively early, said, “I saw on TV that it was raining in the upstream direction of Saku, so I asked my friend in Saku about the situation. I was deter-mined to evacuate after hearing that it was tremen-dous rain.”
In addition, the pumps at the Asakawa Drainage Station had been operating since the 12th, but the drainage from the Asakawa River to the Chikuma River was stopped because the water level exceeded the standard water level around 12:00 a.m. on the 13th. Stopping the pumping station signified a greater risk of the Asakawa River flooding for neighbors. According to the UT Survey, after 12:00 a.m. on the 13th, some residents started evacuating after hearing that information on the pump had stopped. Around 12:30 a.m., Toyono Nishi Elementary School, an evacuation center, was filled with evacuees, and those who arrived later were guided toward Toyono Higashi Elementary School. As shown in Fig. 5, it is estimated that many residents evacuated just around the time the Asakawa pump stopped and before the inland flooding began. It implies that many residents were able to take evacuation actions based on the in-formation of the Chikuma River and the pumping sta-tion in the context of evacuation from the inland flooding of the Asakawa River.
However, according to various reports, some peo-ple in Toyono returned to their homes after dawn, af-ter the Chikuma River’s levee breach37), 38). Although the evacuation instructions were sustained, many res-idents were unaware of the levee breach of the Chikuma River. People who returned to their homes around that time had to be rescued later by boats and other means because of the sudden rise in water level while they were having breakfast or getting ready for the day. This unexpected situation highlights the need to improve the dissemination of accurate information for better actions by residents. 8. SIMILARITIES AND DIFFERENCES IN
SOCIAL BACKGROUND BETWEEN THE TWO COMMUNITIES
In this section, we discuss how prior disaster pre-
vention and disaster experiences have specifically contributed to actual evacuation. The commonalities and backgrounds of the two communities will also be discussed. (1) Why prior disaster preparedness encouraged
evacuation The common aspects between the evacuations of
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Naganuma and Toyono were that systematic activi-ties before the flooding and the call among neighbors were significant factors that encouraged the evacua-tion. As several residents in each area said that “I wouldn’t have evacuated if I hadn’t been advised by neighbors,” rather than taking individual decisions, the momentum to evacuation created in the entire community was important.
However, 53% of Naganuma evacuated in re-sponse to neighbors’ calls, compared to 41% in Toyono; self-judgment or disaster information was 20% in Naganuma, but 34% in Toyono, showing a marked difference. Here, we will summarize the rea-sons why Naganuma had more calls among neigh-bors, and why Toyono had more self-judgment and disaster information.
First, many people evacuated due to calls from neighbors in Naganuma because the criteria for evac-uation were clearly set. The pre-agreed criteria that were the basis for initiating the call allowed the or-ganization to transition to emergency mode rapidly. Despite not experiencing frequent floods from inland water, as in Toyono, the early evacuation decision may be based on this mechanism.
In the same way, the reason for the high number of self-judgment and disaster information in Toyono was that residents were aware of the flooding mech-anisms. According to the Kantele Survey, it is known that Toyono had more residents who comprehen-sively looked at a wide range of information, such as “upstream situation,” “water level of the Chikuma River,” and “operation status of the pumping station,” as well as evacuation information by the government. In other words, the information to be monitored had been recognized in advance. This may be because of the residents’ long-time involvement in flood control in the Asakawa River basin through council activities and experience with floods. These indicate that Na-ganuma and Toyono had different details of the dis-aster prevention activities in advance and different evacuation-promoting factors (calling for evacuation, self-judgment / confirmation of disaster information). (2) Prior flood experience facilitated evacuation
Previous studies8), 10) have shown that prior disaster experiences affect evacuation behavior. However, there are two contradictory facts: the influence of fear and lessons learned from past behaviors and the in-hibiting effect of overconfidence regarding safety af-ter experiencing minor damage10). In terms of this previous experience and corresponding knowledge, the decision not to evacuate could have been a possi-bility for residents in Naganuma who had experi-enced only minor damage in recent years. However, Naganuma started evacuation at an early stage. This is explained by the fact that residents in Naganuma
had begun and continued annual emergency training since the 1983 flood. Moreover, they had predeter-mined evacuation rules to deal with inland water flooding, the minor damage they experienced in 1983, and floods from the Chikuma River, far worse than they had ever experienced before. The leader of Na-ganuma Residents Association and the staff of Tategahana Water Level Observatory were in fre-quent contact during the disaster and predicted the overflow of the Chikuma River according to the pre-cipitation and water-level trends. Therefore, prior flood experience can be an indirect factor promoting preparedness, if rules can deal with not only prior dis-asters but also unprecedented disasters.
Contrastingly, prior flood experiences became a reference point for decision making in Toyono. Some respondents’ behavior was based on the Asakawa flood from inland water instead of the Chikuma River flood. Some residents went back home in the early morning soon after the levee breach of the Chikuma River. In this case, prior disaster experience inhibited appropriate evacuation behavior; however, the prob-lem can be solved by building a warning system that can disseminate information that changes rapidly.
According to certain minutes of the Asakawa River Basin Council in 2003, the chairman was a res-ident of Toyono who had not experienced floods, but she said, “I have been interested in floods and flood control. After I moved to Toyono in need of a new residential area, I was attracted to the open call for participating in this council.” This implies that prior experience with floods can be socially inherited by people who have not experienced the actual floods via the activity of associations such as the Asakawa River Basin Council.
9. CONCLUSIONS
This study attempted to understand the differences in the evacuation behaviors of the Naganuma and Toyono communities and assessed the factors that af-fected their evacuation. However, we cannot con-clude that prior flood experience contributes to evac-uation because the evidence is not sufficient at this point.
The findings of this study would be utilized in the District Disaster Management Plan39). The District Dis-aster Management Plan was established based on the Basic Act on Disaster Management, amended in June 2013, and is a system in which residents may propose to add plans as part of the local plan for disaster preven-tion in the municipality. The Cabinet Office’s District Disaster Prevention Library website provides 181 cases of the District Disaster Management Plan (accessed on March 30th, 2020) available in full text.
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As suggested by the cases of Naganuma and Toyono, the existence of the plan itself cannot pro-mote evacuation, but its actual implementation and functioning can enable it. Some cases in the Cabinet Office’s District Disaster Prevention Library are cre-ated in the same format provided by the municipal office, including minor changes such as the commu-nity’s names. The District Disaster Management Plan could be an opportunity initiating community disaster management; however, the plan needs to be im-proved or customized to work. It is essential to exam-ine the details or the quality of the plan to improve the actual evacuation action and to clarify “what should be improved to save lives.” Since the system was introduced only a few years ago, these examina-tions and clarifications have not been conducted thor-oughly, and this study is presented as one of such at-tempts to provide clarification. ACKNOWLEDGMENTS: The authors are grateful for the sponsorship of the 2019 Hibi Science Founda-tion under the subsidy (General) “Future estimation and analysis of population balance dynamics in the basin,” JSPS KAKENHI Grant Number JP 18K13848. The study was a part of the activities of the Japan Society of Civil Engineers, the investiga-tion team of Typhoon Hagibis, the Committee on Hy-droscience and Hydraulic Engineering, and the Com-mittee on Community Disaster Management of Chubu branch. We would like to thank Kansai Tele-vision Co., Ltd. for providing us with the data and the Committee of Toyono Residents Association, Na-ganuma Residents Association, and staff of the mu-nicipality of Nagano for their cooperation during the interviews. We would also like to thank Mr. Ta-kashima for building the FDMA database and Prof. Masashi Toyota and Prof. Junichi Yoshitani for ad-vising on the data collection. REFERENCES 1) Fire and Disaster Management Agency, Ministry of Internal
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the Typhoon Hagibis: A Case of Naganuma, Nagano: Every Year Drills to Maintain Awareness of Disaster), 2019.11.14 Evening Newspapers, p. 11. (in Japanese)
30) Asahi Shimbun : Nando mo Suigai, Hinan Sasaeau Ruru “Watashi ha Anata no Ashi” Koreisha Hakobu Nagano Chikuma-gawa Ryuiki, Shinsui Chiku (Rules for Support-ing Each Other in Evacuation: “You can rely on me as your legs”: Neighbors Carried Elderly People in Nagano City Flooding Areas), 2019.10.22 Morning Newspaper in Tokyo, p. 27. (in Japanese)
31) Nishida, T. and Bono, T. : Naganuma-chiku no Chiku Bou-sai Keikaku Sakutei no Kouka ni Kansuru Kousatsu (A Study on the Effectiveness of District Disaster Management Plan in Naganuma), C+Bousai, No. 17, pp. 20–21, 2020. (in Japanese)
32) Asahi Shimbun : Kyojo no Ishiki Chiiki de Sodateru (Rais-ing Consciousness of Mutual Support in Community), 2019.11.12 Newspaper. (in Japanese)
33) The Mainichi Shimbun : Jinmei Sukutta “Pair de Hinan” You-shiensha heno Torikumi Kojin Joho Hogo Ho ga Shoheki ni (“Evacuation by Pairs” that Saved Lives: The Act on the Protection of Personal Information Obstruct Helping Person Requiring Support), https://mainichi.jp/ ar-ticles/20191212/k00/00m/040/307000c, accessed 2021. 11.16. (in Japanese)
34) The Yomiuri Shimbun : [Kensho Taifu 19 Gou Gouu Saigai] (1) Chikuma-gawa Teibo Kekkai (Rensai) = Nagano ([In-spection of Typhoon Hagibis] (1) The Chikuma River Levee Breach (Series) = Nagano ), 2019.12.14 Morning Newspa-per in Tokyo, p. 33. (in Japanese)
35) The Mainichi Shimbun : Taifu 19 Gou Nagano, Naganuma Shobo-bundan no 4 nin, Hansho Renda de Hinan Yudo “Ippo Machigaeba Danin mo Higaini” Jimon Jitou (The Ty-phoon Hagibis: Four members of Nagano’s Naganuma Fire-fighting Group Instructed Evacuation by Fire Bells), https://mainichi.jp/articles/20191122/ddl/k20/040/179000c, accessed 2021.11.16. (in Japanese)
36) Urban Redesign Studies Unit, the University of Tokyo : Reiwa Gannen Taifu 19 Gou Fukko Jizen Chosa 1 Ji Hoko-kusho - Nagano-ken Nagano-shi / Fukushima-ken Moto-miya-shi Hen - (1st Report of Typhoon Hagibis of Nagano City and Motomiya City), http://bin.t.u-tokyo.ac.jp/ sur-vey/191114_hagibis_1st_report.pdf, accessed 2021.11. 16. (in Japanese)
37) Japan Broadcasting Corporation : Taifu 19 Gou “Kekkai Shirasezu” Shirazu ni Kitaku no Jumin “Shitte ireba Hinanjo ni” (Residents Return Home Unaware of Chikuma River Levee Breach during The Typhoon Hagibis) , 2019. 10.21 NHK news. (in Japanese)
38) Asahi Shimbun : Teibo Essui “Nami no Youni” Document “Kekkai” Taifu 19 Gou, Chikuma-gawa Hanran kara 1 Ka-getsu (One month after the Typhoon Hagibis: The Chikuma River Flooding was “like a wave”), 2019.11.13 Tokyo Chiho Newspaper/Nagano, p. 24. (in Japanese)
39) Cabinet Office, Government of Japan: Community Disaster Management Plan Guidelines, http://www.bousai.go.jp/ kyoiku/pdf/guidline.pdf, accessed 2021.11.16. (in Japanese)
(Received June 30, 2021)
(Accepted September 7, 2021)
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