Risk communication and evacuation decision making: the case of residents in debris flow vulnerable area in Taiwan
1. Jie-Ying Wu, Ph.D.
Dept. of Urban Planning and Disaster
Ming-Chuan University, Taiwan August 27,2012
2. Overview
1 Background
2 Literature Review
3 Research methods
4 Results and discussion
5 Conclusion
2
3. Background: Discover Taiwan
Taiwan
【 Capital 】 【 Population density 】
Taipei City 632 per km2
【 Area 】 (Switzerland 190 per km2)
36,000 km2 【 Jurisdictions 】
【 Population 】 22 counties/cities & 319 townships
23 million 【 GDP/capita 】
$20,101 (Switzerland $ 41,950)
5. Background
World bank (2005) : 73 % of the population
live in areas that can be affected by more
than 3 types of natural disasters
5
6. Background
Heavy rainfall, usually caused by typhoons,
and frangible geology make debris flow
happen frequently.
Currently 1,578 potential debris flows in
Taiwan, and roughly 20,000 people live in the
impacted areas.
Even the public authority set up various
preparedness works, still lots of deaths .
This study tries to understand the risk
communication operation and the evacuation
decision making among stakeholders. 6
7. Literature Review
Risk communication and disaster
decision making
US National Research Council suggested
interactive approach of risk communication,
from dissemination to dialogue
Lindell and Perry (2000) provided Protective
Action Decision Model (PADM) , and suggest
effective risk communication should cover
households characteristics, social context,
environmental condition
7
8. Literature Review
Warning and evacuation
The warning sources (authority, media, peers--- )
will influence evacuate decision making
People judge the source credible by expertise and
trustworthiness.
Environmental cue such as weather condition and
behavioral response of others tend to prompt to
evacuate.
8
9. Literature Review
Current debris flow preparedness in Taiwan
Soil and Water Conservation Bureau (SWCB) decides
the sector area (vulnerable area) of each debris flow
Survey the households in the vulnerable areas
9
12. Literature Review
Current debris flow preparedness in Taiwan
SWCB examines the precaution rainfall of each
debris flow
SWCB holds training courses and teach residents
regarding yellow and red alerts
Warning Explanation Evacuation
Type order
Yellow Predict rainfall will over Suggest to
Alert precaution rainfall evacuate
Red Alert Current rainfall already Mandatory
over precaution rainfall evacuation
12
13. Literature Review
Warning System Warning-Responding Situations
Source Hearing Environmental cues
(Government, Friend etc.) Risk identification Agent
Credible(Expertise, Handle Behavioral
Trustworthiness) Understanding
Feedback Believing
Accessible Level of Threats
Personalization? Socio-Economic
Attribute
Chanel Risk assessment
Culture and Ethnic
Dissemination Confirming Kinship/ Friendship
Penetration networks
Distortion Responding Household
Feedback Evacuation Attributes
In-place sheltering
Message type and Alternatives action
Protective action
content assessment Psychological
Immediacy Evaluation: Time Attribute
Seriousness needed, Mobile time , Hazard awareness
Precision Cost, Mind Past Experience
Repetition Controllability
Incentives Awareness on
Timing and Language Public aids Alterative action
used NGOs help Self action ability
13
14. Study Design
Choose Liugui District in
Kaohsiung city as study
area.
2009 Typhoon Morakot
caused 43 deaths and
164 houses collapsed
Heavy rainfall caused
debris flows and floods
1,190 mm in 1 day
1,946 mm in 3 days
14
17. Study Design
Baolai
Village
Laonong Village
Xinfa
Village
Liugui Village
Yibao Xinglon Village
Village
Zhongxing Village
Dajin
Village
Xingliao
Village 17
18. Study Design
Households in
# #
Neighborhood Vulnerable
Sampling Response
area
Xinglong Village 48 29 25
Dajin Village 108 65 61
Liugui Village 38 23 10
Yibao Village 97 58 23
Baolai Village 93 56 39
Xinfa Village 73 44 33
Zhongxing
Village
117 70 70
Laonong Village 60 36 19
Xingliao Village 7 4 4
Total 642 385 284 (74% ) 18
19. Results and Discussions
Residents have little knowledge on
evacuation preparedness
62.7% knowing stay in the debris flow
vulnerable area
Only 34.9% clearly understand/ understand the
meaning of red/yellow alert
Only 35.3% clearly understand/ understand the
contents of risk map
51.9% clearly understand/ understand the
evacuation plan
19
20. Results and Discussions
Warning Source from public authority
has high degree of trustworthy
5.00
5
4.00
4 4.13 3.93 3.91
3.63 3.43 3.49
3.00
3 Public 3.12
TV 2.41 2.70
Authority Friends/
2.00
2 Newspaper neighbors Internet
1.00
1
20
0.00
0
78.5% will reconfirm the warning
messages
20
21. Results and Discussions
Environmental Cue is the most important
factor influencing evacuation decision-
making
People consider the signals of debris flow
52.7 % water flux in the steam
55.6% the changes of surrounding condition
People will decide to evacuate if
83.5% rainfall become higher
85.9% seeing the evacuation actions of neighbors
21
22. Results and Discussions
Past disaster experience is the key factor
for resident’s preparedness
By using t-test, households having past
disaster experience will
willing to attend training courses or exercises
higher briefing the debris flow will occur
consider village leader play an important role
during evacuation period
22
23. Conclusions
From the Taiwan case, residents living in
debris flow vulnerable area obviously do
not prepare enough to face the disasters
Risk communication should no longer
one-way message dissemination from
public authority through training course
The public authority should consider
environmental cues and past disaster
experience as important factors while
conducting evacuation order
23
The conclusions: The UP should integrate disaster management concept , especially hazards mitigation and preparedness, to reduce future losses caused by natural disasters. This study suggests the project 6 is the most appropriate one. Suggestion: 1. Future researches needed to provide operational and detail contents on integrating hazards mitigation/ preparedness elements in the UP