The Prevention of Sediment-related Disasters
in Japan(Sabo Department,
Ministry of Land, Infrastructure and Transport)
Yoshiharu IshikawaTokyo University of Agriculture and
Technology
Recent occurrence of sediment-related disasters and victims of natural disasters
0
1000
2000
3000
2000
2001
2002
2003
2004
2005A verage
Number of disaster S lope failre
Landslide
D ebris flow
Present state of sabo works and prevention measures :about 210,000 hazardous areas
Measures for the protection of disaster-vulnerable people
Structural Measures
Installation rate: about 20%Priority
investment itemsNon-
structural Measures
Dissemination of disaster information
Where is dangerous?
• Preparation and distribution of hazard area maps
• Designation of sediment-related disaster hazard area based on the Sediment-related Disaster Prevention Law
When is dangerous?
What to do?
・Development sediment-related disaster forecast system
• Collection and communication of sediment-related disaster information
• Establishment of a warning and evacuation system (conditions, evacuation route, and evacuation place)
Debris flow disaster on July 20, 2003 at Minamata, Kumamoto Victim; dead 14、missing 1、injured 6Damage; totally collapsed house14Continuous rainfall; 314mm (8:00 ,19,July ~ 5:00,
Maximum hourly rainfall; 91mm/hr (4:00~5:00, 20,July
19,July0
20
40
60
80
100
1 4 7 10 13 16 19 22 25
Hourly rainfall(mm)
0
100
200
300
400
500
Continuous
rainfall(mm)
H ourlyrainfall
C ontinuousrainfall
20,July19,July
Debris flow
8 12 0 12
Debris flow disaster in 2003 at Minamata,Kumamoto Pref.
Deposition area
Slope movement
area
Damaged housesDeposition area
Debris flow disaster on July 18, 2004 at Miyama, Fukui Pref. Victim; dead 1、injured 1Damage; totally collapsed houses 25, half collapsed houses 49Continuous rainfall; 283mm (17,July ~ 18,July)
Maximum hourly rainfall; 87mm/hr (6:00~7:00, 18,July)
Mizutani
E. Otukurinishi
Otukurinishi
Takao
Nonoike
Nkao
Akasuna
W.Akasuna
Otubo
Nakaotubo
Debris flow disasters by Typhoon No. 23 on Oct. 20, 2004 at Kagawa Pref. Victim; dead 5、Damage; totally collapsed houses 5Continuous rainfall; 492mm (19 Oct.~ 20 Oct.)
Maximum hourly rainfall; 76mm/hr (13:00~14:00, 20 Oct.)
Slope
failure
がけ崩れ発生(津名町)
がけ崩れ発生(出石市)
がけ崩れ発生(一宮市)
Sediment-related disasters by Typhoon No. 23 on Oct. 20, 2004 at Miyazu,KyotoPref. Victim; dead 2、Damage;
totally collapsed houses 4Continuous rainfall; 282mm (19 Oct.~ 20 Oct.)
Maximum hourly rainfall; 40mm/hr
Debris
flow
Slope movement disasters by the Niigata-Chuetu Earthquake on Oct. 232004 at Yamakoshi, Niigata Pref.
②竹田
0
5
10
15
20
25
30
35
24時 12時 24時 12時 24時 12時 24時
時刻(9月4日~6日)
時間雨量(mm)
0
100
200
300
400
500
600
積算雨量(mm)
11:30, Slope failure,
Dead 2
23:37 Spontaneous Evacuation
Slope failure disaster by Typhoon No. 14 on Sept. 6, 2005 at Takeda, Oita Pref.
Heavy rainfall warning
Hourly rainfall
(mm)
4,July 5,July 6,July
0 12 24
12 24 12 24 Continuous rainfall
(mm)500
35
高峠(アメダス)
0
5
10
15
20
25
30
35
40
24時 12時 24時 12時 24時 12時 24時
時刻(9月4日~6日)
時間雨量(mm)
0
100
200
300
400
500
600
700
積算雨量(mm)
9:30, Debris flow, dead 3
10:43 Evacuation recommendation
19:50 Warning
information
Heavy rainfall warning
Debris flow disaster by Typhoon No. 14 on Sept. 6, 2005 at Tarumi, Kagoshima Pref.
Hourly rainfall
(mm)
Continuous rainfall
(mm)
4,July 5,July 6,July
0 12 24
12 24 12 24
60035
An example of the effect of erosion control works (Sabo)
Sabo dams in the Daibu River, Fukuoka Pref. trapped debris flows and prevented disaster on July 19, 2003
Daibu River, Fukuoka Pref.
Sediment flooded up to the Daibu River Sabo Dam No. 1
Sediment deposited at the Daibu River Sabo Dam
DaibuRiver Sabo Dam No. 1
Torrent without a sabodam
DaibuRiver Sabo Dam No. 2
Volcanic disasters caused by pyroclastic flows & debris flows
Active volcanoes in Japan
Mt.Unzen-Fugendake, Nagasaki Pref.
11
Pyroclastic flow at Mt.Unzen-Fugendake on June 23, 1993
After the eruption of 1990-94, Mt. Unzenand drainage of the Mizunashi River
Municipal government
Fire and disaster
prevention division of P.G
Flow of information provided by the new collaboration and cooperation
Promotion of communication of sediment-related disaster information in collaboration with the
Meteorological Agency
TV and radio
* The red color shows the flow of information provided by the new collaboration and cooperation.
Weather advisory and
warning
Referential information on sediment-related disaster
Residents in A
rea Ain A
rea B
Evacuation
Sabo division of pref. government
Local meteorological
observatory
Early evacuation is ensured
New collaboration &
cooperation
Preparation of rules
20km/h
30km/h
Warning information on sediment-related disaster Joint announcement by Prefecture and Meteorological Observatory
Municipality under warning: City, ××TownWithin two hours from now, the risk level of a sediment-related disaster will increase significantly due to heavy rain. Take every caution in and around the sediment-related disaster hazard area. The maximum hourly rainfall within three hours from now will be 60 mm at some locations in these municipalities.
Municipalities under warningArea which experienced a seismic intensity of 4 or more in the △△ Earthquake
Area under heavy rainfall (30 mm or more/hour)
The length is equal to the moving distance in one hour. For more information:
(Sabo Division of Prefecture)( Meteorological Observatory)
An example of sediment-related disaster warning information
Landslide
Slopefailure
Early evacuation
GPS satellite
EvacuationDebris
flow
Relaystation
Optical fiber cable network User of
cellular phone
terminalUser Monitor station Disaster
information from users
Establishment of a warning & evacuation system utilizing IT
GPS
User of the Internet
TV camera
Mutual information
systemInternet
network
Designation of sediment-related disaster hazard area
Promoting the public awareness of sediment-related disaster hazard areas
Developing of warning and evacuation systems
Designation of special sediment-related disaster hazard area
Control of housing land development projects
Control for building structures
Recommendation of removal of existing houses from hazard areas
Financing and founding for those who remove their houses
Outline of the Sediment-related Disaster Prevention Law
Sediment-related disaster hazard areadesignated under the Sediment-Related
Disaster Prevention Law
Hazard area Special hazard area
Debris flow
Inclination≧2°
Inclination≧30°
Slope failure
Sediment-related disaster hazard area
Hazard area
Special hazard area
Sediment-related disaster hazard area
Landslide
Special hazard area Hazard area
Hazard map on sediment-related disaster, in Hikone, Shiga Pref.
Slope Failure Disaster damages Evacuation Place
Debris flow flowing into a socialwelfare facility in Fukushima Pref.
Aug. 26,1998; Dead 5
A volcanic hazard map is prepared and publicized for 30 active volcanoes (As of June, 2004)
An example of volcanic hazard map(for Mt.Asama)
Promotion of preparation and publication of volcanic hazard map
If a major eruption like the Tenmei Eruption (18th century) occurs…
Monitoring of volcano
Establishment of a buffer zone on the volcanic mountain slope
Unmanned construction
Storing of materials for urgent disaster response
Installation of information equipment at the volcanic disaster prevention station
Plan of urgent disaster mitigation measures for volcanic eruption (new plan)
Real-time simulation calculation
Urgent measures
Warning and evacuation action, risk management
Promotion of preparation of real-time hazard map
Urgent removal of sediment at Mt. Usu
Two days later
One day later
10 hours later
Forecast of development
Eruption
Input of data
・Location information of the
crater
・State of eruption, etc
SEE YOU
Top Related