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

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40

60

80

100

1 4 7 10 13 16 19 22 25

Hourly rainfall(mm)

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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

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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)

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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）

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5

10

15

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25

30

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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)

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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