Jaw-Lieh Wang

5th Sep. 2012

1Environment of
natural disaster2 Characteristics ofnatural disaster

2.1 Typhoon & Heavy rainfall
2.2 Earthquake
2.3 Debris flow

3 Prevention countermeasure
and reconstruction

1. Environment of
natural disaster
Total area : 36,000km2
Population: 23 million
Belong to subtropical climate,average annual rainfall is about
2,500mm, 70% from May toOctober.

Environment characteristic of Taiwan
Steep slop

Vulnerable
geology

Earthquake

3/4 lands of Taiwan are mountains.
High population density andover-development.
Recently, there are higher frequencyof heavy rains in Japan and Taiwan
due to global warming.

TyphoonDebris flow
Flood

Short riversand running
fastMan-madedevelopment

22. Characteristic ofnatural disaster
2-1 Typhoon andHeavy rain

Rivers of steep slope(Upper stream
1/100、Downstream 1/500～1000）.
Weak geology and collapses easily. A
lot of mud from flood brings debris flow.

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Map of Typhoon Route, 1985~2005

TaiwanTaiwan and Okinawa suffered the mosttyphoons

Ref：NASA4

Typhoon Morakot caused the most severe damage toTaiwan in 2009
Heavy rain for 96 hours from 08/06/2009 ~08/10/2009. The devastating landslide andthe flood disaster occurred in central andsouthern Taiwan.

5Typhoon Morakot caused the most severe damage toTaiwan in 2009

Damaged Bridges Summary (8/21/2009)
Provincial County
Highway Roadway

Country
Roadway

Total

CollapsedBridges

41

31761

Disconnect
ed Bridges

500546

31766

Subtotal6Isolated Area Damaged Condition• There are total 8 damaged isolated areas,
one of them has been connected for traffic, the rest 7 isolated areas are still under construction to open the traffic.

7Major Damaged Areas Traffic Condition
Chiayi (Alishan)
Provincial Highway No.18：
Disconnected 126.0km
Open 61.8km
Progress 49.04%
Kaohsiung(Chishan~Jaishian~Namasha)
Provincial Highway No.12：
Disconnected 65.0km
Open 42.1km
Progress 64.8%
Kaohsiung (Liouguei~Tauyuan)
Provincial Highway No.27A and No.
20：
Disconnected 85.0km
Open 45.7km
Progress 53.7%
Kaohsiung (Maolin~Dona)：
Disconnected 16.5km,
Open 2.5km ,Progress 15.1%

Circled areas are theisolated areas thatneed to connect for
trafficNantou(Tongfu~Tongpu~Tatachia)
Provincial Highway No.21 andNo.18：Disconnected 66.0km
Open 22.5km
Progress 34.1%
Taitung(Tauyuan~Lidau~Wulu)
Provincial Highway No.20：
Disconnected 76.3km
Open 26.5km
Progress 34.7%

Pingdong (Sandimen~Wutai)
Provincial Highway No.24：
Disconnected 20.5km
Open 10.1km
Progress 49.3%

Taitung (Taimali~Fonggong)
Provincial Highway No.20：
Disconnected 70.3km
Open 70.3km
Progress 100%
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Road, Bridge Scouring and collapsed of Swan-Yuan bridge
caused by Morakot typhoon底圖來源：成大衛星中心

A1 P1

P14 P16 P19 P22 P25 P28 P31 P34 P37 P40 P43 P46 P49 P52 P55 P58 P61 P64 P67 A2105H.W.L.5.93m

01972河床高程-5-10-15

1981河床高程2003河床高程
2009.8河床高程-209

Road, Bridge
Reconstruction of Swan-Yuan bridge after Morakot

10Collapsed Bridge Rehabilitation Strategy• Large span length, less piers for rebuilt and new-built bridge, scenical bridge integrated with local
landscape• Pier location avoid deep river channel• Stream-flow pier shape• Increase the anti-flood ability for structure• For unstable river, increase the pile length and allowable free standing length for scouring2-2 Earthquake

Active fault map for Taiwan(Ref: CENTRAL GEOLOGICAL SURVEY, MOEA)

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Fault layout and earthquake illustration
Many earthquakes from active fault of Philippine Sea plate slipping
into the Eurasian plate
1906年3月梅山地震(M=7.1)
1935年4月新竹台中烈震(M=7.1)
1941年12月中埔地震(M=7.1)
1964年1月台南白河地震(M=6.3)
1972年4月花蓮瑞穗地震(M=6.9)
1986年11月花蓮地震(M=6.8)
1990年12月花蓮地震(M=6.7)
1998年7月嘉義瑞里地震(M=6.2)
1999年9月集集大地震(M=7.3)
2002年3月331地震(M=6.8)
2010年3月高雄甲仙地震(M=6.4)

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Chi-Chi Earthquake
發震時間：88年 9月21日 1時47分15.9秒震央位置：

北緯23.85°、東經120.82°

震源深度：

8.0 公里芮氏規模：

7.3

Seismic intensity figure of Taiwan
Chi-Chi earthquake(M= 7.3)

Main Shock14

2-3 Debris Flow
Investigation in 1996, 485 rivers have high potential of debris flow,
and it became 722 rivers after Chi-Chi earthquake in 1999.
And there are 1,503 after Morakot typhoon in 2009.
Sediment mass leave after earthquakes and typhoons,debris flow occurs when rainfall of more than 40mm or 150mm

Dangerous Rivers in Taiwan
485條
(1996年)
1996.7
賀伯颱風722條
(1999年)

1999.9921集集大地震

Debris flow &Critical rainfall

1420條
(2001年)

1503條
(2009年)

1552條
(2010年)

2001.7桃芝颱風

2009.8莫拉克颱風

2010.10
梅姬颱風HighLow
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3.Disaster Prevention Policy
Disaster management system of Taiwan

Source of the Law
Law of disaster prevention
and rescue
Rules of procedure
Basic plan
Assigned admin.
Institution

Service plan

Local government

Local service plan16

4. Bridge Reconstruction Procedure After Disaster

DisasterUrgentInvestigation

UrgentReconstruction

Reconstruction
PlanUrgent
MeasureTemporary
TrafficFormal
Reconstruction

Alternative Road
Temporary Bridge
Temporary Road
Urgent Repair

Repair and Retrofit
Rebuild New Bridge

Traffic Control
Urgent Passage

E-Jiang Bridge’s temporary traffic
after Chi-Chi (921) earthquake

Original damaged bridge

Temporary bridge

Temporary roadThe principle of Bridge
Reconstruction for Flood Damage
Up-lifting bridge elevation
Increasing bridge length
Enlarging span
Deep foundation
Consideration of impact force
Anti-collision devices

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The principles of bridge reconstruction
for debris flow damage
Debris flow damage happened on
mountain area
Debris flow will occur at the same place,
Can not reconstruct at same location
The principles of bridge reconstruction fordebris flow damage:
Relocate bridge

Increase bridge clearance

Extend bridge length

Design the impact force

Enlarge spananti-collision device

20Conclusion
Due to the special topographical and geological conditions, there are many natural disasters in Taiwan. So,
mountain, river, bridge and road should be considered
together for disaster prevention.
For the global climate change and extreme weather
condition:
Design standard and safety criteria shall be rechecked.
Establish a low carbon consuming society without global
resource extermination.
Build a risk management for reduction of disaster.

Human beings should make friends with naturalenvironment to avoid tragedy.
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