Japan Society of Civil Engineers 100th Anniversary Commemorative Ceremony – the 3rd RTM on Disaster Management

November 19, 2014 Natural Characteristics of

Disasters Caused by Morakot

Reconstruction of Alishan Highway

Rational Thoughts

2 1. Natural Characteristics of Taiwan Natural Disaster Risk

 According to the report by the World Bank (2005) 「Natural Disaster Hotspots – A Global Risk Analysis」  In Taiwan, 73.1% of Total Area and Population Exposed to Multiple Hazard  Types of Hazard: Cyclones, Floods, Earthquakes, Landslides

Taiwan

4 Typhoon and heavy rain

Map of Typhoon routes, 1985~2005

Taiwan

NASA 5 Typhoon and heavy rain

Average Water Usage per Capita Geographical features and Average Annual Rainfall (mm/yr) (m3/per capita/yr) hydrological background in Taiwan Taiwan India Uk Italy USA 5.4 times 2.5 times France Canada Australia Saudi Arabia Average Slope of River

Dajia River Zhuoshui River

Danshui River EUR. Rhine Elevation Taiwan (m) Japan Shinanogawa USA Colorado River Tonegawa China Mekong River

Distance (m) 6 Eurasian Eurasian Plate Plate

Philippine Sea Plate

Distribution of annual earthquakes

49928 49928 50000 地震次數No. of Earthquake地震次數 50000 1999 5年平均 5年平均Avg. of 5yrs Chichi EQ

40000

28808 數

40000

30000 28097 次

25449 19347 16074 24323

震 22093 No.of No.of EQ

21783

2880816977 數 地 20000 17961 18059 18379

15650 16244 16422

30000 14802 2809714981

次 4319

10000 25449 19347 16074 4933 24323 4682 5446

震 4518 22093 2017 21783 169770

地 20000 17961 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003180592004 2005 2006 2007183792008 15650 16244時 Year 間 16422 14802 14981 7 4319 10000 4933 4682 5446 4518 2017 0 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 時 間 Chichi Earthquake, 1999 Sept. 21

ML=7.3 2505 fatalities, 11,305 injuries

Fault scarp

Shikang dam

8 Chichi Earthquake, 1999 Sept. 21

ML=7.3 2505 fatalities, 11,305 injuries

Fault scarp

Pifong bridge

9 Characteristic of debris flow in Taiwan (massive volume )

Taiwan Ordinary Cases Fongciou Village Taiwan Special Cases

Shibachong River

Sitou Design debris flowdebris Design

Watershed area (Lin and Jeng, 2000 )

10 2. Disasters Caused by Typhoon Morakot Overview of Typhoon Morakot, 2009

a very strong development of convective cloud in August 3~11, 2009 more than 3,000mm of accumulated rainfall, breaking the record in Taiwan

China Japan

CWB 08/08/09:00-11:00 Taiwan QPESUMS 雷達整合回波圖

Philippines 2009 Aug.7 12 Affected area of Typhoon Morakot

China China

Shanghai

Zhejiang Typhoon’s Path Time：2009/08/03~11

Shanghai Fujian

Taiwan

Philippines

Fujian Taiwan Philippines 13 Analysis of rainfall characteristics derived from Typhoon Morakot

12~72 hour of continuous rainfall, close to the world record

12 hr. 72 hr.

The rainfall envelope of the world Largest Rainfall Envelope of the World Largest Rainfall Record of the World Largest Rainfall Record of Taiwan 0807 Flood, 1959 Rainfall=421.6 x duration^0.475 Shirley Typhoon, 1968 Gloria Typhoon, 1963 Herb Typhoon, 1996 Toraji Typhoon, 2001 Nari Typhoon, 2001

Accumulated Rainfall(mm) Accumulated Estimated Rainfall of Tsaoling Landslide Lake Typhoon Morakot Estimated Rainfall of Tongtou Kalmaegi Typhoon, 2008, Kaoping River Morakot Typhoon, 2009,

Duration (hr.)

14 Kaoping River, high-intensity rainfall with long duration of time

Ming-sheng observation station, Kaoping River

Morakot 2009/08/08 Sinlaku 2008/09/11 Kalmaegi 2008/07/16

mm/hr.) Haitang 2005/07/16 Typhoon Morakot Aere 2004/08/23

Toraji 2001/07/28 Rainfall Intensity ( Intensity Rainfall

Duration (HR)

15 High intensity rainfall of Typhoon Morakot

more than 2,000mm of accumulated rainfall in 9% area of Taiwan, mostly in the south 4-day accumulated rainfall as high as 78% of annual rainfall

The highest record

5 3 1 7 6 2 78% 78% 76% 74% 73% 71% 68%

4

1 2 3 4 5 6 7 Tapu Liugui Alishan Sun-di-men Tzuchih Jashen Touyuan 1 Location 8/7~10 accumulated annual rainfall

16 Disasters of Mountainous Roads in Southern Taiwan

Landslides Moulin Township 茂林鄉

18 霧台鄉 Landslides Ali Tribe, Wutai Township 阿禮部落

19 Debris Flow Liugui District 六龜 Sinfa Village Sinkai Village

20 Damaged roads in southern Taiwan

Road Damage Type County Bridge Slope No. of Events 56 26 82 11 48 59 Highway No. 18 Pingtung 14 14 28 Nantou 11 15 26 Chiayi 6 8 14 Taitung 5 7 12 Highway No. 20 2 5 7 Tainan Yunlin 1 5 6 Miaoli 2 3 5 Changhua 3 0 3 Yilan 1 1 2 Taitong Hualien 0 2 2 Highway No. 21 Kaoshiung Taoyuan 0 1 1 Total 112 135 247 Highway No. 20, Highway No. 27, Route No. 133 Highway No. 27-1 Highway No. 3, Pintong Highway No. 24 Highway No. 28

Highway No. 17

21 3. Reconstruction of Alishan Highway １ Hwy18 – 41 locations 2 159甲 – 3 Bridge broken 3 162甲 – 21 4 169 – 42 5 149甲 – 17 162甲 149甲

Roadbase loss

台18 159甲

169

Big landslide Total 123

Damaged spots in the scenic Alishan area St. 37k Highway No. 18

N 40k

40.5k 18 To Alishan 18

38.5k

37.5k 38k

To Chiayi

24 St. 59k Highway No. 18

To Alishan

To Chiyi

25 St. 71k Highway No. 18

N

To Alishan

71.5k

18

71k Rockshed

70.5k

18

To Chiayi

26 Reconstruction of Highway No. 18

St. 37k

Before After

St. 59k

Before After

27 Reconstruction of Highway No. 18

St. 71k

Before After

After After

28 St. 71k

200m

Rock shed

Anchored RW New bridge of Highway No.18 Reconstruction in Alishan

29 4. Rational Thoughts  Roads/bridges are vulnerable to heavy rains Remote village  Using aerial photo & site investigation to evaluate the hydrology, landslide potential and the safe zone for road N

20

21

避開敏感 穩定廊帶 集水區

旗山溪 荖濃溪 河道變遷判釋 Evaluation of Highway Nos. 20 & 21 on the hydrological geology

31 Hydrology To Taitung

N Lakas river Chinshuei river Fuhsing

Butangbunas river

Butangbunastong river 20

Meishiou river

Yushuei river Laonoan river

Dongzuang river

Chinho To Kaohsiung 94年 2009 Chinho Chinho

Laonoan Laonoan river river H=30m

101年 2012

H=10m Riverbed of Laonoan river elevated continuously Chinho-Fuhsing section of Highway No. 20 Riverbed filled with high volume of debris (H > 30m) After heavy rain in 2012 June 10, add 15~20m to H May still elevates 30m higher than the present

Chinshue Butangbunas Meishiou river river river

34 Unstable ground formation and river

Chinshue Butangbunas Meishiou river river river

Meishiou Elevation(m) Chinshue

750 Butangbunas 700

150-290 1190-1300 650 300-450 1350-1480 1350-1490 1300-1350 970-1060 1000-1170 1420-1530 740-900 280-460 1520-1690<200 600 1340-1510<200 330-500 1720-1860 1620-1810 <200 1390-1530 1350-1410 530-650 550 2010-2300

96k 97k 98k 99k 100k 101k Mileage Riverbed variations There were 3 occasions in the previous 2000 years, the riverbed was higher than the present

Fuhsing Height Carbon 14 (m) Chinshue river 10 test results 0

80 50 Morakot m Meishiou

20

0 0 1 2 now Chinho Thousand years before present Environmental geology Flood analysis

Landslide, debris flow and river Q100 flow fluctuation

Relatively stable corridor? Interim road recovery (~10 yr.)

Embankment, 0.86km

Embankment 2.0km Elevated, 1.2km

Planed road Existing road

To Chinho 97k+300 to Fuhsing 98k+500 99k+400 96k+440

101k+440 The recovery plan for Highway No. 20

 EL.660m

A2 P1 A1 修坡處 A2 P17 98k+500 P15 P13 P11 P9 EL.640m Riverbed P7 EL.620~640m P5 P3  P1 A1

97k+300 3D simulation for the bridge section In summary

The topography, geology and meteorology situations in Taiwan are vulnerable to typhoon, landslide and earthquake. Holistic considerations for mountain, river, bridge, road and land development are important to manage risk from natural disasters. Challenges from global climate change and extreme weather conditions： Use practical design and assessment criteria for infrastructures in mountainous area Establish rational ways for the prevention, mitigation and recovery works against natural disasters Use adaptive measures to meet the need of a changing world In addition to engineering techniques, there are always valuable viewpoints from social, economical and environmental aspects that we need to deal with.

41 Thanks for your attention!

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