Non-structural Countermeasures against Debris Flow Disaster in Taiwan

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1 Non-structural Countermeasures against Debris Flow Disaster in Taiwan Wang,Chin-Lun Ph.D, Deputy Director General Soil and Water Conservation Bureau Council of Agriculture, Executive Yuan, Taiwan August 31,

2 1996-Herb Debris Flow Disasters in Taiwan 2001-Toraji 2004-Mindulle 2009-Morakot 2

3 Debris flows caused by typhoon Nanmadol in August, 2011 Source Area Landslides Transportation art Channel erosion Deposition(fan) zone Affected area 3

4 1,719 Torrents 46,676 People Feedback Hardware Potential debris flow torrents Delineation of affected areas Inventory of protected targets Engineering 1. Prevent vulnerability factors 2. Mass energy transformation 3. Diversion 4. Suppression works 5. Restrain works Assessment Land use restrictions Delimitation Announcement Restriction Where? How big (far)? Software Residential Relocation Location Coordination Relocation Framework of Debris Flow Management Evacuation Planning Drill Promotion When? Warning Evacuation Disaster analysis Early warning system Rainfall based model Rainfall > Threshold Feedback Disaster Info. 4

Landslide ratio, drainage slope, sedimentation, geology, vegetation

5 Risk Degree of Potential Debris Flow Torrents Risk Degree=Occurrence degree X Degree of hazards on protected targets Occurrence Degree Landslide ratio, drainage slope, sedimentation, geology, vegetation Protected Targets Buildings, transportation facilities, watershed management performance 5

6 Soil and Water Conservation Bureau, Taiwan Preparedness for Evacuation 1,072 Evacuation routes planned 598 debris flow evacuation drills held Evacuation route map Shelter Potential debris flow torrent Affected area Shelter information Moving direction 6

7 Localized Rainfall-based Debris-flow Warning Model Rainfall Triggering Index (RTI) =Rainfall intensity Effective accumulated rainfall Rainfall Threshold for Debris Flow Warning : 200~600mm with 50mm interval -30hr. -18hr. -12hr. Sea typhoon alarm Sea & land typhoon alarm Rainfall forecast Local government should Advise the inhabitants to evacuate. Predict rainfall >Threshold Yellow Warning Persuasive Evacuation Real rainfall >Threshold Red Warning Mandatory Evacuation Local government should Force the inhabitants to evacuate. 7

Debris-flow Management of SWCB Emergency Operation

tw Real-time weather condition: typhoon route and

399 on-site auto-rain-gauges: refresh every 10 min

news, radio broadcast, website, telephone,

8 Debris-flow Management of SWCB Emergency Operation Task Force Real-time weather condition: typhoon route and rainfall prediction Real-time rainfall data over 399 on-site auto-rain-gauges: refresh every 10 min Debris flow warning announcement Traditional: TV news, radio broadcast, website, telephone, Auto-system: sender, on-line fax, voice broadcast and short message service 8

9 On-site Debris Flow Monitoring 17 Portable stations 3 Mobile stations Display through DDMI system and APPs 246.swcb.gov.tw Communication 21 Fixed stations 9

10 2866 Debris Flow Volunteer Specialists Coverage: 99% 1995 Hanshin Earthquake(M=7.3) Self help: Mutual help: Public help 7 : 2 : 1 10

Local Awareness & Preparation Expand the

propaganda Compound disaster Enhance disaster

11 Local Awareness & Preparation Expand the training of Debris Flow Volunteer Specialist Disaster Resistant Community Evacuation mechanism Evacuation routes, drills and propaganda Compound disaster Enhance disaster resistant capability Mitigation Preparedness (Community) Disaster Awareness 11

evacuated 135 villagers according to the

12 Successful Evacuation Shinshan village, Nantou County Although 21 houses were destroyed by flash flood and debris flows, the village head Ms. Mei-Ling Lin (also the debris flow volunteer specialist) successfully evacuated 135 villagers according to the red alarm issued by the COA (SWCB). No one got hurt. At least 63 people escaped from the possible casualties. President Tsai highly praised the village head 12

13 Enhancing the capability of disaster prevention from individuals to communities 2007 to Establish Disaster Resilient Community places countys ( 資料來源 : 水土保持局網站 )

14 Debris Flow Disaster Prevention in Education 14

15 App for Debris Flow Prevention Google map application ios Android 15

16 Application on Facebook 16

17 Public Warning System (PWS) for Natural Disasters PWS utilizes cell broadcast technology, which can simultaneously send more than 100,000 messages in targeted regions within seconds (2,000 msg / min for telecoms) Earthquake, thunderstorm, debris flow, reservoir drainage 17

18 Debris flows in Heliu tribe, Taoyuan City during typhoon Soudelor on Aug. 8,

19 Process of debris flow disaster in Heliu Rainfall Threshold:350mm accumulated rainfall Hourly rainfall 19

20 Soil and Water Conservation Bureau, Taiwan 15 houses were buried by debris flows 47 residents were evacuated beforehand During typhoon Morakot in 2009, 9,100 people were evacuated. 1,046 people were escaped from the possible casualties. 20

21 Soil and Water Conservation Bureau (SWCB) 賀伯颱50% 45% 40% 35% 30% 25% 20% 15% 10% 5% 0% 七二水2258 羅莎颱45% 玫基颱2500 樂克颱2000 拉克颱1500 芝颱16% 棠颱瑪都颱1000 德姆颱No. of Casualties and Wounded Debris Flows vs Typhoon M=7.3 Chi-Chi earthquake Debris flow disaster resistant community has been implemented since % 1% % 迪勒颱拉颱181 力颱雨暨聖帕颱0 梅姬颱(%) 年風104 年蘇風103 年麥風102 年蘇風101 年蘇風100 年南風99 年1017 豪雨風98 年莫風97 年辛風97 年卡風96 年柯風96 年0809 豪災94 年海風90 年桃風土石流災害傷亡人數 (A) 颱風災害總傷亡人數 (B) 傷亡比 (A/B*100%) Typhoon Soudelor, 2015 Typhoon Matmo, 2014 Typhoon, Soulik 2013 Typhoon Saola, 2012 Typhoon Nanmadol, 2011 Typhoon Megi, 2010 Typhoon Morakot, 2009 Typhoon Sinlaku, 2008 Typhoon Kalmaegi, 2008 Typhoon Krosa, 2007 Typhoon Sepat, 2007 Typhoon Haitang, 2005 Typhoon Mindulle, Typhoon Toraji, Typhoon Herb, 1996 (person) 風93 年(760mm) (881mm) (1181mm) (1469mm) (1079mm) (2859mm) (1093mm) (1007mm) (492mm) (619mm) (564mm) (1994mm) (757mm) (1057mm) (1015mm) No. of Debris Flows (A) No. of Typhoons (B) Percentage A/B*100%

22 Thank You for Your Attention Soil and Water Conservation Bureau Always Working with You 22

A Roundup of Recent Debris Flow Events in Taiwan

2015 International Workshop on Typhoon and Flood APEC Experience Sharing on Hazardous Weather Events and Risk Management A Roundup of Recent Debris Flow Events in Taiwan Hsiao-Yuan(Samuel) Yin Ph.D. sammya@mail.swcb.gov.tw