The Climate Change for Flood and Debris Mitigation after Typhoon - PowerPoint PPT Presentation

(ECW) @ eScience 2016 National Taiwan University Center r for r Weather r Climate and Disaster r Researc rch The Climate Change for Flood and Debris Mitigation after Typhoon Morakot 2009 in Taiwan Professor and Center Director Harold Yih-Chi Tan

L O G O Objective Origin Objective Climate change has l Evaluate impacts of brought huge impacts to flood-prevention works the whole world. Those of Kaoping River due to impacts include: climate change • Severe floods l Risk evaluation of flood- • Spatial land change prevention works • change of hydrological l Strategies and action Kaoping weir conditions plans for improving • etc.. adaptation capacity of flood-prevention works Flood-prevention works due to climate change needs to be re-evaluated Shuangyuan Bridge 2

L O G O Frequency of the extreme rainfall induced by typhoons (the top 20 of the rainfall index between 1970 and 2009) 2000XANGSANE 2001NARI 2001TORAJI 2002NAKRI 2004MINDULLE 2005HAITANG 2007KROSA 2008SINLAKU 2008JANGMI 2008KALMAEGI 2009MORAKOT 2010 FANAPI 1990YANCY 1996HERB 1998ZEB year The frequency of the extreme rainfall 1987LYNN induced by typhoons 1989SARAH Before 2000: once per 3~4 years 1973NORA After 2000: once per year 1974BESS 1978ORA Frequency NCDR(2010) 3

MORAKOT 2009/8/6-8/10 Water Shed L O G O Accumulated Rainfall 324,239 Ha Rainfall Center 4

L O G O Siaolin Siaolin Elementary Elementary School School Siaolin Siaolin Village Village After Typhoon Morakot ü Two potential debris flow torrent n Affected areas: 9.5 million cubic meter ü Potential hazardous areas: Eighty thousand cubic meter n Estimated more than 108 times 水保局 ü Shelter: Siaolin Elementary School n Deep Slide 2009

L O G O Work flowchart Baseline/Target year due to climate change Sea dike Estuary water level Rainfall pattern Discharge Scenarios Climate 1.Current condition Current ： change： 1.Frequency analysis 2.Unit Hydrograph Overbank flow 1. 1. 2.Rainfall pattern simulation astronomical astronomical 2.Surge 2.Surge Hydraulic Model Expert 1. 1D HEC-RAS Methodology Establishment of Committee 2. 2D Overland flow Risk analysis Compound Risk Adaptation Action Plan Risk Evaluation Strategy 6

Scenarios of hydrological conditions L O G O -Sea Level Rise of Estuary Apply ADCIRC (ADVANCED CIRCULATION MODEL) model + sea level rise of 0.27 m. Max. WSL2.61m Historical tidal data for 1947 to 2009 (a) Fast Fourier Transform and regression line (b) EEMD and projected for 2039 7 48hr-Water surface level of estuary of Kaoping River due to climate change

Rainfall for different scenarios L O G O 48hr-Rainfall-Return period:100yr (2020-2039) Cumulative Station Rainfall 累積雨量 站別 Pingtung(5) Jiasian(2) Xinfeng( 新豐 ) Yushan( 玉山 ) 甲仙 (2) 屏東 (5) 新豐 玉山 (mm) (mm) 屏東 (5) [ 甲仙 (2)] Scenario 情境 A1B 1371.98 1143.43 1163.52 569.72 A2 1457.30 1205.66 1197.79 644.11 B1 1466.05 1153.16 1154.14 590.61 A1B 8

Flow Chart Evaluations of Flood-Protection L O G O works Surge Sea level rise Discharge Sediment Deposition 1D hydraulic Model HEC-RAS Steady Unsteady Levee Breach Impact Assessment 2D overland flow 1.Bottleneck section of levees 2.Freeobards 3.Impact assessment of sea dike 9

Discharge increase due to Climate Change L O G O Watershed Control point Designed A1B Simulated (2)/(1) (Q 100 )(1) (Q 100 )(2) Kaoping Jiou cyu-tang 26,800 41,435 155% River ( 九曲堂站 ) 本流 Laonnog Li gang Bridge( 里港大橋 ) 21,100 30,582 145% River 荖濃溪 Confluence of Laonnog 14,200 19,998 River and Ailiao River ( 荖濃 141% 溪與隘寮溪合流前 ) Laonung Bridge( 新發大橋 ) 9,240 13,068 141% Qishan Exit of Qishan ( 旗山溪出口 ) 7,780 10,540 135% River 旗山溪 5,990 8,275 138% Yuemei ( 月眉站 ) Ailiao River Exit of Ailiao River 8,600 11,133 129% ( 隘寮溪出口 ) 隘寮溪 10 Sandimen 6,150 8,513 138% ( 三地門站 )

Risk Matrix L O G O Risk Matrix R = H × V Where, R ： Risk ( 風險 ), presented by Risk Matrix H ： Hazard( 危險 度 )Hazard V ： Vulnerability( 脆弱 度 ) Ø Relative Hazard/ Vulnerability Ø 相對危險等級 / 脆弱度等級 This image cannot currently be displayed. Hazard 危險度 Very high 5 Top20 ％ Very High 4 Top20 ～ 40 ％ Very low Low Medium High high Medium 3 Top40 ～ 60 ％ (1) (2) (3) (4) (5) Low 2 Bottom20-40 ％ Very low (1) (2) (3) (4) (5) Very low 1 Bottom20 ％ (1) Low Vulnerability (2) (4) (6) (8) (10) Ø Relative Risk( 相對風險等級 ) (2) 脆 Very high >20 Top20 ％ Medium 弱 (3) (6) (9) (12) (15) High 14~20 Top20 ～ 40 ％ (3) 度 Medium 10~14 Top40 ～ 60 ％ High (4) (8) (12) (16) (20) (4) Low 5~9 Bottom20-40 ％ Very high Very low 1~4 Bottom20 ％ (5) (10) (15) (20) (25) (5) 11

Historical Levee Breach No. 0.30 Risk of Levee L O G O 0.19 Unit Stream Power 0.20 Deposition or Scouring (Risk) Debris wood (Hazard) 0.09 ＝ Water Surface Elevation 0.22 0.42 0.24 Protection Work × 0.22 Condition of levee Location of flood plain Location of main channel Location of levee (Vulnerability) 0.28 0.36 Type of levee 0.19 Age of levee Questionnaire 0.14 0.32 Pumping Station Affiliated Structures Samples no. : 35, male -30; femail-5 Gate 0.28 0.15 Age ： 20-29 yrs. old ： 4 ； 30 ～ 39 yrs. old ： 0.4 Drainage 14 人； > 40 yrs. old ： 17 12

Vulnerability of Levee (Now) L O G O Levee is old, no flood plain, or located in outside of bends and with gates. 13

Risk of Levee due to Climate Change L O G O High risk of levee located in historical levee breach locations. 14

Conclusion L O G O l The simulated Q 100 for A1B is about 1.3~1.55 times of planned Q . l For A1B scenario, the risk of villages of middle and downstream of Kaoping River is increasing 。 l Plan A (Upstream-7 overflow area+ Middle/downstream 2 retention) : the flooded area reduces 515Km 2 , locations of insufficient freeboard reduces 82%, locations of overbank reduces 86%, and costs 0.65 billion NTD 。 l Plan B (Upstream-4 overflow area+ 1m dredge deep) : the flooded area reduces 515Km 2 , locations of insufficient freeboard reduces 90%, locations of overbank reduces 96%, and costs 10.2 billion NTD 。 15