Sustainable Reservoir Strategy and Flood Management in Taiwan Prof Jinn-Chuang Yang National Chiao Tung University Disaster Prevention and Water Environment Research Center NCTU-DPWE Enhancing Life Security Outlines Natural Environment in Taiwan Landform, geology, & hydrology Water related disasters Short summary Sustainable Reservoir Strategy Flood management Collaboration with Deltares Natural environments in Taiwan Landform and geology Total area 36,000 km2 Mountainous area 66% Population 23 M Population density 639 per km2 (10th highest over the world) Elevation (m) TW Tachia Tamshui Chaoshui River slopes JP Shinanogawa Tonegawa Europe Rhine US Colorado River Distance from the river mouth (km) Elevation distribution Slope distribution From: WRA Natural environments in Taiwan Hydrology • • Annual average: 2,500 mm Rainfall concentrates in May-Oct 63% 76% • • Wet season - Rainfall induced landslide in watershed Storage capacity loss • Reservoir sediment deposition • Turbid water Clean water shortage Dry season - Water demand • Reservoir water supply meet 30% of water demand • Groundwater abstraction meet 20%-40% of water Landsubsidence demand 89% http://mail.tlsh.tp.edu.tw/ 76% Rainfall induced disasters Landslide and Debris Flow Deposition and Water Quality Watershed 圖片來源：水保局網頁 圖片來源：農委會林務局(2006) Overflowing Reservoir Degraded ecological environment 圖片來源：網頁新聞畫面 圖片來源：FISRWG (1998) River instream Damage of instream structure 圖片來源：洪夣祺 圖片來源：網頁新聞畫面 Urban Area Inundation Land Subsidence 圖片來源：地層下陷防治服務團 圖片來源：網頁新聞畫面 Landslide disasters Mountain village Xiaolin 2009 Typhoon Morakot doomed Xiaolin Village Landslide volume > 20 M m3 Casualty > 600 Debris dam Flood disasters 2009 Typhoon Morakot • Rapid river evolution in southeast Taiwan Before 7 After Disasters in subsidence area Legend • Location • Accumulated subsidence in 20 yrs (m) • Annual subsidence (cm/yr) Inundation Sea water intrusion 圖片來源：地層下陷防治服務團 Storage reduction in reservoirs Total storage capacity (M m3) Reservoir Completion Feitsui 1987 344 Shihmen 1963 251 Wuseh 1958 146 Baiho 1965 25 Tsengwen 1973 Nanhua Capacity loss Storage 3 (M m ) capacity loss 57 14.5% 99 32.1% 96 64.0% 16 59.3% 631 257 34.4% 1993 149 62 39.0% Wushanto 1930 103 45 35.7% Agondian 1953 20 9.2 33.8% Mutan 1995 31 3.6 11.4% 70% of all reservoirs storage Averaged 36% of storage capacity loss 17% storage capacity loss in 2009 TP Morakot 12 M m3 sediment dredging during 19972006 Short summary Young Geology & steep hillslope Landslide Reservoir capacity loss River erosion Clean water supply risk Sustainable Reservoir Strategy Hsimen reservoir rehabilitation project one billion dollar 2006-2013 Extreme hydrology Rapid river evolution Economic loss Inundation Life loss Flood management Improvement project for subsidence prone area, 4 billion dollars 2006-2014 Sustainable reservoir strategy - Shihmen Reservoir Brief info on Shihmen Reservoir watershed Watershed: 763.4 km2 Full water level: 245 m Dam Height:133 m Total storage: 309 M m3 Design effective storage: 251 M m3 Effective storage: 209 M m3(in 2011) • Lost 11% storage in 2004 Typhoon Aere • • • • • • Post-Aere Landslide sites Tunnel spillways EL 220m Dia 7.0m 2400 cms Facilities Spillways EL 235m 8600 cms PRO EL 169.5m Dia 1.37m 31 cms Power plant Penstock EL 173m Dia 4.57 m 65/300 cms Stratified water intake shaft From WRA website Damages by 2004 Typhoon Aere Floating debris Power plant valve Turbid water >> 3000 ntu Turbine • 967 mm rainfall in area average • 8600 cms of peak discharge • 665 million m3 of inflow vol. (3 times the effective capacity) • Landslide area: 673 hectares • Sediment deposition 27 M m3 (11% of design capacity) • Water supply stopped for 18 days Trash racks Sustainable reservoir strategy and key technologies Sustainability: Goal Storage preservation and water supply stability Strategy Soil conservation Prevent sediment deposition Objective Reduce sediment inflow Reduce sediment deposition Reduce raw water turbidity Key issue Sediment yield control Sediment discharge through reservoir facilities Water supply improvement under high turbidity Landslide volume estimation Technology developed TDR extensometer piezometer FBG inclinometer piezometer TDR SSC monitoring system Sediment transport & density current models Sediment sluice tunnels & penstock renovation Reduce water supply risk Water supply risk evaluation Stratified water intake shaft Landslide and reservoir sediment deposition Shihmen Reservoir Decrease in capacity Typhoon Landslide area Decreased capacity Percentage of design capacity 2004 Aere 673 ha. 27 × 106 m3 11% Storage capacity history of Shihmen reservoir Annual decreased capacity Total capacity 25 230 280 260 15 KROSA 666 mm 10 ELSIE 493 mm 5 BETTY 607 mm NELSON 538 mm 220 200 0 -5 240 HERB 715 mm 210 高程(m) GLORIA 1,375 mm Total capacity in million m3 20 250 300 AERE 967 mm 190 原始底床 1964(葛樂禮颱風) 2004(艾利颱風) 2007(科羅莎颱風) 2009(莫拉克颱風) 170 150 130 0 1964 1966 1968 1970 1972 1975 1977 1979 1981 1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2004 2006 2008 Annual decreased capacity in million m3 30 Year 2000 4000 6000 8000 10000 累距(m) 180 12000 14000 16000 18000 Sediment yield & reservoir deposition estimation Landslide volume estimation modeling Sediment yield & reservoir deposition Potential landslide volume 100 Potential landslide area 100 Probability (%) 80 60 40 20 0 500 Landslide occurrence probability Variable 200 mm 400 mm 600 mm 800 mm 1,000 mm 1,200 mm 750 1000 1250 1500 1750 2000 Total landslide volume (× × 104 m3) Landslide volume estimation conditional on rainfall amounts Probability (%) 80 2250 Sediment yield 60 Increase sediment discharge efficiency to 40% 40 After treatment of high potential landslide slopes 20 0 0 100 200 300 400 500 Annual decreased storage 600 (× ×104 700 m3) Probability distribution of annual deposition 800 TDR SSC monitoring system TDR advantages: 1. Transmission Line (like TV cable, cheap) mechanism based 2. Waveguides without any electronics 3. Easy installation and maintenance 4. Multi-function and multi-channel 5. (Semi-) profile scan in one cable SSC measurement: • Accuracy ~ ±1000 ppm • Range from 1000 ppm to >300,000 ppm • Particle size independent • Error <15% SSC monitoring during 2013 Typhoon Soulik Peak Inflow 5458cms Peak rainfall 94.2mm/hr Q>300 cms over 47 hrs 19 Sediment transport behaviors–Density current 2008 Typhoon Fungwong Density current submerge section 240 circulation Delta deposition 7月 28上午 3:00 7月 28上午 8:00 Clear/turbid water interface 235 Elevation Density current 7月 28下午 12:00 230 高程(m) Outlet Typhoon Fungwong Peak discharge (cms) 2,040 3,446 1,838 Inflow volume (M m3) 124.47 633.4 227.99 Density current velocity (m/s) 0.38 0.63 0.27 Sinlaku Morakot 225 220 215 Thickness (m) 15 11.5 N/A 7月 28下午 5:00 7月 29上午 12:00 16000 14000 12000 10000 8000 6000 4000 2000 Surface 0 Floating debris SSC profile wrt time at section 24 SSC,mg/L Sediment transport modelingsediment sluice tunnel planning Sluice tunnel Plan D (at Amuping) Under planning 4.2 km 1600 cms For coarse sediment PRO Penstock renovation Completed in 2013 For silt and clay 300 cms Sluice tunnel Plan C (at Dawanping) Under planning 1 km 1200 cms For silt & clay 2D/3D models verified with the TDR SSC monitoring data Sediment discharge and water intake shaft Stratified water intake shaft Penstock renovation EL236 m Water supply failure probability SSC lasts less than 1 day EL 228 m http://www.wra.gov.tw EL 220 m Sediment discharge through penstock 2013 Typhoon Soulik Sediment sluicing and dredging for Shihmen Reservoir Average annual sediment Inflow (106m3) 3.42 Expected average annual sediment outflow Amuping Power plant Dawanping PRO sluice sediment penstock silt sluice way sluice renovation tunnel tunnel 0.15 1.02 0.71 0.64 (4%) (30%) (21%) (19%) 55% Gated sediment sluice tunnels • FEWS may help optimal gate operation 19% Unit: 106m3 Dedging near dam Dredging u/s from reservoir Sum 0.50 (15%) 0.40 (12%) 3.42 26% 100% Flood management Impervious area increasing - Land use in Taipei Basin From: Tsing-Chang Chen et al Flood disasters Dike failure in 2004 TP Mindull •171 typhoons occurred during 1958~2004 •14,456 injured, including 2455 dead, 1098 missing •342,378 houses failed Turbid water by floods Taipei inundation in 2001 TP Nari Bank retreat in 2009 TP Morakot Kalmaegi TP Morakot after math Dike failure in 2008 TP Kalmaegi Coastal erosion Kaohsiung inundation in 2006 TP Tanmi Kaohsiung inundation in 2006 thunderstorm Landslide killed 600 27 Channel erosion 1 2008 Typhoon Sinlaku damaged 5 bridges Tuming Bridge Hofong Bridge 1 Niouming Bridge 2 Wuhuliao Bridge Chiashiang Bridge 4 圖片來源：網頁新聞畫面 3 2 4 5 reintallation 圖片來源：蔡長泰教授 5 3 Flood management Low impact development New Land use management Disaster prevention and mitigation Conventional practices Watershed management Environment and biology Water resources management Ideal flood defense system Structural measures Non-structural measures Soil conservation Land restoration Early warning & evacuation Detention pond Plantation Ring dike Retention basin Household rainfall dten Flood plain management Flood diversion Detention pond Channel desilting Retention in parks Early warning & dodge Flood insurance River dike Channel remediation V-storage between Basement detention pond http://highscope.ch.ntu.edu.tw/ buildings Flood detention ponds 1 1 2 台北大湖 2 3 楊梅高山頂 雲林南公館 4-6 5 4 3 6 7-10 嘉義四股 嘉義白水湖A1 9 8 7 台南立德 嘉義內田考試潭 南科D池 10 台南三舎 台南都會公園 Detention ponds for protecting high value fish farms 新塭北側滯洪池 新塭南側滯洪池 Collaboration with Deltares FEWS_Taiwan River basins 26 rivers ready Models SOBEK HEC-RAS WRF Ensemble Real-time water level correction System FEWS_Taiwan Live System Collaboration groups Deltares, WRA, NCTU Model integration into FEWS Landslide model Reservoir operation model River bank retreat model Look forward to future collaboration R&D Technology integration & development Education NCTU-DPWE Professional training for government employees Enhancing Life Security Increase project spectrum and technology integrity Think Tank Consultancy New problems to be solved Thanks for your patience Comments? Visit NCTU-DPWE at http://dpwe.nctu.edu.tw/en/ Enhance joint security by joining force with Deltares Real-time monitoring and modeling in – – – – Sediment transport River dike safety Landslide forecasting River structure safety Clean water supply & life expectancy of reservoir Life security near river bank Life security near/on slopes Life security near hydro-infrastructure Long term planning – – – – Landsubsidence modeling and monitoring subsidence prevention planning Inundation mapping Levee design and inundation prevention Groundwater resources management Ind. & agr. development Safe drinking water Clean water supply
© Copyright 2024 ExpyDoc
