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Climate Change, Extreme Floods, and Dam Safety in Korea Agenda Kwon, Do-Youp, Vice-Minister, Ministry of Land, Transport and Maritime Affairs, Republic of Korea Ⅰ. Status of Korea’s Water Resources Ⅱ. Climate Change and Extreme Floods Ⅲ. Securing Dam Safety IV. Summary Ⅰ. Status of Korea’s Water Resources Location and Topography • Korean Peninsula : 222,135 ㎢ (South Korea: 100,000㎢/ forest lands: 65.7%/ farmland: 21.9%/ urban area 5.2%, others:10% as of 1988 ) • Around 70% of Korea’s territory is mountains (∴ Vulnerable to floods) • Most rivers flow into the West and South Sea Precipitation Status of Water Resources Total Water Resources (124.0) Streamflow (72.3) Rainy season (52.2) Dry season (20.1) Runoff to Ocean (38.6) River (12.3) Units : billion m3/yr Loss (51.7) Reservoir (17.7) Groundwater (3.7) Total water use (33.7) Source : Long-term Master Plan of Water Resources (Korea, ’06.7.) II. Climate Change and Extreme Floods Global Warming Temperature increased by 0.6℃ during the past 140 years (global aver.) → The Korean average increased by around 1.5℃ •2.0 •1.0 •온 •도 •편 •차 •Temperature variations (°C) •1.5 •0.5 •0.0 •-0.5 •-1.0 •-1.5 •1954 •1964 •1974 •1984 •Time (year) •1994 Changing Climatic Zones • Past: Monsoon → Now: Subtropical Climate (Changes expected in vegetation, fish stocks, ecosystem) • Climate for 20% of territory will change by 2100 Region Vegetation Fish Changing forest (temperate zones ⇒ subtropical zones) South (temperate) 34.99% Middle west (temperate) 16.18% Northern Area Middle eastern Area Middle Western Area Middle east (temperate) 3.16% North (frigid zone) 3.11% East and west Sea Subtropical ※ Source : KEI (Korea Environment Institute, 2003) Southern Area Abnormal Climate • Abnormal climate caused changes in precipitation patterns for the past 20 years Ex) Annual Precipitation: 7%↑( 1,166 mm → 1,247 mm ) Rainy Days: 14%↓(124.9 days/yr → 107.4 days/yr) Intensity: 18%↑(10 mm/d → 11.8 mm/d ) • Risk management against floods, droughts, and dam destruction is crucial Number of days with precipitation Number of day with precipitation (larger than 80mm/day) Annual Precipitation 연 강수량 (b) Total Precipitation 1300 mm 1250 1200 1150 1100 1920- 1930- 1940- 1950- 1960- 1970- 1980- 199029 39 49 59 69 79 89 99 Year Increasing Severity of Rainfall mm/day 1992~2001 1971~1980 Changes in Rainfall Intensity 100~110 110~120 120~130 130~140 Rainfall intensity (mm/day) 140~150 150↑ • Changes in annual precipitation and number of annual typhoon is not outstanding. • However, the number of days with heavy rainfall (100 mm per day and above) rose by 1.5-fold during the past 10 years (222 times →325 times) Changes is Flood Damage Patterns Damage Casualty Rapid increase of damages • Damage in 2000’s up 4.5 times (900 M $/yr) compared to 70’s~80’s • 4.1 B$ in 2002 year Flooded area year year Damages per unit flooded area year • Casualty was halved during same period • Decreasing flooded area but rapid increase of the damage per unit flooded area (7 times up compared to 70’s~80’s) due to excessive urbanization along the river Example of flood damages Yeoncheon hydropower plant collapse - In 1996 due to heavy rain - 700mm in 3 days, daily max. 400mm Levee failure in Pyeongchang river - In 2006 hit by typhoon “Bilis” - Hourly max. 88mm III. Securing Dam Safety Dams in Korea • Present: Total of 18,000 dams 15 Multi-purpose / 14 Water supply / Others (Irrigation, etc.) → Water Supply (17.7 bil.m3/yr), Flood Control (2.8 bil.m3) • Under construction (~ 2012) 5 Multi-purpose dams → Water Supply (95 mil. m3/yr), Flood Control (360 mil. m3) • Future (~2016) Build 7 small dams and rehabilitate 2 agricultural dams → Water Supply (760 M m3/yr) Roles of Dams in Korea Total Storage Capacity: 12.9 billion m3 Single purpose dam Irrigation dam (5%) (9%) Estuary barrage (13%) Multipurpose dam (73%) Total Water use: 33.7 billion m3 Groundwater (11%) Accounts for 80.1% of total flood control capacity Stream (36.5%) Dam (52.5%) ∴Dams are essential in Korea 47.2% of drinking water 68.3% of (drinking + industrial water) Extreme Floods Recently, PMP surged in dam basins compared to the former designed value due to Climate Change → Max. 132% ↑ in multi-purpose dam basin 632→810mm(Soyanggang dam), 424→561mm(Imha dam) Max. 317% ↑ in water supply purpose dam basin 241→715mm(Yeongcheon dam), 272→863mm(Angae dam) New daily rainfall record (547→870.5mm/day, 2002.8) Flood We must secure the Hydrological Stability of Dams (Units : million㎥/yr) against extreme flood History of Flood Control Capacity Enhancement Project • 2002.8 : Typhoon “RUSA” (4.1bil.$ loss, 207 killed) • 2003.4 :『Flood disaster Prevention and Countermeasure Plan』 (The Office for Government Policy Coordination) • 2003.4 : Presidential Directive (Cabinet Council) → Securing Dam stability against extreme flood • 2003~ : Launched『Flood Control Capacity Enhancement Project 』 Structural Reinforcement Project for hydrological stability (Auxiliary / emergency spillway construction) • Total 23 dams (2003~2015, 1.3 b$) → 6 completed, 6 under construction, 11 planning • Types of measures - Spilling capacity ↑ (New, additional or enlarged spillways) - Dam storage ↑ (Parapet wall) Project Period Project Cost ’03~’15 1.3Billion (13years) US $ Finished Under Planning Constructing Total 23 dams 6 6 11 Measure types Auxiliary/emergency spillway, Enlargement, Parapet wall (ex1) Types of reinforcement Type1. Tunnel spillway <Soyanggang dam> Type3. Watergate <expansion> Type2. Open channel spillway <Yeongchon dam> Type4. Parapet wall <highten> (ex2) Very large scale Waterway Tunnel Soyanggang Dam Two tunnels in row Project cost : 0.16 b$ D:14m × L:1,280m Q = 6,700m3/s Imha Dam Three tunnels in a row Project cost : 150 M$ D:15m × L:420m Q = 8,215m3/s Dae-am Dam Two tunnels in a row Project cost : 40 M$ D:10m × L:429m Q = 1,633m3/s IV. Summary • Precipitation has been continuously increasing in Korea due to climate change, causing massive damages. • Dams play a critical role in Korea but are threatened by increasingly frequent and severe floods. • Thus, to secure hydrological stability of dams, the Korean Government launched “Flood Control Capacity Enhancement Project” from 2003 which has been successful so far. Thank you