Download Climate Change, Extreme Floods, and Dam Safety in Korea

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