Sustainable Reservoir and flood management in Taiwan-4

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
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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
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–
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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