Transcript Slide 1

Coastal Cities and Adaptation to
Climate Change: Bangkok Study
Chanchai Vitoolpanyakij
Director
Department of Drainage and Sewerage
Bangkok Metropolitan Administration
Climate forcing on Bangkok
• Temperature changes
• Rainfall changes (local & upper
catchment)
• Sea level rise
• Altered frequency of extreme events
(storm surge)
• Compounding factors
– Flat topography
– Land subsidence
Local and global temperature
• There is a robust
linear relationship
between local
temperature increase
and global mean
temperature increase
•
•
•
•
vertical axis – Bangkok mean
temperature change
horizontal axis - global mean
temperature change
SERS (Special Report on
Emissions Scenarios) Red - A1B,
blue - B1
solid black line - least-square fit to
all data points
Source: Study on Climate Impact Adaptation
and Mitigation in Asian coastal mega cities:
Interim Report, JBIC, 2008
Local temperature trends
• Annual mean (19612007) minimum and
maximum
temperatures in
Bangkok is rising
• Overall, Thailand’s
temperature rise
show similar trend
during the same
period
Sea level rise
• Sea level rise
(Increased
coastal erosion,
inundation of
coastal wetlands,
Increased risk of
flooding and
storm damage)
• Upper Gulf of
Thailand
(includes
Bangkok) - most
vulnerable to
sea-level rise in
Thailand
Chao Phraya
Tha Chin
Bang Pakong
Mae Klong
Chan Thaburi
Ranong
Si Chon
Krabi
Narathivat
Source: Tidal record analysis by the
consultant. Yearly averaged values are
shown here
Extreme events
Chao Phraya
MaeKlong
3
Wter level(msl)
2
Thachin
Bangpakon
g
0
-2
100
– caused strong winds and
heavy rainfall
– significant wave height of
3-4 m was measured
Storm
surge
1
-1 0
• Storm surges and
typhoons are not
uncommon
• Most recent - typhoon
LINDA (1997)
200
300
400
Hours
500
600
700
800
• Altered frequency of
extreme weather events
(Increased waves and
surges, Altered cyclone
zones)
A gloomy future!
• IPCC SERS (Special Report on Emissions Scenarios)
Case
SERS case
Temperature
Rainfall
change (0C) change (%)
Sea level
rise (cm)
A1 FI
1.9
3
29
B1
1.2
2
19
• Source: Study on Climate Impact Adaptation and Mitigation in Asian
coastal mega cities: Interim Report, JBIC, 2008
• Strom surge: 61 cm
Altered flood risks..
• Floods due to altered
extreme precipitation
from the upstream, and in
the Bangkok area and
tide are crucial for
Bangkok
Future floods
Max depth (30-yr return period)
2008 condition
Max depth (30-yr return period)
2050 A1FI + Sea level rise +
Land subsidence + Storm surge
condition
Structural measures
(1995 to present)
Existing and planned
flood protection systems
will not have enough
capacity to cope with
the climate change of
A1FI scenario at the
return period higher
than 10 years
Dike along both sides of
the Chao Phraya River
King’s Dike to protect BMA
east side
Dike to protect BMA west side
Dike to protect BMA east side
expansion (under construction)
Bangkok
+2.50 to +3.00 m.MSL
Dike to protect Suwanaphum
International Airport
+3.60 m.MSL
Improve Pumping System
Structural measures – earlier
proposal
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•
•
•
Large storage dam in the upper basin
Barrage at the river mouth
Diversion channel
Coastal erosion protection –
• the shoreline on the west of the Chao
Phraya River has been eroded about 5
to 10 m per year
Structural measures – current
proposal
• Dikes, pumps, and drainage canal improvement
• Dike crest elevations in the future – include
land subsidence of 0.20 m and free board of
0.30 m
• Three new pumping stations at Klong Khun
Rat Phinit Chai, Phasi Charoen and Sanam
Chai (capacities of 100, 400 and 200 m3/sec
for flood at 30-year return period)
• Improvement of drainage canals
Maximum future inundation
• Inundated
area reduced
from 744.34
to 362.14
km2 or
decreased
382 km2 or
51 .35%.
Without proposed
structural adaptation
With proposed structural
adaptation
Coastal erosion protection –
current proposal
• Pursue shoreline protection of the western area of the
Chao Phraya River (along the shoreline of Bang Khun
Thien) as proposed by BMA (2007)
• Shoreline of the eastern area of the Chao Phraya River,
raise the crest of the proposed rock-pile embankments
along all the length of the embankments.
• The total estimated costs are 35,228 million baht to
protect the against a 30-yr return period flood of the
future
• Non structural measures (next presentation)
Thank you