papa f 20150708_1730_upmc_jussieu_-_room_107
TRANSCRIPT
S
Bangladesh’s coastal vulnerability
under climate change
BanD-AID
M. Becker1, F. Papa1,2, S. Calmant1, V. Ballu3, M. Karpytchev3,
L. Testut1, P. Valty4, F. Hossain5, C. Shum6, A. Liibusk6, Z. Khan7
1. IRD/LEGOS, France
2. IFCWS, IRD-IISc, India
3. CNRS/LIENSs, France
4. IGN/LAREG, France
5. U. Washington, USA
6. Ohio State U., USA
7. IWM, Bangladesh
Our Common Future under Climate Change (CFCC), 7 -10 July 2015, Paris
BanD-AID: Build an Earth Analysis & Prediction System based on space sensors to reduce Bangladesh coastal vulnerability from sea-level rise hazards under climate change.
http://www.belmont-bandaid.org
Delta: Natural state
Eustatic sea level rise 2100 projection IPCC AR5
Withdrawal of groundwater and hydrocarbon
Sediment
Ground Ocean
River influence
subsidence
Sediment trapping by dams and reservoirs
Relative sea level rise
+12-100 mm/yr
+2-10 mm/yr
+8-40 mm/yr
+2-50 mm/yr
Perturbations
Coastal subsidence and relative sea level rise
Relative sea level rise in Bangladesh ?
©C. Ashleigh
120 155
204 195
33 40 56 53
2000 2020 2040 2060 2080 2100
40 million (≈26% of total)
+900 people/km2
Population in delta
Projections (million)
United Nations
Bangladesh pop.
Delta pop.
Which data and tools can be used ?
Mathematical Sea level Reconstruction derived
from satellite altimetry or Ocean general circulation models (OGCMs) and tide gauges.
Relative sea level rise in Bangladesh ?
Satellite altimetry
Sea surface
Tide Gauge Station
GPS Receiver
Crust
Tide Gauges (or Sea Level Gauges)
X TRIBENI
Sea level variability
India : Hooghly River & Tide Gauges
CALCUTTA
DIAMOND HAR.
SAUGOR
GANGRA
HALDIA
TRIBENI
Tide gauges (PSMSL)
X TRIBENI m
m (
+off
set)
Monthly variations of sea level in the Indian side of the Bengal Delta,
the Hooghly River
6 TG along the Hooghly River with time series of ~30-35 years are
available at monthly time scale. The larger seasonality amplitude moving
northward is linked to the river hydrology influence.
India:
Hooghly
river
CALCUTTA
DIAMOND HAR.
SAUGOR
GANGRA
HALDIA
TRIBENI
Dipole Mode Index Tropical Indian Ocean east-west temperature gradient
+IOD +IOD +IOD +IOD +IOD
El Niño
+IOD
+IOD +El niño = dry year
Tide gauges (PSMSL) 12-month moving average
Hardinge discharge
X TRIBENI m
3/s
m
m (
+off
set)
Bangladesh: tide gauges and altimetry Seasonal sea level
Tide gauge (PSMSL)
Altimetry (AVISO)
Common period of time (1993-2012 ), fair/good agreement with ρ>0.85
Hiron Point
Khepupara
Charchanga
Chittagong
Cox’s Bazar
Bangladesh: Tide Gauges/Reconstruction Interannual sea level
v
CHARCHANGA 1979-1998
KHEPURARA 1977-2000
Tide gauge (TG)
Church et al. (2004) TG+ EOF altimetry
Hamlington et al. (2011) TG+ CEOF altimetry
Wenzel et al. (2014) TGNN+ EOF altimetry
Meyssignac et al. (2012, updated)
TG+ EOFREG SODA
TG+ EOFREG GECCO
TG+ EOFREG altimetry
TG+ EOFREG ORAS
Mean
The reconstructions provide an opportunity to compare sea level over the past 60 years. Limitations imposed by : - tide gauge sampling back through time - non-stationarity of satellite altimetry For the Bay of Bengal, our analysis shows that Messignac et al., “SODA” product compares best with TGs (not used to construct the product)
Bangladesh: tide gauges/altimetry/reconstruction Interannual sea level variability
Tide gauge (PSMSL)
Altimetry (AVISO) Reconstruction (Meyssignac et al. 2012, SODA)
24-month moving average
Sea level trends (mm/yr p<0.01)
1960-2012 2.6±0.1
1993-2012 3.4±0.4; 2.8 ±0.3
1983-2002 3.5±0.4; 3.3 ±0.6
Mean globally 1960-2012 = 1.7 mm/year
24-month moving average
Sea level trends (mm/yr p<0.01)
1960-2012
2.6±0.1 1993-2012
3.4±0.4; 2.8 ±0.3 1983-2002
3.5±0.4; 3.3 ±0.6
Sea level trends (mm/yr p<0.01)
1960-2012 2.6±0.1
1993-2012 5.2±0.4; 2.6 ±0.3
TG: no significant trend
Sea level + land motion
24-month moving average
Bangladesh: tide gauges/altimetry/reconstruction Interannual sea level variability
Tide gauge (PSMSL)
Altimetry (AVISO) Reconstruction (Meyssignac et al. 2012, SODA)
Mean globally 1960-2012 = 1.7 mm/year
http://www.belmont-bandaid.org
Understanding relative sea level variability
GPS stations collocated with tide gauge
We have installed 6 GPS/TG
stations since 2013 (green dots)
Conclusions and Outlook
•In Bangladesh, relative sea level rise in combination with land
subsidence resulting from groundwater pumping, sediment load
and/or tectonic motion.
•The separation of the relative sea level change into individual
contributors is important.
influences from hydrology and steric changes ?
•GPS stations, collocated with long-term tide gauge, are crucial
information for the understanding of relative sea level variability.
•BanD-AID field works: to quantify the vertical land motion with GPS
campaign, and calibrate satellite data for sea-level measurements.
Eroded rice field banks, Hatia Island, Bangladesh