[email protected] Future changes in extreme streamflow over the Amazonian sub-basins 1119 (b) - Extreme hydrological events: deciphering changes in hazard and risk at different time-scales Matthieu Guimberteau (LSCE) J. Ronchail, J. C. Espinoza, M. Lengaigne, B. Sultan, J. Polcher, G. Drapeau, J.-L. Guyot, A. Ducharne and P. Ciais
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Future changes in extreme streamflow
over the Amazonian sub-basins
1119 (b) - Extreme hydrological events: deciphering
changes in hazard and risk at different time-scales
Matthieu Guimberteau (LSCE) J. Ronchail, J. C. Espinoza, M. Lengaigne, B. Sultan,
J. Polcher, G. Drapeau, J.-L. Guyot, A. Ducharne and P. Ciais
Recent increase in discharge amplitude at Óbidos
High flows
Low flows
Mean flows
Update of Figure 2 from Callède et al. (2004, Hydrol. Sci. J.)
Ronchail et al. (2014, Env. Géomatique)
Are present-time extreme discharges
precursors of future conditions in the Amazon basin?
Recent increase in discharge amplitude at Óbidos
Historical
meteorological
forcing
ORCHIDEE
Control simulation (1980-2000)
(Guimberteau et al., 2012,
Hydrol. Earth Syst. Sc.)
Protocol
Future climate
change forcing
Historical
meteorological
forcing
ORCHIDEE
Climate
change
simulations
Control simulation (1980-2000)
(Guimberteau et al., 2012,
Hydrol. Earth Syst. Sc.)
Protocol
8 GCMs
3 emission scenarios
Middle and end of the century
Future climate
change forcing
Historical
meteorological
forcing
ORCHIDEE
Climate
change
simulations
Control simulation (1980-2000)
(Guimberteau et al., 2012,
Hydrol. Earth Syst. Sc.)
Climatology of
GCMs outputs
anomalies
Delta downscaling method
Protocol
8 GCMs
3 emission scenarios
Middle and end of the century
Future climate
change forcing
Historical
meteorological
forcing
ORCHIDEE
Climate
change
simulations
Control simulation (1980-2000)
(Guimberteau et al., 2012,
Hydrol. Earth Syst. Sc.) Impact of
climate
change on
discharge
Comparison
Climatology of
GCMs outputs
anomalies
Delta downscaling method
Protocol
Present time Future time Relative difference (%)
Runoff coefficient change
P
QRcoeff
Number of GCMs that project a P increase (2046–2065), SRESA1B scenario
Little change in average P
(+1.1%) but spatial variation !
Annual P change
Number of GCMs that project a P increase in JJA (2046–2065), SRESA1B scenario
Most of the GCMs simulate a P
decrease in the southern regions
during the dry season
JJA P change
No change in high flow of the Amazon
Systematic discharge decrease during the recession period,
leading to a 10% low-flow decrease
Conclusion
No change in high flow of the Amazon
Systematic discharge decrease during the recession period,
leading to a 10% low-flow decrease
A high-flow increase is simulated in the western regions (+7%)
but with low confidence
In the north, the low-flow decrease becomes higher towards the
east (up to -55%)
Conclusion
No change in high flow of the Amazon
Systematic discharge decrease during the recession period,
leading to a 10% low-flow decrease
A high-flow increase is simulated in the western regions (+7%)
but with low confidence
In the north, the low-flow decrease becomes higher towards the
east (up to -55%)
In the southern regions where the dry season would be longer
and more severe (Boisier et al, 2015, Nature Clim. Change), the
low flows would decrease by up to -50% in the south-east
Southern sub-basins with low runoff coefficient become more
responsive to P change
Deforestation is not taken into account in our study
Conclusion
The ORCHIDEE model
Land surface model
LE, H, albedo, LAI ...
Meteorological dataset
P, Q, T,
radiation...
The ORCHIDEE model
Energy model
+
Physically based soil hydrology scheme
Routing scheme
Surface runoff + deep drainage
Prescribed
distribution of the
vegetation
Floodplains
and swamps
River discharge
LE, H, albedo, LAI ...
Meteorological dataset
P, Q, T,
radiation...
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