Monbaliu, J.

Ntegeka, V.

Willems, P.

Open Marine Archive

Geophysical Research Abstracts
Vol. 13, EGU2011-6554, 2011
EGU General Assembly 2011
© Author(s) 2011
Incorporating the correlation between upstream inland, downstream
coastal and surface boundary conditions into climate scenarios for flood
impact analysis along the river Scheldt
Victor Ntegeka, Patrick Willems, and Jaak Monbaliu
Katholieke Universiteit Leuven, Department of Civil Engineering, Heverlee, Belgium (victor.ntegeka@bwk.kuleuven.be, + 32
16 32 19 89)
Climate change scenarios have been developed that are useful for flood impact studies along the river Scheldt
in Belgium. They consist of scenarios for the downstream coastal boundary (sea level rise, storm surges), the
upstream inland boundary (rainfall and related runoff discharges) and the surface boundary along the Scheldt
reaches (wind speed and direction). Correlations between the climatic changes at the three boundaries have been
considered.
For each of the boundaries, the climate change scenarios are based on statistical analysis of an ensemble
set of (at least 20) simulation results with regional climate models (RCMs). The RCM results are provided by
several databases, including the CERA database (2 CLM runs), the EU-FP5 PRUDENCE database (31 runs with
12 RCMs) and the EU-FP6 ENSEMBLES database (18 RCM runs). RCM results of precipitation, temperature,
potential evapotranspiration, wind speed, wind direction and sea level pressure (SLP) have been validated for
historical periods (e.g. 1961-1990, 1981-2000) and analyzed for future changes till 2100 (e.g. for the near future,
2011-2040 or 2016-2035, the not so near future, 2041-2070 or 2046-2065, and the longer term future, 2071-2100
or 2076-2095). The validation is done for daily and monthly mean values, and daily extremes in different seasons.
Future changes take the form of change factors, dependent on season, return period (for the extremes) and time
scale. Based on the ensemble set of change factors, tailored climate scenarios (tailored for the specific application
of flood impact analysis along the Scheldt) have been developed. After statistical analysis of the whole range of
change factors, a reduced set of climate scenarios (“high”, “mean” and “low”) was derived for each boundary
(upstream, downstream and surface). Smart combinations of these scenarios account for the correlations between
the boundary changes.
Changes in SLP were transferred to changes in storm surges at the Scheldt mouth (at Vlissingen) based on
a correlation model between the SLP at the Baltic Sea and the storm surge level. This model was derived
after analysis of SLP composite maps and SLP-surge correlation maps for days where the surge exceeds given
thresholds (for different return periods).
Changes in inland precipitation and evapotranspiration were transferred to corresponding changes in runoff
discharges (upstream along the Scheldt) based on simulations in rainfall-runoff models of the upstream river
basins. After calibration of the rainfall-runoff models to historical series, the precipitation and evapotranspi-
ration input series were stochastically perturbed to account for the changes in the number of rain storms,
the rain storm intensities and the correlated changes in evapotranspiration. This was done for each of the
tailored climate scenarios. Extreme value analysis on the rainfall-runoff model results allowed assessment of the
changes in runoff discharges at the upstream Scheldt boundaries, in relation to the return period of the runoff event.


Incorporating the correlation between upstream inland, downstream coastal and surface boundary conditions into climate scenarios for flood impact analysis along the river Scheldt

Incorporating the correlation between upstream inland downstream coastal and surface boundary,           
conditions into climate scenarios for flood impact analysis along the river Scheldt            
Vi t Nt k 1 P t i k Will 1 d J k M b li 1c or ege a , a r c ems , an aa on a uFaculty of Engineering         
D t t f Ci il E i iepar men o v ng neer ng   
MotivationHydraulics Division1 
Kasteelpark Arenberg 40
BE 3001 L There has been increased concern of the potential climate change threats that- euven 
i l i l l i d fl di d imay negat ve y mpact coasta popu at ons Increase oo ng an eros on may. NORTH SEA
t l 32 16 32 16 56 b f hi h l l f th N th S f hi h k fl
 
e + occur ecause o g sea eve s rom e or ea or rom g pea ows.     
Victor Ntegeka@bwk kuleuven be from the upstream catchments or the combination of the two Hence it is. . . . ,
instructive to investigate the correlations between upstream and downstream
www kuleuven be/hydr diti Th S h ldt E t i B l i l t d t d it. . con ons e c e s uary n e g um was se ec e as a s u y s e. .
Historical correlation for SLP vs Surge    
A strong negative correlation ( 0 5 and more) was found for the- .
B l i i d h O d ( ll ia t c sea reg on an t e sea surges at osten e a w nters
f 1925 till 2000) H t ti ti l i l tirom . ence, a s a s ca regress on re a on Wi d l i S h ldt i [51N 52N 3E 4 5E]n ana ys s c e reg on , ; , .
was developed to relate the SLP at the Baltic sea with the
     
h B l i 14
 
surges at t e e g an coast 1990s.
2020s
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Rainfall Uccle perturbation [-] Rainfall Uccle perturbation [-]
Main conclusions:PRUDENCE RCM runs 2071 2100 vs 1961 1990     -  . -
hP t b ti f t f t t / t t •Wind speed extremes(> 90t percentile) and directions do not varyer ur a on ac or= u ure ex remes presen  ex remes           
i ifi tl ith hi t i l d ts gn can y w s or ca a a   
•The high scenario for the 2080s vs 1961 1990: downstream peaks (↑25%)F di id d b       -      un ng prov e y:  
+ upstream surges (↑15%) during winterEuropean Union within FP7 THEME 6 Environment including climate         -   - ,  .
Th l i f h 2080 1961 1990 d k (0%)• e ow scenar o or t e s vs - : ownstream pea s +            
pstream s rges (0%) d ring interTHESEUS (I ti t h l i f f E t i h i li t ) u u u wnnova ve ec no og es or sa er uropean coas s n a c ang ng c ma e                


Incorporating the correlation between upstream inland, downstream coastal and surface boundary conditions into climate scenarios for flood impact analysis along the river Scheldt

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