Transcript Dia 1

Impact of climate change on
hydrological extremes in Belgium
prof. dr. ir. Patrick Willems
K.U.Leuven – Hydraulics Division
Hydrological climate change impact
research for Belgium
•
Waterbouwkundig Laboratorium
impacts on high and low flows
BelSPO: CCI-HYDR
climate change scenarios
for hydrological impact analysis
incl. extremes
•
VMM:
−
−
•
impacts on floods (non-navigable rivers 1st
category)
update urban drainage design guidelines
INBO: impact on nature
incl. comparison with KNMI’06 scenarios
•
MIRA-S & NARA 2009
•
BelSPO: SUDEM-CLI: interfacing
climatology –hydrology – ecology
•
EU-FP7: Theseus: correlation with storm
surge and wave scenarios Belgian Coast
Climate change scenarios
for Belgium
Based on simulation runs by global and regional climate
models & IPCC SRES greenhouse gas emission scenarios
till 2100
GCM
RCM
31 runs (A2,B2) & 26 runs (A1B) by 10 RCMs
17 runs by ECHAM5 (A1B)
IPCC AR4: 27 runs by 21 GCMs (A2, A1B, B1)
DMI 25 km
Greenhouse gas emission
scenarios
IPCC SRES, 2001 & 2007:
Climate change scenarios
for Belgium
• Validation regional climate model runs for control period
(monthly temperature, 1961-1990):
Climate change scenarios
for Belgium
• Increase in monthly temperature:
summer:
+2 to +7°C
winter:
+1.5 to +4°C
Climate change scenarios
for Belgium
• Change in monthly precipitation:
GCMs 1961-1990 :
RCMs 1961-1990 :
GCMs 2071-2100 :
RCMs 2071-2100 :
winters natter
zomers droger
Climate change scenarios
for Belgium
• Change in monthly precipitation:
: increase in winter
: decrease in summer
(lower no. of small rain storms)
winter:
up to +60%
summer:
a.l.a. -70%
no. wet days
summer:
a.l.a. -50%
Climate change scenarios
for Belgium
• Change in precipitation
– Intensity increase for most extreme storms
most extreme storm
in 2 years
Climate change scenarios
for Belgium
• Change in precipitation
– Intensity increase for most extreme storms
most extreme storm
in 10 years
Historical climate trends for
Belgium
• Historical trend analysis
– DJF rainfall extremes Uccle (10 min -> seasonal) 1898 –2005:
anomaly in extremes [%]
30
Global warming
impact
20
10
Multidecadal
climate oscillation
0
-10
-20
winter, 10-year window
winter, 15-year window
long-term average
approximate cyclic variations
cyclic variations plus climate change
climate change effect
-30
-40
-50
1900
1910
1920
1930
1940
1950
1960
year [-]
1970
1980
1990
2000
2010
Climate change scenarios
for Belgium
• Consistency check with historical trend analysis
– Example: Winter (DJF), daily rainfall extremes:
1.35
Regional climate model simulations
SHMI-MPI-A2
1.3
High = Wet
SHMI-MPI-B2
Perturbation factor
1.25
CNRM-DE6
DMI-ECC-A2
1.2
DMI-ECC-B2
CNRM-DE5
1.15
ICTP-A2
HS2 / HS3 / CNRM-DC9
Historical trend 30 years blocksize
CNRM-DE7 / SHMI-HC22
GKSS-A2
GKSS-sn-A2 / METNO-A2
SHMI-HC-A2
ICTP-B2
DMI25 / KNMI
METNO-B2
1.1
Historical trend 30 years blocksize:
part c.c. increase
1.05
1
Mean = Mild
ETH / HS1
SHMI-HC-B2
Current
Control period
(1960-1990)
0.95
1960
1970
1980
Low = Dry
Scenario period
(2070-2100)
1990
2000
2010
2020
2030
2040
2050
2060
2070
2080
2090
2100
Climate change scenarios
for Belgium
• Regional differences
– Rainfall change about 10% higher along the Belgian coast
More wet in winter:
Low = Dry
Mean = Mild
High = Wet
Climate change scenarios
for Belgium
• Regional differences
– Rainfall change about 10% higher along the Belgian coast
Less dry in summer:
Low = Dry
Mean = Mild
High = Wet
Statistical downscaling
Large Scale
150 – 300 km; seasonally – monthly
General
Circulation Models
(GCMs)
Dynamical
downscaling
± 50 km; weekly - daily
± 25 km; daily
river catchment; hourly
Hydrological scale
Regional
Climate Models
(RCMs)
Statistical
downscaling
Perturbation tool
• Day -> hour (river), 10-min (sewer system)
• Based on quantile perturbations:
– change in rain storm frequency and rain storm intensity
– dependent on return period rainfall intensity, season, weather type, …
• Time horizons till 2030, 2050, …, 2100
Wet day frequency
perturbation
Wet day intensity
perturbation
Combined perturbation
Daily
Hourly
10min
High = Wet
Time
series
Month i
Month i
Month i
Time
series
Mean = Mild
Low = Dry
Perturbation tool
• Preserves physical consistency (dependency) between
seasons and variables (precipitation, temperature and
ETo)
Winter
Day-Winter
Day-Summer
Summer
1.4
1.2
1.2
factor
Precip. change
Rainfall Perturbation
[-]
factor
Precip. change
Rainfall Perturbation
[-]
1.4
1
High
High
Mean
Mean
Low
Low
0.8
0.6
0.4
1
0.8
0.6
0.4
0.8
1
1.2
1.4
Eto Perturbation [-]
ETo change factor
1.6
1.8
0.8
1
1.2
1.4
Eto Perturbation [-]
ETo change
factor
1.6
1.8
Perturbation of rainfall series
• Change in rainfall IDF-relations:
– Based on Uccle 10 min rainfall series 1898-2005:
Return period:
100 years
10 years
1 year
1 month
Perturbation of rainfall series
• Change in rainfall IDF-relations:
– Daily rainfall results, climate model runs:
Return period:
100 years
10 years
1 year
1 month
Perturbation of rainfall series
• Change in rainfall IDF-relations:
– 10 min downscaling results, climate model runs:
Return period:
10 years
1 year
1 month
Climate change impact on urban
drainage
• Change in rainfall IDF-relations:
– High, mean and low climate scenarios:
100 years
50 years
10 years
2 years
1 year
2 months
1 month
Perturbation of rainfall series
• Change in rainfall IDF-relations:
– Shift in return period high climate scenario:
Perturbation of “design” storms
• Change in rainfall IDF-relations:
– Change in composite storms, example T = 2 years:
High
Mean
Low
Hydro-impact modelling
Rainfall, ETo
Rainfall-runoff
NAM, PDM: conceptual
Spatially distributed:
SCHEME (KMI/IRM),
MIKE-SHE
WetSpa (VUB)
Bridge over tributary
(culvert + weir)
River
hydrodynamics
Physicochemical river
water quality
MIKE11
InfoWorks-RS
+ quasi 2D overstromingen
TRIBUTARY
Left floodplain
Right floodplain
MAIN RIVER
MIKE11 EcoLab
Spills
Calculation nodes
numerical scheme
Hydrological impacts
• Impact of climate scenarios on hourly runoff peaks:
80
variatie piekafavoeren (%)) )
High
High
Mean
Mean
Low
Low
60
rainfallincrease
40
20
0
-20
-40
0.1
1
10
Terugkeerperiode (jaar)
100
EToincrease
Hydrological impacts
RUNOFF PEAKS
Low scenario, Runoff peaks
(-70%)
(-49%)
(-29%)
(-21%)
(-12%)
- (-50%)
- (-30%)
- (-22%)
- (-13%)
-0
• Impact of climate scenarios on hourly runoff peaks:
Low scenario, Runoff peaks
Mean scenario, Runoff peaks
RUNOFF PEAKS
(-70%)
- (-50%)
(-14%)
- (-13%)
(-49%)
- (-30%)
(-12%)
(-29%)
- (-22%)
(-11%)
- (-9%)
(-21%) - (-13%)
(-8%)
(-3%)
(-12%) - 0
(-2%) - 3%
High scenario, Runoff peaks
Mean scenario, Runoff peaks
0
(-14%)
(-13%)
1% - -22%
(-12%)
23 %- 24%
(-11%)
(-9%)
25 %-- 32%
(-8%)
(-3%)
33% - 37%
(-2%) - 3%
Climate 2100, Flanders
High scenario, Runoff peaks
 Change in flood risks is highly uncertain
0 -43 - -34
-33 - -19
1% - 22%
 Runoff peaks due to rainfall/ETo change decrease in low
scenario and increase in high scenario (up to 35%)
2100, Flanders
 Major influence due to sea level rise (Scheldt tidal Climate
river)
Demer.shp
23 %- 24%
-74 - -71
25 %32%
-70 - -56
33%-55
- 37%
- -44
CLIMAR
Climate change scenarios for
Belgium
• Sea level rise:
+20cm to
+2m
about 20cm past 100 years
Impacts on floods
• Flood map current climate:
T = 100 year
Current climate
Impacts on floods
• Flood map after climate scenarios:
T = 100 year
High scenario
High = Wet
Hydrological impacts
Low scenario
Low scenario, Runoff peaks
LOW FLOW PEAKS
(-88%)
(-87%)
(-67%)
(-62%)
(-54%)
- (-68%)
• Impact of climate scenarios on low flows
extremes:
- (-63%)
Low scenario
Mean
scenario
Mean
scenario,
Runoff peaks
Low scenario, Runoff peaks
- (-55%)
- (-48%)
LOW FLOW PEAKS
(-88%)
(-56%) - (-55%)
(-87%)
(-68%)
(-54%) -- (-52%)
(-51%) -- (-47%)
(-67%)
(-63%)
(-46%) -- (-40%)
(-62%)
(-55%)
(-39%) -- (-30%)
(-54%)
(-48%)
Meanscenario
scenario
High
Meanscenario,
scenario,Runoff
Runoffpeaks
peaks
High
(-35%)- -(-55%)
(-32%)
(-56%)
(-31%)
(-24%)
(-54%) - (-52%)
(-23%)- -(-47%)
(-21%)
(-51%)
(-20%) - (-15%)
(-46%) - (-40%)
(-14%) - (-10%)
(-39%) - (-30%)
Climate 2100, Flanders
High scenario
High scenario, Runoff peaks
-43 - -34
 Low flow risks increase significantly in
-33 - all
-19 scenarios
(-35%) - (-32%)
(-31%) - (-24%)
Demer.shp
(-23%)
- (-21%)
- -71
(-20%) -74
- (-15%)
-70
- -56
(-14%) - (-10%)
 May increase problems rel. water quality, navigation, drinking
water production, irrigation, ecological state
river valley, ...
-55 - -44
Climate 2100, Flanders
Hydrological impacts
• Drier summer climate can have severe impacts
• Mean water availability in Flanders and Brussels is very
limited: 1480 m3/(person.year)
– International standards: <2000 “zeer weinig”, <1000 “ernstig
watertekort”
– Causes:
• High population density:
– high urbanisation, pavements: increased surface runoff, decreased
infiltration
– high drainage in agriculture
– groundwater abstractions for drinking water supply (region of Waregem:
groundwater table levels >100m lower than natural conditions)
• (in Scheldt basin): less than half of available water is due to local rainfall
• strong dependency on neighbouring regions (The Netherlands: Meuse and canal
Gent-Terneuzen)
Climate change impact on urban
drainage
• Change in overflow frequencies storage + infiltration
facilities:
– Reservoir model:
Climate change impact on urban
drainage
• Change in overflow frequencies storage + infiltration
facilities:
– Change in storage capacity needed:
constant
throughflow
[l/(s.ha)]:
50
40
30
25
20
15
10
5
2
1
Return period overflow [years]:
0.5
+35%
+25%
+18%
+18%
+16%
+17%
+17%
+13%
+13%
+9%
1
+18%
+16%
+13%
+14%
+18%
+20%
+20%
+17%
+14%
+10%
2
+17%
+17%
+12%
+12%
+13%
+11%
+19%
+17%
+14%
+10%
5
+29%
+25%
+30%
+31%
+27%
+22%
+20%
+18%
+15%
+10%
10
+24%
+31%
+29%
+25%
+26%
+22%
+24%
+24%
+30%
20
+33%
+27%
+25%
+22%
+21%
+13%
+17%
+20%
+18%
Climate change impact on hydrology
Climate scenarios for Belgium till 2100:
Impact on water systems:
– Winter season:
• Rainfall increase
• ETo increase
• Sea level rise
Unclear impact on inland river floods
Increase in coastal flood risks
– Summer season:
• Rainfall decrease
Increase in low flow / water scarcity problems
• ETo increase
• More intense convective summer storms
Increase in sewer floods
Climate change impact on hydrology
For specific conditions of river basins in Flanders/Belgium:
• Climate scenarios up to 2100:
– Evolution towards more droughts
– Impact on flood risk along inland rivers unclear (<-> coast)
– Increase in short-duration rainfall extremes
• But: climate scenarios not equal to predictions !
– Evolve along with our knowledge and understanding
– High uncertainties; part of the uncertainties not accounted for
• Adaptation measures ?
– Use climate scenarios in water management planning !
– Take high uncertainties into account !
“concept of risk = probability * consequences”
“no regret” measures, “climate proof” investments
 design a flexible strategy (adaptable measures/investments)
Actions or adaptation measures
• See river basin and subbasin management plans
• New Sigmaplan
– Geactualiseerd Sigmaplan: gecontroleerde overstromingsgebieden
en natuurgebieden (1650 ha in 2030) en dijkverhogingen in steden
en industriegebieden
• Prediction of and warning for flood risks:
• Real-time prediction and warning system
• Real-time regulation of reservoirs: more efficient use of available storage capacity
by model-predictive control algorithms
Actions or adaptation measures
• Against drier summer climate:
– Maximum upstream holding of rain water in infiltration facilities,
ditches, low-lying spaces, ...
– Revision of regulations (vergunningen- en heffingenbeleid) and
water-pricing system (sturend waterprijzenbeleid: variabele tarieven
voor drinkwater, progressieve tarieven naargelang verbruik)
– Reduction of water consumption, water loss, reuse of water
(sensibilisering rationeel watergebruik)
– “Water-audit” for new or renovated buildings
– Innovation programmes for water efficient industrial production and
irrigation
Actions or adaptation measures
• Against increased temporal variability of rainfall: drier
summers + increased short-duration rainfall extremes:
– calls for more attention to (local) rain water management (also at
municipal level)
– additional (upstream and local) rain water storage and infiltration
needs
• More small scale solutions (at large scale)
• More important role to local water managers
Actions or adaptation measures
Accept increased frequencies of “water in the streets”
 local scale measures can significantly reduce the damage (for
same flood frequency)
Actions or adaptation measures
More local upstream storage (local terrain depressions)
 combined effect: reduces sewer flood frequencies & rain water
feeds groundwater table
Actions or adaptation measures
Better integration of water management and spatial planning /
urban design
Multiple functions to
open spaces (e.g.
parks) in the city:
FWO research project
together with
K.U.Leuven - ASRO
(PhD researchers
Isabelle Putseys
& Christian Nolf)
Actions or adaptation measures
Better integration of water management and ecological / nature
management
Role of wetlands:
SUDEM-CLI cluster
project for BelSPO
(cooperation with
U.Antwerp – ECOBE)
Actions or adaptation measures
Better integration of water management and agriculture
Avoid winter runoff (and erosion) and increase infiltration by
“adapted” agricultural management practices:
• groenbemesting
• ploegrichting
• bufferstroken naast rivier
Additional needs
• Improved cooperation between water managers and spatial
planners / urban designers, managemers of green zones in
the city (parks, playing gardens)
• Improved interlinking between:
– Guidelines for design of urban drainage systems (code van goede
praktijk voor het ontwerp van rioleringssystemen)
– “Watertoets”
– Building regulations (gewestelijke stedenbouwkundige verordening;
andere stedenbouwkundige voorschriften)
More info
Research project CCI-HYDR on
“Impact of climate change on hydrological extremes (peak and low
flows) along rivers (Scheldt and Meuse basins) and urban drainage
systems in Belgium”
(for Belgian Science Policy Office):
http://www.kuleuven.be/hydr/CCI-HYDR
Impact studies:
Instituut voor Natuur- en Bosonderzoek (INBO):
http://http://www.inbo.be
Vlaamse Overheid:
Waterbouwkundig Laboratorium:
http://www.watlab.be
Vlaamse Milieumaatschappij:
http://www.milieurapport.be
http://www.watertoets.be/publicaties