PowerPoint-presentatie

Climate change scenarios

for hydrological impact

analysis (floods, droughts)

Parisa Hosseinzadehtalaei, Hossein Tabari,

Els Van Uytven, Patrick Willems

KU Leuven - Hydraulics Section

Climate change impact analysis

GCMs

RCMs

Urban hydrological

impact models

Statistical

downscaling

incl. bias

correction

Large ensemble (>200): CMIP5

Reduced ensemble:

CORDEX

Climate scenarios

Coarse resolution climate models

-> need for downscaling + bias correction

Thanks to CORDEX.be

GCMs

RCMs

LAMs

Statistical

downscaling

incl. bias

correction

Large ensemble (>200): CMIP5

Reduced ensemble:

EURO-CORDEX

Climate scenarios

High resolution (2.8 4 km)

convection permitting models

Urban hydrological

impact models

Changes in precipitation extremes

Influence of number of model runs?

Hosseinzadehtalaei P, Tabari H, Willems P (2017) Uncertainty assessment for climate change impact on intense

precipitation: How many model runs do we need? International Journal of Climatology, 37(S1), 1105-1117

Climate model based variance analysis for extreme precipitation:

At least 10-15 runs needed for

obtaining unbiased & reliable

change factors

Climate scenarios

GCMs

RCMs

LAMs

Statistical

downscaling

incl. bias

correction

Large ensemble (>200): CMIP5

Reduced ensemble:

EURO-CORDEX

Climate scenarios

Urban hydrological

impact models

CORDEX.be runs

-> downscaling

CORDEX.be runs

-> downscaling + lower bias for precipitation extremes

Tabari H, De Troch R, Giot O, Hamdi R, Termonia P, Saeed S, Brisson E, Van Lipzig N, Willems P (2016)

Local impact analysis of climate change on precipitation extremes: are high-resolution climate models needed

for realistic simulations? Hydrology and Earth System Sciences 20: 3843-3857

Coarser resolution

models, daily

LAM fine resolution models, hourly

Tabari H, De Troch R, Giot O, Hamdi R, Termonia P, Saeed S, Brisson E, Van Lipzig N, Willems P (2016)

Local impact analysis of climate change on precipitation extremes: are high-resolution climate models needed

for realistic simulations? Hydrology and Earth System Sciences 20: 3843-3857

Saeed S, Brisson E, Demuzere M, Tabari H, Willems P, van Lipzig N (2017) Multidecadal convection permitting

climate simulations over Belgium: Sensitivity of future precipitation extremes. Atmospheric Science Letters

18(1): 29-36

Coarser resolution

models, 3-hourly

LAM fine resolution

models, 15min

CORDEX.be runs

-> downscaling + lower bias for precipitation extremes

ALARO model

Changes in precipitation extremes

Tabari H, De Troch R, Giot O, Hamdi R, Termonia P, Saeed S, Brisson E, Van Lipzig N, Willems P (2016)

Local impact analysis of climate change on precipitation extremes: are high-resolution climate models needed

for realistic simulations? Hydrology and Earth System Sciences 20: 3843-3857

Relative changes till 2071-2100:

Strong (potential) dependency of climate

change factor on time & spatial scale

CCLM model

LAM fine resolution, hourly

Coarser resolution models, daily

Changes in precipitation extremes

Higher changes for higher return periods & shorter durations:

Changes in precipitation extremes

Higher changes for higher greenhouse gas concentrations:

Conclusions

Because at least 10 to 15 different models should be considered for

obtaining reliable climate change factors

& no large ensemble of super resolution climate model runs available yet:

hydrological impact modellers have to rely on:

combining available climate change projections from:o GCMs (large ensemble available; CMIP5)

o RCMs (smaller ensemble available; EURO-CORDEX)

o LAMs (few models and runs available; CORDEX.be)

to be further downscaled applying statistical methods

where statistical downscaling assumptions have to be applied with caution and validated as much as possible

Applications

Changes in precipitation extremes -> Changes to design storms (design of urban drainage systems):

0

10

20

30

40

50

60

70

-100 -50 0 50 100

Rai

nfa

ll in

ten

sity

[mm

/h]

Time [min]

historical climate

mean climate scenario

high climate scenario

Applications

Changes in precipitation, temperature, ETo statistics -> Perturbed historical time series (river catchment

hydrological impact analysis: floods, droughts, ):

Spills

Calculation nodes

numerical scheme

Right floodplainLeft floodplain

Bridge over tributary(culvert + weir)

MAIN RIVER

TRIBUTARY

Climatic change signals:

Climatic Perturbation Tool:

Hydrological & hydraulic impact models:

Impact results:

Current climate

Climate scenarios

>200 GCMs CMIP5 (RCP based) for Uccle: change for 100 years (2000 -> 2100):

Change in mean monthly temperature:

Strong increase in temperature

(mainly in summer)

Current climate

Climate scenarios

>200 GCMs CMIP5 (RCP based) for Uccle: change for 100 years (2000 -> 2100):

Change in mean monthly rainfall:

Winter: increase in rainfall

Summer: strong decrease in rainfall

Climate scenarios

>200 GCMs CMIP5 (RCP based) for Uccle: change for 100 years (2000 -> 2100):

Change in number of wet days:

Current climate

Summer: strong decrease in number of rainy days

Climate scenarios

>200 GCMs CMIP5 (RCP based) for Uccle: change for 100 years (2000 -> 2100):

Change in rainfall intensity for 20-year storm:

Increase in extreme rainfall intensities

Current climate

Applications

Changes in precipitation, temperature, ETo, statistics: Climate Perturbation Tool

Month i Month i Month i

Wet day frequency

perturbation

Wet day intensity

perturbation

Combined perturbation

Time

series

Time

series

Perturbs historical series to high/mean/low climate scenarios

Time scales: daily, hourly, 10-minutes

Based on quantile perturbations:

change in rain storm frequency and rain storm intensity

dependent on return period and season

Time horizons till 2030, 2050, , 2100

High = Wet

Mean = Mild

Low = Dry

Daily

Hourly

10min

High/mean/low climate scenarios, tailored for

hydrological climate change impact analysis

High / Wet

Mean / Mild

Low / Dry

IMP

AC

T

Floods

Low flows

Hydrological impact analysis

Rainfall, ETo

Rainfall-runoff

River

hydrodynamics

Physico-

chemical river

water quality

PDM, NAM, VHM:

conceptual

Spatially distributed:

MIKE-SHE

WetSpa

Modflow

InfoWorks (RS, ICM)

MIKE11

+ floodplains

Spills

Calculation nodes

numerical scheme

Right floodplainLeft floodplain

Bridge over tributary(culvert + weir)

MAIN RIVER

TRIBUTARY

Our recent CORDEX.be papers on the topic:

Tabari H, De Troch R, Giot O, Hamdi R, Termonia P, Saeed S, Brisson E, Van

Lipzig N, Willems P (2016) Local impact analysis of climate change on

precipitation extremes: are high-resolution climate models needed for realistic

simulations? Hydrology and Earth System Sciences 20: 3843-3857

Saeed S, Brisson E, Demuzere M, Tabari H, Willems P, van Lipzig N (2017)

Multidecadal convection permitting climate simulations over Belgium:

Sensitivity of future precipitation extremes. Atmospheric Science Letters

18(1): 29-36

Hosseinzadehtalaei P, Tabari H, Willems P (2017) Uncertainty assessment for

climate change impact on intense precipitation: How many model runs do we

need? International Journal of Climatology 37(S1): 1105-1117

Hosseinzadehtalaei P, Tabari H, Willems P (2017) Precipitation intensity

durationfrequency curves for central Belgium with an ensemble of EURO-

CORDEX simulations, and associated uncertainties. Atmospheric Research

200: 1-12; doi:10.1016/j.atmosres.2017.09.015

Contact:patrick.willems@kuleuven.be