impact of climate scenarios on freshwater resources in the ......walter collischonn iph ufrgs...

Impact of climate scenarios on freshwater resources in the Rio

Grande - Brazil

Márcio NóbregaWalter Collischonn

IPH UFRGS

Instituto de Pesquisas Hidráulicas

Universidade Federal do Rio Grande do SulPorto Alegre,

Brazil

• 60% of hydropower production in Brazilcomes from the Paraná river and its tributaries

• Itaipu dam

2 The rio Grande basin: headwaters of the Paraná river

2 The rio Grande basin: Potential impacts

• Hydropower is the most important source of electric energy in Brazil

in recent years there was an increase in natural gas and nuclear power share

2 The rio Grande basin: Interest points

- drainage area of 145000 km2

- used extensively for hydropower generation (~12% of Brazilian total)

Hydroelectric reservoirs

Annual Precipitation: ~1400 mm.year-1

Wet SummerDry Winter Annual runoff: ~540 mm.year-1

Long term runoff coefficient: 0.39

3 The MGB-IPH large scale hydrological model

• Similar to the VIC (Univ. Washington) and LARSIM (Univ. of Freiburg) models

• Distributed (regular cells or small catchments)• Daily or hourly time steps• Typically applied in 6 minutes (0.1 degree)

latitude and longitude resolution


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GRUs

• Basin divided in grid cells• Grid cells divided in Grouped Response Units, or Hydrological

Response Units, according to soil types and vegetation cover or land use

• Parameters are related to GRUs and can be calibrated


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of cell i

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3CALIBRATION AND VERIFICATION OF THE HYDROLOGICAL MODEL

- In both calibration and verification, the values obtained for NS and NSlog coefficients were about 0.9 in all but one of the catchments;

- Values of volume bias were also acceptable, with values less than 0.05% during calibration and less than 7% at validation.

Verification period – outlet of Furnas catchment

The MGB-IPH large scale hydrological model

4 PREDICTION OF CLIMATE CHANGE IMPACTS

Scenarios

dados cenário períodocccma +2C 2040-2069 okcsiro +2C 2040-2069 ok without vapour pressure dataecham5 +2C f fhadgem1 +2C 2040-2069 okipsl +2C 2040-2069 okncar +2C 2040-2069 ok without vapour pressure dataukmo HadGEM1 A1B 2006-2100 ok without vapour pressure datacccma_A1B A1B f fCSIRO mk3.0. A1B 2006-2100 ok without vapour pressure dataecham5_A1B A1B 2006-2100 okhadcm3_a1b A1B f fhadcm3_a2 A2 2006-2100 okhadcm3_b1 B1 2006-2100 okhadcm3_b2 B2 2006-2100 okipsl_A1B A1B 2006-2100 okncar_A1B A1B 2006-2100 okhadcm3 +1 +1C 2040-2069 okhadcm3 +2 +2C 2040-2069 okhadcm3 +3 +3C 2040-2069 okhadcm3 +4 +4C 2040-2069 okhadcm3 +5 +5C 2040-2069 okhadcm3 +6 +6C 2040-2069 okdetrend 1961-90 CRU TS 2040-2069 detrend okBaseline CRU TS 3.0 1930-2002 CRU TS 3.0 data set okMGB-IPH 1970-1980 observed ok

2 degree prescribed warming scenarios

Hadley temperature cenarios

obs.




obs.


Scenarios


Concluding remarks regarding CRU usability

• CRU slightly underestimates rainfall in the Rio Grande Basin

• underestimation is higher in smaller basins• at Água Vermelha (close to basin outlet) the

underestimation of CRU is only 7% compared to naturalized streamflow

• the same magnitude of error was found during hydrological model verification

We can conclude that CRU satisfactorilyrepresents rainfall in the rio Grande basin




obs.


Scenarios


MGB-IPH using CRU with and without trend




obs.


Scenarios: one GCM (Hadley Centre) with different prescribed temperatures


• Streamflow will increase in all months in all scenarios• Higher global temperatures will result in higher rio

Grande discharge • 8 to 9% increase for each 1 degree increase in

temperature• Most important changes will occur in November and

December, which corresponds to the start of the wet season

• But what are the predictions of other GCMs?





obs.


Prescribed-temperature change scenarios with different GCMs


Prescribed-temperature change scenarios with different GCMs


Relative differences between GCMs in +2 scenarios and detrended series


Relative differences between GCMs in +2 scenarios and detrended series

2 degree scenarios

-40.0%

-30.0%

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% fr

om d

etre

nded

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rage

CCMA

CSIRO

ECHAM

HADGEM

NCAR

IPSL

Comments: +2 scenario difference between GCMs

• Three GCMs predict that average streamflow of the rio Grande will increase, while other three GCMs predict that average streamflow will decrease.

• Increase or decrease occurs both for low and high flows with no visible pattern

• A new generation of the Hadley Center model gives a prediction which is completely different from the previous generation.



Different GCMs and emission-based scenarios




obs.


Different Hadley Center emission scenarios

2061 - 2100

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hadcm3_a1bhadcm3_a2hadcm3_b1hadcm3_b2


Different GCMs same emission scenario (A1B)

2061 - 2100

-60%

-50%

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-30%

-20%

-10%

0%

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40%

1 2 3 4 5 6 7 8 9 10 11 12

ccma_a1b

csiro_mk30 x

echam5_A1B

hadcm3_a1b

ipsl_A1B

5 Impact assessment

Conclusions:

There is no consistency in climate change predictions in the RioGrande Basin.

5 Impact assessment

Future developments:

• Use the hydrological model outputs to feed the Long-term planning model of the hydropower system (NEWAVE) and see how energy costs will be affected

• Limited approach because several other basins in the region should be considered:

• less rainfall in one basin could be balanced by more rainfall inanother (energy production would be less affected)

5 Low frequency variability

Sequences of dry / wet years

impact of climate scenarios on freshwater resources in the ......walter collischonn iph ufrgs...

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