The hydrological regime of the Iberá and Pantanal wetlandsThe hydrological regime of the Iberá and Pantanal wetlands y g gand the potential impacts of Climate Changeand the potential impacts of Climate Changep p g

Natalia Montroull1 ,* Ramiro Saurral1 ,2 Inés Camilloni1 ,2Natalia Montroull , , Ramiro Saurral , ,  Inés Camilloni ,

*nmontroull@cima.fcen.uba.arnmontroull@cima.fcen.uba.ar1C t d I ti i d l M l At ó f (CONICET UBA)1Centro de Investigaciones del Mar y la Atmósfera (CONICET‐UBA), 

UMI IFAECI/CNRS, Buenos Aires, Argentina2Departamento de Ciencias de la Atmósfera y los Océanos (FCEN, UBA)p y ( , )

Buenos Aires, ArgentinaBuenos Aires, Argentina

MotivationMotivationTh L Pl t B i (LPB) i th t S th A i h t th P t l d Ib á tl d th l t ti f h t tl d i S th A i Th h t l fl d f i i i th ld f thThe La Plata Basin (LPB) in southeastern South America hosts the Pantanal and Iberá wetlands, the largest continuous freshwater wetlands in South America. They host several flora and fauna species unique in the world, some of themvulnerable and threatened. Wetlands are ecosystems characterized for being covered or saturated by water for all or part of the year. Therefore, the hydrological regime is determinant for their presence and permanence. Both land use changesand climate variability and change modify the hydrological conditions of the systems and consequently could affect the wetlands biodiversity. A detailed knowledge of the hydrological variability in the region will be an important tool for they g y y g y q y y g y g y g pdevelopment of better management practices and adaptation strategies for the conservation of the region.development of better management practices and adaptation strategies for the conservation of the region.

Obj iObjectives Estimate future hydrological scenarios in the study area consideringjEvaluation of the ability of the Variable Infiltration Capacity (VIC)

Estimate future hydrological scenarios in the study area consideringh i i it ti d t t f th 21 t t d i d f

y p y ( )hydrology model to estimate river discharges downstream of the Iberá

changes in precipitation and temperature for the 21st century derived fromhydrology model to estimate river discharges downstream of the Iberá

d P l l dthe ECHAM5/MPI‐OM Global Climate Model

and Pantanal wetlandsthe ECHAM5/MPI OM Global Climate Model

D d M h d lData and Methodologygy

• The Variable Infiltration Capacity (VIC)p y ( )hydrology model (Liang,1996) was used to The delta change approach was used forTemperature data Precipitation datahydrology model (Liang,1996) was used tosimulate the present water balance and to

The delta change approach was used for t ti li t h i d t t d

p p

simulate the present water balance and toassess the potential impacts of future climate

constructing climate change scenarios data sets and assess the potential impacts of future climateh h h d l f h C i (CB)

assess projected changes in flows of the Upper Paraguay change on the hydrology of the Corriente (CB)

p j g pp g yand Corriente riversand Upper Paraguay (UPB) basins, which and Corriente rivers.

Thi h d i i ddi h f h b liinclude the Iberá and Pantanal This method consists in adding a change factor to the baseline

wetlands respectively period time series of climate observations. The change factorswetlands, respectively.(percentage change in precipitation and absolute change in

Th d l i l t d th b i

(p g g p p gtemperature) were derived by calculating the differences between• The model was implemented over the basins

ºtemperature) were derived by calculating the differences betweenannual mean projected and baseline daily maximum and minimumat a 1/8º grid spatial resolution. annual mean projected and baseline daily maximum and minimumt t d i it ti i l t d b th ECHAM5/MPItemperature and precipitation simulated by the ECHAM5/MPI‐

• The meteorological forcing data used for the model• Runoff provided by the VIC model was OM. These model outputs were chosen for this study as it is one of• The meteorological forcing data used for the model

lib ti d il ti i f i dRunoff provided by the VIC model wasrouted using an offline routing model enabling the best GCM in representing the present climate in LPB (Saurralcalibration are daily time series of maximum androuted using an offline routing model enablingthe computation of streamflow at selected

p g p (

2010) as compared with others included in the WCRP‐CMIP3 multi‐minimum temperature and precipitation for the periodthe computation of streamflow at selected

( ll

2010) as compared with others included in the WCRP CMIP3 multimodel dataset1990‐1999 (baseline period). All meteorological data was

closure points within a basin (LosLos LaurelesLaureles in model dataset.( p ) ggridded into the 1/8° grid using the Kriging method.

CB and LadarioLadario in UPB).hi l i l d d i f h

gridded into the 1/8 grid using the Kriging method.)

• This new meteorological data set were used as input for the• Observed monthly streamflow data for the period

Thydrological model• Observed monthly streamflow data for the period

1990 1999 h i i d lib2)(∑ −T

tt QQ 1990‐1999 at the two gauging stations used to calibrate

10 )(

1∑=t

mQQNSE • Three future time slices (2020‐2029 2050‐2059 and 2080‐the VIC model results were provided by the Argentine• The quality of VIC in simulation the

2__

11∑=−= T

t

tNSE Three future time slices (2020 2029, 2050 2059 and 20802089) and three emissions scenarios (A1B A2 and B1) wereWater Resources Secretary and the Brazilian Waterhydrological cycle was assesed by the the

200 )(∑ −t QQ 2089) and three emissions scenarios (A1B, A2 and B1) were

id d

yResources Agency respectively

y g y yNash‐Sutcliffe coefficient of efficiency (NSE).

100∑

=t considered.Resources Agency respectively.Nash Sutcliffe coefficient of efficiency (NSE).

VIC d l f áVIC model performance Future hydrology scenarios in the Pantanal and Iberá wetlandsp Future hydrology scenarios in the Pantanal and Iberá wetlands

• The flat topography of this basin leads to low runoff ratios in Los Laureles at the outlet of Iberá Corriente River Basin (CB)• The flat topography of this basin leads to low runoff ratios in Los Laureles, at the outlet of Iberá.Despite this the VIC model reasonably represents the annual cycle and variability which is reflected in a

( )Despite this, the VIC model reasonably represents the annual cycle and variability, which is reflected in a

d l ffi i (NSE) f 0 68 P i it ti The changes in precipitation and temperature result in amplifiedmodel efficiency (NSE) of 0.68. Precipitationchange

The changes in precipitation and temperature result in amplifiedd b bl t d i t i th C i t Ri• Although the model tends to delay the peak in May, the annual cycle is properly represented as well change and probably exaggerated increments in the Corriente River

as the mean streamflow with a difference between the mean simulated and observed values of 0.1%. streamflow for all time slices and scenarios.

In all cases, streamflow increments are consistent with theIn all cases, streamflow increments are consistent with thepositive changes in precipitation projected for this basin although the

Corriente River at Los Laurelespositive changes in precipitation projected for this basin although therelative streamflow changes are up to 3 or 4 times larger than therelative streamflow changes are up to 3 or 4 times larger than the

di i f ll h i d b h GCM f h Ib áTemperature

corresponding rainfall changes estimated by the GCM for the IberáTemperature

change wetland region.change

Upper Paraguay Basin (UPB)Projected temperature, 

Upper Paraguay Basin (UPB)rainfall and streamflow

changes with respect to the  Precipitation changebaseline period (1990‐1999)  

The VIC model represents adequately the annual cycle and the mean streamflow of the Paraguayfor 

The VIC model represents adequately the annual cycle and the mean streamflow of the ParaguayRi ith ti bi f 4 5% lth h it t ti ll ti t th i d d

CB and UPBRunoff changelRiver with a negative bias of 4.5%, although it systematically overestimates the maximum and reduces @ Los Laureles

the duration of the flood season.

In this case the NSE is negative but the highest number of rainfall stations considered in the UPBIn this case, the NSE is negative but the highest number of rainfall stations considered in the UPBshows an improvement of the hydrological model performance in this basin in comparison with previous

Temperatureshows an improvement of the hydrological model performance in this basin in comparison with previoust di (S l 2009 S l 2010)

changestudies (Su et al. 2009; Saurral 2010).

T t h l th th bt i d f thTemperature changes are larger than the ones obtained for theParaguay River at Ladario Iberá wetlands .g y

Precipitation changes for the region are highly variablePrecipitation changes for the region are highly variablebetween the three emissions scenarios Runoff change @ 

L d i

between the three emissions scenarios.Ladario

f fChanges in streamflow of the Paraguay River at Ladario resultprincipally from the changes in precipitation.p p y g p p

C l iConclusions

Alth h t d d t t i i i bl i it ti d t t th fi t h th t t ff t h i ff i th t l d b i P j t d i d it b tlAlthough water resources are dependent upon two main primary variables, precipitation and temperature, the first one has the greatest effect on changes in runoff in the two analyzed basins. Projected warming and its subsequentlyeffect in increasing the evapotranspiration and reducing the runoff do not compensate the increment in precipitation. Moreover, positive changes in rainfall in the Paraguay and Corriente basins resulted in amplified changes in streamflow.

There are many uncertainties in the hydrological projections presented in this study mainly associated to climate change scenarios. However, the ability of the VIC model to simulate the basic features of the streamflow annual cycle ofy y g p j p y y g , y ythe Corriente and Upper Paraguay rivers and its use considering temperature and precipitation outputs from a GCM that represents adequately regional present climate allow us to make a first order assessment of the potential impacts ofthe Corriente and Upper Paraguay rivers and its use considering temperature and precipitation outputs from a GCM that represents adequately regional present climate allow us to make a first order assessment of the potential impacts ofclimate change on two of the largest world’s freshwater wetlandsclimate change on two of the largest world s freshwater wetlands.

AcknowledgmentsBibliography gBibliography

The research leading to these results was partially funded by the European Community’s Seventh Framework Programme (FP7/2007‐2013)The research leading to these results was partially funded by the European Community s Seventh Framework Programme (FP7/2007 2013)under Grant Agreement 212492 (CLARIS LPB: A Europe‐South America Network for Climate Change Assessment and Impact Studies in La Plata

• Liang, X., D. P. Lettenmaier, and E.F. Wood, 1996: One‐dimensional statistical dynamic representation of subgrid spatial variability ofi i i i h l V i bl I fil i C i d l J G h R 101 (D16) 21403 21422

g ( p g pBasin) and by grants ANPCYT PICT07‐00400, CONICET PIP5400 and University of Buenos Aires UBACYT‐X033.

precipitation in the two‐layer Variable Infiltration Capacity model, J. Geophys. Res., 101 (D16), 21403‐21422.• Saurral R 2010 The hydrological cycle of the La Plata Basin in the WCRP CMIP3 multi model dataset J Hydrometeor 11(5) 1083 1102

y g yThe authors would like to acknowledge the Program for Climate Model Diagnosis and Intercomparison (PCMDI) for collecting and archiving the

• Saurral, R., 2010: The hydrological cycle of the La Plata Basin in the WCRP‐CMIP3 multi‐model dataset, J. Hydrometeor., 11(5), 1083–1102.• Su F and D P Lettenmaier 2009: Estimation of the surface water budget of the La Plata Basin J Hydrometeor 10 981 998

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