2013 International SWAT Conference & Workshops - Toulouse, France July 15-19, 2013, Toulouse

Using SWAT to understand the eco-hydrological response to droughts of a dry Mediterranean agro-forested catchment, southern Portugal

Juliana Santos, Júlio Lima, Madalena Moreira, Elsa Sampaio, João Pedro Nunes

Centre for Environmental and Marine Studies University of Aveiro (Portugal)

Institute of Mediterranean Agricultural and Environmental Sciences University of Évora (Portugal)

GOVERNMENT OF THE PORTUGUESE REPUBLIC

ERLAND Project

Guadalupe

Climate change is expected to increase aridity in the Mediterranean rim of Europe, leading to concerns on consequences for water resources availability in a region already under water stress

- Understanding how streamflow availability and vegetation growth have responded to past droughts

- How this might reflect future water availability conditions

Introduction

Study Site: Guadalupe

GUADALUPE:

Agro-forested catchment

Area: 446 ha

Elevation: 260 to 380 meters

Mediterranean inland climate with hot and dry summers and mild winters:

Mean annual precipitation (1973-2012): 533 mm

Mean annual temperature: 15.5ºC

Urban: 0.3 %

Annual Crops: 10.7 %

Olive groves: 2.6 %

Pasture: 5.4 %

Cork/holm oak (>50%) + pasture: 52.9 %

Cork/holm oak (30-50%) + pasture: 28.1 %

Representative of the dry regions of southern Portugal

0

200

400

600

800

1000

1200Total Yearly Rainfall (mm)

The catchment is representative of the streamflow sources for a network of reservoirs in the Évora region which provide water for irrigation and hydroelectric power generation

Hidrometric Station

Guadalupe

Study Site: Guadalupe

Évora city

Discharge:

0

2

4

6

8

10

12

14

16

18

Set/12 Out/12 Nov/12 Dez/12 Jan/13 Fev/13 Mar/13

Flo

w (

mm

)

Date

Flow(stream flow) mm

Soil Moisture:

0

10

20

30

40

50

600

100

200

300

400

500

600

Mai/11 Set/11 Jan/12 Mai/12 Set/12 Jan/13

PP

(m

m)

SWC

(m

m)

Date

SWC_mm

PP_mm

Data Collection:

Study Site: Guadalupe

Climate Data: • Rainfall • Wind Speed • Solar Radiation • Temperature • Relative Humidity

Hidrometric Station

Guadalupe

Évora - Mitra Évora - Cidade

Évora – Cidade Évora

0

200

400

600

800

1000

1200

19

73

19

74

19

75

19

76

19

77

19

78

19

79

19

80

19

81

19

82

19

83

19

84

19

85

19

86

19

87

19

88

19

89

19

90

19

91

19

92

19

93

19

94

19

95

19

96

19

97

19

98

19

99

20

00

20

01

20

02

20

03

20

04

20

05

20

06

20

07

20

08

20

09

20

10

20

11

Total Annual Rainfall (mm)

Mean = 533 mm

Data Collection:

Climate stations

Study Site: Guadalupe

Évora

2 Eddy covariance flux towers: Carbo Euro Flux 1999-2008

Guadalupe

PT – Mi1 Portugal - Mitra (Evora)

EBF (Evergreen Broadleaf

Forest)

D= 5 km

EBF (Evergreen Broadleaf Forest)

Grassland

D= 11 km

GRA (Grassland)

PT – Mi2 Portugal - Mitra IV (Tojal)

Data Collection:

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.000.00

2.00

4.00

6.00

8.00

10.00

12.00

PP

(m

m)

PET

an

d E

ET (

mm

/day

)

Precipitation (mm) PET_mm/d EET_mm/d_Mitra2

Dry - 2004/2005 Wet - 2005/2006 Wet - 2006/2007 Dry - 2007/2008

PP = 350 mm PP = 632 mm PP = 715 mm PP = 360 mm

ET

Aquifer Recharge

Streamflow Base flow

SW

SWAT Evapotranspiration:

• Soil Moisture • Plant Type • Stage of the plant development • Weather conditions

±

1,000 0 1,000500 Meters

Legend

SwatSoilClass(LandSoils1)

Classes

SROASBL

SROAPmn

SROAPMG

SROAPGD

SROAPG

• HRU definition

1

3

2

4

5

6

8 9

7

10

10 subbasins

Classes of Slope

Soil Type Land Uses

SWAT

±

1,000 0 1,000500 Meters

107 HRUs ±

1,000 0 1,000500 Meters

Legend

SwatSoilClass(LandSoils1)

Classes

SROASBL

SROAPmn

SROAPMG

SROAPGD

SROAPG

National Soil Cartography 1:25000

±

1,000 0 1,000500 Meters

Legend

SwatSoilClass(LandSoils1)

Classes

SROASBL

SROAPmn

SROAPMG

SROAPGD

SROAPG

• Parameterization

±

1,000 0 1,000500 Meters

Legend

SwatSoilClass(LandSoils1)

Classes

SROASBL

SROAPmn

SROAPMG

SROAPGD

SROAPG

SOIL LANDUSES

Coluvisols

Brown Mediterranean Soils - Schists

Brown Mediterranean Soils - Plutonic Rocks

Non-Humic Litholic Soils - Granite (shallow)

Non-Humic Litholic Soils - Granite

Olive groves: 2.6 %

Pasture: 5.4 %

Cork/holm oak (>50%) + pasture: 52.9 %

Cork/holm oak (30-50%) + pasture: 28.1 %

Annual Crops: 10.7 %

Urban: 0.3 %

SWAT

COS 2007 1:25 000

Hidrometric Station

Guadalupe

PT – Mi1

PT – Mi2

0

0.5

1

1.5

2

2.5

3

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

Dez

/04

Jun

/05

Dez

/05

Jun

/06

Dez

/06

Jun

/07

Dez

/07

Jun

/08

Dez

/08

LAI (

m2

/m2

)

Ab

ove

-Gro

un

d b

iom

ass

(kg/

m2

)

Above-Ground Biomass (kg/m2) LAI (m2/m2)

0

5

10

15

20

25

30

35

40

0

1

2

3

4

5

6

7

8

SWC

(%

)

PET

/EET

(m

m)

EET(LE)_mm/d

PET_mm/d

SWC 15 cm

MITRA 2 - PASTURE

SWAT Observed Data:

2004/2005 2005/2006 2006/2007 2007/2008

0

0.5

1

1.5

2

2.5

3

LAI (

m2

/m2

)

LAI sim (m2/m2)

LAI obs (m2/m2)

SWAT

PASTURE

Figure: Pasture production curve in rainfed Mediterranean conditions

Autumn Winter Summer Spring

Management Operations - PASTURE

Observed Data: D

aily

Gro

wth

0

0.5

1

1.5

2

2.5

3

LAI (

m2

/m2

)

Date

LAI sim (m2/m2)

LAI obs (m2/m2)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

EET

(mm

)

EET obs PT-Mi2 (mm)

EET sim (mm)

SWAT

PASTURE - Daily

Preliminary Results:

0

20

40

60

80

100

120

No

v/0

4

Dec

/04

Jan

/05

Feb

/05

Mar

/05

Ap

r/0

5

May

/05

Jun

/05

Jul/

05

Au

g/0

5

Sep

/05

Oct

/05

No

v/0

5

Dec

/05

Jan

/06

Feb

/06

Mar

/06

Ap

r/0

6

May

/06

Jun

/06

Jul/

06

Au

g/0

6

Sep

/06

Oct

/06

No

v/0

6

Dec

/06

Jan

/07

Feb

/07

Mar

/07

Ap

r/0

7

May

/07

Jun

/07

Jul/

07

Au

g/0

7

Sep

/07

Oct

/07

No

v/0

7

Dec

/07

Jan

/08

Feb

/08

Mar

/08

Ap

r/0

8

May

/08

Jun

/08

Jul/

08

Au

g/0

8

Sep

/08

EET

(mm

)

Observed EET (mm) Simulated ET (mm)

SWAT

PASTURE - monthly

Preliminary Results:

R2 = 0.59 NSE = 0.41 PBIAS = 11.1

2004/2005 2005/2006 2006/2007 2007/2008 R2 = 0.85

R2 = 0.66

R2 = 0.36

R2 = 0.84

• Baseflow separation with filter

• Recession curve analysis (Arnold et al, 1995)

Baseflow Separation

AlphaBf= (-1/N) ln(Qn/Qo) N=Number of day Qo=Q at the beginning of the recession Qn=Q at the end of the recession

Parameter Range

mean min max

Alha_Bf (day)

0.09 0.02 0.58

0

2

4

6

8

10

12

14

16

18

Set/12 Out/12 Nov/12 Dez/12 Jan/13 Fev/13 Mar/13

Flo

w (

mm

)

Date

Flow(stream flow) mm

bt (base flow) mm

0

2

4

6

8

10

12

14

16

18

Set/12 Out/12 Nov/12 Dez/12 Jan/13 Fev/13 Mar/13 Abr/13 Mai/13

Observed Flow (mm) Simulated Flow out (mm)

Preliminary Results:

SWAT

Conclusions

• The Evapotranspiration is a very important

parameter to understand the water balance

and can be simulated in SWAT

• The most sensitive parameter to calibrate LAI and evapotranspiration was heat unit

Ongoing:

• Compare the data with satellite data

• Future work will include the upscaling of the model for regional catchments, and its application to evaluate the impacts of climate change scenarios

ET

Aquifer Recharge

Streamflow Base flow

SW

Thank you for your attention