Implications of climate change on existing and planned water resource development in the Volta

River Basin

GWSP 2013 Conference21-24 May 2013, Bonn Germany

Matthew McCartney, Gerald Forkour, Aditya Sood, Barnabas Amisigo, Fred Hattermann and Lal Muthuwatta

Research funded by:

Background

• Water resources in the Volta basin is vital

- Hydropower, agriculture, fisheries, livestock, tourism, etc.

• Inability to manage rainfall variability is a key constraint to agriculture and economic development.

• Increasing pressure on water resource

• Plans to build more dams for hydropower and irrigation

• CC and its associated uncertainty, may aggravate pressure on water resource

Objectives

• Simulate water demand for major production activities (existing and planned)

• Evaluate the possible implications of CC on water resources/scheme performance (how do long-term benefits change?)

• Assess impacts of water resources development and CC on river flows

Approach

Climate change simulation (CCLM)• temperature • rainfall • potential evapotranspiration

Hydrological modeling (SWAT)• actual evapotranspiration • groundwater recharge • river flow

Water Resources Modeling (WEAP)• irrigation • hydropower• river flow

Changing climate (Downscaled A1B)

Rainfall (mm)

Potential Evapotranspiration

(mm)

Actual Evapotranspiration

(mm)

Groundwater Recharge (mm)

1983-2012 835 2,729 717 76

2021-2050 757 2,813 668 53

2071-2100 666 3,323 606 36

Basin wide annual averages

400

500

600

700

800

900

1000

1100

1980 2000 2020 2040 2060 2080 2100

Rain

fall

(mm

)

2500

2700

2900

3100

3300

3500

3700

3900

4100

1980 2000 2020 2040 2060 2080 2100

Pot.

Evap

otra

nspi

ratio

n (m

m)

0

20

40

60

80

100

120

140

160

180

1980 2000 2020 2040 2060 2080 2100

Gro

undw

ater

Rec

harg

e (m

m)

Rainfall(mm) PE(mm) Groundwater Recharge(mm)

Impacts on flow

1

10

100

1000

10000

100000

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

1983 -2012 2021-2050 2071-2100

0

500

1000

1500

2000

2500

3000

3500

4000

4500

1980 2000 2020 2040 2060 2080 2100

Flow

(m3 s

-1)

m3s-1 CV

1983-2012 1,610 0.34

2021-2050 1,217 0.49

2071-2100 885 0.67

Development Scenarios

A1B scenario run with three development scenarios:

• Current Development (baseline)

• Intermediate Development: Planned development (feasibility

studies)

• Full Development: Potential development

(Basin Master Plans)

Existing and Planned schemes

Current Dev.

Inter. Dev.

Full Dev.

Irrigation (ha)

30,468 63,253 78,007

Hydropower (MW)

1,044 1,547 2,032

Storage (Bm3)

153 180 203

Nanggodi

Dapola

Kanazoe Dam (75 Mm3)

Yakala

WayenIrrigation(66.2 Mm3)Bagre Dam

(1700 Mm3)

Irrigation(2.6 Mm3)

Nawuni

Sabari

Livestock3.5 Mm3

Irrigation (46.4 Mm3)

Irrigation (19.2 Mm3)

NwokuyLerinord

Livestock3.8 Mm3

Blac

k Vo

lta

Arly

Livestock3.3 Mm3

Hydropower 577 Mm3

Irrigation 27 Mm3

Livestock1.3 Mm3

Prang

Irrigation81 Mm3

AkosomboHydropower 38,660 Mm3

Tono (93 Mm3)

Irrigation 67 Mm3

Vea (16 Mm3)Irrigation

Lerinord Seouro (277 Mm3)

Whi

te V

olta

Livestock5.5 Mm3

Livestock16.3 Mm3

Livestock5.5 Mm3

Livestock13.4 Mm3

Livestock12.5 Mm3

Livestock2.6 Mm3

Ekumdipe

Diversions

Reservoir

Koumangou

Oti

Low

er V

olta

Noumbiel

Bamboi

Pwalugu

Kompienga

Mango

Senchi

Livestock4.9 Mm3

Estuary

Flow gauging station

Burkina Faso

Togo

Burkina Faso

Ghana

Togo

Benin

Ghana

Benin

SRs: (0.6 Mm3)

SRs: (41.6 Mm3) SRs: (7.7 Mm3)

SRs: (5.8 Mm3)

SRs: (1.0 Mm3) SRs: (24.3 Mm3) SRs: (12.9 Mm3)

SRs: (22.6 Mm3)

SRs: (2.1 Mm3)

SRs: (6.5 Mm3)

SRs: (42.6 Mm3)

SRs: (64.9 Mm3)

SRs: Small reservoirs

Ziga Dam (200 Mm3)

Subinja dam (135 Mm3) Tanoso dam

(125 Mm3)

Amate Dam (120 Mm3)

Results: Irrigation

13500

14000

14500

15000

15500

16000

16500

1980 2000 2020 2040 2060 2080 2100

Avg.

Ann

ual I

rrig

ation

dem

and

(m3 h

a-1)

0

400

800

1,200

Currentdevelopment

Intermediatedevelopment

Full development

Volu

me

of w

ater

(MCM

)

Scenario

Irrigation water delivered Unmet demand

0

400

800

1,200

Currentdevelopment

Intermediatedevelopment

Full development

Volu

me

of w

ater

(MCM

)

Scenario

Irrigation water delivered Unmet demand

0

400

800

1,200

Currentdevelopment

Intermediatedevelopment

Full development

Volu

me

of w

ater

(MCM

)

Scenario

Irrigation water delivered Unmet demand

1983-2012

2012-2050

2071-2100

Results: Hydropower

Current Development

Intermediate Development

Full Development

1983-2012 4,678 6,975 8,467

2021-2050 3,159 4,779 5,673

2071-2100 1,569 2,599 2,701

0

5000

10000

15000

20000

25000

30000

1983 1998 2013 2028 2043 2058 2073 2088

Gen

erat

ed E

lect

ricity

(GW

hy-1

)

Full development Intermediate development Current development

Conclusion

• The exact impact of CC on water resources of the Volta basin is still uncertain

• Mid-range CC is likely to impact the performance of planned irrigation and hydropower schemes significantly by the end of the 21st century.

• Fulfilling irrigation demand and meeting hydropower potential production will be increasingly difficult. Prospects for development and economic growth in Ghana could be hindered by CC

• Adaptation to climate change and development are clearly linked and need to be considered together.

• In comparison to the past, planning of water storage needs to be much more systematic and integrated across a range of levels and scales

Thank you