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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