Implications of climate change on existing
and planned water resource development in
the Upper Blue Nile
AFRICA 2013 Conference: 16-18 April 2013
Matthew McCartney, Michael Girma and Solomon Demissie

• 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
Objectives

Modeling
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

Application of WEAP
• Water accounting model (mass balance) –
simulates water use across a range of
demands
• Data from:
– MoWR/EEPCo/NMA
– Basin Master Plans
– Irrigation efficiency studies
– New scheme feasibility studies
• Simulation 1983-2100 (monthly time step)

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)

Schematic of development scenarios
Current
development
Intermediate
development
Full
Development

Existing and Planned schemes
Current
Development
Intermediate
Development
Full
Development
Irrigation (ha) 15,345 272,018 364,355
Hydropower (MW) 218 2,194 10,276
Storage (Bm3) 11.6 70.2 167

Hydrological Impacts
-60
-40
-20
0
20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
%changeinannualflow
Sub-Basin
A1B scenario:changes inflow
2021-2050 2071-2100
-40
-30
-20
-10
0
10
20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
%changeinannualflow
Sub-Basin
A1B scenario: changes in groundwater recharge
2021-2050 2071-2100

Climate Impacts (A1B scenario)
19
20
21
22
23
24
25
26
27
1980 2000 2020 2040 2060 2080 2100
Temperature(oC)
Basin: annual temperature (oC)
600
800
1000
1200
1400
1600
1800
2000
1980 2000 2020 2040 2060 2080 2100
Rainfall(mm)
Basin: annual rainfall
1200
1250
1300
1350
1400
1450
1500
1550
1600
1650
1980 2000 2020 2040 2060 2080 2100
Potentialevapotranspiration(mm)
Basin: potential evapotranspiration
Impacts greatest in the
second half of the century

Climate impacts summary
Average annual
temperature (oC)
Average annual
rainfall (mm)
Potential Evapotranspiration
(mm)
1983-2102 20.9 1,310 1,363
2021-2050 21.9 1,290 1,405
2071-2100 24.9 1,110 1,535

Irrigation (1)
6,000
7,000
8,000
9,000
10,000
11,000
12,000
1980 2000 2020 2040 2060 2080 2100
Averageannualirrigation
Requirment(m3ha-1)
Basinaverage irrigationrequirement
1983-2012: 8,244
2021-2050: 8,491
2071-2100: 9,726
0
500
1,000
1,500
2,000
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Irrigationdemand(m3ha-1)
Average monthly requirement
1983-2012 2021-2050 2071-2100

Irrigation (2)
1983-2012
2021-2050
2071-2100
0
500
1000
1500
2000
2500
3000
3500
Current
Development
Intermediate
Development
Full development
Mm3
Irrigation water delivered Unmet demand
0
500
1000
1500
2000
2500
3000
3500
Current
Development
Intermediate
Development
Full development
Mm3
Irrigation water delivered Unmet demand
0
500
1000
1500
2000
2500
3000
3500
Current
Development
Intermediate
Development
Full development
Mm3
Irrigation water delivered Unmet demand

Hydropower (1)
0
10,000
20,000
30,000
40,000
50,000
60,000
1983
1989
1995
2001
2007
2013
2019
2025
2031
2037
2043
2049
2055
2061
2067
2073
2079
2085
2091
2097
HydrolectricityGenerated(GWhy-1)
Current development Intermediate Development Full Development

Hydropower (2)
Current Development Intermediate Development Full Development
Electricity
Generated
(GWhy-1)
% of
potential
Electricity
Generated
(GWhy-1)
% of
potential
Electricity
Generated
(GWhy-1)
% of
potential
1983-2012 1,397 100 12,814 98 40,803 91
2021-2050 1,390 100 12,962 99 44,245 98
2071-2100 1,138 82 8,422 64 28,449 63

Lake Tana: water levels
1,783
1,784
1,785
1,786
1,787
1980 2000 2020 2040 2060 2080 2100
Waterlevel(masl)
Lake Tana: average annual water level
Currentdevelopment Intermediate Development Full Development

Flows
0
200
400
600
800
1,000
1,200
1,400
1,600
1980 2000 2020 2040 2060 2080 2100
Flow(m3s-1)
Annual flowat Kessie
Current development Intermediate Development Full Development
0
500
1,000
1,500
2,000
2,500
3,000
1980 2000 2020 2040 2060 2080 2100
Flow(m3s-1) Annual flow at the Ethiopia-Sudanborder
Current development Intermediate Development Full Development

Flow Summary (m3s-1)
Current Development Intermediate Development Full Development
Outflow
Tana
Kessie Border Outflow
Tana
Kessie Border Outflow
Tana
Kessie Border
1983-2012 177 617 1,655 81 522 1,622 87 528 1,599
2021-2050 158 659 1,713 61 563 1,678 63 564 1,683
2071-2100 45 444 1,327 10 409 1,305 21 421 1,301

Conclusions
• Combining climate, hydrological and water resources
models provides a useful tool to assess the possible
water resource implications of CC.
• Results indicate:
• long time horizon for full effect of climate change
(“end of the century“)
• considerable spatial variability in hydrological
impacts of CC
• clear trends but increasing variability in many
hydrological variables
• Mid-range climate change is likely to impact the
performance of planned irrigation and hydropower
schemes significantly by the end of the 21st century.

Thank you