Rethinking water storage for agricultural
adaptation to climate change in SubSahara Africa
Dr. Matthew McCartney and Dr. Irit Eguavoen
Tropentag Zürich, 16. September 2010
Research funded by:
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Project
Project rationale – water storage as adaptation to CC
Water Storage Continuum
Approach
Research results – example Koga watershed
Project output – evaluation metrics
Project 2008-2011
Objective
Guidance on storage options that ensure optimal adaptation to CC-induced impacts on water
availability in SSA
Research Questions
• How can the need for water storage and the effectiveness and suitability of different
storage options be evaluated and compared for different climate scenarios?
• How can water resource planning and management processes be modified to better
account for the uncertainties arising from climate change?
Principal output
Guidelines on how to build climate change into decision-making processes for the planning
and management of agricultural water storage in sub-Saharan Africa
Project 2008-2011
Blue Nile River basin/
Ethiopia
Volta River basin/ Ghana
Partners
• Arba Minch University (AMU), Ethiopia
• Ethiopian Economic Association (EEA)
• Water Research Institute (WRI), Ghana
• Institute of Statistical, Social and Economic Research (ISSER), Ghana
• Center for Development Research (ZEF), Germany
• Potsdam Institute for Climate Impact Research (PIK), Germany
Project Rationale
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Water storage is widely advocated as a key mechanism for CC adaptation
Little analysis of how CC affects existing water storage or how to account for CC in the
planning and management of new water storage
Physical Water Storage Continuum
Conceptual overview developed by project participants (IWMI Policy Brief 31)
Project Approach
Blue Nile basin watersheds
Koga – Gumara – Indris
Volta basin watersheds
Vea (Yaragagna) – Saata – Golinga
Basin scale analyses
Evaluation of climate change
impacts on storage at basin scale
► effectiveness
Site level analyses
Understanding storage at the local
(hydrological, economic, sociopolitical aspects)
► need, effectiveness & suitability
Evaluation metrics to determine
• The need for water storage
• The effectiveness of different options
• The suitability of different options
Basin scale analyses (Blue Nile and Volta)
Climate - rainfall, temperature, evaporation
• Historic climate
• CC scenarios (downscaled to the basins)
Hydrological model (SWAT/ SWIM)
Results:
Flow at key locations (sub-catchments)
Water resource modeling (WEAP)
• current water resource development
• future water resource development
Results:
Water availability for irrigation/hydropower
Effectiveness of existing and planned storage
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P
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D
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Current and future storage
plus water use in each basin
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Evaluation of climate change
impacts on storage at the
basin scale
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Analysis of sub-catchments/
watersheds
Climate Modeling (Blue Nile and Volta)
• Approaches of downscaling
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Dynamical climate models: CCLM and REMO (both for A1B) + bias correction
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Statistical climate model: WettReg (for different scenarios and GCMs)
• Resolution: 0.5° (attempt 10 km but not yet complete)
• Further regionalization / interpolation to locations of interest
Mean annual total
precipitation (mm)
1971-2000
Source:
Hattermann 2010
Hydrological Modeling (sub-catchments)
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Rainfall-Runoff simulation to determine
impacts of CC on flow regimes and
groundwater recharge
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Daily simulation to deduce impacts on
extremes – floods and droughts
Blue Nile – Models
STREAM
Resolution 1km,
SWIM
Soil Water Model (root zone and deep soil water)
Modified MWB
Three parameter lumped model – gridded 10km
Volta – Models
SWAT
Soil and Water Assessment Tool – Hydrological Response Units
Water Resource Modeling
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Water Evaluation and Planning (WEAP) Model at basin level/ of selected subcatchments
Water accounting model (mass balance) – optimizes water use (monthly time-step)
Sources of data
Blue Nile basin
Volta basin
MoWR
Hydrological Services Department
Basin Master Plans
Volta River Authority
Irrigation efficiency studies
Ghana Water Resources Management Study
New scheme feasibility studies
Site Level Analyses/ Ethiopia
Ethnographic research
• acquisition of storage facilities
• rules & regulations
• land & water rights
• management bodies
• resettlement & compensation
• livelihood change
• gender aspects
Socio-economic surveys
• 200 hh per watershed
• identification of water sources
• cost & benefits of water storage
• farmers´ perception of storage
and climate change
(data analysis on-going)
Indris
Source: ZEF
Research results – Blue Nile basin
Blue Nile/ Ethiopia
Existing and planned schemes
Mean Monthly Flow (Mm 3 )
18,000
16,000
14,000
12,000
Current
Near future
Distant future
Irrigation (ha)
10,000
210,000
451,000
Hydropower (MW)
218
2,194
6,426
Storage (Bm3)
11.5
56.8
~100
Simulated natural and 2025 scenario flow at the border Simulated natural MAF = 47.0 Bm3
Simulated current MAF = 46.9 Bm3
Simulated 2015 MAF = 44.8 Bm3
Simulated 2025 MAF = 44.4 Bm3
30,000
25,000
)
m 20,000
M
( 15,000
w
10,000
lo
F
5,000
3
10,000
8,000
6,000
4,000
2,000
0
0
1
2
3
4
Natural flow 5
6
7
2015 flow
8
9
10
11
0
6
‐
n
aJ
12
1
6
‐l
Ju
3
6
‐
n
aJ
4
6
‐l
Ju
6
6
‐
n
aJ
7
6
‐l
Ju
9
6
‐
n
aJ
0
7
‐l
Ju
2
7
‐
n
aJ
3
7
‐l
Ju
5
7
‐
n
aJ
6
7
‐l
Ju
8
7
‐
n
aJ
9
7
‐l
Ju
1
8
‐
n
aJ
2
8
‐l
Ju
4
8
‐
n
aJ
5
8
‐l
Ju
7
8
‐
n
aJ
2025 flow
Simulated natural flow at the border
Simulated 2025 scenario flow at the border
Results (no climate change)
Current
Near
future
Distant
future
Irrigation Demand (Bm3)
0.20
3.65
5.13
Hydropower (Gwhy-1)
1,383
12,908
31,297
Sources: Mc Cartney et al. 2009
8
8
‐l
Ju
0
9
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n
aJ
1
9
‐l
Ju
Water Resource Modeling
Unregulated flows
(downstream of
proposed dams and
unregulated rivers)
Regulated flows
Beles hydropower
transfer
Gilgel Abay
1925
Megech
176
Koga
Ribb
216
Gumar
244
a
Intermediate
2180
flow
Gondar town
116
WEAP model set up for
Lake Tana sub-basin
246
Lake
pumpin
g
scheme
s
Andass 270
a
Legen
Irrigation Scheme
d
116 Mean annual
inflow (Mm3)
Dam
Withdrawals
Return flow
Tis Abay
power
plants
Tis Issat
Falls
Abay (Blue
Nile)
Lake level (masl)
Lake Tana
1788
1787
1786
1785
1784
1783
1
3
Natural
5
7
9
11
FDS with TBF
13
15
17
19
FDS with VEF
Rivers
Source: McCartney et al. 2010
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23
Year
25
27
29
31
33
35
Koga site
Research results – Koga watershed
Evaluating the technical Performance of the Koga and Gomit reservoirs in the Blue Nile
under Existing Conditions and Possible Climate change
Fuad Abdo Yassin & Matthew McCartney
Metrics
Indicators
Reliability
• the probability that the system is in a satisfactory state (i.e. can meet demands).
Resilience
• the capability of the system to return to a satisfactory state from a state of failure
Vulnerability
• the maximum duration and the cumulative maximum extent of system failure
RRV for Koga and Gomit dams in the Nile Basin:
Reliability
Resilience
Vulnerability
Koga
Gomit
Koga
Gomit
Koga
Gomit
Historic climate
0.992
0.950
0.037
0.032
37
71
-20% rainfall
0.968
0.874
0.020
0.016
64
88
+20% rainfall
1.000
0.979
1.000
0.055
0
44
Challenge = need to be able to compute these metrics
for a number of storage types within a storage system
Research results – Koga watershed
Tropentag 2010
poster session: water management
Evaluating the technical Performance of
the Koga and Gomit reservoirs in the
Blue Nile under Existing Conditions and
Possible Climate change
Fuad Abdo Yassin & Matthew McCartney
Research results – Koga dam & irrigation
Institutional and organizational aspects of irrigation management
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Pilot project for farmer-based management - runs at risk to fail
Re-organization of farmers in groups – unclear formal/ legal status
Training and involvement of farmers – not sufficient
Livelihood changes through irrigation agriculture – unexpected workload
Conflicts with Christian orthodox authorities – holidays and religious duties
How Winners become losers. Relocatees re-establishment of livelihood.
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Delay in land allocation - long period of non-farming
400 households were relocated to close town
Irregularities in compensation payments
Change of livelihood - giving up livestock rearing/ urban activities
Process of urbanisation, integration in small town settlement
Problems with land for houses
Importance of social networks
New sources of vulnerability (e.g. HIV/ AIDS)
Sources: Tesfai 2010, Marx 2010
Project output - evaluation metrics
Evaluation metrics to determine
• The need for water storage
• The effectiveness of different options
• The suitability of different options
Need/ effectiveness
technical
economic
Suitability
environmental
social
Evaluation metrics should be as far as possible:
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Objective /quantitative
The same for all storage types
Applicable across a range of scales
Applicable now and under climate change scenarios
Transparent in its evaluation approach
Easy to use by advisers and policy makers
Illustrate policy options
Include veto/ exit options, if needed
► score-based approach, possible to visualize
socioeconomic
Project output - evaluation metrics
Metrics to determine
• The need for water storage
• The effectiveness of different options
technical
economic
Water storage needed? YES.
Metrics to determine
• The suitability of different options
environmental
social
Water storage effective? YES.
socioeconomic
Social evaluation criteria
1.
2a.
2b.
3.
4.
Accessibility
Social cost
Social benefits
Management/ Maintenance
Options to Adapt
2a. Social cost - Measures the social cost of the storage system.
Topics: relocation/ compensation, social stratification, social and patronage networks, bargaining
power, conflict, health
The lower the social cost the greater the social value of the storage system.
Social cost scores (emic perspective)
Class
Description
Score
No social cost
The potential beneficiaries of the location where the storage facility is
situated do not report on social cost.
4
Low social cost The potential beneficiaries of the location where the storage facility is
situated report on minor social cost but indicate that it is definitely
worth taking this cost to enjoy the economic water storage benefits.
3
High social
cost
The potential beneficiaries of the location where the storage facility is
situated report on high social cost but indicate that it is still worth
taking this cost to enjoy the economic water storage benefits.
2
Very high
social cost
The potential beneficiaries of the location where the storage facility is
situated report on very high social cost and are unsure whether taking
this cost is outweighed by the economic water storage benefits.
1
Unacceptable
social cost
The potential beneficiaries of the location where the storage facility is Veto
situated report on very high social cost which cannot be outweighed by
the economic water storage benefits.
Does the project entail high social costs? ► No (score 4-3). ► Considerably high (score 2) ► Continue
► Yes (score 1 - veto) ► Stop because not suitable.
Thank you.
Project leadership:
Dr. Matthew McCartney
IWMI East African regional office Addis Ababa
m.mccartney@cgiar.org
IWMI project homepage:
http://africastorage-cc.iwmi.org/Default.aspx
ZEF project homepage:
http://www.zef.de/1393.html
References
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Eguavoen, I. (2009) The aquisition of water storage facilities in the Abay River basin, Ethiopia.
ZEF Working Paper 38.
Hattermann, Fred (March 2010). Regional climate scenarios for the Blue Nile and Volta. PIK
presentation.
IWMI (2009) Flexible Water Storage Options and Adaptation to Climate Change. Policy Brief 31
Johnston, R.& McCartney M. (2010) Inventory of Water Storage Options in the Blue Nile and Volta
River basins. IWMI Working Paper 140.
Marx, S. (2010) Chances and Obstacles in Implementing a large-scale Irrigation Scheme
managed by Farmers: Koga Irrigation and Watershed Management Project. Field research report.
Bonn. ZEF.
McCartney, M.P., Ibrahim, Y., Seleshi, Y. & Awulachew, S.B. (2009) Application of the Water
Evaluation and Planning Model (WEAP) to simulate current and future water demand in the Blue
Nile. In: Awulachew, S.B., Erkossa,T., Smakhtin, V. & Fernando, A. (Eds) Improved water and
land management in the Ethiopian Highlands: Its impact on downstream stakeholders dependent
on the Blue Nile: Intermediate Results Dissemination Workshop 5-6 February, 2009. Addis Ababa,
Ethiopia. 78-88.
McCartney, M.P., Alemayehu, T., Shiferaw, A. & Awulachew, S. B. (2010) Evaluation of current
and future water resources development in the Lake Tana Basin, Ethiopia. Colombo, Sri Lanka:
International Water Management Institute. Colombo, Sri Lanka: International Water Management
Institute. IWMI Research Report 134.
Tesfai, W. (2010) Relocatees re-establishment of livelihood in the Koga irrigations project,
Amhara Region, Ethiopia. Field research report. Bonn. ZEF.