Food security in Africa is likely to be “severely compromised” by climate change with production halved by 2020 > 95% of Africa’s agriculture currently depends on rainfall Changes in hydrology will aggravate other stresses and threaten sustainable development As a consequence of climate change: 80,000 km2 “constrained” will improve 600,000 km2 currently “moderately constrained” will become “severely limited”

1. GTZ project
Rethinking water storage for climate change
adaptation in Sub-Saharan Africa

2. Background
• Food security in Africa is likely to be “severely compromised” by
climate change with production halved by 2020
• > 95% of Africa’s agriculture currently depends on rainfall
• Changes in hydrology will aggravate other stresses and threaten
sustainable development
• As a consequence of climate change:
• 80,000 km2 “constrained” will improve
• 600,000 km2 currently “moderately constrained” will become
“severely limited”

3. Adaptation: More storage required

4. More storage required (?)
Type of storage and how it is used is important

5. Range of storage options

6. Project Purpose
Guidance on:
“ …..storage options that ensure optimal adaptation to climate change
induced impacts on water availability in SSA”
• How do we determine storage needs (now and in the future) ?
needs assessment
• How do we choose between different storage options?
options assessment

7. Adaptation Strategies

8. Physical Storage Continuum

9. Research questions
• How is climate change likely to affect future water demand ?
e.g. Irrigation demand under different conditions of rainfall, temperature and
evaporation
• How is climate change likely to affect water availability and what are the implications for different
types of storage?
e.g. river yields, groundwater recharge, runoff,
evaporation from storage
• How is climate change likely to affect “externalities” of different storage types?
e.g. Public health impacts (e.g. malaria, schistosomiasis)
Environmental impacts (e.g. runoff, river flows)
• How do we build climate change change into decision making process for storage?

10. Method (1)
1) Determine evaluation criteria
Criteria Technical Social Economic Environmental
Reliability
Resilience
Sustainability
Vulnerability
As far as possible:
• Objective /quantitative
• Applicable to different storage types
• Applicable across a range of scales
• Applicable now and under climate change scenarios

11. Method (2)
2) Basin scale anlaysis (Nile and Volta)
• Evaluation of climate change impacts on storage at basin scale
Activity Method
Determine impact of climate Rainfall, Downscaling of GCM data
change on climate in each temperature,
basin PE
Determine impact of climate g/w recharge Downscaled GCM data + cc
change on basin hydrology Runoff scenarios, through
(2 scenarios) – A2 and B2 Flow hydrological model (SWAT,
STRM)
Evaluate impact of climate Large scale irrigation For each scenario,
change on existing and Hydropower hydrology modified by cc
planned water storage Well fields applied to water resource
model (WEAP)
Evaluate consequences For each scenario assess in
terms of evaluation criteria

12. Method (3)
3) Site level analyses (locations in each of Nile and Volta)
• Evaluation of climate change impacts on different storage types
Activity Method
Evaluate -Water stored and how its Surveys, site investigations
suitability/effectiveness of used to obtain information for the
different storage types -Economic performance evaluation criteria
under current conditions -Livelihood impacts
(Access, Equity)
Evaluate -Water stored and how its Downscaled cc to evaluate
suitability/effectiveness of used biophysical implications of
different storage types -Economic performance different scenarios
under climate change -Livelihood impacts Likely implications based on
conditions (Access, Equity) evaluation criteria

13. Method (4)
4) Develop Guidance
• Draw together lessons learned into guidance on introducing
climate change into decision-making processes for storage

14. Project Progress
• Inception workshop (April 2008)
• Project website established
– http://africastorage-cc.iwmi.org/Default.aspx
• 3 case study sites selected in Ghana (site visits undertaken)
• 3 possible sites identified in Ethiopia (field trip just completed)
• Baseline reviews of existing storage in Volta and Nile
• Report on acquisition of storage in the Nile
• Notes on current plans for future storage in the Nile and Volta
• 1 MSc student (Homboldt University) started in Volta
• 3 MSc students (Arba Minch University) started in the Nile
• 1 PhD student (Frei University) started in the Nile

15. Volta: Inventory
Boreholes > 6,000
Large dams
Total reservoir storage: 165 Bm3 (4 x MAR)
Formal irrigation: 10,000 ha Small dams in Northern Ghana
Potential irrigation: 346,000 ha

16. Ethiopian Blue Nile Inventory
Nile: Inventory
Potential Irrigation
Hand dug wells – Amhara Region
Potential Dam locations
Total reservoir storage: 11.5 Bm3 ( 0.25 x MAR at Sudan border)
Formal irrigation: 10,000 ha
Potential irrigation: 800,000 ha

17. Water Resource Development in the
Ethiopian Blue Nile
Irrigation upstream of
Lake Tana 7,200 ha
Lake Tana
Outlet Lake Tana
Tis Abbay
Beles hydropower
Bosheilo
SUDAN Border
Welaka
North Gojam
South Gojam Jemma
ETHIOPIA Wonbera
Muger
Irrigation upstream of
Lake Tana 69,053ha
Dabus Finchaa
Irrigation Diversions
8,145 ha Lake Tana Pumping from
Reservoir 2,424 Lake Tana 5,000ha
Guder Beles
Didessa Irrigation scheme
Finchaa Outlet Lake Tana
Upper Beles 53,700 ha
Upper Dinder 10,000 ha
Bosheilo
Border
Welaka
Lower Beles North Gojam
Current
85,000 ha
South Gojam Jemma
ETHIOPIA Wonbera
Karadobi Muger
Irrigation upstream of
Lake Tana 69,053 ha
Dabus
Anger
Lake Tana NW Lake Tana
Finchaa Pumping 6,720ha
Irrigation Diversions
20,145 ha 2,424
Anger
14,450 ha Reservoir Outlet Lake Tana
Didessa 14,670ha Guder
Upper Dinder 10,000 ha Beles
Didessa Irrigation scheme Bosheilo
Finchaa Border
SUDAN Welaka
Upper Beles 53,700 ha
2015 ETHIOPIA
Lower Beles
85,000 ha
South Gojam North Gojam Jemma
Wonbera
Lower Beko Abo
Dabus Mendaya Karadobi Muger
Upper
Lower
Dabus Nekemte 11,220ha
Dabus 9,661ha Didessa
Anger Finchaa &
Neshe Guder Diversions
Dabus
Didessa 27,217 ha 4,896 ha
Anger
irrigation 14,450 ha Reservoir
53,668 ha
Irrigation scheme
Finchaa
Didessa 14,670ha
Guder diversion 4,100ha
Didessa Guder
2025

18. Water Resources plans for the
Ethiopian Blue Nile
Current 2015 2025
Irrigation (ha) 10,000 210,000 390,000
Hydropower (MW) 218 2,194 6,500
Large Dam Storage
11.5 56.8 ~100
(Bm3)
Impact on flow with no climate change (Bm3):
Natural Current 2015
Outlet Lake Tana 3.9 4.0 0.9
Kessie 14.9 14.9 11.9
Border with Sudan 45.7 45.6 43.5

19. climate change Impacts
Climate in the Volta and Nile:
Already experience high variability
• Likely consequence of climate change:
• Warmer temperatures, more extreme temperatures
• Greater variability, more floods/droughts
• Higher evaporation and transpiration
• Lower confidence:
• Direction and magnitude of rainfall changes
• Changes in extremes (frequency/intensity)

20. Scenarios – to be downscaled to
basins and sites
Simulation results of the dynamical regional model REMO
– scenario (2001-2050 vs 1960-2000).

21. Three Conclusions
1) Water storage is the key to climate change adaptation for agriculture in
Africa
2) climate change will affect the function and operation of different storage
types, differently
3) Important to assess the effectiveness and suitability of different storage
types under uncertain conditions of climate change
Need to Rethink water storage options for
climate change adaptation

22. Thanks