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Re-optimization and
reoperation study of the
Akosombo and Kpong dams
- Scenario selection
Dr Marloes Mul
Thor Windham-Wrig...
Scenario 1 current flow regime
• Optimising baseload
hydropower generation
• Minimum flow fluctuations
• Average flow of 1...
Scenario 2&3 Environmental Management
Classes A & B
• Statistical approach using GEFC
• EMC A: Natural rivers with minor
m...
Scenario 4 Weeds control and fishery
production
• Weeds control through
• Reintroducing saltwater gradient
• Increasing fl...
Scenario 4 Weeds control and fishery
production
flow targets/levels correct
dry season
wet season
Additional things to co...
Scenario 5 Irrigation optimisation
• Provide sufficient water for
irrigation activities during dry
season
• Provide suffic...
Scenario 5 Irrigation optimisation
flow targets/levels correct
dry season
wet season
Things to consider in C/B analysis
•...
Scenario 6 Spilling levels 2010
• Wet season levels at 2010
spillway levels (confirm
discharge from VRA)
• Drawing from kn...
Discussion
• For each scenario
• Confirm/estimate flow targets
• Dry season
• Wet season
• Identify impact on (sub-)sector...
Final discussion
• Summarize impact of all scenarios on different (sub-) sectors
Qualitative
• Quantitative Weed Fish Agri...
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Flow scenarios of the re-optimization and reoperation study of the Akosombo and Kpong dams (Ghana)

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Presented by IWMI researcher Marlos Mul on potential flow scenarios for of reoptimization and reoperation of the Akosombo and Kpong dams (Ghana). Presented during a stakeholder workshop held in Accra, August 2015, to explore the potential positive and negative impacts of changing flows.

Published in: Environment
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Flow scenarios of the re-optimization and reoperation study of the Akosombo and Kpong dams (Ghana)

  1. 1. Re-optimization and reoperation study of the Akosombo and Kpong dams - Scenario selection Dr Marloes Mul Thor Windham-Wright
  2. 2. Scenario 1 current flow regime • Optimising baseload hydropower generation • Minimum flow fluctuations • Average flow of 1,000 m3/s
  3. 3. Scenario 2&3 Environmental Management Classes A & B • Statistical approach using GEFC • EMC A: Natural rivers with minor modification of in-stream and riparian habitat • EMC B: Slightly modified and/or ecologically important rivers with largely intact biodiversity and habitats despite water resources development and/or basin modifications Realistic scenarios? What are the impacts of different sectors?
  4. 4. Scenario 4 Weeds control and fishery production • Weeds control through • Reintroducing saltwater gradient • Increasing flow velocity • Fishery production increment • Clams – increase saltwater intrusion • Freshwater fish – increase flooded area during wet season • Maximize saltwater intrusion during dry season • Maximize flood peaks during Sep-Oct • Gradual transition between seasons • Total flow is less than natural flow because of Evap losses of the lake
  5. 5. Scenario 4 Weeds control and fishery production flow targets/levels correct dry season wet season Additional things to consider in cost- benefit analysis: - Breaking sandbar - Continual manual removing of weeds (necessary?) - Moving of intakes - Protect valuable infrastructure along the river - Impact on irrigation
  6. 6. Scenario 5 Irrigation optimisation • Provide sufficient water for irrigation activities during dry season • Provide sufficient water during dry season so that saltwater intrusion is not affecting other water users (intakes) • Compensated by increment of wet season flow to benefit fisheries and other sectors
  7. 7. Scenario 5 Irrigation optimisation flow targets/levels correct dry season wet season Things to consider in C/B analysis • Protect valuable properties • Manual removal of weeds
  8. 8. Scenario 6 Spilling levels 2010 • Wet season levels at 2010 spillway levels (confirm discharge from VRA) • Drawing from knowledge of the spill and current low flows (confirm discharge from VRA)
  9. 9. Discussion • For each scenario • Confirm/estimate flow targets • Dry season • Wet season • Identify impact on (sub-)sectors • Compared to current or past situation • Identify issues/potential conflicts • Additional measures required
  10. 10. Final discussion • Summarize impact of all scenarios on different (sub-) sectors Qualitative • Quantitative Weed Fish Agric Health GW Sed Other w1 w2 Sc1 Sc2 Sc3 Sc4 Sc5 Sc6 ++ very good + good +/- neutral - bad -- very bad Voting on feasibility of scenarios and selection of scenarios for modelling

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