1. Sustainability Considerations in the Design of Big Dams: Merowe, Nile Basin
Mentor: Prof. El Fatih Eltahir
Group: Anthony Paris, Teresa Yamana, Suzanne Young

2. Outline Introduction and motivation Nile hydrology The model Climate
Sedimentation
Public health
Future Work

3. Goals and Motivation
Simulate the role of environmental engineers in large scale projects
Analyze the effect the Dam will have on the environment and local population, and make recommendations to mitigate effects
Assess whether long-term effects will significantly decrease Dam’s lifetime and plan accordingly

4. Introduction Sudan needs Energy Merowe Dam Dam Design Details
19-year old Civil War
Frequent power blackouts
Merowe Dam
Utilizing hydropower
Creating hope
Dam Design Details
Ten turbines – 1,250 MW Capacity
Long in relation to height
Active reservoir storage 8.3 bcm

5. General Layout

8. “The Model”
The New Model

9. Storage to Elevation Relationship

10. Matlab Model dS/dt = inflow – evap – Q_out(turbines) – Q_out(overflow)
Determines what volume to make available to turbines
Pessimistic Model – use as much water as possible
Gradual Release Model – ration storage in dry season
Constant Head Model – Q_out=Q_in
Determines the number of turbines to turn on
Calculates volume, area, Power

11. Pessimistic
Gradual Release
Constant Head

12. The Effect of Climate Change on Dam Performance Suzanne Young

13. Climate change
Changes in chemical composition of atmosphere  global warming
Temperatures increase, precipitation?
Literature review: Predictions of Nile flows confounded by different simulations giving conflicting results

14. Range of discharges for major points along the Nile (Summary of Yates 1998b results)
Two numbers on ends of each line represent extreme discharges of six GCM scenarios, whereas boxed number is historic average; Additional tick marks on each line are remaining GCM scenarios, which indicate range of climate change induced flows of Nile Basin.
Two numbers on ends of each line represent extreme discharges of six GCM scenarios, whereas boxed number is historic average; Additional tick marks on each line are remaining GCM scenarios, which indicate range of climate change induced flows of Nile Basin.

15. Climate scenarios Climate scenario Years Average flow
Deviation from long term
[km3/yr]
average 88 km3/yr
No change 88 --
Wetter climate
102
+15%
Drier climate 74
-15%
Also varied maximum storage height of reservoir from 294 m to 298 m

17. Potential Hydropower Power = γQh γ = ρg
ρ = density of water = 1000 [kg/m3]
g = gravity = 9.8 [m/s2]
Q = flow at dam [m3/s]
h = drop in head between intake to powerhouse and outlet to river [m]

18. Results
Wetter climate = highest power (~30% higher than no change in climate)
Reservoir storage height increase gives linear increase in power (~10%/m)
Pessimistic model > Gradual release model
Drier climate power yields higher than no change in climate (!)

19. Pessimistic model Gradual release model No change in climate
Wetter climate
Drier climate
Gradual release model

20. Pessimistic model yields higher power than Gradual Release model

22. Seasonal variations

23. Recommendations
Use pessimistic model as basis for operating parameters
Increase height of maximum reservoir storage pending economic analysis

24. Sedimentation into the Reservoir Anthony Paris

25. Erosion: Sources of Nile Sediments
Ethiopian Highlands (~90%)
Travels through the Blue Nile and Atbara
The sediment load is most significant during flood season (July-Oct.)
million tones per year

26. Sedimentation Analysis
1) How much sediment will settle in the reservoir?
2) Where will the sediment settle?
3) How long is the economic life of the project?
4) What things can be done to improve the situation?

27. Hand Calculations Calculating Trapping Efficiency – 1st Round
Brune’s Curve
C = Capacity
I = Inflow

28. Hand Calculations Calculating VS – 1st Round
β = Bulk density of clay loam
QC = sediment load [tons/yr]
VS = Volume of sediment retained [m3/yr]

29. Borland & Miller Reservoir Classification
H = any water lvl.
HO = lowest bed lvl.
VH = res. Vol. at H
α = coef.
M = coef. (slope)
Lake
65% dead storage
35% active storage

30. Economic Life of Reservoir
Scenarios
Flow Rate
Suspended Load
Estimated Bed Load
Economic Life 1
44 billion m3/yr
30 million 5%
350 yrs 2
63.7 billion m3/yr
50 million
15%
205 yrs 3
77 million
105 yrs 4
158 million
65 yrs 5
137 million
70 yrs 6
228 million
45 yrs

31. Improvements 1) Trapping 2) Sluicing 3) Dredging 4) Flushing
Creating dams upstream to catch sediment
2) Sluicing
Opening low level-lying sluices to flush out sediments, only effects local area
3) Dredging
$$$ May be cost effective towards end of life
4) Flushing
Allow the high sediment filled flood waters to flush through the system

32. The Effect of the Dam on Public Health Teresa Yamana

33. Dams’ Threat to Public Health
As a development project, obligation to protect public health
Merowe Dam expected to increase incidence of Malaria, Schistosomiasis, River Blindness and Rift Valley Fever
Stagnant water in reservoirs and irrigation ditches provide habitat for vectors
Constant supply of water - Dry season no longer limits vectors

34. Malaria Protozoa Plasmodium transmitted by Anopheles mosquitoes
A. funestus breeds in illuminated shoreline throughout the year
A. gambiae breeds in reservoir drawdown area in dry season (November – June)

35. Drawdown area:
129 km2
Illuminated shoreline:
2-48 km2

36. Malaria Control Strategies
Reduce Mosquito habitat through operating parameters
Chemical or biological control strategies
Reduce bites by using window screens, bednets
Provide vaccination and treatment for at risk or infected population

37. Schistosomiasis
Parasite carried by snails living in illuminated shore line
Reduce human contact to water – piped water supply
Provide sanitation services – break link in life cycle
Control snail population

38. Annual Power Generated
River Blindness
Transmitted by black fly – fast moving water
Water-washed – provide piped water supply
Stop flow through dam 2 days per 2 weeks July – September
Annual Power Generated
normal
with RB control
Percent reduction
Var 1
2.05E+11
1.96E+11
4.39
Var 2
1.99E+11
1.89E+11
5.03
Var 3
1.87E+11
1.77E+11
5.35

39. River Blindness – Variation 2

40. Rift Valley Fever Transmitted from livestock to humans via mosquitoes
Occurs when reservoirs are filled
Vaccinate or remove livestock
Quarantine contaminated livestock and meat
Warn livestock and meat workers
Control mosquito habitat

41. Model Preferences A. gambiae – Variation 3
A. funestus and Schistosomiasis snails – Variation 1
River Blindness blackfly – add control
Which is Most Important?
Need more data!
What diseases will cause the most problems?
Formulate strategy based on regional priority
GOAL – no increase in disease caused by dam

42. Future Work
Integrate 3 Climate, Sedimentology and Public Health concerns
Thorough cost-benefit analysis
Climate
More experimentation with various climate scenarios
Sedimentation
2-D and 3-D models to predict delta formations and identify problem spots
Public Health
Prioritize between diseases to find optimal operating parameters

43. THANK YOU!! Prof. El Fatih Eltahir
Prof. Dennis McLaughlin & Sheila Frankel
Profs. Ole Madsen & Dara Entekhabi
Dr. Sadeqi of the Kuwait Fund
Valeri Ivanov
1E seniors!

44. Hope!
Hope!
Hope!
Hope!
Hope!
Hope!