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Sustainability Considerations Sustainability Considerations in the Design of Big Dams:in the Design of Big Dams:
Merowe, Nile BasinMerowe, Nile Basin
Mentor: Prof. El Fatih EltahirMentor: Prof. El Fatih Eltahir
Group: Anthony Paris, Teresa Yamana, Group: Anthony Paris, Teresa Yamana, Suzanne YoungSuzanne Young
OutlineOutline
Introduction and motivationIntroduction and motivation Nile hydrologyNile hydrology The modelThe model ClimateClimate SedimentationSedimentation Public healthPublic health Future WorkFuture Work
Goals and MotivationGoals and Motivation
Simulate the role of environmental Simulate the role of environmental engineers in large scale projectsengineers in large scale projects
Analyze the effect the Dam will have on Analyze the effect the Dam will have on the environment and local population, the environment and local population, and make recommendations to mitigate and make recommendations to mitigate effectseffects
Assess whether long-term effects will Assess whether long-term effects will significantly decrease Dam’s lifetime and significantly decrease Dam’s lifetime and plan accordinglyplan accordingly
IntroductionIntroduction
Sudan needs EnergySudan needs Energy 19-year old Civil War19-year old Civil War Frequent power blackoutsFrequent power blackouts
Merowe DamMerowe Dam Utilizing hydropowerUtilizing hydropower Creating hopeCreating hope
Dam Design DetailsDam Design Details Ten turbines – 1,250 MW CapacityTen turbines – 1,250 MW Capacity Long in relation to heightLong in relation to height Active reservoir storage 8.3 bcm Active reservoir storage 8.3 bcm
Average Longterm Monthly Nile flows, 1872-1986
0
5
10
15
20
25
January February March April May June July August September October November December
Dis
char
ge (
km^3
/mon
th)
Storage to Elevation RelationshipStorage to Elevation RelationshipReservoir Characteristics
260
270
280
290
300
310
320
330
340
350
0 1E+09 2E+09 3E+09 4E+09 5E+09 6E+09 7E+09
Surface Area (m^2)
Ele
va
tio
n (
m)
Reservoir Characteristics
260
270
280
290
300
310
320
330
340
350
0 2E+10 4E+10 6E+10 8E+10 1E+11 1.2E+11 1.4E+11
Storage (m^3)
Ele
va
tio
n (
m)
Matlab ModelMatlab Model
dS/dt = inflow – evap – Q_out(turbines) – dS/dt = inflow – evap – Q_out(turbines) – Q_out(overflow)Q_out(overflow)
Determines what volume to make available to Determines what volume to make available to turbinesturbines Pessimistic Model – use as much water as possiblePessimistic Model – use as much water as possible Gradual Release Model – ration storage in dry seasonGradual Release Model – ration storage in dry season Constant Head Model – Q_out=Q_in Constant Head Model – Q_out=Q_in
Determines the number of turbines to turn onDetermines the number of turbines to turn on Calculates volume, area, PowerCalculates volume, area, Power
The Effect of Climate Change on Dam The Effect of Climate Change on Dam PerformancePerformance
Suzanne YoungSuzanne Young
Climate changeClimate change
Changes in chemical composition of Changes in chemical composition of atmosphere atmosphere global warming global warming
Temperatures increase, precipitation?Temperatures increase, precipitation? Literature review: Predictions of Nile flows Literature review: Predictions of Nile flows
confounded by different simulations giving confounded by different simulations giving conflicting resultsconflicting results
Range of discharges for major points along the NileRange of discharges for major points along the Nile (Summary of Yates 1998b results)(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.
Climate scenariosClimate scenarios
Climate scenario Years Average flow Deviation from long term
[km3/yr] average 88 km3/yr
No change 1943-1969 88 --
Wetter climate 1872-1898 102 +15%
Drier climate 1979-1986 74 -15%
Also varied maximum storage height of reservoir from 294 m to 298 m
Nile discharge, 1872-1986
40
50
60
70
80
90
100
110
120
130
1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980
An
nu
al d
isch
arg
e (k
m^3
/yea
r)
Longterm annual average = 88.1 km̂ 3/year
Potential HydropowerPotential Hydropower
Power = γQhγ = 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]
ResultsResults
Wetter climate = highest power (~30% Wetter climate = highest power (~30% higher than no change in climate)higher than no change in climate)
Reservoir storage height increase gives Reservoir storage height increase gives linear increase in power (~10%/m)linear increase in power (~10%/m)
Pessimistic model > Gradual release Pessimistic model > Gradual release modelmodel
Drier climate power yields higher than no Drier climate power yields higher than no change in climate (!)change in climate (!)
Pessimistic model: Comparison of climate scenarios
2.05E+11
2.10E+11
2.15E+11
2.20E+11
2.25E+11
2.30E+11
2.35E+11
2.40E+11
294 295 296 297 298
Maximum storage height of reservoir [m]
Ave
rag
e an
nu
al p
ow
er [
Wat
ts]
No change
Wetter climate
Drier climate
Seasonal variationsSeasonal variations
Wetter No change DrierJanuary 4.95 3.82 3.30February 3.44 2.84 2.60March 2.79 2.21 2.17April 2.01 1.91 3.20May 1.71 1.95 2.81June 2.04 2.55 2.74July 6.02 6.92 4.87August 20.84 18.50 14.79September 25.05 20.77 18.24October 17.30 14.12 9.95November 9.53 7.62 5.36December 6.70 4.88 3.97Annual 102.39 88.09 73.54
Climate scenario
RecommendationsRecommendations
Use pessimistic model as basis for Use pessimistic model as basis for operating parametersoperating parameters
Increase height of maximum reservoir Increase height of maximum reservoir storage pending economic analysisstorage pending economic analysis
Erosion: Sources of Erosion: Sources of Nile SedimentsNile Sediments
Ethiopian Highlands Ethiopian Highlands (~90%)(~90%)
Travels through the Travels through the Blue Nile and AtbaraBlue Nile and Atbara
The sediment load is The sediment load is most significant most significant during flood season during flood season (July-Oct.)(July-Oct.)
50-228 million tones 50-228 million tones per yearper year
Sedimentation AnalysisSedimentation Analysis
1) How much sediment will settle in the 1) How much sediment will settle in the reservoir?reservoir?
2) Where will the sediment settle?2) Where will the sediment settle? 3) How long is the economic life of the 3) How long is the economic life of the
project?project? 4) What things can be done to improve 4) What things can be done to improve
the situation?the situation?
Hand CalculationsHand Calculations
Calculating Trapping Efficiency – 1st RoundCalculating Trapping Efficiency – 1st Round Brune’s CurveBrune’s Curve C = CapacityC = Capacity I = InflowI = Inflow
TI
C
Hand CalculationsHand Calculations
Calculating VCalculating VSS – 1st Round – 1st Round
ββ = = Bulk density of clay loamBulk density of clay loam QQCC = sediment load [tons/yr] = sediment load [tons/yr]
VVSS = Volume of sediment retained [m = Volume of sediment retained [m33/yr]/yr]
CTS QV
Borland & Miller Reservoir Borland & Miller Reservoir ClassificationClassification
H = any water lvl.H = any water lvl. HHO O = lowest bed lvl.= lowest bed lvl.
VVHH = = res. Vol. at Hres. Vol. at H
αα = coef. = coef. M = coef. (slope)M = coef. (slope)
LakeLake 65% dead storage65% dead storage 35% active storage35% active storage
MOH HHV
log H vs log C
y = 4.4794x + 2.2173
8.6
8.8
9
9.2
9.4
9.6
9.8
10
10.2
1.45 1.5 1.55 1.6 1.65 1.7 1.75 1.8
log H-Ho
log
C
Economic Life of ReservoirEconomic 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 44 billion m3/yr 77 million 5% 105 yrs
4 63.7 billion m3/yr 158 million 15% 65 yrs
5 44 billion m3/yr 137 million 5% 70 yrs
6 63.7 billion m3/yr 228 million 15% 45 yrs
ImprovementsImprovements
1) Trapping1) Trapping Creating dams upstream to catch sedimentCreating dams upstream to catch sediment
2) Sluicing2) Sluicing Opening low level-lying sluices to flush out Opening low level-lying sluices to flush out
sediments, only effects local areasediments, only effects local area 3) Dredging3) Dredging
$$$ May be cost effective towards end of life$$$ May be cost effective towards end of life 4) Flushing4) Flushing
Allow the high sediment filled flood waters to flush Allow the high sediment filled flood waters to flush through the systemthrough the system
The Effect of the Dam on Public HealthThe Effect of the Dam on Public Health
Teresa YamanaTeresa Yamana
Dams’ Threat to Public HealthDams’ Threat to Public Health
As a development project, obligation to As a development project, obligation to protect public healthprotect public health
Merowe Dam expected to increase Merowe Dam expected to increase incidence of Malaria, Schistosomiasis, incidence of Malaria, Schistosomiasis, River Blindness and Rift Valley FeverRiver Blindness and Rift Valley Fever
Stagnant water in reservoirs and irrigation Stagnant water in reservoirs and irrigation ditches provide habitat for vectorsditches provide habitat for vectors
Constant supply of water - Dry season no Constant supply of water - Dry season no longer limits vectors longer limits vectors
MalariaMalaria
Protozoa Protozoa PlasmodiumPlasmodium transmitted by Anopheles transmitted by Anopheles mosquitoesmosquitoes
A. funestusA. funestus breeds in breeds in illuminated shoreline illuminated shoreline throughout the yearthroughout the year
A. gambiaeA. gambiae breeds in breeds in reservoir drawdown area in reservoir drawdown area in dry season (November – dry season (November – June)June)
Malaria Control StrategiesMalaria Control Strategies
Reduce Mosquito habitat through Reduce Mosquito habitat through operating parametersoperating parameters
Chemical or biological control strategiesChemical or biological control strategies Reduce bites by using window screens, Reduce bites by using window screens,
bednetsbednets Provide vaccination and treatment for at Provide vaccination and treatment for at
risk or infected populationrisk or infected population
SchistosomiasisSchistosomiasis
Parasite carried by snails living in Parasite carried by snails living in illuminated shore lineilluminated shore line
Reduce human contact to water – piped Reduce human contact to water – piped water supplywater supply
Provide sanitation services – break link in Provide sanitation services – break link in life cyclelife cycle
Control snail populationControl snail population
River BlindnessRiver Blindness
Transmitted by black fly – fast moving waterTransmitted by black fly – fast moving water Water-washed – provide piped water supplyWater-washed – provide piped water supply Stop flow through dam 2 days per 2 weeks July Stop flow through dam 2 days per 2 weeks July
– September– September
Annual Power Generated
normal with RB controlPercent
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
Rift Valley FeverRift Valley Fever
Transmitted from livestock to humans via Transmitted from livestock to humans via mosquitoesmosquitoes
Occurs when reservoirs are filledOccurs when reservoirs are filled Vaccinate or remove livestockVaccinate or remove livestock Quarantine contaminated livestock and Quarantine contaminated livestock and
meatmeat Warn livestock and meat workersWarn livestock and meat workers Control mosquito habitatControl mosquito habitat
Model PreferencesModel Preferences
A. gambiaeA. gambiae – Variation 3 – Variation 3 A. funestus A. funestus and Schistosomiasis snails – and Schistosomiasis snails –
Variation 1Variation 1 River Blindness blackfly – add controlRiver Blindness blackfly – add control Which is Most Important?Which is Most Important?
Need more data! Need more data! What diseases will cause the most problems?What diseases will cause the most problems? Formulate strategy based on regional priorityFormulate strategy based on regional priority
GOAL – no increase in disease caused by damGOAL – no increase in disease caused by dam
Future WorkFuture Work Integrate 3 Climate, Sedimentology and Public Integrate 3 Climate, Sedimentology and Public
Health concernsHealth concerns Thorough cost-benefit analysisThorough cost-benefit analysis ClimateClimate
More experimentation with various climate scenariosMore experimentation with various climate scenarios SedimentationSedimentation
2-D and 3-D models to predict delta formations and 2-D and 3-D models to predict delta formations and identify problem spotsidentify problem spots
Public HealthPublic Health Prioritize between diseases to find optimal operating Prioritize between diseases to find optimal operating
parametersparameters
THANK YOU!!THANK YOU!!
Prof. El Fatih EltahirProf. El Fatih Eltahir Prof. Dennis McLaughlin & Sheila FrankelProf. Dennis McLaughlin & Sheila Frankel Profs. Ole Madsen & Dara EntekhabiProfs. Ole Madsen & Dara Entekhabi Dr. Sadeqi of the Kuwait FundDr. Sadeqi of the Kuwait Fund Valeri IvanovValeri Ivanov 1E seniors!1E seniors!