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ESTIMATING THE EFFECT OF
CLIMATE CHANGE ON THE
HYDROLOGY OF THE NILE
RIVER IN THE 21ST CENTURY
International System Dynamics Conference
Delft, Netherlands
24 July 2014
Bruce Keith, Radley Horton, Erica Bower, Jonathan Lee, Andrew Pinelli, & Diane Dittrick
Introduction




Aligning two undergraduate capstone teams at two universities
with one product
Linked Columbia University Sustainable Development Capstone
& USMA Dept. Systems Eng Capstone
Erica Bower (Columbia University)
 Team: Perihan MacDonald, Nikhil Krishnan, Andrew Pinelli,
Alex O’Hagan, Etsegenet Wakjira
 Advisors: Radley Horton & Diane Dittrick
Jonathan Lee (US Military Academy—West Point)
 Team: Kevin Epp, Michael Houghton, Robert Mayville, USMA
 Advisor: Bruce Keith
Purpose
The purpose of our study is to examine the impact of
environmental and human factors on the carrying capacity
(streamflow) of the Nile River throughout the 21st Century.
We employ estimates from 33 General Circulation Models (GCM),
inclusive of Representative Concentration Pathways (RCP) 4.5 and 8.5,
within Vensim to model the dynamic interplay between climate change
and streamflow for the Nile River Basin. We subdivided the time
periods into 30-year intervals for 2010-2039 (early century), 20402069 (mid century), and 2070-2099 (late century).
Using this model, we estimate the potential effect of the proposed
reservoir fill rate of the Grand Ethiopian Renaissance Dam on
streamflow for downstream countries.
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Climate Modeling Overview


Weather versus climate
33 General Circulation Models (GCMs) provided by
NASA Goddard Institute
Numerical models representing physical processes in
atmosphere
 Simulate the response of the global climate system to
increasing greenhouse gas concentration
 Output = 2 Variables of Interest (VOI)

Temperature
 Precipitation


2 Representative Concentration Pathways (RCPs)
RCP 4.5: emissions stabilization
 RCP 8.5: emissions status quo maintained

Cutting Edge Models

Coupled Model Inter-comparison Project Phase 5
(CMIP5)
 Developed
for IPCC Fifth Assessment Report (AR5)
 Higher spatial resolution and include more diverse
model types
 Earth
System Models of interaction between chemistry,
aerosols, vegetation, ice sheets, and biogeochemical cycles
Areas of Study
Region 1. Upper Nile
(Egypt)
Weather Station Included: Cairo
Latitude: 32°N to 22°N
Longitude: 30°E to 35 °E
Region 2. Lower Nile
(Sudan)
Weather Station Included:
Khartoum
Latitude: 22°N to 15°N
Longitude: 30°E to 35°E
Region 3. Blue Nile and Atbara
Basin (Ethiopia)
Weather Station Included: Addis
Ababa
Latitude: 15°N to 7°N
Longitude: 31°E to 40°E
Region 4. Subat, Bahr El Jabal,
Bahr El-Ghazal River Basins
Weather Station Included: Malakal
Latitude: 11°N to 2°N
Longitude: 25°E to 36°E
Methodology
Inputs
(Temperature and
Precipitation)
• 3 Time Periods
• 33 GCMS
• 2 RCPs
Outputs
(per 4 Regions)
• 66 Predictive Outcomes
(compared to model
baselines 1971-2000)
Analysis of Variability
• RCP Comparison
• Interquartile Analysis
• Sub-Annual Analysis
• Spatial Analysis
Seasonal Summary
Region
1
2
3
4
Temperature
Precipitation
Model Baseline
Unimodal- Peak Jun-Aug
Unimodal- Peak OctMar
Range
~1 C to ~6 C
~-40 % to ~100%
Greatest Difference
Increase most in July-Aug
Increase most in AugSept
Model Baseline
Unimodal-Peak May-Oct
Unimodal- Peak JuneSept
Range
~1 C to ~5.25
~-50 % to ~125%
Greatest Difference
Increase most in June-Sept
Increase most in Oct and
Jan
Model Baseline
Bimodal- Peak April and
Oct
Unimodal- Peak JulyAug
Range
~1 C to ~4.25 C
~-15% to ~120%
Greatest Difference
Increase fairly consistent
Jan-Dec
Increase most in Dec
Model Baseline
Bimodal- Peak March and
Nov
Unimodal- Peak JuneOct
Range
~1 C to ~4 C
~-15% to ~115%
Greatest Difference
Increase fairly consistent
Jan-Dec
Increase in Dec-Jan
Nile River Basin Rainfall Change in 21st Century
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Nile River Basin Temperature Change in 21st Century
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Incorporating Climate Change Data
Percent Change in Blue Nile Flow as a
Percent of Precipitation Change
Region 3 Early Century
Percent Change in Rainfall
Region 3 Precipitation
Change
Region 3 Percent
Rainfall Change
Region 3 Mid Century
Percent Change in Rainfall
Region 2 Percent
Precipitation Change
Region 2 Early Century Percent
Change in Rainfall
Region 2 Percent Rainfall
Change
Region 2 Mid Century Percent
Change in Rainfall
Region 3 Late Century
Percent Change in Rainfall
Percent Change in Atbara River Flow as
a Percent of Precipitation Change
Region 3 Temp Change Early Century
Region 3 Absolute
Temperature Change
Region 3 Temp Change Mid Century
Region 2 Percent Change in Nile
River Flow as a Percent Change of
Precipitation Change
Region 2 Late Century
Percent Change in Rainfall
Region 3 Percent Change in Nile River
Flow as a Result of Absolute Change
in Temperature
Region 2 Temp
Change Early Century
Region 3 Temp Change Late Century
Region 2 Absolute
Temperature Change
Region 2 Percent Change in Nile
River Flow as a Result of Absolute
Change in Temperature
Region 2 Temp
Change Mid Century
Region 2 Temp
Change Late Century
<Time>
lower region
unit multiplier
upper region unit
multiplier
Climate Change
Toggle Button
Region 1 Temp Change Early Century
Region 4 Temp Change Early Century
Region 4 Temp Change Mid Century
Region 4 Absolute
Temperature Change
Region 4 Percent Change in Nile
River Flow as a Result of Absolute
Change in Temperature
Region 4 Late Century
Percent Change in Rainfall
Region 1 Percent
Rainfall Change
Region 1 Percent Change in
Nile River Flow as a Percent
of Precipitation Change
Region 1 Temp Change Late Century
Region 4 Early Century
Percent Change in Rainfall
Region 4 Mid Century
Percent Change in Rainfall
Region 1 Percent Change in Nile
River Flow As a Result of Absolute
Change in Temperature
Region 1 Temp Change Mid Century
Region 4 Temp Change Late Century
Region 4 Precipitation
Change
Region 1 Absolute
Temperature Change
Region 4 Percent
Rainfall Change
Percent Change in White Nile Flow as a
Percent of Precipitation Change
Region 1 Percent
Precipitation Change
Region 1 Early Century
Percent Change in Rainfall
Region 1 Mid Century
Percent Change in Rainfall
Region 1 Late Century
Percent Change in Rainfall
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Into Nile River Basin Streamflow Model
<Region 3
Precipitation
Change>
Ethiopia Annual
Rainfall
Ethiopia
Percentage
Rainfall
Captured
Ethiopia Surface
Water Produced
Internally
GERD Reservoir
GERD
Discharge Rate
GERD Reservoir
Outflow to Sudan
+
GERD fill rate
-
Time to Outflow
Blue to GERD
Initial Value
Blue Nile
Initial Value
Atbara River
<Percent Change in
Atbara River Flow as a
Percent of Precipitation
Change>
Initial Value
White Nile
Blue Nile
Inflow to Blue
Nile
<Region 4 Percent Change in
Nile River Flow as a Result of
Absolute Change in
Temperature>
Time to Ouflow
to Med
Blue Outflow to
Sudan
Nile River Sudan
Atbara
Inflow to Atbara
Atbara Outflow
to Sudan
White Nile
Inflow into
+
White Nile
Nile Outflow to
Egypt
+
-
Nile River Egypt
+
Nile Outflow to
Mediterranean
Sea
Time to Outflow
to Egypt
White Outflow to
+ Sudan
Time to Outflow
White to Sudan
<Region 4
Precipitation
Change>
<Region 2 Percent Change in
Nile River Flow as a Result of
Absolute Change in
Temperature>
Time to Outflow
Atbara to Sudan
<Region 3 Percent Change in
Nile River Flow as a Result of
Absolute Change in
Temperature>
<Percent Change in
White Nile Flow as a
Percent of Precipitation
Change>
+
Sudan Nile Available
for Consumption
Sudan Nile
Consumption
Time to Outflow
Blue to Sudan
<Percent Change in Blue
Nile Flow as a Percent of
Precipitation Change>
<Region 2 Percent Change in
Nile River Flow as a Percent
Change of Precipitation Change>
+
Time to Outflow
GERD to Sudan
+
Blue Outflow
to
GERD Reservoir
Sudan Treaty
Adherance
Sudan Max
Consumption Nile
<Region 1 Percent Change in
Nile River Flow as a Percent of
Precipitation Change>
<Region 1 Percent Change in
Nile River Flow As a Result of
Absolute Change in
Temperature>
Renewable Inflow
to White Nile
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Modeling Assumptions
1.
2.
3.
4.
5.
6.
Water hydrology in the Nile River occurs exclusively through an
interaction between precipitation and temperature.
The Nile and its major tributaries are regenerated annually by rainfall.
Ethiopia will adhere to the treaty with the sole exception of drawing
water from the Blue Nile to fill the dam’s reservoir. All other upstream
countries will adhere to the treaty and draw no water from the White
Nile River.
In accordance with treaty adherence, Sudan will draw not more than
25 percent of the total streamflow from the Nile River Sudan.
Per capita water consumption will remain constant throughout the
century.
Technology will remain constant such that innovations in irrigation
systems, desalinization, and/or farming practices will have no
discernible effect on water utilization.
Climate Change Not Activated
Represents a
baseline
streamflow
using
historical
averaged
inputs.
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Climate Change Activated
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Power of Vensim Mental Models
• Enhance value of collaborative discussions
• Inform regional policy analyses
Case in point: impact of Grand Ethiopian
Renaissance Dam (GERD) on Blue Nile
streamflow
Blue Nile Streamflow for GERD Reservoir Fill Rates
Reservoir fill rate
likely to vary between
5% and 25% per year
Models fill rate of
GERD reservoir (50
BCM), as would be
chosen by the
government of Ethiopia
Fill rates can reduce
Blue Nile streamflow
by up to 20% for
duration of fill period.
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How Meaningful Are these Findings?
The Need for Model Validation
Compares model
estimates with historic
values from 1980-1993
Predicted estimates
provide adequate
generalization of
streamflow trends
 Comparisons with extant
literature
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Pulling Needles from the Haystack:
Moving Forward with “Best Models”
Key Findings
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Temperature is projected to increase continuously in all assessed
regions of Nile River Basin throughout 21st Century.
Precipitation is projected to increase streamflow capacity in source
countries (Regions 3 and 4), maintain a moderately constant
capacity in Region 2 (Sudan), and decrease streamflow in Region 1
(Egypt), particularly after 2050.
The Nile River Basin is on course to overshoot its water capacity
after 2050.
A reservoir fill rate of 10 to15 %, given projected increases in
streamflow within the Blue Nile region, would build hydroelectric
capacity in Ethiopia while maintaining a constant level of streamflow
throughout Sudan and Egypt.
Validation efforts suggest averages across 33 GCM models may
truncate volatility in streamflow, leading to an assessed need to look
within selected GCM models.
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Preliminary Policy Recommendations

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Reservoir fill rate of 10 to15 %.
Divert anticipated increases in streamflow into
reservoir to reduce problems associated inundation
and subsequent flooding of arable land in the
vicinity of the Blue Nile.
Assess plausible scenarios for sustainable water
management systems within the Basin capable of
incorporating both agricultural and energy
production and the creation of new water sources
including desalinization (via Nile Basin Initiative).
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