Assessment of Grand Ethiopian Renaissance Dam impacts using Decision Support System

Abstract

Ethiopian government undertakes plans to develop massive hydropower potential with the
construction of a large scale Grand Ethiopian Renaissance Dam (GERD) upstream of the Ethiopian-Sudan
border in an effort to utilize the water resources potential, improve the water and energy security in order to
reduce poverty, create an atmosphere for social change and bring economic growth to the country.The Analytic
Hierarchy Process (AHP) is one of the most widely used multi-criteria decision analysis in water resources
management and energy planning. AHP was used to study the trade-offs of reservoir capacity design plans in
order to promote a sustainable strategy for water resources management in the Eastern Nile countries that
includes Egypt, Ethiopia and the Sudan, without dangerous impacts on the environment and riparian countries.
Several environmental, economic and social criteria were considered when choosing the best alternative for
sustainable water resources management in the Eastern Nile countries to mitigate the adverse impacts resulting
from the construction of GERD to downstream countries. The results of this study showed that the “Do nothing” is the most appropriate option with regard to the environmental impact on the Eastern Nile
countries compared to the original plan and the new applied one (running now).

Full text

IOSR Journal of Computer Engineering (IOSR-JCE)
e-ISSN: 2278-0661,p-ISSN: 2278-8727, Volume 18, Issue 5, Ver. VI (Sep. - Oct. 2016), PP 08-18
www.iosrjournals.org
DOI: 10.9790/0661-1805060818 www.iosrjournals.org 8 | Page
Assessment of Grand Ethiopian Renaissance Dam impacts using
Decision Support System
Ghada Soliman1, Hoda Soussa2& Sherif El-Sayed3
1PhD in Environmental Engineering, Institute of Environmental Studies and Research, Ain Shams University.
Senior Software and Service Architect, Orange Labs Egypt, Cairo, Egypt,+2 012 010 66019
2Professor of Water Resources Engineering, Faculty of Engineering, Ain Shams University
3Associate professor, Head, Numerical Modelling Department, Hydraulics Research Institute, National Water
Research Centre
Abstract: Ethiopian government undertakes plans to develop massive hydropower potential with the
construction of a large scale Grand Ethiopian Renaissance Dam (GERD) upstream of the Ethiopian-Sudan
border in an effort to utilize the water resources potential, improve the water and energy security in order to
reduce poverty, create an atmosphere for social change and bring economic growth to the country.The Analytic
Hierarchy Process (AHP) is one of the most widely used multi-criteria decision analysis in water resources
management and energy planning.AHP was used to study the trade-offs of reservoir capacity design plansin
order to promote a sustainable strategy for water resources management in the Eastern Nile countries that
includes Egypt, Ethiopia and the Sudan, without dangerous impacts on the environment and riparian countries.
Several environmental, economic and social criteria were considered when choosing the best alternative for
sustainable water resources management in the Eastern Nile countries to mitigate the adverse impactsresulting
from the construction of GERD to downstream countries. The results of this study showed that the “Do-
nothing” is the most appropriate option with regard to the environmentalimpact on the Eastern Nile
countriescompared to the original plan and the new applied one (running now).
Keywords: Analytic Hierarchy Process; dam impacts; decision support systems; environmental impacts;
GERD; Nile River; water management
I. Introduction
The Nile Basin is considered one of the most complex and unique river basinsdue to its size and
varying climate, hydrology, topography and demography (Sileetet al. 2013). This variation poses many
challenges to the management of transboundary water resources of the basin, under the growing pressure from
increasing population, poverty, famine, climate change, shrinking water levels of dams and related power
shortages, dams‟ construction and agricultural development plans within the basin(Batisha 2013). These
challenges could trigger social, political and economic conflicts that would threaten the stability of communities
and nations among riparian states. Transboundary water resources offer a great opportunity for developing and
sharing the water resources of the region for personal and household needs, hydropower generation, agriculture,
navigation and several other social needs. The full potential of these shared water resources has not been fully
realized due to the lacking of investment funding requirements. Shared water resources represent a source of
cooperation and negotiation that need to be greatly enhanced at all political levels and the institutional support
for the management and the sustainable use of these water resources (Nile Basin Initiative 2012).
The Nile constitutes of two important water supply sources. The Eastern Nile Basin (Blue Nile) has
about 85% of the flow of the Nile that is originated from Ethiopia whereas Eastern Equatorial Nile (White Nile)
has the remaining of the flow that is about 15% of the flow. The Blue Nile has about 60% of the total flow at
Aswan and is still considered an important river basin to the Eastern Nile countries that includes
Egypt, Ethiopia and the Sudan (Mulat and Moges 2014). The major water uses are irrigation and hydropower.
Both Egypt, and to a less extent Sudan, are dependent significantly on water that come from the Nile for use in
irrigation in both countries (Waterbury 2002). On the other hand, Ethiopia contributes with less than 5% of the
irrigable land in the basin and less than 3% of the hydropower potential (Block et al. 2007). Ethiopia has a
plenty of water resources and abundant hydropower potential that is estimated to be about 30 000 MW with a
total potential of 159 TWh/year (World Energy Council 2007). Currently, 94% of Ethiopia‟s population still
depends on fuel wood for cooking and heating and 83% has no access to electricity (Thomson 2006).
The Nile riparian countries have substantial potential energy resources that include hydropower, natural
gas, oil, coal, peat, biomass, geothermal, solar, and wind energy. Hydropower remains the preferred renewable
energy source in which the power is producedas the result of moving the energy of water from higher to lower
elevations. It takes the dominant and central role among the various energy options for several reasons. One of
the key reasons is the low price-competitive technology that makes electricity affordable to urban and rural

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areas. It is reliable power supply and pollution free. It also provides abundant employment opportunities during
construction and operation with additional benefits for flood control and river flow regulation, irrigation,
transport and navigation, aqua farming, recreation, industrial and domestic supply. Moreover, it allows the
construction of infrastructure projects as for roads, electrification, telecommunication, schools, health centers,
government services, commercial and industrial use and thus, delivers additional benefits to rural communities
(Nile Basin Initiative 2012).
1.1. Hydroelectric plans of GERD
The hydroelectric potential in the Nile Basin is massive that is estimated at 150,000 MW of
hydropower potential. Despite the region‟s endowment with enormous hydropower potential, a small fraction
has been utilized by the downstream countries except for Egypt, whose hydropower potential is fully utilized.
There are also restrictions and challenges that impede the full utilization of the region‟s hydropower potential
that demand an implementation of mitigation measures for the negative impacts from hydropower planning
projects in the region. Hydropower potential has also limited ability to meet the energy needs in the region in the
long term. The projections indicated that the total demand and the total hydropower potential will be equated in
the region by 2030. Thus it becomes urgent to explore alternative scenarios to optimize power supply that
requires regional cooperation and power integration, thereby making the region more exposure to investments in
the power sector (Nile Basin Initiative 2012).
Therefore,the Ethiopian government has ambitious plans and programs to develop hydropower in an
effort to utilize the water resources potential, improve the water and energy security and thus reduce poverty,
develop an atmosphere for social change and thus bring economic growth to the country (Whittington et al.
2005).A Large scale hydropower dam known as Grand Ethiopian Renaissance Dam (GERD) is under
construction on the Blue Nile River in the upstream of the Ethiopian-Sudan border in Ethiopia. The GERD will
create a reservoir with storage capacity of 74 billion m3 and is expected to produce 6000 MW of hydropower
energy. By this, Ethiopia will have a massive upgrade over the existing hydroelectric power. At the same time,
this will have a significant impact on the Nile flow for countries downstream of the GERD (Mulat and Moges
2014). The larger the project, the greater the impacts on the natural and social environment is to be expected.
Large-scale development demands integrated planning for an entire river basin before initial implementation of
individual project(s). As the Nile river basin isan international river shared by eleven riparian countries, such
planning fosters further international cooperation.
1.2. Impact of GERD project on Downstream Countries
The international panel of experts submitted its final report in May 31, 2013 submitted a report with the
impact of GERD to Egypt and Sudan and the main gaps on GERD project studies. The report concludes that the
main dangerous impact in Egypt will be a reduction in power generated at Aswan High Dam when the water
levels of Lake Nasser is decreased, salinization of Egypt‟s agricultural lands in the Nile Delta due to the
increased upstream withdrawals resulting from GERD operation and large scale loss of flood recession
agriculture in Sudan during GERD impounding and operation (IPoE 2013).
A Group of professional from Egypt published a recommendation report for their government on the
effects of Ethiopian Grand Renaissance Dam Project (GERDP) on Egypt in June, 2013 of social, economic, and
political impact as consequences of Ethiopian dams. The report concludes that the impact will be a reduction in
the water share of Egypt resulted in securing the future supply of water to Egypt for drinking, agriculture and
industry, production of electricity from the High Dam and the Aswan Dam during the impound and operation of
GERD especially during the drought period, abandoning agricultural lands, and water pollution, navigation,
tourism, fish farms, and catastrophic consequences in both Sudan and Egypt due to GERD rupture where the
water released by GERD‟s saddle dam failure would flow that includes drowning of major towns and villages
exposing millions to the dangers of death and relocation (GNB 2013).
1.3. Environmental impact of GERD project
The environmental impact of the implementation of the Grand Ethiopian Renaissance Dam include
direct and indirect impacts on the biological, physical and chemical features of the river and the environment
where it is located (International Rivers, n.d.-b). Due to the transformation of the riverine ecosystem upstream
of the dam into an artificial lake, the river‟s natural plant and animal species are undermined. Riverine plants
and animals are often not adapted to live in a lake environment (Federal Democratic Republic of Ethiopia
Ministry Of Water Resources, 2002a; International Rivers, n.d.-b; Than, 2011).The changes in water
temperature, dissolved oxygen, chemical composition, salinity and the physical properties of the impoundment

Assessment of Grand Ethiopian Renaissance Dam impacts using Decision Support System
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generally happen too fast for the species to adapt themselves (International Rivers, n.d.-b; Than, 2011). In
addition, the survival of natural animals and plants could be further undermined by the presence of non-native
and invasive species. A second undermining factor could be the separation of animals‟ spawning habitats and
rearing habitats due to the dam (Federal Democratic Republic of Ethiopia Ministry Of Water Resources, 2002a;
International Rivers, n.d.-b). Also, the distribution of wild life and vegetation in the river catchment is affected.
The inundation of the forests and riverbanks will force animals and plants to migrate uphill (Ahram online,
2013; International Rivers, 2012b). Quick habitat changes could threaten animals and plants with extinction,
which endangers the catchment‟s biodiversity (International Rivers, 2012b).
The (involuntary) resettlement of inhabitants living in the project region is one of the most challenging
and controversial outcomes of large dam projects (LererandScudder, 1999; Tilt et al., 2009). The Consulate
General of Ethiopia in Los Angeles (2012), states that the project is located in an area without significant human
settlements or economic activity and will, therefore, involve minimal social and environmental costs. On the
opposite, a field survey conducted by International Rivers (2012b) states that the dam construction will induce
the resettlement of at least 5110 inhabitants that are now living in the reservoir area and downstream of the dam.
Additionally, an approximately 7380 inhabitants living in villages near the future dam impoundment will be
relocated. A survey for resettlement purposes was conducted in the communities threatened with resettlement,
which are almost all areas inhabited by indigenous people (International Rivers, 2012b). It is important to
anticipate on the emergence of conflicts about resource division and utilization between resettled residents
(International Rivers, 2012b). The construction of the Grand Ethiopian Renaissance Dam project on the Blue
Nile can be considered as a perfect example of a top-down process. They state that the involvement and opinion
of local residents was completely neglected during the preparation phase of the project (Bosshard, 2011;
ImhofandLanza, 2010; International Rivers, 2012b). According to Bosshard (2011), the Ethiopian government
currently does not even shy the suppression of everyone who adopts a critical attitude towards the construction
wave of large hydropower projects. However, at least the inhabitants threatened with resettlement should be
involved in the planning of their future (Imhof andLanza, 2010; International Rivers, 2012b).
1.4. Purpose of Study
In this study, the Analytic Hierarchy Process (AHP), a technique in Multicriteria Decision Analysis
(MCDA), was used to assess the trade-offs of reservoir capacity design plans relating to its social,
environmental, and economic indicators in the Eastern Nile Basin in order to secure the regional electricity
market without adverse impacts on the environment and riparian countries, and thus promote a sustainable
strategy for water resources management in the Blue Nile Basin. It also fosters the cooperative management of
shared water resources between riparian countries, thus allowing a sustainable and equitable way to ensure
prosperity and security for all its communities, reducing poverty and promoting economic integration under
conservative environmental prospect.The aim of this study is to assess the potential impact of the GERD Dam
on the downstream riparian countries in the Eastern Nile Basin with the use of the decision support system,
mainly the Analytical Hierarchy Process (AHP), a multi-criteria decision technique based on social,
environmental, and economic indicators.
II. Positive and Negative impacts of Dam
This section summarizes the positive and negative impacts of Dam on the environment:
 Employment opportunities: The power project is expected to generate employment opportunities during
both construction and operation associated with the construction of transmission lines, and an additional
people will probably get direct and indirect jobs during operation(ADBG 2010).Improving access to
electricity in the rural areas will encourage the development of rural industries and services and thus open
up many opportunities for young people at minimum cost to national economies (NBI 2012).
 Gender Issues: Women will have equal employment opportunities as well as men that will be created
during construction within the project skills requirements; and from convenient and safe access road
facility. Women can obtain further income generating activities for women such as food catering/restaurants
for workers on the construction sites and the selling of local products to construction camp workers and
thus maximizing the purchase of local products and services(ADBG 2010).
 Physical displacement and resettlement:Dam construction brings considerable disadvantages to local
communities. Due to the newly created reservoir,some people may lose their land and assets whilst the need
to be resettled. People, who remain in the construction area, may find their livelihoods affected by changes
in river flow (NBI 2012). Local communities do not share the same benefits of the hydropower project,
while they carry most of the burden due to the construction of the dam. The agricultural lands and the
resettlementof millions of families will be also affected due to the reduction in the water share of
downstream countries.
 Public Health:Newly created water bodies can produce water related diseases such as malaria and bilharzia
that affect public health. Some infectious diseases can spread around hydroelectric reservoirs, in specific in

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warm climates and densely populated areas (NBI 2012).The possible health impacts caused by
theimplementation of large dam projects for inhabitantsclose to the dam site, but also upstream,
downstream and eventually even nationally or internationally are presented in Table 1 (Lerer and Scudder,
1999). Table 1 Potential Health Impacts of Large Dam Projects (Lerer and Scudder, 1999)
Impact Area
Effect of the Dam
Health Impact
Upstreamcatchment and river
Loss of biodiversity, increased
agriculture, sedimentation and flooding,
changes in river flow regime
Changes in flood security, water related
diseases, difficulties with
transport and access to health facilities
Reservoir area
Inundation of land, presence of large
man- made reservoir, pollution, changes
in mineral content, decaying organic
material
Involuntary resettlement, social
disruption, vector- borne diseases,
water- related diseases, reservoir-
induced seismicity
Downstreamriver
Lower water levels, poor water quality,
lack of seasonal variation, loss of
biodiversity
Food security affected on flood plains
and estuaries (farming & fishing),
water-related diseases,
dam failure and flooding
Irrigation areas
Increased water availability and
agriculture, water weeds, changes in
flow and mineral content, pollution
Changes in food security, vector-borne
and water- related diseases
Construction activities
Migration, informal settlement, sex
work, road traffic increase, hazardous
construction
Water- related diseases, sexually
transmitted diseases, HIV/AIDS,
accidents and occupational
Injuries
Resettlement areas
Social disruption, pollution, pressure
onnaturalresources
Communicable diseases, violence and
injury, water- related diseases, loss of
food security
Country/ regional/
Global
Reduced fuel imports, improved
exports, loss of biodiversity,
reallocation of funding, sustainability
Macro- economic impacts on health,
inequitable allocation of revenue, health
impacts of climate change
 Water Supply: Dams create reservoirs that supply water for many uses, including domestic, industrial and
agricultural. The seasonal and annual changing in stream flow may cause water rarity problems to people
in the riparian countries. It is expected that the livelihoods of farmers and other rural people in downstream
countries would be substantially impacted.
 Safety and Security: Dam safety concerns are related to faulty design or wearing out of materials used for
construction. FEMA (“Why Dams Fail”, 2015) outlined several reasons to why dams can fail, including (a)
overtopping caused by floods that exceed dam capacity; (b) Structural failure of materials used in dam
construction; (c) movement and/or failure of the foundation supporting the dam; (d) settlement and cracking
of concrete or embankment dams; (e) piping and internal erosion of soil in embankment dams; and (f)
improper sufficiency of maintenance and upkeep.
 Improve Investments: A country is characterized by reliable power supply is definitely an attractive to
investors leading to supporting expansion, of the industrial and service sectors, creating employment and
improving living standards. An effort is required to speed up the implementation of the transboundary
transmission interconnector to move energy from countries with surplus to countries with deficit, and thus
embracing peak power swapping in an aim to boost the economy with the volume of investments required
(NBI 2012).
 Fisheries: Hydroelectric projects often have major effects on fish and other aquatic life. Reservoirs
positively affect certain fish species (and fisheries) by increasing the area of available aquatic habitat.
However, the net impacts are often negative because (a) the dam blocks upriver fish migrations, while
downriver passage through turbines or over spillways is often unsuccessful; (b) many river-adapted fish and
other aquatic species cannot survive in artificial lakes; (c) changes in downriver flow patterns adversely
affect many species, and (d) water quality deterioration in or below reservoirs (usually low oxygen levels;
sometimes gas super-saturation) kills fish and damages aquatic habitats. Freshwater organisms are even
more sensitive to these changes than most fish species, due to their limited mobility (Ledec and Quintero,
2003).
 Irrigation:It is expected that the increase in the water surface area will lead to evaporation losses from
water reservoir.As the result, water shortagewill impact the water efficiency reached in the agriculture by
means of irrigation that has substantial economic impact.Also diversion of water through irrigation further
reduces the water supply for downstream.
 Cultural assets: Cultural property that includes archaeological, historical, paleontological, and religious
sites and objects, can be inundated by reservoirs or destroyed by associated quarries, borrow pits, roads, or
other works (Ledec and Quintero, 2003).

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 Downstream Flow regime:Major downriver hydrological changes can damage riparian ecosystems that
depend on periodic natural flooding, water pollution degradation during low flow periods, and increase of
saltwater intrusion near river estuaries.
Agriculture and human water supplies can be damaged due to (a) reducing sediment and nutrient loads in
the downriver of dams leading to an increase in the river-edge and coastal erosion and damage the
biological and economic productivity of rivers and estuaries, and (b) diversion of water to another portion
of the river, or to a different river kills fish and fauna and flora dependent on the river (Ledec and Quintero,
2003).
 Water quality:Serious water quality declination will occur due to the reduced oxygenation and dilution of
pollutants by relatively stationary reservoirs, flooding of biomass and resulting underwater decay, and/or
reservoir stratification where deeper lake waters lack oxygen (Ledec and Quintero, 2003).
 Greenhouse gas emission:In northern regions, Greenhouse gases (carbon dioxide and methane) emission
from hydroelectricity are significantly smaller than corresponding from thermal power plants alternatives
varying from < 2% to 8% of any kind of conventional thermal generation alternative whereas in tropical
region, these emissions cover a much wider range of values, varying from less than 1% to more than 200%
of the emission factors reported for thermal power plant generation (Tremblay et al. 2002)
 Floating aquatic weeds:Floating aquatic vegetation can rapidly increase in eutrophic reservoirs, causing
problems such as (a) degraded habitat for most species of fish and other aquatic life, (b) improved breeding
grounds for mosquitoes and other nuisance species and disease vectors, (c) impeded navigation and
swimming, (d) blocking of electro-mechanical equipment at dams, and (e) increased water loss from some
reservoirs.
 Climatic variability and change:Large areas in the basin are vulnerable to drought because of high
variability in rainfall and high evapotranspiration rates. Seasonal shortages in water associated with natural
climate variability make it difficult to maintain peak generation capacity throughout the year, and may
reduce the long term economic feasibility of candidate hydropower projects. The negative impacts of
climate on the power sector are expected to greatly increase with global climate change (NBI 2012).
 Tourism: It provides additional income for local populations throughout recreational facilities and water
sports. Accommodation areas offer an income-generation option for the local residents. When the dam site
attracts tourism, it creates an incentive for maintaining environmental sustainability in the area.
 Navigation:Dams create barriers for upstream-downstream navigation and movements of fish and other
creatures. Dams can also substantially change the flow of water and transport of sediment, nutrients, and
food materials that supply downstream aquatic ecosystems and estuaries, with impacts commonly extending
for hundreds of kilometres downstream (Krchnaket al. 2009). Lower water levels have an adverse impact
on tourism and boating used for movement and trades downstream the river. With increased sediment
transport, serious changes are occurred to navigation channels and harbours.
 Industrial growth:Electricity plays a significant role in poverty alleviation and in promoting the economic
productivity. The production of hydropower would allow the expansion of power-requiring industries and
factories in the surrounding urban areas and thus creating more permanent job opportunities for local
community.
III. Materials and Methods
Multi-Criteria Decision Analysis (MCDA) is an approach that provides a systematic way for decision
makers to reach same consensus by identifying, assessing and scoring options against a set of decision criteria. It
helps solve complex problems by creating structured framework that allows the decision maker to select the
optimal alternative scenario, according to the identified set of criteria.
3.1. Analytical Hierarchy Process (AHP)
Analytical Hierarchy Process (AHP) is one of Multi Criteria decision making methodsoriginally
proposed by Saaty (1980). It is a theory of measurement through pairwise comparisons that relies on the
judgments of experts to derive priority scales.It represents a decision support tool which can be used to solve
complex decision problems. It uses a multi-level hierarchical structure of objectives, criteria, and alternatives.
The priority scales are derived by using a set of pairwise comparisons. These comparisons are used to obtain the
weights of importance of the decision criteria. It provides a mechanism for improving consistency if the
comparisons and judgments are inconsistent. Thus, it helps the decision makers to achieve better judgments
based on hierarchy, pairwise comparisons, judgment scales, allocation of criteria weights, and selection of the
best alternative from a finite set of alternatives.
The methodology of AHP involves four main steps that can be explained in brief as follows:

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1. Decompose the complex problem into a hierarchical structure with decision elements descending from an
overall goal to the objectivesfrom a broad perspective, the criteria in the intermediate levels, and then the
alternatives in the lowest level. The multilevel decision hierarchyprovides an overview of the relationships
inherent in the context for practical problem solving. It helps to decompose the complex decision problems
into more comprehensive ones that can be easily evaluated independently. Figure 1 illustrates the hierarchy
structure corresponding to the example.
2. Construct a set of pairwise comparison matrices of various criteria and all decision alternatives under each
criterion, based on Saatyqualitative preference rating scale as per Table 2. Each elementin an upper level is
used to compare the elements in the level immediately below with respect to it.The diagonal elements of the
matrix is 1 indicates the comparison of the criterion to itself.The criterion i is more important than criterion
j if the value of the element (i, j) is greater than 1. The criterion i is less important than criterion j if the
value of the element (i, j) is less than 1.
3. Develop the relative weights for the criteriato produce the priority vector of a pairwise comparison matrix.
The relative weights are computed by using the geometric mean of each row. That is, the elements in each
row are multiplied with each other and then the nth root is taken (where n is the number of elements in the
row). Next the numbers are normalized by dividing them with their sum.
4. Check the consistency of the judgments used to develop the pairwise comparison matrix that can be
measured using the consistency ratio (CR). The pairwise comparisons in a judgment matrix are considered
to be consistent if the corresponding consistency ratio (CR) is 10% or lower (Saaty, 1994). The judgments
are considered random if the consistency ratio (CR) exceeds 10%. The judgments should revise the pairwise
comparison matrix and the pairwise comparison matrix should be recomputed.
5. Aggregate the relative weights of the criteria to perform the overall evaluation of the alternatives. Each
alternative can be evaluated in terms of the relative importance (or weight) of each criterion.
Table 2The pairwise comparison scale
Intensity
of importance
Definition
Explanation
1
Equal Importance
Two activities contribute equally to the objective
3
Moderate importance
Experience and judgment slightly favor one activity over another
5
Strong importance
Experience and judgment strongly favor one activity over another
7
Very strong or
demonstrated importance
An activity is favored very strongly over another; its dominance
demonstrated in practice
9
Extreme importance
The evidence favoring one activity over another is of the highest
possible order of affirmation
2, 4, 6, 8
Intermediate importance
between adjacent scale
values
Compromise is needed between two judgment
Source: Saaty (1977)
3.1.1. Compute the criteria weights
1. Construct the pairwise comparison matrix A. The matrix is n×n where n represents the number of criteria to
be evaluated. Each element aijis derived quantitatively based on Saaty qualitative preference rating scale as
per Table 1. The rating scale is used measure the relative importance of criterion i in comparison to
criterion j for each criteria pair (i, j). The pairwise comparison matrix can be represented in the following
form:
=112  1
21 1 2
 22  
121
2. Calculate the geometric mean of the ith row by estimating the nth root of the product of the pairwise
comparison values in each row.
= 

=1 1

3. Derive the relative weight of each criterion by normalizing the aforementioned nth root of criteria

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= 

=1

4. Produce a matrix of priority vector representing the relative weights of the criteria as follows
= 12 
3.1.2. Calculate the consistency ratio (CR)
1. Compute the eigenvalue by the sum of the jth column and then multiplying it to normalized principal
eigenvector or the relative weight of respective criterion.
λ=

=1
2. Calculate the maximum eigenvalue(λmax)of the priority vector by summing them as principal eigenvalue.
It can be used to estimate consistency in a matrix, as reflected in the proportionality of preferences (Saaty
1995, 1980).
λ = λ

=1
The closer λmax is to the number of elements n in the matrix A, the more consistent the matrix will be.
λ 
3. Calculating the Consistency Index (CI) to measure the inconsistency and deviations from the consistency is
expressed by the following equation (Albayraket al. 2004; Lee et al. 2002; Saaty1995). The smaller the
value of CI, the smaller is the deviation from the consistency.
= λ  1
4. Derive the Random Index (RI) from Table 3 on the basis of the size of matrix (or n), where n = the number
of the elements in the matrix.
5. Calculating Consistency Ratio (CR) by dividing Consistency Index (CI) by Random Index (RI). If the CI is
less than 0.10, the consistency of the decision-maker is considered satisfactory. But if CI exceeds 0.10,
some revisions of judgment may be required (Lee et al. 2002).
= 

Table 3Random Index (RI) for size of matrix
Size of matrix(n)
1
2
3
4
5
6
7
8
9
Random Consistency Index
0.00
0.00
0.58
0.90
1.12
1.24
1.32
1.41
1.45
3.2. AHP Hierarchy Tree
In this study, a hierarchical decision making approach based on multi-criteria decision making
approach according to the criteria such as social, environmental, and economic, was presented in order to
prioritize the alternatives for reservoir capacity planning for power generation. The hierarchy tree is composed
of 3 main criteria, 18 sub-criteria, and 3 alternatives.
Figure 1The hierarchical structure for the selection of the reservoir capacity planning

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3.3. Indicators
The comparative evaluation of proposed alternatives was based on criteria and indicators that are of
fundamental importance for the assessment of GERD construction according to the categories identified,
including Social, Environmental, and Economic. The following table (Table 4) summarizes the indicators that
are used to measure the impacts of alternatives.
Table 4Criteria used for the alternatives evaluation
Criteria (Level 2)
Sub-Criteria (Level 3)
Symbol
Social
Physical displacement and resettlement
SO1
Gender equality and women empowerment
SO2
Water Supply
SO3
Public Health
SO4
Safety and Security
SO5
Environmental
Fisheries
EN1
Downstream Flow regime
EN2
Cultural Assets
EN3
Water quality
EN4
Greenhouse gas emission
EN5
Floating aquatic weeds
EN6
Climatic variability and change
EN7
Economic
Employment opportunities
EC1
Navigation
EC2
Energy production
EC3
Irrigation
EC4
Industrial growth
EC5
Tourism
EC6
3.4. Alternatives
This section identifies the alternatives to the hydropower GERD dam construction in Ethiopia:
1. Alternative 1: “Do-Nothing”: With the “Do-nothing” alternative, the quality of life would remain at a low
level for local community. It indicates that no increase in economic activity would occur. The existing
conditions of the socio-economic and biophysical environment would remain unchanged.
2. Alternative 2: “Dam-planned”:The proposed capacity of GERD was 1200 MW with a reservoir of 14
BCM water volume.On the other hand, Ahmed and Elsanabary (2015) proved that the best accepted
scenario for constructing the dam is by charging a reservoir with 10 BCM/year or less in 3.8 years. This
amount of water will be sufficient for power generation and less impacts on the upstream counties.
3. Alternative 3: “Dam-reality: The GERD is projected to have 6,000 MW with a reservoir of 74 BCM
water volume when it is completed in 2017 that will constitute a significant threat to downstream countries.
IV. Results and Discussion
The relative weights of main criteria and sub-criteria that were considered in the reservoir capacity
planning for power generation, is shown in Figure 2. According to these weights, the environmental criteria
seemed to be the most important criteria in the selection of the best alternative with regard to the construction of
GERD dam. The criterion with the least significance seems to be the economic criteria.

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DOI: 10.9790/0661-1805060818 www.iosrjournals.org 16 | Page
Figure 2 Relative weights with respect to main and sub-criteria
Following is to determine the importance values for alternatives, this study showed that the “Dam-
reality” alternative was ranked last (0.115) behind the “Dam-planned” (0.297) and “Do-nothing” (0.587) as
shown in Figure 3.
Figure 3 Ranking of alternatives
If the GERD Dam was a multipurpose project for water storage, irrigation, or flood regulation as well
as for hydroelectricity, then the “Dam-planned” would be a considerable reasonable. However, the Ethiopian
government has stated that the dam will be used solely for electricity generation. This means that, in theory, if
the decision makers give marginal attention to the environmental and social aspects, then the decision was not
made to build the dam.
V. Conclusion
This study investigated the impacts of constructing such a dam from social, environmental, and
economic aspects using decision support system. The approach of AHP is relatively new in the field of water
resources, even having its high usefulness in the public sector decision making and resolving controversies and
conflicts. Thus AHP proved to be one of suitable methods in accordance to the problem nature on the scale of
hydropower development in the eastern Nile Basin from application point of view as many criteria are involved
in the decision making.
Poor project design can lead to soil erosion, water quality deterioration, and eutrophication during the
construction and operation of hydropower facilities. The very high sediment loads in the headwater areas
(especially in the eastern Nile region) will affect the economic feasibility of possible hydropower projects by
reducing the storage capacity and water volume available for generating electricity. Trapping the sediment load
in the new reservoir has the effect of altering downstream scour and deposition patterns, ultimately producing

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changes in river morphology (NBI 2012).The Ethiopian government has planned to postpone the filling of the
reservoir until after the river‟s sediment peak to reduce the sedimentation in the basin of the Grand Ethiopian
Renaissance Dam (International Rivers, 2012b). According to International Rivers (2012b), the population in
the study area knows about the implementation of a development project on the Blue Nile in their area but they
were not properly informed about the project.Therefore, they did not have the chance to understand the impact
the Grand Ethiopian Renaissance Dam could possibly have on their lives (International Rivers, 2012b).
According to Michaela Schoeters (2013), the benefits of the GERD- project are rather limited. So to
maximize the dam‟s benefits, the project should be implemented as part of an integrated water management
plan, in which the impact of this project is described while bearing all the river-based developments planned and
build in the entire river basin in mind.
Transboundary watercourses traversing different states present a challenge in terms of management as
each country has differing interests as per their national and local needs. It sets a stage to potential
disagreements pointing to the need for cooperation between countries and even lower levels (UNEP
2013).Water resources management affects everybody and should be undertaken with the participation of
relevant stakeholders to promotecooperation and joint action between three co-basin countries of the Blue Nile
through win-win solutions without severe environmental degradation.
Acknowledgement
I‟d like to thank Hoda Soussa for the provided guidance, support, and unbiased opinion while tackling
this topic. I‟m also thankful to Sherif El-Sayed for his contribution from an expert point of view and unbiased
feedback during this research. References
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