Fuzzy MCDM for Dam Site Selection
Fuzzy MCDM for Dam Site Selection
   KEYWORDS                        Abstract. Selection of suitable site for dam is one of the problems associated with
   Dam site selection;             water resources management, and it is dependent on a set of qualitative and quantitative
   Fuzzy AHP;                      criteria. Such problems can be resolved using Multi-Criteria Decision-Making (MCDM)
   Multi-Criteria                  approaches. This study aims to develop a MCDM method integrated with fuzzy logic and
   Decision-Making                 group decision-making, speci cally focused on dam site selection. A fuzzy AHP method
   (MCDM);                         was extended to group decision making, and then the resulting group fuzzy AHP was
   VIKOR;                          combined with the VIKOR method. In the integrated method, fuzzy concepts were used
   Water resources                 to account for decision-makers' subjective judgments when considering the uncertainties of
   management.                     the site selection process. Group fuzzy AHP was used to determine the weights of di erent
                                   criteria and VIKOR was used to rank alternatives. The integrated method was applied to
                                   selection of the optimal site for an earth dam in Harsin city, Iran. The results show that
                                   the proposed method is an e ective and reliable method in selecting the optimal dam site.
                                   © 2015 Sharif University of Technology. All rights reserved.
      Multi-Criteria Decision Making (MCDM) meth-                 San Francisco river basin management [11], urban
ods are very suitable in addressing these problems. In            water supply of Zahedan, Iran [12], prioritization of
MCDM, among all possible alternatives, the best one               water management for sustainability [13], urban water
is selected based on evaluation criteria. MCDM meth-              supply, Melbourne city, Australia [14], ranking the
ods have been usually introduced based on classical               reservoirs systems [15], environmental assessment of
mathematics. Often MCDM problems are dependent                    water programmers [16], water resources planning [17],
on di erent and in some cases, con icting criteria.               assessment model of water supply system [18], applica-
It is also possible that complying with the nature of             tion of recycled water for household laundry in Sydney,
decision making problems, the expert opinions could               Australia [19], mapping urban water demands [20],
be di erent, or there could exist no exact information            evaluating water transfer projects [21], and ood risk
about them. In such conditions, utilizing traditional             assessment [22].
MCDM methods does not render the capacity to handle                      The main objectives of the present study are
uncertainties and may in some cases lead to wrong                   rstly to determine e ective criteria in dam site se-
decision making results. To address this problem,                 lection, secondly to present a fuzzy MCDM method to
researchers have expanded the MCDM methods based                  determine the criteria weights based on opinions of a
on fuzzy sets (fuzzy MCDM methods).                               decision making group and rating proposed sites, and
      Analytic Hierarchy Process (AHP) which was rst              thirdly to select the optimal site for the Harsin dam as
introduced by Saaty [1], is one of the most powerful              a case study.
and simplest MCDM methods. Many researchers                              A fuzzy AHP approach was extended to group
have extended the AHP based on fuzzy sets (fuzzy                  decision-making. The resulting group fuzzy AHP was
AHP methods). Fuzzy AHP methods are systematic                    then combined with VIKOR. Group fuzzy AHP was
approaches to the determination of the criteria weights           used to determine the weights of criteria, and VIKOR
and justi cation problem by using the concepts of                 was used to rank alternatives. The integrated method
fuzzy set theory and hierarchical structure analysis.             was applied to the selection of the optimal site for an
The most important and earliest fuzzy AHP methods                 earth dam in Harsin city, Iran.
include the following: Van Laarhoven and Pedrcyz [2]
presented the rst study on the application of fuzzy               2. Method
logic principle to AHP; Buckley [3] initiated trapezoidal
fuzzy numbers to express the decision maker's evalua-             The method used in this study is based on the integra-
tion on alternatives with respect to each criterion while         tion of fuzzy AHP and VIKOR methods. The weights
Van Laarhoven and Pedrcyz [2] used triangular fuzzy               that are obtained from group fuzzy AHP calculations
numbers; Chang [4] introduced a new approach for han-             are considered and used in VIKOR calculations. Deci-
dling fuzzy AHP with the use of triangular fuzzy num-             sion making in this integrated method involves several
bers for pair-wise comparison scale of fuzzy AHP, and             essential steps.
the use of the extent analysis method for the synthetic           2.1. Forming a team of decision makers
extent values of the pair-wise comparisons; Cheng [5]             This team involves dam construction experts and deci-
proposed a new algorithm for evaluating naval tactical            sion makers.
missile systems by the fuzzy AHP based on grade value
of membership function; Deng [6] presented a fuzzy                2.2. Determining e ective criteria and
approach for tackling qualitative multi-criteria analysis              potential alternatives
problems in a simple and straightforward manner.                  In this step, e ective criteria in locating the dam site
      The VIKOR which is an abbreviation of the                   are determined by using comprehensive review of liter-
Serbian expression of \VlseKriterijumslca Optimizacija            ature and expert opinions. The potential alternatives
I Kompromisno Resenje", meaning \multi-criteria op-               are then proposed based on determined criteria.
timization and compromise solution" [7], was rst                  2.3. Developing the hierarchical structure
introduced by Opricovic [8] as an MCDM method. The                The hierarchy diagram is a graphic representation of
VIKOR is used to solve discrete multi criteria problems           a complex problem in which objectives, criteria, and
with non-commensurable and con icting criteria. It                alternatives are at the highest, intermediate and lowest
focuses on ranking and selecting from a set of alter-             levels, respectively.
natives, and determines compromise solutions for a
problem with con icting criteria. It is one of the most           2.4. De ning the fuzzy scale
widely used MCDM methods in rating problems.                      In order to express the importance of criteria and
      To date, MCDM and fuzzy MCDM methods have                   formation of the pair-wise comparison matrix, a fuzzy
been used in the various elds of water engineering by             scale is de ned by decision makers. Table 1 shows a
many researches. These include urban water supply                 fuzzy scale that was used in this study. The graphical
of Zahedan city, Iran [9], watershed management [10],             form of this scale is shown in Figure 1.
                           Y. Minatour et al./Scientia Iranica, Transactions A: Civil Engineering 22 (2015) 319{330                                                321
Qi (minimum) will be reached if the following two                  Annual yield (C3 ): It is the annual volume of the
conditions (Condition 1 and Condition 2) are satis ed:             water that passes through the cross section of the river
                                                                   at the dam site. Annual yield plays an important role
Condition 1. Acceptable advantage:                                 in locating the dam site.
Water diversion and transfer (C11 ): The dam                      residential lands for dam construction, reservoir dewa-
site should be located where the costs of water diversion         tering and also utilizing the dam water in downstream
during construction and water transfer to consumption             should be considered.
location are minimum.
                                                                  Political impacts (C18 ): The dam construction goals
Annual volume of sediment (C12 ): If the annual                   for reducing political tensions including water supply
volume of sediment entering the reservoir is kept to              of a city, preventing grievances and immigration of
minimum, the volume of the reservoir during its useful            residents of a border city, etc. are among the attributes
life, water quality and the eciency of dam would be              that should also be considered.
higher.                                                                 After collecting and evaluating the required in-
                                                                  formation based on the selected criteria (mentioned
Probability of dam break (C13 ): The dam should                   above), four feasible alternatives were proposed for the
be constructed in a place that minimizes the socio-               Harsin earth dam site. The locations of the proposed
economic risks posed by a possible dam break.                     alternatives are shown in Figure 3 and identi ed by `A',
                                                                  `B', `C' and `D' letters.
Probable maximum ood (C14 ): The maximum                                After selecting the criteria for locating the earth
volume of water caused by thawing snow and ice                    dam site and considering alternatives (see Figure 3),
or other atmospheric precipitation occurring within               the integrated fuzzy AHP and VIKOR method was
a speci ed return period in rivers is called probable             applied to select the best site. Figure 4 shows the
maximum ood.                                                      problem of Harsin earth dam site selection using a
                                                                  hierarchical structure. The structure has three levels:
Average annual evaporation (C15 ): Due to the                     objective (locating the Harsin earth dam site), criteria
annual average temperature di erences in di erent                 (C1 to C18 ) and alternatives (A, B, C, and D).
regions in Iran, evaporation from the dam reservoirs                    To assess the relevance of the criteria incorporated
varies regionally. This variability has e ects on the             in the fuzzy AHP group method, a questionnaire was
retention time of water in the reservoir (in terms of             developed, and 4 experts (E1 , E2 , E3 and E4 ) involved
volume) and consequently on the eciency of the dam.              in Harsin earth dam project were asked to express the
                                                                  importance of each criterion using linguistic variables
Environmental impacts (C16 ): Changing weather                    which were inserted in the questionnaire. Table 2
conditions, vegetation, and wild life are other at-               summarizes the expert opinions about the importance
tributes that play signi cant roles in locating the dam           of the di erent criteria.
site.                                                                   The aggregated fuzzy weights of the criteria were
                                                                  obtained by integrating expert opinions using Eqs. (1)
Social impacts (C17 ): The social impacts of relo-                and (2). Then, a fuzzy pair-wise comparison matrix
cation of population centers and the integration of               for determining the weights of criteria was formed
di erent ethnic cultures due to the appropriation of              according to Table 3 (see Eqs. (3) to (5)).
                        Y. Minatour et al./Scientia Iranica, Transactions A: Civil Engineering 22 (2015) 319{330                325
                     Figure 4. Problem of the Harsin earth dam site selection using a Hierarchical structure.
Table 2. Expert opinions about the importance of the                     W 0 = (1:000; 0:960; 0:989; 0:978; 1:000; 0:995; 0:989;
di erent criteria.
            Criteria              Expert                                      0:973; 0:960; 0:949; 0:995; 0:968; 0:955;
                            E1    E2 E3         E4
               C1           VH    VH     VH     VH
                                                                              0:960; 0:960; 0:955; 0:929; 0:887)T :
               C2           M      L      H      H                     After normalization, the normalized weights of the
               C3           VH    H      VH      H                     criteria were calculated using Eq. (16) as:
               C4            H    VH      H     M                        W = (0:0575; 0:0552; 0:0568; 0:0562; 0:0575; 0:0572;
               C5           VH    VH     VH     VH
               C6           VH    VH     VH      H                            0:0568; 0:0559; 0:0552; 0:0546; 0:0572; 0:0556;
               C7            H     H     VH     VH
                                                                              0:0549; 0:0552; 0:0552; 0:0549; 0:0534; 0:0509)T :
               C8            H     H     M       H
               C9            L     H      H     M                      The VIKOR method was then applied to rank the
                                                                       alternatives. The normalized decision matrix was
               C10           H    M       L      L                     obtained using Eqs. (18) and (19), and the resulting
               C11          VH    H      VH     VH                     matrix is given in Table 7. Table 8 presents the values
               C12          M     M       H      H                     of fj and fj with respect to each criterion using
                                                                       Eqs. (20) and (21).
               C13          M      H     M       L                           Using Eqs. (22) and (23), the values Si and Ri for
               C14           H     H      L     M                      alternative i were obtained as:
               C15          M      H      L      H                       SA = 0:5424;       RA = 0:0575;
               C16          M     M       H      L
               C17          M     M       L      L                       SB = 0:3452;       RB = 0:0572;
               C18           L     L      L      L
                                                                         SC = 0:6012;       RC = 0:0575;
Table 4. The value of fuzzy synthetic extent with respect                                       QA = 0:8850;               QB = 0:0000;
to the ith object.
                       Si               Value                                                   QC = 1:0000;               QD = 0:3016:
                      S1        (0.009,0.079,0.813)                                         In the nal step, the alternatives were ranked based on
                      S2        (0.002,0.048,0.750)                                         Si , Ri , Qi as individuals and the results are presented
                      S3        (0.007,0.070,0.809)                                         in Table 9. Based on Qi , B and D are the alternatives
                      S4        (0.004,0.061,0.799)                                         with the rst and second positions, respectively. For
                      S5        (0.009,0.079,0.813)                                         these two alternatives, Condition 1:
                      S6        (0.007,0.075,0.809)                                                                                          1
                                                                                                (QD        QB = 0:3016) < (                       = 0:33);                  (30)
                      S7        (0.007,0.070,0.809)                                                                                    n 1
                      S8        (0.004,0.057,0.799)                                         is not satis ed based on Eq. (29), but Condition 2
                      S9        (0.002,0.048,0.750)                                         is satis ed. Therefore, with respect to these results
                      S10       (0.002,0.039,0.750)                                         (Table 9), B and D are proposed as the best alternatives
                      S11       (0.007,0.075,0.809)                                         for the Harsin earth dam site. Figure 5 shows the front
                      S12       (0.004,0.053,0.799)
                                                                                            view of these alternatives.
                      S13       (0.002,0.044,0.750)
                      S14       (0.002,0.048,0.750)
                                                                                            4. Sensitivity analysis
                      S15       (0.002,0.048,0.750)                                         To evaluate the performance of the proposed method,
                      S16       (0.002,0.044,0.750)                                         a comprehensive sensitivity analysis was carried out
                      S17       (0.002,0.035,0.585)                                         based on the importance of the criteria. In one of
                                                                                            the tests, the e ect of each criterion was examined
                      S18       (0.002,0.026,0.420)                                         by reducing the weight of each criterion separately by
                       Y. Minatour et al./Scientia Iranica, Transactions A: Civil Engineering 22 (2015) 319{330                                327
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    22(8), pp. 1017-1029 (2008).                                    Yasser Minatour has received his BSc from Mining
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    ter management for sustainability using hydrologic              University in September 2008. He nished his MSc
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    techniques", Journal of Environmental Management,               2012. His research interests span a wide range of topics
    90(3), pp. 1502-1511 (2009).                                    including numerical modeling in water engineering, wa-
14. Kodikara, P.N., Perera, B.J.C. and Kularathna,                  ter reservoir management, evolutionary optimization,
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330                Y. Minatour et al./Scientia Iranica, Transactions A: Civil Engineering 22 (2015) 319{330
Jahangir Khazaie has graduated as a civil engineer                mining, mine management, operation research and
from Bu-Ali Sina University in September 1994. He                 optimization in mine operations, computer applications
  nished MSc at Amikabir University of technology                 in mining, open pit design, decision making, fuzzy logic
in February 1997. He obtained his PhD degree in                   and genetic algorithm applications in mining. He is the
Numerical Analysis of Soil and Large Scale Foundation             author of 8 books. Dr. Ataei has published 130 journal
Statically Interactions from Amirkabir University of              papers and more than 150 conference papers. He is
technology in September 2008. Currently he is an                  currently holding 2 patents.
Assistant Professor at Razi University Kermanshah,
Iran. His research interests span a wide range of topics          Akbar Javadi received his BSc degree in Civil Engi-
including nite element modeling, improvement soil,                neering in 1989 and MSc degree in Hydraulic Structures
deep excavation, unsaturated soils, decision making,              in 1991, both from Tabriz University, and his PhD
modeling and control of seawater intrusion and evo-               in Geotechnical Engineering in 1998 from Bradford
lutionary optimization. The results of his research               University in UK. He is currently a Professor of
have been published in over 35 papers in international            Geotechnical Engineering and Head of the Computa-
journals, conference proceedings, book chapters and               tional Geomechanics at the University of Exeter in
research reports.                                                 the UK. His research interests span a wide range of
                                                                  topics including nite element modeling, unsaturated
Mohammad Ataei has received his BSc from Mining                   soils, ow and contaminant transport in saturated and
Engineering Department at Shahid Bahonar Univer-                  unsaturated soils, modeling and control of seawater
sity in September 1995, and his MSc from Amikabir                 intrusion, fracture mechanics, biomechanics, evolution-
University of Technology in August 1997. He obtained              ary optimization, engineering applications of arti cial
his PhD degree in modeling of optimum cuto grade                  intelligence and data mining and storm water collec-
for multi-metal deposit from Amirkabir University of              tion systems. The results of his research have been
Technology in July 2003. Currently he is a Professor              published in over 230 papers in international journals,
at Shahrood University of Technology, Shahrood, Iran.             conference proceedings, book chapters and research
His specialists are about open pit and underground                reports.