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iastman et al, 1995; Malczewski, 1996). The criterion
pairwise comparison matrix takes the pairwise comparisons
as an input and produces the relative weights as output, and
the AHP provides a mathematical method of wanslating this
matrix into a vector of relative weights for the criteria.
(Malezewski (1996) and Eastman et al. (1995) have evaluated
this procedure very clearly.
A decision rule is a method of weighting or scoring criteria to
assess their importance (Heywood et al., 1993). It is the
procedure by which criteria are combined to arrive at a
particular evaluation, and by which evaluations are compared
and acted upon (Eastman et al., 1995). The aim of MADM
analysis is to choose the best or the most preferred
alternative. There are many decision rules that can be used in
MCDM process. Weighted Linear Combination (WLC) is the
most often used techniques for tackling spatial MADM and
this approach was used as a decision rule in this study.
2.5 Sensitivity Analysis
The main purpose in sensitivity analysis is to examine how
sensitive the choices are to the changes in criteria weights.
This is useful in situations such as where uncertainties exist
in the definition of the importance of different factors.
Sensitivity analysis with examples can be found in Lowry et
al. (1995).
3. CASE STUDY
3.1 Study Area
The West of Black Sea in the north of Turkey has the heavy
local rains and snow melting, especially in springs. In this
region, there are two main river basins: Filyos Basin and
Bartin Basin. Being a floodprone area, Bartin is selected as
the study area (Figure 3.1). It covers the subbasins of
Ovacuma and Ulus Creeks, which are two of the upstream
branches of Bartin River. Black Sea climate is dominant in
the basin and heavy rainfall and variable plant cover are
observed in the basin. The mean annual rainfall observed at
Ulus meteorological station is 984.5 mm (Türkiye Akarsu
Havzalari Tagkin Yilligi, 1998).
3.2 Criteria Evaluation
For all criteria that are seen as map layer, the criterion values
are generated. The causative factors for the flooding in every
watershed like annual rainfall, size of watershed, basin slope,
gradient of main drainage channel, drainage density, land use
and the soil type were taken into account according to the
literature surveys (Eimers et al, 2000; Henderson et al.,
1996; and Pramojanee et al, 2001). The selected three
criterion maps (drainage density, land use and soil type) are
illustrated with their classification values in Figure 3.2. The
original values can be found in Yalcin (2002).
3.3 Assigning Criteria Weights
The purpose of the criterion weighting is to express the
importance of each criterion relative to other criteria. The
more important criterion had the greater weight in the overall
evaluation. In this study ranking method and pairwise
comparison method were introduced and applied. The results
were compared with the Boolean Overlay Approach. GIS
should act as the interface between technology and the
361
decision maker with integrating MCE methods into the GIS
(Hey wood et al., 1993). Different decision makers may apply
different criterion and assign different weights for each
criterion according to their preferences. The decision maker
selects the criteria and compares them in a comparison
matrix. The weights of the criteria and the consistency ratio
of weighting procedure were calculated in interface module.
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Figure 3.1: Study area.
Figure 3.2: The selected three criterion maps with criterion
values.