3.7 Sensitivity Analysis
The most important element to consider in sensitivity analysis is criterion weight Malczewski, 1999. This is because criterion weights are the essence of
value judgments and are subjective numbers about which decision maker disagree. A sensitivity analysis involving weights consist of investigating the sensitivity of
the alternatives to small change in the value of attribute weights. If the ranking remain unaffected as the weights are varied, error in the estimation of attribute
weights can be considered insignificant. If the ranking of alternatives prove to be sensitive to one or more weights, the accuracy in estimating weights should be
examined carefully. The Fuzzy-AHP provides the sensitivity analysis that can be performed by
changing the values of the alpha α and lambda λ. These values are the
measures for addressing the vagueness in the decision making process by expert. The changes in alpha
α and lambda λ values will show the sensitivity of the process.
3.8 Map Comparison
The research also will compare the vulnerability map resulted from using Fuzzy AHP method with existing impacted area by overlay these two maps.
Beside that, the resulted vulnerability map is also overlaid with land use map especially settlement area to show the vulnerability of this area from hazard. The
overlay and comparison resulted was used to offer recommendation. The existing impacted area is overlaid with study area as displayed in Figure 3.6.
46
pacted area prepared by BPLS
a and most of the areas become mu
o accordi
sometim standard operational procedure SOP is applied for this area. The area outside
mu o
subside los
submer future
Figure 3.6 Map of im
The impacted area is identified by red are d p nd. The area inside mud pond is classified as very high hazardous area
ngly this area is permanently submerged by mud, the high subsidence that es suddenly occur and also accumulation of gas from bubbles. The
d p nd is classified as high hazardous area because this area is susceptible to nce, mud overflow frequently occurred which caused significant economic
t and severe water pollution. The area at the Western part has ever been ged by mud overflow and there is a possibility to be flooded again in the
BPLS, 2007.
47
III. METHODOLOGY
3.1 Time and Location
This research was conducted from March to July 2008 including process of developing method and implementation of method. Developing the method was
accomplished at Bogor Agricultural University, while implementation of method was conducted for study area in Sidoarjo Regency, East Java Province.
3.1.1 General Overview of Study Area
The study area is working area of The National Sidoarjo Mudflow Mitigation Team Badan Penanggulangan Lumpur Lapindo or BPLS, which is
located in Sidoarjo Regency, Province of East Java covering three districts i.e. Porong, Jabon and Tanggulangin. The location is shown in Figure 3.1.
Figure 3.1 The study areas in Sidoarjo, East Java
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