108
f. Fuzzy AHP Performance of Criteria at Alpha = 1
Performance Overall Weight
Weighted Performance Alpha cut 1
Criteria Vulnerability lower middle upper lower middle upper lower middle upper left right
Z1 0.275 0.566 1.137 0.046 0.105 0.351 0.013 0.059 0.399 0.059 0.059
Z2 0.109
0.276 0.614
0.005 0.029 0.215 0.029 0.029 Z3
0.049 0.104
0.284 0.002 0.011 0.100 0.011 0.011
Subsidence Z4
0.032 0.054
0.114 0.001 0.006 0.040 0.006 0.006
Z1 0.269 0.552 1.140 0.016 0.117 0.934 0.004 0.065 1.065 0.065 0.065
Z2 0.107
0.269 0.615
0.002 0.031 0.575 0.031 0.031 Z3
0.048 0.131
0.331 0.001 0.015 0.309 0.015 0.015
CH
B
4
B
Z4 0.030
0.048 0.114
0.000 0.006 0.106 0.006 0.006 Z1
0.145 0.378 0.866 0.007 0.056 0.503 0.001 0.021 0.436 0.021 0.021 Z2
0.066 0.184
0.501 0.000 0.010 0.252 0.010 0.010
Z3 0.050
0.109 0.296
0.000 0.006 0.149 0.006 0.006 H
B
2
B
S Z4
0.033 0.059
0.152 0.000 0.003 0.076 0.003 0.003
Z1 0.104 0.291 0.729 0.004 0.020 0.168 0.000 0.006 0.122 0.006 0.006
Z2 0.067
0.189 0.501
0.000 0.004 0.084 0.004 0.004 Z3
0.051 0.111
0.319 0.000 0.002 0.054 0.002 0.002
CO
B
2
B
Z4 0.034
0.061 0.160
0.000 0.001 0.027 0.001 0.001 Z1
0.287 0.566 1.135 0.111 0.387 1.228 0.032 0.219 1.394 0.219 0.219 Z2
0.147 0.317
0.670 0.016 0.123 0.822 0.123 0.123
Z3 0.068
0.153 0.338
0.008 0.059 0.416 0.059 0.059 Flooded Area
Z4 0.029
0.044 0.084
0.003 0.017 0.103 0.017 0.017
109
Performance Overall Weight
Weighted Performance Alpha cut 1
Criteria Vulnerability lower middle upper lower middle upper lower middle upper left right
Z1 0.267 0.538 1.092 0.090 0.315 0.965 0.024 0.169 1.053 0.169 0.169
Z2 0.126
0.290 0.633
0.011 0.091 0.611 0.091 0.091 Z3
0.047 0.125
0.295 0.004 0.039 0.284 0.039 0.039
Water Quality Z4
0.030 0.047
0.109 0.003 0.015 0.105 0.015 0.015
Spatial Multi Criteria Analysis for Mud Volcano Vulnerable Area in Sidoarjo District, East Java Province
1
Candra Dewi
2
, I Wayan Astika
3
, Gatot H. Pramono
4
ABSTRACT
Managing an area for further planning requires information on risk level of area from natural hazard. Since May 29
th
2006, a sea of hot mud has been gushing from the ground in Sidoarjo, East Java which caused economic, social, health and environmental impacts. Determining vulnerable area of hot mud volcano is
important to provide information on the extent of the area affected by the hazard. Vulnerability analysis requires set of factors determining dangerous level of particular area from a defined hazard source.
Vulnerability analysis for natural hazard also deals with vagueness arising from expert judgment on related parameters.
The objectives of this research are to develop multi criteria evaluation method using fuzzy analysis approach for mud volcano vulnerable area and to develop mud volcano vulnerable map using proposed
method. This research handles imprecision and subjectiveness involved in expert knowledge by using Fuzzy Analytical Hierarchy Process AHP. The alpha cut analysis and lambda function is performed in Fuzzy AHP
process to assess the confidence level of experts about their preference.
The method was then applied to generate mud volcano vulnerability for settlement area in Sidoarjo. The criteria used in the evaluation consist of subsidence, bubble gases, mud flooded and water quality. The
experts that give their judgment in form of Pairwise Comparison Matrix PCM represent all elements of the society such as The National Sidoarjo Mudflow Mitigation Team BPLS, Settlement Agency of Sidoarjo,
Centre of Environmental Geology, academic disaster researchers and the public as a victim of Lapindo mud. Having established Fuzzy AHP to obtain criterion performance, the spatial analysis was done by applying
this performance to criterion layer to create vulnerability area. The sensitivity analysis of the method was analyzed by using alpha cut values 0.4, 0.6 and 0.8 and lambda function values 0, 0.5 and 1. Performing
these alpha cut and lambda value showed the highest sensitivity could be observed at alpha 0.4 and lambda 0.
The comparison of vulnerability map resulted from applying Fuzzy AHP method at 100 confidence level with existing impacted area prepared by BPLS showed that these two maps have different
class of vulnerability. The result of multi criteria analysis showed that settlement areas located in impacted area were mostly categorized as high and moderate vulnerable class, while impacted area prepared by BPLS
is categorized as high hazardous area. However, the surface area of the merged class Z1 and Z2 from vulnerability analysis covered area was almost same with impacted area prepared by BPLS.
Key words: Vulnerability analysis, Multi Criteria Evaluation Method, Fuzzy AHP, Alpha cut, Lambda function, Spatial analysis
1
The paper is part of thesis, submitted at seminar and examination MIT for NRM Program
2
MIT Student, Bogor Agricultural University
3
Supervisor, Faculty of Agricultural Engineering- Bogor Agricultural University
4
Co-supervisor, National Survey and Mapping Agency
I. INTRODUCTION
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