modeling areas exposed to oil pollution in the coastal city of bandar abbas using electre-i and ahp models

modeling areas exposed to oil pollution in the coastal city of bandar abbas using electre-i and ahp models 1-introduction persian gulf coasts, is considered if the beach oil - gas, fisheries, trading and residential. during the persian gulf coast of the role of communication and sea transportation due to the national and international trade, legal and illegal, from oil and gas activities and fishing and the coastal fisheries is an economical three principal approaches. coasts are the most important areas of the world that is inhabited by humans and uses its resources strongly. sensitive areas of coastal are regions that have sensitive source or dependent on the sea coast. and this sensitivity by biodiversity, species richness, species at risk, vulnerable and rare, vital social being on the verge of ecological tolerance, sensitivity to pollutants, healing, environmental damage and problems caused by clean up the environment caused by environmental pollutants. because more than 30 percent of the country's borders, formed coastal boundaries, detect sensitive sea areas of the coast of iran is the great importance. therefore, the first step to control and clean up quickly and accurately at the time of sudden oil pollution, determination of the degree of sensitive coastal areas is to manage the crisis and to minimize damage. this step is necessary to be done carefully and use appropriate tools and techniques. by using spatial multi-criteria decision-making methods and geographic information system can the role and importance of various criteria to be considered and also multiple scenarios to be considered sensitive coastal areas to oil pollution. that this can be important role in making correct decisions by managers and planners. according to the economic importance of coastal areas of southern iran and the persian gulf coast ecosystem conservation, this research is planned. in this regard electre-i and ahp models have been used. 2- materials and methods the study area is includes the part of the coast that dry side of the border based on the highest facing the sea on land and water is determined based on the watermark line. it is this part of the land adjacent sea in the stormy conditions placed under the direct influence of the sea water, so contains the unstable and seating sand dunes and vegetation of the land is one of the signs. in this study also considered the potential and actual activities in adjacent areas. so land use in the onshore coastal border villages were considered. electre-i model was introduced in the late 1980s and is considered one of the best multi-criteria decision making techniques. this model is based on non-ratings relations, that is not to rank all factors leading, may be less than the value of options that the decision also be removed. all stages of the implementation of this method is based on a set of coordinated and uncoordinated series. to runinng this model in forms picture and spatial mode was used matlab software. in the ahp, the comparison between the criteria used in pairs and weight of each criteria and sub-criteria for the ratio as output. in this method, creating hierarchy of decision-making compared the relationship between each level will be discussed in the form of a matrix. this model was implemented in software arcgis 10.1. effective criteria in determining sensitivity of coastal areas to oil pollution in the present study, assessment of the current situation in the region, and the views of experts in the management of coastal areas as well as review of the studies, the criteria has been studied in three general groups: the criteria are categorize in three categories of criteria related to beach physics (landforms, kind of sediments, slope, liquefaction and earthquick), biological criteria (protected areas and ecological potential) and human criteria (ports and docks, industrial units, aquaculture, settlements and ...). the importance and the sensitivity of each of the criteria and sub-criteria to the oil pollution were used in five degrees (from very low to very high sensitivity). weighting the criteria the purpose of weighting is to be stated the importance of each criteria relative to other criteria. in this study, the weights according to average experts of specialists determined by delphi method. in this regard, the questionnaire was designed and completed by several people. then mean of their argumentation entered in expert choice software and final weight was obtained after the pair-wise comparison of criteria with ahp method. the pair-wise comparison matrix are calculated and weights in the tables 2 to 4 for each criteria. in table 5 matrix pair-wise comparison is formed between the main criteria. biological criteria weighed 0.369 has greatest weight and human resources criteria and beach physics with the weight of 0.335 and 0.297 respectively, were the next priorities. 3- conclusions in this part of the implementation of the ahp and electre-i in determining the locations susceptible to oil pollution in the coastal city of bandar abbas explains: ahp model in this method, you create a hierarchy of decision-making compared the relationship between each level will be discussed in the form of a matrix that it dine from high to low levels. next, the relative weight of the different layers are multiplied together. then this layers overlay as base weighted overlay algorithm in the gis. so places is detected with different sensitivity (low to high sensitivity). figure 12 shows map sensitivity class of the implementation of ahp model in the coasts of bandar abbas county. more sensitive areas are shown on the map by a darker color. electre-i model if a problem multi-criteria exists n criteria and m options; in order to choose the best option using electre-i, the following should be done: step1) normalization: at this stage the decision matrix becomes a scale without matrix. step2) scale weighted matrix: at this step raster map of normal weight matrix of each layer multiplied in the layer. step3) identified sets of coordinated and uncoordinated (pros and cons) step4) calculation of coordinate matrix step5) calculation of uncoordinated matrix step6) determine the effective coordination matrix step7) determine effective inconsistent matrix figure 13 shows the map of run electre-i model. as it is seen in regions are located in 5 classes of sensitivity (very low, low, medium, high, very high). class 1 areas with very low sensitivity and class 5 areas with very high sensitivity. in this map coastal areas with red color show the coastal areas with very high sensitivity. 4- discussion of results - in this research, in addition to identification of the factors affecting production, distribution and accumulation of oil pollution, the criteria are categorize in three categories of criteria related to beach physics, biological criteria and human criteria. biological criteria weighed 0.369 has greatest weight and human resources criteria and beach physics with the weight of 0.335 and 0.297 respectively, were the next priorities. - in both models the highest areas coastal city of bandar abbas show medium sensitivity (sensitivity class 3). -figure 14 the results of class sensitivity between the values of classification model electre-i suggest that, respectively, the highest rate of approximately 76 km2 of coastal city hypersensitive average, 32 km2 of high sensitivity and approximately 12 km2 sensitive too are high. - the results of the sensitivity classes were classified in the amounts of ahp model showed that respectively about 160 km2 of the coast city has an average sensitivity, 113 km2 of high sensitivity and low sensitivity are approximately 71 km2. - the results of numerical indicators show areas around the port shahid rajai, the port shahid bahonar and parts of the coastal port city of bandar abbas, have a very high sensitivity to oil pollution. in addition, the east parts of coastal area of bandar abbas that are mostly mangrove protected areas have moderate to high sensitivity.