pattern recognition of informal settlements using ahp model in gis, case study: karaj city

one of the most important issues that faced cities in developing countries with a crisis is expanding informal settlement in them. these settlements with differences in definition are known as occupational, changing, marginal, self-made and uncontrolled housing. it is estimated that about 1 billion man in all over the world live in such kinds of places. these zones are the texture for creation and expanding on sustainability and disorder. so far, much effort has done for replying this issue which comprises a range of strict approaches and cleaning up to enabling and renewing actions. karaj city due to short distance and vary access to tehran in one side and establishing main part of base activities in its surrounding, it has been focused in considerable part of migrant population in tehran urban district and one of its important issues is creation and expanding the informal settlements. accurate recognition of these settlements of different aspects could be an appropriate guidance for presenting regulatory strategies. in this field and in first step, using a method for recognition of informal settlement zones in which it has accuracy and ease, and low cost indexes is very necessary. the aim of this study is presenting a sample with above features for identification of informal settlement. the method of study in this paper comprises 3 steps. in first steps, documents studies and studying verity researches of general features is studied. the second step including on lab researches and modeling and last step is based on field studies, questioning and visiting from the site. in processing of this paper, first criterions and general pattern for identifying the informal settlement is defined. then according to features and access information of karaj city, criterions are converted into measurable quantities in gis software and special pattern for identification of informal settlement is represented in karaj city. recommended pattern has two- level. in first level, by compounding of analytical hierarchy process (ahp) with gis and using analytical capabilities of this software primary identification is done. and in second level, using data of field studies and questioning; final identification of informal settlement in karaj city is done. application of this pattern in karaj city shows that in addition to enough accuracy in recognition of informal settlement, it has been affective in decreasing of time and cost. also, another result of this study is giving a method for converting quality criterions of informal settlement recognition to quantities criterions measurement in gis. proposal pattern will be generalized to other cities of country. in addition, the features of other cities of country and the rate and access information of them could be revise the using criterions in the first and second level of pattern.