تبیین محیطی پدیدآیی و ناپایایی سکونتگاه‌های روستایی با رویکرد ارزیابی چندمعیارۀ فضایی (GIS-MCE) در استان اصفهان

Introduction
Rural settlements are actually the primary spatial patterns of man and nature interaction, reflecting the environmental effects on community behaviors. Inevitable evolution of these patterns temporally can affect environmental non-environmental factors. One of the major structural evolutions of rural areas, beyond a demographic one, is extraordinary migration depopulating some villages, namely rural exodus, which can be considered as a geographical phenomenon related to the environmental contexts. Transformation of irregular extended rural-urban migrations to the escape of rurality and rural life style is one of the serious environmental, socioeconomic and structural dilemmas of third world under developed countries. Technological evolutions have extended the broadness, impacts and importance of this phenomenon. The problem is originated from the incompetent structures and foundations for encountering the contingences of the new era. These situations are unfortunately reproduced in all of the third world countries such as Iran as an unavoidable reality that generates and expands a significant abnormalities and shortages against the indigenous development process of the societies, especially rural communities. In other words, from a systemic point of view, rural-urban migrations and escape of villagers toward the cities, is one of the chain-work mutual interactivities among the weakened communities to encounter the new world mechanisms. In such bi-polarized societies, the process of development has been imbalanced towards the urban areas. Centralization of investments in the forms of developmental infrastructures and import technologies often in the progressive urban areas has changed them to the destination of mass populations of undeveloped and under developed rural areas. This action is taking place inevitably as a last resort against the new global contingences. This has weakened and disabled the old traditional societies and their orders for living.
Methodology 
This study is aimed firstly at identifying depopulated rural settlements over a quarter century since 1986 in Isfahan province and secondly representing an environmental interpretation of the phenomena using statistical methods and spatial analysis in the geographic information system environment. To do this, the layers of spatial distribution of settled villages in 1986 and identified depopulated areas of the study are based on the detailed reports of public censuses from Iran statistical center in ArcGIS environment. The rural settlements exodus have been analyzed based on the prepared environmental layers of altitude, slope, aspect, temperature, land types and distance from wells and springs.
Results and discussion 
Spatial analysis of exoduses in relation to each of these environmental factors indicated that there is a significant relationship between exoduses and environmental factors of slope, land types, altitude and distance from wells. Environment’s potential (or poverty) emanates from mutual and especially none compensatory relationships between all environmental factors. Therefore, the land inhabitability necessitates the least liability of all none comprisable environmental functionalities and their simultaneity to guarantee the communal durability and livelihood. Taking this principle into consideration, the exodus of rural settlements have also been analyzed based on the overplayed raster layers of all studied environmental parameters, calculated as their Weighted Linear Combination (WLC), using map algebra in ArcGIS. To do this, the layers normalized linearly and different relative importance of the layers evaluated and obtained using the eigenvector method, based on the experts’ pairwise comparison judgement. Like the previous individual indices, two statistical indicators calculated and used for spatial and environmental analysis of rural settlements’ exodus; “the density of settled villages at the beginning year 1986” and “relative proportion of depopulated villages over the study period with respect to the total”. The indicators calculated separately for each of five environmental potency/poverty classes has been verified using the natural breaks method in GIS. The standardized scores of overall environmental potency/poverty for any of the classes have been calculated using the “zonal mean statistic” function from the spatial analyst tool of ArcGIS. Correlation analysis of environmental potency/poverty and previously mentioned indicators, revealed 80 percent of positive relationship between the environmental potency and settling density, and 56 percent of positive relationship between the environmental poverty and relative exodus. 
Conclusion
Although the role of the environment is undeniable in both formation and the exodus of rural settlement, its role is more determinant in terms of formation and continuity of rural settlements compared with their exodus and depopulation. It is perceivable that the exodus and depopulation of rural settlement is affected by various none environmental parameters and mechanisms even more than environmental elements. In this regard, internationally it is mentionable that the predominant industrial development approach caused by the industrial revolution and the information and communication revolution of the contemporary era, have also deepened the gap and inequalities between the quasi-developed urban and undeveloped rural areas of the third world countries. The strategy of rural areas in facing with these undesirable national and international situations interacting with environmental disadvantages has commonly been expansion of the rural-urban migrations, in some instances as a geographical phenomenon of villages’ depopulation and rural exodus. Both of the rural origins and urban destinations have disadvantaged from such of unavoidable rural depopulation. In this regard, counter-ruralism is the attitudes and psychological situation of villagers. This drives them to leave the village. It is so developed that the synergic trade-offs between the “poverty of environmental functionalities” and “socio-economic insufficiencies” reproduce and accelerate this inauspicious phenomenon, conducting subsequently to delay and deficiency of the whole society’s development process.