فصلنامه مطالعات جغرافیایی مناطق خشک
پیاپی 36 (تابستان 1398)

City-region qua a system of concepts has a theoretical, empirical and epistemological significance. On the strength of such a capacity, this system is applied to better understand the structures of production of space in different scales (global, international, national, regional and urban).

Using Henri Lefebvre’s conception of Urban Fabric, this paper tries to bring about a different reading of the concept of city-region. Not only the concept of city-region per se but also the whole system of this concept (region, neo-regionalism and city-region) is read in light of Lefebvre’s Urban Fabric. On the one side of this reading are subjects and their lived experiences, and on the other are institutions, governmental and administrative bodies. This reading emphasizes the importance of the subject in producing the scale, the gravity of the concept of scale itself and the importance of governance under the condition of neoliberal production of space. In the age of globalization and capitalist production of the city under neoliberal production of space, how does the city have its life and institutional content? The concept of Urban Fabric combines these two elements, and at the same time transcends them. This concept is the mediation between the two extreme limits of city region, i.e. the rural (hinterland) and its urban core. This concept also functions as a kind of perspective or standpoint, which qua the mirror of the relation between urban society and land manifests the mode of production of urban land within the urban institutional structure through its dissolution, which leads to the expression of Urban Fabric.

During the recent neoliberal production of space, there happens to emerge forms of city-region through the implosion-explosion of the urban core. Consequently, up to the urban hinterland, the thrown pieces of Urban Fabric are extended here and there. This reading of city-region tries to explain fractures and disintegration of the city and its extension to its surrounding during late capitalism, investigating it from institutional, structural and subjective dimensions. Urban Fabric demonstrates the social condition of the production of urban tissues under globalized circumstances. As a kind of embodiment of subjectivity in post-industrial age, Urban Fabric draws the condition of urban expansion, which as such, displays the state’s position as an entrepreneur and an enterprise. This would lead to the emergence of the condition of production of housing and commodification of space in order to prepare regions to compete with other international city regions. The conceptual hierarchy in this analysis begins with the everyday, spatial practices, which finally reaches its form. In other words, forms, the lived and the rational, are traceable in Lefebvrian Urban Fabric.

Today, Urban Fabric can be proposed for subjects such as uneven development, territorial differentiation and center-periphery polarity. In the age of globalization, whatever that was considered urban or in a way deemed as its features, such as definitive industrial and financial rationality, extends outside the city as if the region becomes a the Urban Fabric of the city. In each stage of urban implosion-explosion, the scale of effect and the extension of Urban Fabric becomes different, since the speed and quality of urbanization is different. If today, there are variety of the concept of city-region, it is because of the different effect it exerts upon social space.

Due to the growth of urban population in recent years and the desire to live in cities (immigration), open lands inside and around the cities has been used and also changed their usage. On the other hand, the development of cities in the past and present has been carried out by people and over time; and these developments have usually been without regard to natural hazards, including floods,earthquakes, and so on.Basically, natural hazards affect the organization and foundation of urban life more intensively and more than villages and other human settlements. One of the natural hazards that we are faced with in Iran is the earthquake. The city of Neyshaboor, as one of the middle cities of Khorasan Razavi province, has been faced with increasing population and changing the use of agricultural and open lands. In addition to its population, the city also accommodates an immigrant population every year and also provides part of the need for small towns and surrounding villages. Therefore, the present study investigates the development of cities in response to the natural hazards of the earthquake with the aim of studying and forecasting land use changes in Neishaboor city.

The present study is an applied type that was conducted through library and field studies. A major part of the research is obtained through survey work. In this study, OLI and ETM sensor images of Landsat satellite from 2000 and 2009 and 2018, were used. Initially, Landsat satellite images were geometric and radio-metric corrections. Then, the study area was separated from the images and then satellite data were classified .The method used to classify information is a supervised method. In this method, educational examples are used to classify pixels. It is also necessary to explain that the maximum similarity algorithm is used for classification of monitoring. In this method, the reflectance value of any unknown pixel are analyzed based on the variance and covariance of that particular spectral reaction class. It is assumed that the distribution of the data of each class is based on the normal distribution around the pixel of the average of that class. In fact, the variance and covariance and the average of each satellite's images in different class are calculated for the classification of phenomena, so that each pixel belongs to a class whose presence in that class is more likely to occur. Finally, based on the Markov chain model, we investigate the development of the city and investigate the active faults.

The present study consists of three parts: reviewing the changes of major city uses, evaluating the development of the city with regard to the earthquake risk and forecasting the development of Neyshaboor.Land use change study: At this stage, according to satellite images of 2000, 2010 and 2018, the boundaries of Neyshaboor and surrounding areas, agricultural lands, pasture lands and Wasteland were determined. In 2000 range built in Neyshaboor city and around it was  8%, it reached 10.5% over 10 years in 2010 and reached 14.3% over the next 7 years in 2008,which indicates an increase in urban use such as residential, commercial, service, transportation and so on. And most of the construction tended to the north and northeastern parts of the city and around it. And Population from 2006 to 2016 indicate that the population growth is due to the city's rate of growth and the natural growth rate of the migratory of Neyshaboor city and around it, which is important for increasing urban construction. Evaluating the development of the city with regard to the earthquake hazard: At least 4 historical earthquakes with M> 7 occurred in less than 200 years of 1209-1405 AD near Neyshaboor in northeastern Iran. The mechanism of known faults in the Neyshaboor range is compressive or have an important component of compression. Around the Neyshaboor city there are three active faults: Binaloud fault, North Neyshaboor fault and Neyshaboor fault. The north faults of Neyshaboor and Binaloud are in the range of the Binaloud Mountain, north of Neyshaboor.City Development Forecast: Based on the Markov chain and CA Markov model, city development is forecasted. The future development of the Neyshaboor city tends to be closer to the north and northeast, while the mentioned range is within the average earthquake hazard range. And south of the city, which is in low hazard zone, is not the desired direction for future development. By the year 1409 (2030) the best direction for the development of the city is the south and southwest of the city.

What can be emphasized as the results of this research can be presented in the following cases?The Markov chain and the CA Markov model have great potential for forecasting urban development.With regard to the earthquakes occurring throughout history of Neyshaboor and its surrounding area, the earthquake for this city, like other cities in Iran, is the most important natural hazard.The development direction of the city is the northern and northeastern regions where the low depth of the earthquake is also in these areas. And earthquakes with more than 4.7 magnets have also occurred in these areas, while both of these factors increase the risks.The study area is located 170 to 340 meters from the faults, which requires safety and rehabilitation considerations.The future development of the city of Neyshaboor tends to be closer to the north and northeast, while the mentioned range is within the average earthquake hazard range. And south of the city, which is in low hazard zone, is not the desired direction for future development. By the year 1409 (2030) the best direction for the development of the city is the south and southwest of the city.In general, the northern part of the city, which is the main urban area and the main direction of city development, is more at risk, because it is located in the zone of earthquakes with a low depth and is located in the earthquake zone of more than 7.4 magnets and have a fewer distances with active faults.One of the best solutions to reduce earthquake effects is to observe the standard distance from earthquake and fault zones.The revision of Neyshaboor Urban Development Plan will protect urban management from future risks.The results of the research findings show the geography position in urban development projects more than before.

Throughout history, natural hazards, especially floods and floods, have been one of the biggest and most important environmental crises, killing thousands of people every year and causing great damage to human society and the environment. This phenomenon has sometimes had more effects in arid and semi-arid regions and has also increased the amount of damage. Flood zoning is the first and most basic step in flood management and damage assessment. In this regard, this research, which is of applied type, has been collected with the aim of identifying and zoning of settlements in danger of flood occurrence in arid areas, especially in Farrokhi Abriz basin. The method used is to use simultaneous descriptive-analytical methods that use the Geographic Information System (Gis) to identify flooding and hazardous areas and height, rainfall, vegetation, distance from the main river, land Recognition, slope, drainage network and land use have been considered and their maps have been extracted. The results of studies and analyzes showed that the central parts of the Farrokhi Basin, as well as some high and sloping areas west of the basin, are most at risk of flooding. The residential centers of Varzeq, Varzeg, Abbas Abad, Gorganj and Borj Mohad are in severe danger and need sufficient attention to prevent life-threatening and financial risks. Also, Farrokhi, Mehdiabad and Khoshk-e-Khoshkh residential centers are located in areas with low and very low risk of flooding.

In recent years, the increasing possession and changing in land use of river bed not only have posed a threat to healthy water availability, but also have increased the risk of floods, as droughts continue. Managing water resources and converting flood water into a divine gift is impossible without understanding and analyzing the response of hydrological components to climate change and human interference, including changing in the land use of river bed. This study was performed in 2017 in Ardak River Basin, Mashhad. The ASTER satellite images and HEC-GeoHMS software were used to outline catchment boundaries and extract its physical parameters. The existing river bed map and its periphery were prepared and added as a new layer to the basin land-use map. By integrating land-use maps and soil hydrological groups of basin in GIS environment, the CN map of catchment area and average CN of each sub-basin were calculated. After entering data into HEC-HMS model, the model was run and flood was simulated with different return periods. Land use and soil hydrological group maps were reformed. Then the new CN map and the average CN of each sub-basin were determined and introduced to the model based on the changes in the land-use map. The HEC-HMS model was re-run for the conditions where the mean CN of the sub-basins changed and their other characteristics remain constant was ran. The results showed that by changing the riverbed land use to agriculture, the maximum flood discharge and runoff volume decreased while the decrease rate reduced with increasing flood return periods. As for floods with 25 year return period, due to changing land use of river bed, maximum flood discharge and runoff volume  decreased by 3.3% and 2.6%, respectively.

The Hamedan-Bahar plain has experienced a severe drop in groundwater levels during recent salinities, which has caused the region to be exposed to subsidence hazards. Accordingly, in this study firstly, using groundwater level information in the study area, the groundwater level in the study area was evaluated using 5 piezometers in the study area. Then, using the Sentinel 1 satellite imagery (2016/01/11 to 2017/12/19) and the SBAS time series method, the vertical displacement of the region is evaluated. Groundwater assessment results indicate that the range of studies in recent years has seen an increasing trend in groundwater levels, with water levels in some wells reaching up to 2 m / year, which has caused There has been a sharp drop in water levels in that area. Also, the results of the evaluation of the displacement rate of the area indicate that this area has been subsidence by 133/2 mm over the 2 year period. In addition, the results of correlation between annual water level decline and area subsidence indicate that there is a direct relationship between water level decline and area subsidence and the correlation coefficient of ./94 percent.

Mighan Arak wetland  is a closed area where all runoff and groundwater are directed to the wetland. Major cities such as Arak and Ashtian, industrial towns such as Arak, Khairabad and Aibak Abad, as well as large agricultural activities are located  in upstream of wetland  and sewage and wastewater containing heavy metals enter the Mighan wetland.In addition, the Mighan wetland has ecotourism attractions, as migratory birds as well as geo-tourists as the sodium sulfate mine. To determine the severity of contamination of pollutant metals and contaminant sources in Mighan wetland, water samples were taken from saline water applications including ponds, Mighan lake and Amlah company sewage and freshwater inputs to wetland such as municipal wastewater, water agriculture.Concentrations of toxicants such as Hg, As, Pb, Co, Cu, Pb and Zn were determined by atomic absorption. Comparison of these elements with the international drinking water standard indicates that the wetland is desirable. But evaluation of pollution indices, contamination degree and contamination threshold showed that the wetland was contaminated with elements such as Hg, As and Pb. The most important sources of contaminants being municipal wastewater and agricultural effluent.