جستجوی مقالات مرتبط با کلیدواژه "dynamic potential" در نشریات گروه "جغرافیا"

Cities have an increasing population and physical growth. Their physical growth by changing land cover/use has many environmental and climatic effects. Neglecting the ecological dimensions of cities has caused a decrease in their environmental quality. Among the most important of them we can mention the increase in thermal loads and air pollution, and reduction of dynamic potential. Two-dimensional urban climate maps are an analytical tool that integrates urban climate factors with urban factors so policymakers and urban planners can easily use them. climate approach is divided into two general categories of weather station data for analyzing the city's climatic conditions and spatial information layers used to integrate and calculate the map of planning recommendations. The results of integrating information layers in the geographic information system, Tehran was classified into five urban climate planning zones (UCPZ). These areas include urban climate planning area one with 25% coverage of protection zones and urban climate planning area two with 35% coverage and strategic measures. The changed areas include urban climate planning of region three with 22% attention to reducing harmful factors, urban climate planning of region four including 16% with strategic action to reduce necessary and recommended measures, and planning of urban climate region five with 3%. With strategic measures for necessary reduction, recommendations are also provided for each class with a detailed urban climate planning approach.

An urban climate map is an analytical tool that integrates urban climate factors with human and urban factors. Then, using obtained the results, it provides instructions and recommendations based on the climate characteristics in the city and creates a two-dimensional spatial map in a format that specialists and urban planners can easily use. In other words, the urban climate map is an interdisciplinary study and practical program that examines urban climatology and urban planning together and focuses on the application of climate knowledge in the field of planning. A proper understanding of climate conditions and planning recommendations can be implemented in actual physical planning processes of cities such as city/municipal master plan, zoning plan and land use plan. As the planning guidelines refer to specific areas, the use of urban climate maps (UCMaps) is also recommended as an information base. The created maps are considered very important physical tools for planning and as a tool with specific information to establish communication with managers, policymakers, decision-makers and those interested in urban issues. 

The data used in this research is of the type of location information that contains the information layers of the city of Tehran; The building blocks are urban land use/cover, topography, urban green spaces, surface hydrographic network and road network, which were prepared from the Information Technology Organization of Tehran Municipality. These layers of information were directly used in the calculation of the urban climate maps of Tehran in the urban climate analysis map section.
The research method is based on the analysis and integration of spatial information layers. First, the urban climate analysis map (UC-AnMap) was prepared. Calculating the climate map of the urban planning guidelines, the information contained in the urban climate analysis map is examined and based on the physical, environmental and activity conditions and realities within the city, this information is classified together. The climate map of urban planning guidelines and recommendations has classes known as urban climate planning zones (UCPZ). Each of these urban climate planning areas has guidelines and strategies with implementation capabilities that provide climatological recommendations to maintain or reduce the thermal conditions of each climate area.

To obtain a map of Tehran's urban planning guidelines, variables and effective components were examined. Based on 8 classes of urban climate analysis maps and according to physical characteristics, natural ventilation potential, thermal load and urban climate classes, Tehran was integrated into 5 Urban Climate Planning Zones (UCPZ). The status of urban development planning zones and their recommendations are as follows: UCPZ1 has covered 24% of the urban area. This part of the city includes areas that, with their natural and suitable vegetation, do not hinder the flow of air and wind. UCPZ2, with 35% of Tehran's urban area, has the highest amount of coverage, and the northern areas of Tehran have this feature of the climate zone. UCPZ3 has covered 22% of the urban area and the central areas of the city have the characteristics of this climate zone. UCPZ 4 has covered 16% of the urban area of ​​Tehran and its distribution includes the central areas of Tehran and areas such as 10, 11, 12, 6 and the south of areas 2 and 5. They cover most of this area. UCPZ5 has covered 3% of the urban surface and the main areas of the climate zone are found in the 21st, 16th, 12th and 11th districts of the municipality. Other southern and central areas of the city have small and limited spots of this climatic zone.
The pattern of population distribution and density determines the amount of man-made environmental thermal load in the city as well as the natural ventilation potential of the air. This study, which is based on urban climate maps (UCM), climate zones and planning recommendations, is based on two components of thermal load and dynamic potential of urban areas. The roads in the central parts of the city are generally narrow and full of traffic, which leads to poor natural ventilation conditions and an increase in thermal load. Weakness in natural air ventilation has a significant effect on the amount of air pollution in urban areas, in addition to intensifying the environmental thermal load. Warehouses, industries, and uses such as gas stations and road traffic are the main sources of air pollution in different areas and neighborhoods. The urban climate planning recommendation map (UC-ReMap) shows five climate zones. This map realistically shows the climatic conditions of the city according to physical characteristics, urban geometry, urban green and open spaces and proximity to natural spaces. Therefore, it provides information on urban climate for urban planners, and based on this, they analyze regional and strategic planning based on the climatic condition of urban areas.

The central areas are characterized by unfavorable conditions of high thermal load and weak natural ventilation with urban heat island phenomenon: therefore, reducing the building load in these areas is necessary; In the vicinity of the central areas of the city, climate zone 4 has been obtained, which is characterized by hot conditions, and in them, it is recommended to reduce the number of structural measures. In districts 21 and 9, the type of roof materials and the continuity of asphalt surfaces and ground covering in parking lots, warehouses and silos of factories are among the reasons for the high environmental thermal load in these areas. Therefore, it is concluded that the areas with the unfavorable urban climate of Tehran are caused by three factors high building density; continuous metal and asphalt pavements; And the road network dense and narrow. On the other hand, the open and green spaces in the inner areas of the urban fabric and the mountainous suburbs in the north and agricultural suburbs in the south of the city provide favorable climatic areas with weak thermal load and high dynamic potential and natural ventilation. In climate zones one to three, it is necessary to protect and maintain relatively favorable climatic conditions, and in this context, it is necessary to avoid extensive land use conversion and restore favorable climatic conditions in the affected areas.

City is a living, dynamic being evolving over time in the context of physical and anthropogenic components and complex relationships between them. It is the reflection of the role and attitude of man-kind influenced by social, economic, political, cultural and geographical factors and conditions. Increased population and density in urban areas have far-reaching consequences, such as increased consumption of natural resources, land-use changes, climate change, and disruptions in the exchange of material and energy. Consequently, cities face many issues and problems, the most important of which are issues related to urban design. These include poor ventilation, high heat load, air pollution caused by the physical characteristics of cities, and insufficient attention to the capabilities, natural characteristics and climate of the region and the city.

The present study seeks to prepare an urban climate analysis map to study and analyze spatial and climatic information collected from Tehran. Urban Climate Map (UCMap) is an information-based and analytical tool that combines factors of urban climate with urban planning factors and some environmental conditions to provide an image of urban climate issues in a two-dimensional environment. Urban climate map consists of an urban climate analysis maps (UCAnMap) and an urban climate recommendation map (UCReMap). Urban climate analysis maps apply various spatial information layers of heat load maps such as building volume, urban topography and green space along with layers of land cover, natural landscape, and proximity to open spaces in dynamic capacity maps. The proposed model is generally based on the evaluation and analysis of variables affecting climatic conditions. Based on six layers of building volume, land cover, topography, proximity to open spaces, green space, and natural landscape, maps were prepared in Arc/GIS10.4.1 environment for Tehran urban area. To eliminate the unit and reach comparability and overlap, the layers were standardized and used to prepare maps of ambient heat load and dynamic capacity.

Three layers of building volume, topography, and green space were weighted and combined to create a heat load map. The other three layers of land cover, natural landscape, and proximity to open spaces were also combined to create a dynamic capacity map. Afterwards, these two maps were combined to create an UCAnMap. The resulting map was close to the on the ground realities. For example, building volume has a negative effect and increases heat load in urban areas. On the other hands, green space reduces heat load and has a positive effect. The central and southwestern parts of the city have a high heat load and core areas of the urban heat island have been calculated and obtained in these areas. The resulting map was classified into 8 categories to create urban climate analysis map of Tehran.

Results indicated that 59% of the urban area in Tehran, mostly located in the northern part of the city, has a good cooling and ventilation condition while 19% of the study area, mainly in the central, southern, and southwestern parts, faces heat stress and lacks an appropriate air ventilation condition. 22% of the study area, scattered all over the city but mostly located in the northern, western and eastern parts, faces an intermediate condition. According to the calculated heat load map, the central, southern, and western parts (in region 21) of the study area face a high and unfavorable ambient heat load. And many parts of the 4th, 1st, 2nd, 5th, and 22nd urban districts are characterized with low ambient heat load and favorable climatic conditions.