تحليل الگوي توسعه پراكنده كلانشهر تبريز با استفاده از مدل شانون و تعيين جهت گيري توسعه ي فيزيكي آن

Analysis of Urban Sprawl Pattern of Tabriz City, Using Shannon’s Entropy and Indicating Urban Growth Directions

امروزه جريان توسعه كالبدي شهرها با سرعت بيشتري دنبال مي‌گردد و حاشيه‌هاي امروز شهرها جز لاينفك بافت اصلي شهر در آينده نه چندان دور مي‌باشند. رشد فيزيكي نابسامان شهرها در اثر توسعه فيزيكي ناپيوسته و پراكنده و عمدتاً در قالب شكل‌گيري قطعات منفرد و جدا از هم است؛ لذا تحليل وضعيت فيزيكي موجود و پيش بيني آينده گسترش شهرها به دليل تاثير آن بر سياست ها و مديريت منابع شهري و انساني از اهميت به سزايي برخوردار است. با توجه به عوامل متعدد موثر برتوسعه فيزيكي پراكنده شهرها، مقاله حاضر ميزان رشد افقي كلانشهر تبريز را از دو بعد مساحت و جهت رشد، مورد ارزيابي قرار داده است. روش تحقيق در اين مقاله تحليلي- تطبيقي بوده، و با توجه به سير تحول الگوي كالبدي- فضايي كلانشهر تبريز در طي دوره زماني 1385-1335، از مدل انتروپي شانون1 براي سنجش ميزان پراكندگي سطوح افقي شهري و از مدل قطاعي- جغرافيايي جهت تعيين مسير رشد افقي، استفاده شده است. نتايج حاصل از تحليل يافته ها نشان داده است كه پراكندهرويي2 در كلانشهر تبريز اتفاق افتاده و بيشترين ميزان آن در محدوده سال 1375 بوده است و جهات گسترش افقي با موقعيت كريدورهاي اصلي ورودي منطقه شهري تبريز، بيشترين انطباق را دارند.

Nowadays the urban growth pattern of cities is growing dramatically; and current suburbs of cities will form the inseparable components of the main city in the near future. In all cities of world vertical and horizontal urban growth have been one of the most important factors noticed by urban managers and planners. Urban growth is a spatial - structural process that refers to the increased importance of towns and cities as a concentration of population within a particular economy and society. Increase in urban points as quantitative issue shows itself in the forms of increase in population of cities and development in built up area scale. The unorganized physical growth of cities is due to their physical discrete and separate development which is mostly in form of forming individual and separate parts. Hence, analysis of the current physical status, and prediction of the future development of cities due to its influence on the politics and management of city and human resources, is of great importance. Regarding the numerous factors affecting the inharmonic physical urban growth, the present article has investigated the rate of urban horizontal growth from two aspects of area and direction.The research method in this article is analytical- comparative and with respect to the evolution of the physical- spatial pattern of Tabriz metropolitan in the 1956-2006 period. Shannon’s Entropy model is utilized for evaluation of the rate of the urban horizontal growth diversity. In order to use this model first we draw the complete and detailed plan of Tabriz city in concentric buffers with width of one kilometer between years 1956-2006 using Auto Cad software and the physical gravity center of Tabriz city which is the same center of cultural- historical part has been considered as basis for buffering modulation, and Sectoral- Geographical model is used for specification of urban growth directions. . In the next phase center of city gravity has drawn in the form of circle with determined diameter and the center of this circle was considered as basis for modulation of geographical sectors and sectoral buffering in 12 geographic directions. The attained results of analyzing the research findings has shown that the sprawl growth and diversity of inharmonic development has occurred in Tabriz metropolitan. The maximum of this rate has happened on the year 1996 and directions of horizontal urban growth are completely coincided on the margins of main connection corridors of city.