حفاظت از منظر شهری تاریخی با بهرهگیری از تکنیک سطوح حفاظت بصری (VPS) (موردکاوی: منظر شهری تاریخی دروازه قرآن شیراز)
محورهای موضوعی : فصلنامه علمی و پژوهشی پژوهش و برنامه ریزی شهریمهسا چیزفهم دانشمندیان 1 , مصطفی بهزادفر 2
1 - دانشکده معماری و شهرسازی، دانشگاه علم و صنعت ایران، تهران، ایران
2 - استاد دانشگاه علم و صنعت ایران
کلید واژه: "منظر شهری تاریخی", "سطوح حفاظت بصری (VPS)", "ضوابط ارتفاعی", "حفاظت", "آستانه ارتفاعی",
چکیده مقاله :
در دو دهه اخیر، حفاظت از منظر شهری تاریخی در مقابل توسعه ساخت و سازهای بلند مرتبه به عنوان یکی از مهمترین موضوعات در حوزه نگهداری از میراث جهانی و ملی شهرهایی با سابقه تاریخی مطرح شده است. منظر ورودی شهر شیراز از سوی دروازه قرآن یکی از ارزشمندترین مناظر این شهر به حساب میآید، که نهتنها از برنامه حفاظتی ویژهای برخوردار نمیباشد، بلکه با اجرای طرحهای مصوب موجود مورد تهدید جدی قرار خواهد گرفت. هدف اصلی این پژوهش آسیبشناسی منظر تاریخی دروازه قرآن، با تأکید بر تقویت دید به دو عنصر شاخص حرم شاهچراغ و علیبنحمزه میباشد. تفاوت اصلی مقاله حاضر با سایر پژوهشهای مشابه در این است که تنها به بررسی معیارهای کیفی طراحی اکتفا نشده و تلاش شده تا با به کارگیری آخرین روشهای تحلیل کمی در محیط سهبعدی به بررسی دقیق موضوع پرداخته شود. روش تحقیق به کارگرفته شده به صورت آمیختهای از روشهای کمیـکیفی است. در گام اول با بهرهگیری از تکنیک سطوح حفاظت بصری (VPS) در نرمافزار ArcGIS و Rhino به تعیین آستانه ارتفاعی مجاز ساختمانها در محوردید دورازه قرآن و مقایسه تطبیقی آن با طرح تفصیلی شیراز پرداخته شده و پس از آن تصاویر شبیهسازی شده دیدهای ناظر پیاده مورد بررسی قرارگرفت. نتایج نشان میدهد که قوانین و ضوابط ارتفاعی طرح تفصیلی شیراز در پهنه مؤثر این منظر تاریخی به علت بیتوجهی به بعد کالبدی- بصری دارای نقص جدی میباشد، به طوریکه با اجرای ضوابط ارتفاعی موجود، شامل ساختوساز تا ارتفاع 24 متر در بخش شمالی خیابان حافظ و تا ارتفاع 5/33 متر در محل پل علیبنحمزه، دید افراد پیاده از دروازهقرآن به سمت حرم شاهچراغ و علیبنحمزه در معرض خطرات جبران ناپذیری قرار خواهد گرفت. نتایج اعمال تکنیک فوق حاکی از آن است که با کاهش ارتفاع از 1 تا 14 متر در 93 قطعه ساختمانی و نظارت شدید جهت جلوگیری از افزایش تراکم غیر مجاز در پهنه محدودی از این محور میتوان موجبات صیانت کامل از این منظر شهری تاریخی برای آیندگان را فراهم نمود.
The main goal of this research is to assess the future problems and protect of the historic urban landscape of Qur'an-gate, is known as one of the most valuable landscapes of Shiraz, against the development of contemporary construction. The main difference between this article and other similar research is the attempted to use the latest quantitative analysis methods in a three-dimensional environment to accomplish the accurate result Instead of general qualitative methods. Hence, the research method is a combination of both quantitative and qualitative methods. In the first step, Visual Protection Surface (VPS) technique in the ArcGIS and Rhino was used to determine the permitted threshold of buildings and compared with the similar values in the master plan of Shiraz. Then the simulated pedestrian views have been checked.
The results show that the standards height determined by the master plan of Shiraz in the effective area of the historic urban landscape of Qur'an-gate have undergone from the serious defect. It means by implementing the existing altitudes, including construction up to 24 meters in the northern section of the Hafez-street and up to 33.5 meters in the Ali-ibn-Hamzeh-bridge, the pedestrian views of this non-renewable landscape will collapse completely. The results of applying the above technique indicate that by reducing the height from 1 to 14 meters in just 93 construction blocks and also strict monitoring to prevent the increase of unauthorized density, the full conservation from this historical urban landscape simply provides for the present and future generations.
Extended Abstract
Introduction
Protecting historic urban landscape against the swelling high-rise construction has become known as one of the urgent issues in the field of preserving the world and national heritage of valuable historic cities over the past two decades. Urban historic landscapes, especially panoramic views of highlands and city entrances, are among the most important elements that tourists encounter. The northern entrance of Shiraz city, Iran, (Qur'an-gate) is considered as one of the city's most valuable sights, which designed from16th century to present the most appealing view of the whole city in a glance. This view has impressed many local and international tourists throughout history as the oldest and most valuable image of the city belongs to this view, painted by Andre Daulier-Deslandes in 1664 AD. Today, there is no special protection plan for the Qur'an-gate’s view. The sites around this entrance are constantly developing to support vehicle transportation needs, regardless of the potentials that this viewpoint can bring for the city. This issue not only poses a threat to physical damage for Qur'an-gate landscape but also poses a concern to omitting the unique identity and reminisce of this valuable viewpoint. Maybe in the next 10 or 20 years, it has forgotten behind the mass of urban construction. Thus the main goal of this research is to assess visual problems faced with this historic landscape, with emphasis on two integral landmarks namely: Shah-e-Cheragh shrine and Ali-ebn-Hamzeh shrine.
Methodology
The research method is a combination of both quantitative and qualitative techniques. At the first step, three- dimensional analysis which known as the Visual Protection Surface (VPS) technique was implemented, using parallel steps at ArcGIS and Rhino. The simulation is conducted using two main data: 1) the location of viewpoints and 2) three dimensional model of the city. The viewpoints were selected by accurate geometrical calculation and field study method and the 3D model was made by the current floor-count data of Shiraz’s master plan (2006) and also digital elevation model (DEM) of the whole city. In the second step, another 3D model was made based on the predicted height authorized by Shiraz’s master plan (2006). A comparative analysis of the simulated images of the future situation in accordance with the criteria of the last detailed plan adopted and the results of the VPS technique are compared. Then the simulated pedestrian views have been checked. The main difference between this article and the similar researches in the field of landscape analysis is attempted to use an accurate quantitative analysis method in landscape analysis Instead of general qualitative methods.
Results and discussion
From 2085 parcel which located in site, only 115 parcels are directly affected by the VPS of two elements of Shah-e-Cheragh shrine and Ali-ebn-Hamzeh shrine. The result of comparative analysis of VPS model and future 3D model in scale of this parcels is also very significant. Since the proposed elevation of the latest Shiraz’s master plan in 56 parcels are above the VPS elevation thresholds. This means that if construction is done completely based on rules in accordance with Shiraz’s master plan, this historic urban landscape will be in danger. Nevertheless, the full conservation of this historical urban landscape can be simply provided for the present and future generations by reducing authorized height only in quantity of 1 to 14 meters and also strict monitoring to prevent the increase of unauthorized density. Fortunately, since now, no destructive construction in any of these 56 parcels have done except the one, which has no serious effect on the whole landscape; This 6-story building is located in the southern part of Hafez Street, just in the background of Ali-ebn-Hamzeh shrine view. However there is an urgent need to correct and rewrite the construction rules, regulations, and also prepare specific guidelines in various dimensions as soon as possible, to preserve this valuable historical landscape of the city.
It is noteworthy that the visual analysis is not a close-ended issue. Applying the height threshold for these 56 parcels just guarantees protection of the Qur'an-gate landscape to two elements from one effective point. Hence, the other views from the other points on the site should be seen. It helps to have an integrated skyline in the whole site while the previous threshold may decrease or other parcels need to fall down. The result of examining the micro-scale pedestrian views of the nearby streets shows that we have to add 37 other parcels in the north of Hafez Street to the list of the essential need to decrease height. Eventually, 93 parcels need to reduce height.
Conclusion
The results show that among the effort of international institutions which have the responsibility of preserving the historical heritage of the cities, the attitudes towards the urban landscape have changed from static state to dynamic being, from centralized to decentralize and from two-dimensional to three-dimensional. It also reveals necessitates of a holistic approach to manage urban landscape with all its intrinsic complexity. Unfortunately, this attitude has received less attention in the Iranian cities. This filed study in Qur'an-gate site shows, although the current condition of the Qur'an-gate landscape is less or more acceptable now, authorizing Shiraz’s master plan height in the effective zone may strictly threated this non-renewable landscape. It means by implementing the existing heights, including construction up to 24 meters in the northern section of the Hafez-street and up to 33.5 meters in the Ali-ibn-Hamzeh-bridge, this 600-year historic landscape will collapse completely. Applying the above technique indicates that by reducing authorized height in just 93 construction blocks in a range from 1 to 14 meters and also strict monitoring to prevent the increase of unauthorized density, the full conservation of this historical urban landscape simply provides for the present and future generations. The visual protection surface technique (VPS) is an accurate and up-to-date technique that can complete urban plans and documents to have considerable results for managing the city development in harmony with the original patterns of historic cities.
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