ارزيابي تعريف حدود رشد شهر در طرح هاي توسعه شهري ايران از طريق پايش 11 گونه شهري

Evaluation of Urban Growth Boundary Definition in Urban Development Plans in Iran; Trough 11 Different Type of Iranian Cities Monitoring

شهرهاي ايران با سرعت بالايي در حال رشد هستند. ابزار طرح هاي توسعه شهري در زمينه مديريت رشد در خلال 5 دهه گذشته ، تعريف حدود رشد بوده كه كماكان بدون تغيير بنيادين استفاده مي گردد. با وجود شواهد نسبي مبني بر نامناسب بودن اين ابزار ، هنوز به جاي آن جايگزين مطمين و مورد توافقي ارايه نشده است. عدم تلاش در زمينه اتخاذ راهكارهاي جايگزين در زمينه مديريت رشد تا حد زيادي به نبود بررسي هاي علمي در زمينه ميزان توفيق ابزار كنوني بر مي گردد. اين بحث به واكاوي مديريت رشد شهر از طريق تعريف دو شاخص سنجش شامل خطاي تعريف و نيز ناكارايي در 11 گونه شهري ( طي 4 دهه اخير) پرداخته است. نتايج حاصل نشان مي دهد ابزار كنوني در دو بعد روايي و كارايي دست به گريبان مشكلات بنيادين است به نحوي كه لزوم تجديد نظر در اين ابزار را ايجاب مي نمايد.

One of the most ingenuous realties about cities is their perdurability. Expansion of city peripheries –desired or not desired – causes such areas to be annexed to the main body of the city. As in many developing countries, Iranian cities are growing in population and physically expanding at a high rate. For approximately the past five decades, after formulation of the first series of urban development plans, defining the urban growth boundary (UGB) has been an important policy tool of (central) government and urban management agencies. Provision of urban development plans in Iran is under the authority of the central government. Throughout this period, and despite clear evidence indicating the ineffectiveness of the UGB whose policy has been adhered to with no major modifications. Perhaps lack of effort in this area goes back to the absence of scientific studies in the field of level of success of the policies and available tools. It is such an extent that current trend of urban growth management is considered as an appropriate approach. This article, while paying attention to relevant theoretical topics, analyses urban growth management and boundary in Iran .Evaluation of the current growth management process is conducted through definition of special quantitative indices and sample monitoring using non-parametric analysis techniques in GIS.UGB definition error reveals the ignored part of the primary city at the time of provision of urban development plans, located outside the UGB. Thus, this index can represent the credibility of the proposals of urban development plans for the definition of the UGB. It is obvious that neglecting some parts of urbanized areas can cause future inefficiencies in urban growth management.UGB inefficiency index shows the proportion of the final, developed urban area that extends outside of the approved final urban growth zone, that is, outside of the approved UGB. This index reveals the efficiency of the UGB in incorporating urban growth and preventing urban sprawl. This is, then, a reliable basis for evaluation of the efficiency of urban growth management. As a result through a quantitative framework, this research demonstrates the weaknesses in the current procedure (inaccuracy and inefficiency of UGB). The evaluations reveal that the former and current definition of UGB in Iranian urban development plans have not been without error. This is partly because of incorrect assumptions with respect to urbanized areas in urban development plans. In some cases, because of intentional or unintentional mistakes in classifying a part of an urbanized area outside of the urban limits, the UGB does not even cover the real city edge in urban development plans. Another issue is the inefficiency of defined limits in restricting urban growth. Apart from the reality of to what extent the restrictive policies over urban growth are justifiable and necessary, it seems that some part of urbanization occurs outside of the approved urban limits. These two fundamental blunders cast doubt over the accuracy and credibility of the urban management mechanisms in Iran. Applicable results from the research include the necessity to revise the current policy tools.