ارزیابی کاربرد شاخص‌های تعیین تنوع در اختلاط کاربری‌های شهری (مطالعه موردی نواحی و محلات منطقه هفت شهرداری تهران)

نویسندگان

چکیده

  طی چند دهه گذشته توسعه اختلاط کاربری­ها، به الگوی برنامه­ریزی مکانی مهم در کشورهای پیشرفته تبدیل شده است. نحوه قرار‌گیری کاربری ­ های شهری، تأثیر بسزایی در سطح کیفیت زندگی و کارایی خدمات مربوط به کاربری­های مختلف دارد. در این تحقیق به بررسی روش­های مختلف ارزیابی میزان تنوع اختلاط کاربری­های شهری، به کمک GIS پرداخته شده است و ضمن مشخص نمودن نقاط ضعف و قوت آن­ها، یک روش نوین برای ارزیابی تنوع و گوناگونی اختلاط کاربری­های شهری معرفی و پیشنهاد شده است. در این پژوهش از روش­های مختلف به منظور ارزیابی شاخص­ تنوع، برای بُعد افق در مقیاس محلات و نواحی شهری در منطقه هفت شهرداری تهران استفاده شده است. تحلیل عملی روش­های ارائه شده، حاکی از توانایی روش­های پیشنهاد شده برای ارزیابی میزان تنوع اختلاط کاربری­ها در محدوده مورد مطالعه است. با توجه به نتایج حاصله، شاخص­های HH و آنتروپی برای ارزیابی تنوع اختلاط کاربری­های شهری برای بیش از دو نوع کاربری و مجموعه شاخص­های ( A0.1 ، A0.5 ، A0.9 ) Atkinson به منظور ارزیابی تنوع اختلاط کاربری­های شهری برای دو نوع کاربری پیشنهاد می­گردد. یافته­های حاصل از اجرای مدل در محدوده مطالعه موردی حاکی از آن است که، در سطح نواحی شهری، ناحیه­ پنج و در سطح محلات، محله­های دبستان، خاقانی، امجدیه و کاج در بهترین وضعیت از نظر تنوع اختلاط کاربری­های شهری بین دو نوع کاربری (مسکونی و غیر مسکونی) قرار دارند، همچنین از نظر تنوع اختلاط کاربری­های شهری در بیش از دو نوع کاربری در سطح نواحی شهری، نواحی پنج و چهار و در سطح محلات، محله­های امجدیه، دبستان، خاقانی و کاج در وضعیت بهتری قرار دارند.

کلیدواژه‌ها


عنوان مقاله [English]

Evaluating various criteria for determining diversity of urban Mixed Land Use via GIS (Case Study: neighborhoods and districts of Tehran Municipality No.7)

نویسندگان [English]

  • M. Karimi
  • M. Taleai
  • Gh. Javadi
چکیده [English]

  Evaluating various criteria for determining diversity of urban Mixed Land Use via GIS (Case Study: neighborhoods and districts of Tehran Municipality No.7)       Gh. Javadi, M. Taleai, M. Karimi   Received: March 02, 2012/ Accepted: August 12, 2012, 7-12 P           Extended abstract   1-Introduction  Methods of zoning and land use allocation are experienced in the history of urbanism and its weak and strong points are clearly investigated. In spite of some advantages, this kind of spatial planning has its own disadvantages. New ideas of urbanism support the viewpoint of mixed land use and consider it as the key element for urban sustainability. In recent decades, mixed land use is introduced as a key element in Transit Oriented Development, Traditional Neighborhood Development, smart growth and new urbanism.   Mixed land use means every combination of land uses that can be vertically, horizontally or time combined with each other. The concept of mixed land use from the viewpoint of spatial planners is an important tool to achieve sustainable development .   In order to evaluate the presented model from the viewpoint of mixed land use, a proper spatial criteria and an evaluation method is required. In this study, many methods of evaluation of versatile criteria and a positional criterion for evaluating mixed land use are investigated. Then, a Geographic Information system is used as a powerful means of analyzing and administrating the spatial data. The method in this paper is applied for the horizontal dimension in the 7th regional municipality of Tehran city.     2- Theoretical bases   Evaluation criteria for mixed land use can be categorized based on different concepts. With respect to effective factors in mixed land use (four dimensions: Horizontal, vertical, shared premises and time dimensions, land uses, Geographic scale and spatial criteria), this procedure is a very complex issue.   Compositional pattern of land use mixture is a method to determine spatial assimilation of land development and is very important in the study of mixed land use. To evaluate mixed land use model, this criterion is divided into Evenness and Diversity and clustering. In this study, the aim of criteria evaluation is to determine the diversity of urban mixed land use via GIS.   Mixed land use model evaluation based on Diversity   Evaluation of Diversity in mixed land use compares its distribution in the presented region. In this study and to evaluate this analysis, Balance and Gini criteria are used to evaluate mixed land use and HH and Entropy criteria are used to evaluate more than two mixed land uses. Also, Dissimilarity and Atkinson criteria are used for evaluating two and more mixed land uses.     2-1- Balance Index  This index can evaluate two mixed land uses. When two land uses are distributed evenly, this criterion is unit and when there is only one land use in the region of analysis, this index would be zero. This Index’s merit is its computational ease.    2-2- Herfindahl-Hirschman index (HHI)  This index is defined as the squared area summation for every land use in the region of analysis. When there is only one land use this index is 10000. In this index the more close to 10000 the less the level of diversity in mixed land uses. This index is very simple and its limitation is its relation to Modifiable Areal Unit Problem.      2-3- Dissimilarity Index  This index shows the level of sameness of the distribution model of land use in a smaller analysis unit and a larger analysis unit. The value of this index is between zero and unit. Unity shows the perfect sameness and the zero shows Dissimilarity. This index can analyze diversity in two or more mixed land uses. Although this index is simple and easy to implement, it has many limitations.    2-4- Gini index  This index can only investigate two land uses in their diversity and can have a value between zero and unity. Zero shows a perfect sameness and unity shows inhomogeneous distribution.    2-5- Entropy index  Entropy index is a method to evaluate variations and diversity. Zero shows that all the uses in the region are the same as each other. Unity shows a perfect inhomogeneity. This criterion can investigate more than two land uses for the analysis of mixed land uses diversity in different level. Although other index like Dissimilarity index can also evaluate more than two land uses, simplicity of this criterion made it the perfect option for the analysis.    2-6- Atkinson index  Atkinson index is one of those rare methods that not only evaluates inhomogeneous distributions but also assigns a weighting value to subunits. The range of values for this index is between zero and unity. Unity shows a great homogeneity of land uses distribution. This index can investigate two or more mixed land use diversities. This index creates a great practical opportunity for assigning different weighting values to different land uses distributions and makes the fundamental modifications.    3– Discussion  To evaluate the results of distribution pattern (diversity) of urban mixed land use via GIS in the mentioned region, according to the conceptual model of Mixed Land Use, this analysis based on the diversity index is done for the 7th region of Tehran city.  Implementation of the presented methods consists of two steps:   · To evaluate MLU Diversity between two land use (residential and non-residential land uses) in district and neighborhood level, Dissimilarity index, Gini index and Atkinson index are implemented. Results obtained from thee presented indexes demonstrates these 5th district and Dabestan, Khaghani, Amjadieh and Kaj ’s neighborhoods from viewpoint MLU Diversity are in better condition. Calculated criteria according to obtained results from evaluation of MLU Diversity show a great correlation for the criteria. Criteria A0.5 is more like the DN and GN criteria. This is because an A0.5 criterion is not modified for the area-related dimension. In this study, as we mentioned before, to calculate DN and GN squares with side length of 100 meters are used and the obtained results as expected show a great correlation between these two criteria. It is seen that these criteria not only are sensitive to the diversity of subunit interior but also their results are dependent to the positions of the cells.   · To evaluate diversity of urban MLU in more than two land uses (residential and nonresidential land uses) in district and neighborhood level, Dm and Entropy and Atkinson are implemented. With respect to this, region or district that has only one application has the number zero and the regions with more applications have a number more than zero and less than unity. Results obtained from the proposed criteria demonstrate in the 4th and 5th districts and Amjadieh, Dabestan, khaghani and Kaj ’s neighborhoods are in better condition with respect to diversity of MLU And about correlation between indicator show that values for HH and Atkinson have great correlation for these criteria.     4– Conclusion  Urban land use planning deals with how to assign different land use to Land. Over the past few decades mixed land uses development become a model for urban planning, and due to social, economic and environment benefits has been well received in the advanced countries. In this study, Identify the strengths and weaknesses of indicators of diversity in MLU, the proposed indicators for the horizontal dimension urban neighborhoods and districts in the 7th regional municipality of Tehran city will implement. Practical analysis of indicators for the analysis presented above in the study area, indicating the ability of the proposed indicators to evaluate the MLU diversity in the study area.  Based on the results of this study, using criteria set Atkinson (A 0.1, A 0.5, A 0.9) to evaluate the diversity for mixing of the two types land use (for example in research, non-residential and residential land use) is recommended. The reasons of propose for these indicators include:   · Weaknesses of other methods (indices of dissimilarity and Gini) to reflect the correct amount of diversity in the Urban mixed land use. For example, the Gini and dissimilarity indices are not a very discriminating indicator and two very different distributions can have exactly the similar indicators. In order to implement the dissimilarity index, in order to implement this index, both types of the land uses must be present in the study area. In our example, the index would not be computed for the neighborhoods with either only residential or only non-residential land uses.   · Indices of Atkinson provide a practical opportunity for assigning weights to various land use distributions and making normative adjustments. In this index, 14 خµ'> , inequality aversion paramater, get amounts to between zero and infinity. Depending on the type and purpose of evaluation we can assign the proper value to the 14 خµ'> . If a value greater than zero but less than 0.5, areal units of the proportion of nonresidential land uses is smaller than the study area’s average contribute more to the index and for values ​​greater than 0.5 to 1, the opposite is true. When is equal to 0.5, such areas contributing equally.     After analyzing the results of each index, the HHI and Entropy indicator, to assess the diversity in MLU for more than two (e.g. in this research, land uses of housing, urban civil service, cultural and leisure, commercial, administrative and law enforcement and other land uses) is recommended reasons of propose for this indicator:   · The ability to model more than two land uses in the calculation   · Simplicity in computation and less computational time   · And these indicators are more understandable public .     5– Suggestions   It seems that integrating urban planning models with Geographic Information Systems should lead to the development of new models for integrating the various aspects of the spatial planning. The urban planning based on GIS, in addition to supporting the development of new analytical models, leads to the release of restrictions in the conventional urban models and enables us to think beyond the issues raised in the past decades. In this regard, urban planners in dealing with new issues in urban use from GIS -based development tools , apply appropriate flexibility in analysis and integrate them with other spatial planning models. Although the proposed indicators in this study have a proper assessment of the diversity of urban MLU , success came is not a complete solution of this problem and the other research in this direction should be considered .   The suggestions for future:   · Formulations of mixed uses development are insufficient in terms of diversity criteria. It also comprises other features such as the urban experience, the nature of uses, definitions of public and private, land use Incompatibility, conflict and security.   · It is suggested that to evaluate urban Mixed land use, in addition to diversity index, other indicators such as the amount of accessibility of housing to other fundamental land use, such as commercial , office , leisure and etc., amount of Clustering Land uses, amount of intensity in the area of analysis, and also incompatibility between land uses be considered in the future research.   · In order to improve diversity and positive impact of mixed land uses in the area of study, aggregation of the proposed models in this research and GIS, site selection and allocation of land uses for area of analysis towards the goals and advantages of mixed land uses are proposed.   Key Words: Mixed land uses, diversity of land uses, urban planning, GIS, land use evaluation     References   Atkinson, A. 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کلیدواژه‌ها [English]

  • Mixed land uses
  • diversity of land uses
  • urban planning
  • GIS
  • land use evaluation