یک مدل جایگزین برای ارزیابی شهرسازی پایدار

In recent years, there has been rapid urbanization worldwide, resulting in both benefits and problems. Sustainable urbanization has become an important aspect in promoting sustainable development. Existing studies have introduced various methodologies to guide urbanization towards sustainable practices. The application of these methods has contributed to improving urban sustainability. To further support the effective applications of the principles of sustainable urbanization, a tool is needed to evaluate whether a particular process of urbanization is sustainable. In this paper, we introduce an alternative model for evaluating sustainable urbanization by investigating the relationship between urbanization and urban sustainability. The practice of sustainable urbanization is defined as a dynamic process that enables urban sustainability to improve or to maintain a certain level of practice. By employing this definition, we introduce a sustainable urbanization elasticity coefficient eSU, which is defined by two parameters: urbanization velocity (VμR) and urban sustainability velocity (VμS). The sustainability of an urbanization process is measured by the value of eSU or read from the VμR–VμS coordinate. A case study demonstrates the application of the measure eSU and the VμR–VμS coordinate. The proposed model is an effective tool to help policy makers understand whether the urbanization processes they support are sustainable and thus whether to correct practices. The model also allows comparison of different urbanization practices and thereby encourages the sharing of successful experiences.

Urbanization, which is defined as a movement of people from rural to urban areas with population growth equal to urban migration, has been one of the most prominent trends of the 20th and 21st century (Street, 1997 and United Nations, 2010). According to a report by the United Nations (2010), the ratio of urban populations rose from 13% in 1900, to 29% in 1950, to 50% in 2009, and it is projected to be 69% in 2050. Urbanization brings many benefits, such as diversity, market efficiency, jobs, education, and health improvement (Christopher, 2008 and Glaeser, 1998). It is these benefits that attract a continuous flow of people from rural to urban areas. However, due to the rapid pace of urbanization, natural ecosystems are increasingly replaced by cities (Attwell, 2000 and United Nations Population Fund, 2007). It has been increasingly noted that urbanization leads to many problems, such as air and water pollution, depletion of cultivated land due to urban sprawl, global climate change, and others (Li et al., 2009 and Yigitcanlar, 2009). These problems present barriers to achieving sustainable development. Consequently, with the global promotion of sustainable development, the problems created by urbanization have attracted efforts to find solutions from various sectors, including academics. The principles of sustainable development have been increasingly applied across all sectors, with the development of various management systems. For example, the Building Research Establishment Environmental Assessment Method (BREEAM) (1990), the Leadership in Energy & Environmental Design (LEED) (1993), and Green Star (2003) have been applied to improve environmental performance. Corporate Social Responsibility (CSR) has been promoted as a strategy to improve social sustainability (Mathias, 2005). In line with these developments, sustainable urbanization is promoted as an important component of sustainable development (UN-Habitat/DFID, 2002). An urbanization process that fulfills the principles of sustainable development characterizes sustainable urbanization (Roy, 2009). Governments have advocated various policies on sustainable urbanization, and current research has also introduced various methodologies to assist in promoting sustainable urbanization. Drakakis-Smith and Dixon (1997) developed an integrative framework to understand concerns regarding sustainable urbanization from the perspectives of economic, social, political, demographic, and environmental performances. A report by the UN-Habitat/DFID (2002) identified the main challenges to achieving sustainable urbanization, including potential conflicts between economic growth and environmental sustainability, inequity due to lack of political and social inclusion, inadequate governance capabilities, and difficulties in achieving coordinated urban–rural development. Pivo (1996) reviewed the experience of sustainable urbanization in Mainstreet Cascadia and summarized six principles of urban planning for promoting sustainable urbanization, including compactness, completeness, conservation, comfort, coordination, and collaboration. Other studies investigated how various technological methods, such as low carbon emission, air and noise pollution control, and waste management contribute to urban environmental protection and sustainable urbanization (e.g., Brown, 2008, Jenerette and Larsen, 2006 and Leach et al., 1997). In recent years, advanced technologies, such as remote sensing, the Cellular Automata model, the SLEUTH model, and the System Dynamics model have been used to monitor the impact of urbanization on the environment and to analyze future scenarios of changes in land use to facilitate policy making for promoting sustainable urbanization (e.g., Encalada and Caceres, 2009, Haase et al., 2008, Irwin et al., 2009, Jantz et al., 2003 and Ward et al., 2000). Furthermore, various urban models have been introduced to guide the practice of urbanization towards better sustainability. Haughton (1999) suggested four types of urban models to contribute to sustainable development, namely “free market’’, ‘‘redesigning’’, ‘‘self-reliant’’, and ‘‘fair shares’’ city. Holden (2004) described four models of urban development, namely “urban sprawl”, “the green city”, “large (monolithic) compact city”, and “decentralized concentration”, with the model of decentralized concentration favored for better sustainability. Jabareen (2006) discussed the models of “compact city”, “eco-city”, “urban containment”, and “neo-traditional development” and recommended applying the compact city model to promote sustainable urbanization. The above discussions show that studies have introduced various models and methods to guide the design and practice of sustainable urbanization. Appreciation of these models and methods invites our investigation of how to evaluate their effectiveness. It appears that few studies have addressed this issue, which is important for applying effective methods and for encouraging sustainable urbanization. Therefore, there is a need for a tool to evaluate whether a particular practice of urbanization is sustainable. This tool should be able to incorporate the principles of sustainable urbanization with the characteristics of a particular practice of urbanization. This paper aims to develop such a tool for evaluating the sustainability of urbanization.

To create sustainable urbanization, it is essential to evaluate whether a particular process of urbanization is consistent with the principles of sustainable development. In this paper, we presented a model for evaluating the sustainability of urbanization that helps to understand the effectiveness of methods established to guide the process of urbanization. The model captures the dynamic nature of the process of urbanization by two parameters: urbanization velocity (VμR) and urban sustainability velocity (VμS). The two parameters are used to form a VμR–VμS coordinate, which presents four scenarios of urbanization practice, depicted in four quadrants. Furthermore, the sustainable urbanization elasticity coefficient (eSU) is developed based on the two parameters VμR and VμS. The value eSU can be calculated and used to examine whether a process of urbanization is sustainable, i.e., whether there is improvement in sustainability performance in a particular process of urbanization. The case study showed the application of the VμR–VμS coordinate and the elasticity coefficient eSU to be effective. This paper also presented an alternative approach for supporting the study of sustainable urbanization. The approach yields results that help policy makers to understand whether an ongoing process of urbanization is consistent with the principles of sustainable development. The results of the evaluation can provide valuable data for identifying the causes of poor practices, and thus, appropriate policies can be implemented to guide the process of urbanization toward better sustainability. Because various practices of urbanization exist due to different economic, social, and environmental backgrounds, the sharing of experiences should be encouraged. The proposed model also allows comparison of various processes of urbanization and thus encourages the sharing of experiences from different practices.