Drivers of Urban Growth and Environmental ImpactsIn this study, we analyze the past and anticipated environmental impacts of urban growth in China using Shenzhen, a rapidly growing city in the Pearl River Delta, China as a case study. Although, Shenzhen has drawn considerable attention both in popular media and scholarly literature (Yeung and Chu 1998, Seto and Kaufmann 2003, China Daily 2005) an important criticism directed towards most of these studies is the lack of a coherent systemic view of the city that is needed to properly appreciate the feedbacks between multitudes of factors contributing to this metamorphosis (Ng 2002). Our study of Shenzhen is aimed to provide insight into the feedback dynamics between the drivers of urbanization and their environmental impacts. Although we use Shenzhen as a case study, our goal is to increase understanding of the relationships between urban growth and the environment, and gain insight into general patterns that are applicable to other rapidly developing urban areas worldwide. The achieve this goal, we construct a framework that explicitly incorporates the feedbacks between the social-economic factors into the analysis of environmental impacts of urbanization to help develop better policy options. The study has two components. First, we build a systemic dynamic feedback model of Shenzhen to identify the key connections between the socioeconomic factors of urbanization and urban growth and the resulting environmental impacts. Second, we forecast likely environmental impacts of different development and policy scenarios (Lutz et al. 2002). In order to understand the feedbacks and relationships in the urban system of Shenzhen, we employ a system dynamics modeling approach that allows for explicit representation of the linkages between socioeconomic factors that drive the growth of the city and their environmental impacts. The model consists of eight submodels representing the social and economic structuring and land base of the city and quality of its environment (Figure 1).The time frame of the study is 51 years, from year 1979 to 2030. Results from the base run and different natural growth rate scenarios indicate that Some of the needed data from the region are either unavailable or unreliable. This somewhat constrained the more detailed modeling of certain aspects of the city. So, although the available validation results are an important initial step in the right direction, there is room for improvement. the migration will continue to be the fundamental cause of population growth even though the flow of migrants start to decrease during the second half of the simulations. This implies that control or manipulation of migration flows will be a high leverage policy tool in coming decades. The pressure will certainly increase on the education system as more and more migrants become temporary residents and have children. The total GDP in year 2030 will reach somewhere between 75 to 100 million US dollars in 1990 prices. The base run, however, suggests emergence of chronic levels of unemployment towards the end of the simulation horizon. The available land will be used up most likely towards year 2020 confirming earlier predictions (Bai 2000). This certainly has the potential to impact the city’s economy. The demand for electricity and potable water reach much higher levels in the near future further validating the calls for more efficient usage practices (Figure 2a-b, Ng 2002). Air quality will be adversely affected most notably due to NO2 emissions because of the increased traffic flow (Figure 2c-d). |
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