The shape compactness of urban footprints
The shape compactness of urban footprints
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DOI：
10.1016/j.progress.2018.12.001
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发表时间：
2020-07-01
影响因子：
6.4
通讯作者：
Blei, Alejandro M.
中科院分区：
文献类型：
--
作者：
Angel, Shlomo;Franco, Sara Arango;Blei, Alejandro M.
城市人口密度作为城市的关键紧凑性属性，已在大量关于紧凑型城市范式的文献中占有一席之地，但城市足迹的形状紧凑性几乎不值一提。本文试图纠正这一点。我们回顾了关于紧凑型城市范式的文献，特别关注城市形态和气候变化之间的关系，并重点讨论了使城市或多或少紧凑的12个物理属性。在其他条件相同的情况下，人口密度和形状紧凑度都有助于确定城市的平均出行距离，从而影响城市的能源消耗和温室气体排放。它们还影响基础设施线路的长度和通勤长度。因此，原则上，增加城市的形状紧凑度或人口密度可以在不同但相似的措施上为减缓气候变化做出贡献。有强大的力量推动城市足迹变得更加紧凑--即形状为圆形或接近圆形--这些力量随着时间的推移而演变。也有强大的力量推动城市足迹随着时间的推移变得不那么紧凑。我们介绍了这些力量，并说明了它们对特定城市的影响。然后，我们将重点放在衡量城市形状紧凑度的一小部分指标上。我们使用它们来测量从卫星图像中获得的城市足迹，该样本包括三个时间段：1990、2000和2014年的全球200个城市的分层样本。我们发现，世界各地城市足迹的形状紧凑度与城市规模、面积、密度和收入无关，并且毫不奇怪，它受到地形的强烈影响。我们还发现，在1990年至2014年期间，它总体上有所下降，并解释了这种下降的一些来源。我们通过评估可以增加城市形状紧凑度的方法来总结这篇论文，以使它们能够在未来几十年更好地缓解气候变化。
Urban population density has featured in a large body of literature on the Compact City paradigm as the key compactness attribute of cities, yet the shape compactness of urban footprints has hardly deserved a mention. This essay seeks to correct that. We review the literature on the Compact City Paradigm with a special focus on the relationship between urban form and climate change, and focus on twelve physical attributes of cities that make them more or less compact. Other things being equal, both population density and shape compactness help determine the average travel distances in cities, and hence affect their energy consumption and their greenhouse gas emissions. They also affect the length of infrastructure lines and the length of commutes. In principle, therefore, increasing either the shape compactness or the population density of cities can contribute-in different yet similar measure-to mitigating climate change. There are strong forces that push urban footprints to become more compact-that is, circular or near circular in shape-and these forces have evolved over time. There are also powerful forces that have pushed urban footprints to become less compact over time. We introduce these forces and illustrate their effects on particular cities. We then focus on a small set of metrics for measuring the shape compactness of cities. We use them to measure urban footprints obtained from satellite imagery in a stratified global sample of 200 cities in three time periods: 1990, 2000, and 2014. We find that the shape compactness of urban footprints the world over is independent of city size, area, density, and income and that, not surprisingly, it is strongly affected by topography. We also find that it has declined overall between 1990 and 2014 and explain some of the sources of this decline. We conclude the paper by assessing the ways in which the shape compactness of cities can be increased to make them better able to mitigate climate change in decades to come.