Who gets what, where, and how much? Composite index of spatial inequality for small areas in Tehran

Urban spatial inequality is multidimensional and complex. The extant literature identifies three main theoretically-informed dimensions of spatial inequality—accessibility, environmental conditions, and socio-economic conditions. We combine geospatial data on measures across these three theoretical dimensions to derive a composite index for the city of Tehran, Iran. We draw on these three dimensions respectively from the relative geographic locations of urban facilities and services, satellite images, and census and survey data. The application contributes to the evidence-base on urban spatial inequality and may inform urban policy decisions aimed at reducing spatial inequality. La desigualdad espacial urbana es multidimensional y compleja. La bibliografía existente identifica tres dimensiones principales de la desigualdad espacial basadas en la teoría: la accesibilidad, las condiciones ambientales y las condiciones socioeconómicas. En este estudio se combinan datos geoespaciales de medidas de estas tres dimensiones teóricas para obtener un índice compuesto para la ciudad de Teherán (Irán). El estudio se basa en estas tres dimensiones, respectivamente, a partir de las ubicaciones geográficas relativas de las instalaciones y los servicios urbanos, imágenes de satélite y datos de censos y encuestas. La aplicación contribuye al acervo de evidencia sobre la desigualdad espacial urbana, y puede informar las decisiones sobre políticas urbanas destinadas a reducir la desigualdad espacial. 都市部における空間的不平等は、多元的で複雑である。既存の研究により、理論的に情報に基づいた、主に3つの空間的不平等の側面、すなわちアクセシビリティ、環境的な条件、社会経済的な条件が特定されている。本稿では、3つの理論的な側面すべての測度に関する地理空間データを組み合わせて、イランのテヘランのコンポジット・インデックスを導出した。さらに、都市施設とサービスの相対的な地理的立地、衛星画像、国勢調査と調査データから、3つのそれぞれの側面を利用する。この応用は、都市の空間的不平等に関するエビデンスの基礎に寄与するものであり、空間的不平等を低減することを目的とした都市政策の意思決定に資するものである。 Scanlon (2018) listed six reasons why all types of inequality is morally objectionable; it is humiliating, gives superior power to the rich, decreases equality of economic opportunity, harms the fairness of political institutions, violates equal concern to all people, and is rooted in unfair economic institutions. Simply put, the social and individual costs of inequality are taken for granted (Buitelaar et al., 2018; Dorling, 2019; Lardner Weeks et al., 2013; Wrigley, 1987). Also, there is a strong relationship between inequality and other social problems; to name a few, poverty (Ahluwalia, 1976; Buitelaar et al., 2018; Weeks et al., 2013; Wrigley, 1987), social justice (Kabeer, 2010; Runciman Yousefi Kanbur Kazepov, 2005; Kim, 2008; Lobao et al., 2007; Weeks et al., 2013). Chiappero-Martinetti and Moroni (2007) suggested analytical frameworks to conceptualize socio-economic problems (e.g., poverty) at five different levels: Metaethical, Ethical, Explicative, Metric, and Anankastic. The Chiappero-Martinetti and Moroni framework can be applied to a number of equally complex and related concepts, such as inequality (Chiappero-Martinetti Kim, 2008; Shorrocks Shorrocks Morenoff et al., 2001; Neckerman et al., 2009). In this paper, our approach is holistic in that we seek to derive a composite index from measures drawn from multiple dimensions of the urban landscape at a granular area scale; a local scale based on 100 m × 100 m grid cells of the city. For these grids we derive attributes of the physical, built, and socio-economic environment. We harness a wide variety of geospatial data that were available (the year 2002) for urban Tehran and used these to construct a composite index of spatial inequality for small areas using raster-based modelling. An essential question in spatial inequality studies is “Who gets what, where?” (Smith, 1977). The question “who gets what, where?” formalizes our main aim; to measure and model spatial inequality in Tehran and we extend this to ask “Who gets what, where, and how (much)?” That is, we ask who are the residents that have access to X amount of public benefits and/or exposure to X amount of risk, and where in the city are they found. Basic questions at the metric level include: Can we identify the main dimensions of inequality in Tehran? How can we measure these dimensions of inequality? Can we combine these dimensions? What is special about spatial inequality in Tehran? In particular, the paper combines an array of measures to develop a composite index, and does so at a fine spatial scale (100 m × 100 m grid) generating a higher resolution map (and data) than typically found in the literature. In addition to maps as end-products, the paper provides two other contributions. First, the paper offers a replicable methodology for measuring and combining the main dimensions of urban spatial inequality rather than a mono-dimensional measurement of spatial inequality. The method, while data-intensive, is straightforward to operationalize, and is practicable and reproducible in cities with similar sociospatial contexts. Second, the paper paves the way for mapping vulnerable areas and priority maps for urban managers to apply ‘area-based target policy’ and thus shaping spatially informed urban development strategies that may potentially alleviate or reduce urban spatial disparities within cities at the local scale. Tehran, in 2020, is one of the largest and fastest-growing cities in the world. The last official census (2016) showed 8.73 million inhabitants. While there is no consensus about its current population, some unofficial sources suggest that there are 14 million inhabitants. Tehran, with a total area of 730 km2, lies at the southern edge of the Alborz mountain range. This geographical location provides Tehran with a topographical gradient; the northern sections of the city are higher in elevation than the southern sections (the height difference between the lowest and the highest points of the city is approximately 1,000 metres). This north–south topographical gradient is consistent with a generalized socio-economic gradient within the city (Rabiei-Dastjerdi and (iii) socio-economic conditions will be explained. Finally, after mapping all three dimensions of spatial inequality, they were combined to produce a composite index of spatial inequality at a small area scale. For Harvey (1973), social equality means an equitable distribution of resources, services, and power. Consequently, everyone, wherever they live, must receive equal services or “proportionate distribution of resources in an equitable manner” (Harvey, 1973, p. 98). Briefly, the physical accessibility of an individual to a destination can be referred to as spatial accessibility (Ashik et al., 2020; Kwan We used green spaces and as an for measuring conditions because it is one of the most important factors in creating a better environmental and ecological in the city. spaces and urban have and in a the and both and urban green spaces public parks to the but there are other of green include urban and in the city, green spaces in spaces such as and the and small and limited green spaces et (2007) that having a of and (e.g., and of the landscape can and and et that parks with of the and landscape has effects on people, including reducing and et al., 2003). with and a variety of can to & 1 the methodology for measuring and modelling spatial inequality in Tehran. 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