Resilient Cities in a Changing World AMPS | City, University of London Page 40 vulnerability mapping, this includes concerns about the extent of how the population can behave to be resilient to disasters and natural hazards.25 Therefore, this research applies this assessment approach to integrate social-demographic and socioeconomic data into environmental indices, to acknowledge factors that may influence heat vulnerability. For heat vulnerability assessment, it can also represent the intra-urban variation of heat risk and comprehensively consider the variation of social and environmental conditions, in particular at a more detailed spatial scale within the urban area. Study Areas For the UK, a previous study developed the heatwave vulnerability index for London based on the census data in 2011,26 yet the assessment of the latest census data has not been undertaken after the extreme heat event in 2022. In contrast to previous cases, this study aims to select two cities in the UK that possess distinct characteristics in the comparison, taking respectively an old and smaller city (Cambridge) and a newly developed green city (Milton Keynes) into account, as these two cities possess different social characteristics and urban forms, but both with large coverage of green spaces. Cambridge is a small city located around the banks of the River Cam. This city is well-known for its research, education, and knowledge-based enterprises, and possesses substantial historical background. It covers an area of 40.7 km2 and encompasses a population of 621,200. According to the statistics from the City Council, this city boasts 743.59 hectares of Protected Open Space (POS), including green commons and parks and gardens owned by Cambridge University. This amounts to around 6.2 hectares of protected open space per 1,000 residents, of which 2.9 hectares per 1,000 persons are available to be publicly accessed. This city suffered heat issues during the past years and the heatwave in July 2022 surpassed the earlier record (new record as 38.7 ℃) and was far more intense than those previous years. In addition, the uneven distribution of accessible green spaces and socioeconomic inequality may bring larger challenges to this city. Milton Keynes is a relatively new city built during the late 20th century. It is in Buckinghamshire, approximately 72 km from London. It covers about 89 km2 of area size with almost 6,000 hectares of green spaces. 270,200 people are living in this city, and the ratio of elderly people accounts for 20%. It has been ranked as the top local government in terms of open space per citizen and has been perceived as one of the greenest cities in the UK.27 This ‘manmade’ city is planned under the concept of the Garden City, which attempted to construct a metropolis with an emphasis on green belt regions and population management. A unique urban form consisting of green grid carriageways dividing the city into sub- defined neighbourhoods is also seen in Milton Keynes. However, some areas in Milton Keynes are among the most deprived areas in England in terms of building conditions and socioeconomic profiles28, reflecting a high level of sensitivity to extreme heat events. Data Sources and Calculation This research first utilises an open-source platform: Google Earth Engine (GEE) for processing and downloading Landsat 8 satellite imagery for land surface temperature data acquisition.29 The temporal coverage of data is between June to September 2022. These images are pre-processed with cloud masking and then used to calculate the average temperature to meet the same spatial scale as the social demographic data. The green infrastructure index of the Normalised Difference Vegetation Index (NDVI) is also acquired through GEE. Pixels indicating NDVI values larger than 0.2 are considered as green spaces and used to calculate the green coverage in each tract. The data on Open Green Spaces released by the Ordnance Survey is later used to calculate the distance from settlements to these open green spaces, which indicates the accessibility to cooling infrastructure.
