Last modified: 2016-07-08
Abstract
This paper develops and trials a model for integrating physical and socio-economic data to assess heat vulnerability within the urban areas of Taipei City. Spatial planning for resilience to climate-related events such as excess heat requires understanding of the differences in physical exposure and socio-economic vulnerability that can exist within a city. Moreover, societal vulnerability is determined not only by economic or demographic factors, but also by less tangible cultural drivers. We exemplify our integrated model for physical and social vulnerability assessment through application to the case of Taipei City, Taiwan.
Due to the difference in urban development pattern, heat is not evenly distributed in cities so as to the magnitude of heat exposure. This study adopted remotely sensed data from LANDSAT 8 to assess the relationship between the thermal patterns and landscape characteristics whereby a set of exposure indicators was determined. Three exposure indicators, namely impervious surface rate, proximity to mountains, and tree and water proportion, were included, because: 1. the normalized difference built-up index (NDBI) has a strong positive linear relationship with land surface temeprature; 2. areas closer to mountains were cooler and; 3. trees and waters have cooling effect.
Socio-economic vulnerability for each village within Taipei City was calculated by integrating publicly-available datasets from the Department of Statistics, Ministry of the Interior. Based on a review of existing social science literature into factors influencing sensitivity and adaptive potential for climate change adaptation, key variables from the datasets were selected. These reflected not only population demographics and economic characteristics, but also less tangible determinants of vulnerability such as social capital, access to information and access to knowledge within each village. The variables were assigned relative weightings according to their importance in extant literature. In turn, a socio-economic vulnerability score and ranking was calculated for each village within Taipei, allowing quantitative comparison with land surface temperature.
The socio-economic indicators suggest the most vulnerable areas are located in the Da’An and Zhongzheng areas of the city - areas of higher than average income. This suggests a complex range of factors such as inequality and social capital may inform the vulnerability of an area to heat-related events, and reinforces the need for spatial data which can give decision-makers a sense of the socio-cultural makeup of an urban space in order to more effectively plan for resilience.
Based on the Taipei case we caution that there can be marked differences in the nature, extent and resolution of socio-economic data within and between municipalities. Researchers must therefore be prepared to be flexible with how they use socio-economic data in particular to assess vulnerability, and should exercise caution to avoid assumption about what the most ‘important’ variables will be in a given social context. It is imperative to reflect on where the scale of socio-economic data may mask differences or inequalities within spatial units. Moreover, cognisance should also be paid to potential ethical issues (distress, stigmatisation) that may arise when marking areas out as 'vulnerable' through spatial data analysis.