Spatio-Temporal Analysis of Urban Heat Vulnerability: The Case study of Dire Dawa City, Ethiopia

Abstract

Dire Dawa City has faced the adverse effect of climate change with the problem of overwhelming increase in temperature as compared from year to year. The effects significantly influence internal urban microclimate at a local scale. And, the rapid urbanization has produced a remarkable effect on the surface thermal response. Thus, the aim of this study was to analyze spatio-temporal distribution of urban heat vulnerability in Dire Dawa City by employing geospatial technologies tools. To achieve the objective of the study, heat vulnerability index through aggregation (additive approach) were used to identify vulnerable areas to heat. Based on Intergovernmental Panel on Climate Change (IPCC’s) approach of vulnerability assessment which comprises exposure, sensitivity and adaptive capacity. Four sub components of vulnerability indicators were identified and their values were normalized to a number which ranges between 0-1, as the values approaches to 1, vulnerability increases. In this study, land surface temperature and land use land cover types extracted from Landsat 5 TM (1995) and Landsat 8 OLI/TIRS (2020). Erdas imagine 2014 and ArcGIS 10.8 were used for data pre-processing, preparation and map composition. Results from land use land cover dynamics in relation to land surface temperature changes between 1995 and 2020 revealed that, a noticeable increase in built-up area by 5.38 km2 exhibited a high change of surface temperature by 5.120C. While, sparse vegetation has been gradually decline by 2.07 km2 exposed surface temperature to increase by 5.03 0C. Also, urban land development raised surface temperature by 6.87 0C (highest) for kebele 02 and 5.30 0C (lowest) for kebele 07. And, the normalized values of spatial distribution of population per kebele score of sensitivity result were highest (1.0) for kebele 02 and lowest for kebele 06 (0.0). On the other hand, normalized average adaptive capacity result shows highest (1.00) for kebele 06 and lowest (0.06) for kebele 03. Relative heat vulnerability index score ranges from 0.12(lowest) in kebele 03, goes to 0.63 (highest) found in kebele 07; by superimposing the heat vulnerability indicators, kebele 07, 02, 09, 06 and 08 kebeles were identified as highly vulnerable to heat incidence; highest heat vulnerability are derived from factors associated with the raised land surface temperature, high population density, limited green area coverage’s and poor accessibility of water. Generally, urban heat vulnerability maps that developed for Dire Dawa City are able to identify not only where are the hottest areas are located but also where the most vulnerable people of the City are located in the City. In addition, there are also able to visualize the current state of adaptive capacity to extreme heat based on the availability of greenery, water accessibility for public health.