Abstract
Spatial urban growth and its impact on land surface temperature (LST) is a high priority environmental issue for urban policy. Although the impact of horizontal spatial growth of cities on LST is well studied, the impact of the vertical spatial distribution of buildings on LST is under-investigated. This is particularly true for cities in sub-tropical developing countries. In this study, TerraSAR-X add-on for Digital Elevation Measurement (TanDEM-XDEM), Advanced Spaceborne Thermal Emission and Reflection (ASTER)-Global Digital Elevation Model (GDEM), and ALOS World 3D-30m (AW3D30) based Digital Surface Model (DSM) data were used to investigate the vertical growth of the Dhaka Metropolitan Area (DMA) in Bangladesh. Thermal Infrared (TIR) data (10.6-11.2µm) of Landsat-8 were used to investigate the seasonal variations in LST. Thereafter, the impact of horizontal and vertical spatial growth on LST was studied. The result showed that: (a) TanDEM-X DSM derived building height had a higher accuracy as compared to other existing DSM that reveals mean building height of the Dhaka city is approximately 10 m, (b) built-up areas were estimated to cover approximately 94%, 88%, and 44% in Dhaka South City Corporation (DSCC), Dhaka North City Corporation (DNCC), and Fringe areas, respectively, of DMA using a Support Vector Machine (SVM) classification method, (c) the built-up showed a strong relationship with LST (Kendall tau coefficient of 0.625 in summer and 0.483 in winter) in comparison to vertical growth (Kendall tau coefficient of 0.156 in the summer and 0.059 in the winter), and (d) the ‘low height-high density’ areas showed high LST in both seasons. This study suggests that vertical development is better than horizontal development for providing enough open spaces, green spaces, and preserving natural features. This study provides city planners with a better understating of sustainable urban planning and can promote the formulation of action plans for appropriate urban development policies.
Highlights
Unplanned spatial growth of cities is a major cause of increasing land surface temperatures (LST) and the development of urban heat islands (UHI) [1]
The geo-statistical based comparative analysis of Digital Building Height (DBH) extracted from three Digital Surface Model (DSM) (TanDEM-X, ASTER, and Advanced Land Observation Satellite (ALOS) World 3D-30m (AW3D30)) and ground-based building height is presented in the figures (Figure 7, Figure 8, and Figure 9) for the Dhaka South City Corporation (DSCC), Dhaka North City Corporation (DNCC), and fringe area, respectively
The mean building height extracted by TanDEM-X reveals the similarity with ground-based building height data except for the ward numbers S-03, S-09, and S-13 of DSCC
Summary
Unplanned spatial growth of cities is a major cause of increasing land surface temperatures (LST) and the development of urban heat islands (UHI) [1]. Wong and Yu [2] reported that the highest concentration of hard surfaces such as buildings, roads, impervious areas, and fewer open spaces are the reasons for increasing urban surface temperature. Spatial growth denotes a tremendous increase in population and buildings in cities, which leads to the drastic reduction of vegetated areas while leading to an increase of impervious areas [6]. The physical growth of cities brings numerous environmental problems, among them being the “urban heat island” effect, which is a well-documented climatological effect of human activities on the urban environment [2,8]
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