2D and 3D urban morphology effects on land surface temperature and thermal comfort in arid environments

Urbanization significantly alters the thermal environment of cities, particularly in hot-arid regions where extreme heat and limited vegetation intensify thermal stress. Understanding how urban morphology influences land surface temperature (LST) and human thermal comfort is therefore essential for climate-responsive urban planning. This study investigates the relationship between urban form, surface temperature, and thermal comfort by integrating both two-dimensional (2D) and three-dimensional (3D) urban morphology indicators in two contrasting urban fabrics of the M’zab Valley, Algeria: the traditional ksar of Beni Isguen and the planned settlement of Tafilalet. The originality of this research lies in the combined analysis of 2D shape indices (Miller, Morton, Gravelius, and elongation) and 3D morphology indicators (building density, building height, sky view factor, and fractional vegetation cover) together with satellite-derived LST and human thermal comfort indices (Discomfort Index DI and Urban Thermal Field Variance Index UTFVI and the approximated wet-bulb globe temperature index AWBGT). LST was retrieved from Landsat-8 OLI/TIRS imagery acquired on 22 June 2025 and analyzed using spatial correlation and regression techniques. Results reveal clear thermal contrasts between the two urban fabrics. LST values range from 35.6 to 38.5°C in Tafilalet and from 36.2° to 38.8°C in Beni Isguen, with the compact urban core of Beni Isguen consistently showing lower surface temperatures than peripheral zones. Morphological indicators highlight substantial structural differences between the settlements, with higher compactness in Beni Isguen (Miller index = 0.94) compared to Tafilalet (0.34). Correlation analysis indicates that building density, building height, and vegetation cover are negatively associated with LST, whereas higher sky view factor and fragmented urban geometry correspond to increased surface temperatures. Thermal comfort analysis shows Discomfort Index values between 26.7°C and 28.6°C, indicating moderate thermal stress in both settlements, although Tafilalet presents stronger spatial variability and more pronounced heat-stress hotspots according to UTFVI classification. These findings suggest that compact urban morphology and reduced sky exposure contribute to improved thermal regulation in hot-arid environments. The study highlights the climatic relevance of traditional urban forms and provides evidence supporting the integration of compact layouts, controlled sky view factors, optimized density, and targeted vegetation strategies in future urban planning for arid regions.