Urban Expansion and its Relation to the Urban Heat Island Effect: A Case Study of Tripoli, Libya

Abstract

Urban expansion is a defining feature of rapidly growing cities and has important implications for urban thermal behaviours, particularly in hot and semi-arid regions that are increasingly vulnerable to the effects of climate change. Tripoli, the capital of Libya, has experienced substantial urban growth over recent decades under conditions of weak planning and uneven development. Despite this, the relationship between Tripoli’s urban form and its thermal characteristics remains poorly understood.
This study examines how urban expansion in Greater Tripoli (2000-2025) relates to Land Surface Temperature patterns and the Urban Heat Island effect. Multi-temporal Landsat imagery was analysed using GIS and remote sensing methods. Urban areas were mapped through spectral index classification and change-detection techniques, and Shannon’s Entropy was used to assess the spatial dispersion of growth. Land Surface Temperature was derived from thermal infrared data, and Urban Heat Island Intensity was calculated by comparing average temperatures of urban and non-urban areas. Statistical tests evaluated the significance of thermal differences and their relationship to urban metrics.
Results show that Tripoli’s urban area more than doubled over the 25-year period, expanding from a compact coastal core into a dispersed inland pattern. High entropy values indicate sustained sprawl rather than a shift toward compact growth. Thermal analysis reveals a strong coastal-inland temperature gradient, and urban areas consistently exhibited lower average Land Surface Temperatures than surrounding non-urban areas, producing negative Urban Heat Island Intensity values. While temperature differences between urban and non-urban areas were statistically significant, no significant correlation was found between Urban Heat Island Intensity and either urban extent or spatial dispersion. These findings suggest that urban thermal behaviour in Tripoli is influenced by more than the urban form alone. The study contributes new evidence from a data-scarce context and demonstrated the value of GIS and remote sensing for long-term urban climate analysis in semi-arid coastal regions.

Popular Abstract

Cities around the worlds are growing rapidly, and this growth is often blamed for rising urban temperatures. A common idea is that cities become much hotter than their surrounding countryside, a phenomenon known as the Urban Heat Island effect. This thesis explores whether this assumption holds true for Tripoli, Libya’s capital city, which has experienced extensive urban expansion over the past 25 years.
Tripoli has grown mainly outward from its historic centre along the Mediterranean coast, spreading inland into drier and more sparsely vegetated areas. Using satellite images and Geographic Information Science, this study mapped how the city expanded between 2000 and 2025 and examined how surface temperatures changed during the same period. Satellite data allowed the analysis of both land cover changes and surface temperatures across the entire city and its surroundings.
The results show that Tripoli’s urban area has more than doubled during the study period, with development occurring in a scattered sprawling pattern. Surprisingly, however, the city did not consistently become hotter than its surroundings. In many case, urban areas were actually cooler than nearby non-urban land. This happens because Tripoli is located along the Mediterranean coast, where sea breeze and coastal conditions help moderate temperatures, while inland areas are dominated by bare, dry soil that heats up very quick. As a result, the city behaved more like a “heat sink”, staying cooler than its surroundings.
Why this matters?
These results challenge the idea that urban growth always leads to higher temperatures. Instead, they show that local geography and climate can be more important than the size or shape of the city itself. For Tripoli, the cooling influence of the Mediterranean Sea and the heat-absorbing nature of inland soils play a bigger role than urban expansion. This insight is valuable for planners and decision-makers, who often rely on general assumptions about urban warming. It highlights the need for climate-sensitive planning that considers local environmental conditions rather than applying one-size-fits-all solutions.
Understanding how cities like Tripoli respond to growth can help guide future development in hot and semi-arid regions. As climate change intensifies heat stress worldwide, knowing when and where cities actually warm up – and when they don’t – becomes essential for designing healthier, more resilient urban environments.

• author: Ben Said, Nour Abdulmagid A
• supervisor: Lina Eklund
• organization: Department of Earth and Environmental Sciences (MGeo); Dept of Physical Geography and Ecosystem Science
• course: GISM01 20261
• year: 2026
• type: H2 - Master's Degree (Two Years)
• subject: Earth and Environmental Sciences
• keywords: Geography, GIS, Physical Geography, urban expansion, urban sprawl, land surface temperature, Urban Heat Island, remote sensing, Tripoli
• publication/series: Master Thesis in Geographical Information Science
• report number: 211
• language: English
• id: 9226850
• date added to LUP: 2026-05-22 15:33:11
• date last changed: 2026-05-22 15:33:11