Quantifying Four Decades of Urban Expansion and Densification in Erbil Governorate Using the Global Human Settlement Layer (GHS-BUILT-S)

Ismael, Mustafa Salih

doi:10.37653/juah.2025.167315.1389

	Quantifying Four Decades of Urban Expansion and Densification in Erbil Governorate Using the Global Human Settlement Layer (GHS-BUILT-S)
Journal of University of Anbar for Humanities
Volume 2026, Issue 1, March 2026, Pages 212-228 PDF (4.77 M)
Document Type: Research Paper
DOI: 10.37653/juah.2025.167315.1389
Author
Mustafa Salih Ismael^*
Collage of Arts, Salahaddin University-Erbil- Iraq
Abstract
*Aims: This study aims to analyze the urban transformations witnessed in the city of Erbil over the period (1980–2025), with a focus on measuring patterns of urban expansion and tracking the evolution of urban density. The study seeks to employ built-up surface data derived from the Global Human Settlement Layer (GHS-BUILT-S) product to identify spatiotemporal changes in built-up surface ratios at high spatial resolution, understand the relationship between population growth and urban land use transformations, and assess urban development trends and their spatial and temporal implications. Methods: The study relied on analyzing built-up surface data extracted from the GHS-BUILT-S dataset (R2023A), which provides a continuous measurement of built-up surface percentage at a spatial resolution of 100 meters. Data were retrieved for eleven temporal epochs (from 1980 to 2025) and processed using the Google Earth Engine platform for image analysis and preparation. Subsequently, the extracted values were reclassified into five categories according to built-up intensity (from very low to very high density). Statistical analyses were conducted using MATLAB software to measure temporal trends and spatial patterns of urban expansion. Results: The results revealed a clear and consistent increase in built-up areas in Erbil, with a gradual transition from low-density development patterns (0–25%) to high-density development patterns (exceeding 50%), particularly after 2000. The highest density category (75–100%) increased more than fivefold, while areas of very low density declined significantly. Statistical analysis revealed a strong negative correlation (r = -0.85) between population and low-density built-up areas, while a strong positive correlation (r = 0.82) emerged between population and high-density built-up areas. These findings indicate that demographic pressures and economic growth serve as primary drivers of both horizontal expansion and increased urban density. The study also demonstrated that Erbil's growth passed through two main phases: the first, before 2000, characterized by low-density horizontal expansion, and the second, after 2000, witnessing a remarkable increase in urban density due to improved economic stability and growing investments. Conclusions*: The study concludes that utilizing long-term, high-resolution built-up surface data is crucial for tracking urban changes and analyzing their patterns, as it provides deep insights into the relationship between population dynamics and spatial transformations. The findings confirm that urban planning in rapidly growing cities like Erbil requires integrated strategies that account for both horizontal expansion and density increase. The study recommends integrating these methodologies into sustainable urban planning processes to ensure a balanced urban future.
Keywords
Keywords: urban expansion; built-up intensity; Google Earth Engine; remote sensing; urban densification

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