Remote Sensing Technique For Temporal and Spatial Mapping of the LST and Surface Urban Heat Island (SUHI) Development Between 1990–2025 in Plovdiv, Bulgaria

Miroslav Ivanov¹, Vladimir Karadzhov², Emilia Patarchanova³, Veselina Dalgacheva⁴

^1,2,3,4 Department of Geography, Ecology, and Environmental Protection, Faculty of Mathematics and Natural Sciences, South-West University “Neofit Rilski” – Blagoevgrad

ORCID IDs: ¹ 0000-0002-2347-8029, ² 0000-0002-7514-5517, ³ 0000-0002-1806-557X, ⁴ 0000-0002-1976-5367

Corresponding Author: Miroslav Ivanov, m_ivanov@swu.bg

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https://doi.org/10.63711/ijdr.net20250409

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ABSTRACT

The main objective of this study is to map the temporal and spatial development of land surface temperature (LST) and surface urban heat island (SUHI) within the city of Plovdiv, Bulgaria, for the period between 1990 and 2025. The analysis is based on satellite imagery and remote sensing techniques, using Landsat data processed through Google Earth Engine and geographic information system software. Average summer LST and the normalized difference vegetation index (NDVI) were calculated for selected reference years in order to assess long-term trends in urban heat accumulation and their relationship with land cover characteristics. The results indicate a clear increase in LST over the studied period, with the highest values observed in densely built-up areas, industrial zones, and large open surfaces with limited or no vegetation. In contrast, areas with well-developed green infrastructure, including urban parks and the Maritsa River corridor, exhibit lower surface temperatures and a mitigating effect on urban heat intensity. The analysis also reveals the gradual formation of a surface urban heat island belt surrounding the city core, as well as the emergence of localized micro-scale heat islands in newly urbanized peripheral areas. These patterns reflect the combined effects of urban expansion, land-use change, and regional climate warming. The study confirms the reliability of satellite-based remote sensing for assessing urban thermal environments and highlights its practical relevance for sustainable urban planning, climate adaptation measures, and smart city development.

Keywords: Remote sensing, Land surface temperature, Surface urban heat island, NDVI, LST, Landsat satellites, Urban climate, Plovdiv, Bulgaria

Research Area: Remote Sensing, Urban Climate, Sustainable Cities

Copyright © 2025 The Author(s). This article is licensed under CC BY 4.0.