Spatio-Temporal Characteristics of UHI in Coastal Urban Area and its Impact on Land Unit: A Case Study in the Southeast Sulawesi Province, Indonesia

Abstract

The dynamics of urban heat island (UHI) in urban thermal environments will be more complex and crucial along with the region rapid growth, coupled with increasingly an unforeseen global temperature condition. This study aims to observe the characteristics of UHI and its effects on land units in coastal cities in Southeast Sulawesi province from 2019 to 2023. Landsat 8/9 imagery is used for Land Surface Temperature (LST) retrieval. Urban Landscape Composition (ULC) is developed based on the spectral index method through VrNIR-BI, NDVI and MNDWI. Land units are developed using overlay techniques from four input data including ULC, terrain slope, soil type and geological formation. The results of the study reveal that LST variations significantly affect UHI formation throughout the study area. Surface temperatures in both regions continued to increase throughout 2021-2023, is getting warmer in 2023 between August and November. Meanwhile, the ULC conditions in both regions experienced major transformations, especially in the areas of impervious surface and green space. Nevertheless, over 70% of the total area in both regions is covered by vegetation. Spatially, the UHI changes in Kendari city tends to moved towards the western region and are more massive to the southern region. Meanwhile, the UHI area in Baubau city is still relatively in the downtown area, but several areas in the northern region of Baubau are beginning to show substantial UHI concentration. Global warming that occurred in 2023 further worsened the UHI in both regions. The UHI area is typically affect more land units categorized as impervious surface with relatively flat terrain slopes and hapludalfs soil types. This study emphasizes the importance of studying the dynamics of microclimate in urban thermal environments in the disaster mitigation efforts, providing valuable insights for regional development planning strategies to create environmentally friendly, resilient and sustainable cities