Spatial Variation of Land Use/Cover Composition and Impact on Surface Urban Heat Island in a Tropical Sub-Saharan City of Accra, Ghana

Abstract

Rapid urbanization is one of the most crucial issues in the world of the 21st century. Notably, the urban heat island phenomenon is becoming more prominent in megacities and their hinterlands in temperate and subtropical climatic regions. In the daytime in summer, there exists a high possibility of accelerating the land surface temperature (LST) in desert cities, due to the alterations made by human beings in the natural environment. In this study, we investigate the spatial formation of LST in a tropical sub-Saharan city of Accra, a gateway to West Africa, using Landsat data in 2003 and 2017. Machine learning techniques and the different spatial and statistical methods such as tasseled cap transformation (TCT), urban-rural gradient, and multiresolution grid-based and landscape metrics were employed to examine procured land use/cover (LUC) and LST maps. LUC was classified into five categories: Built up, Green 1, Green 2, Bare land, and Water. The results of the analysis indicate that Built up, Green 2, and Bare land had caused the highest heating effect while Green 1 and Water had caused the considerable cooling effect during the daytime in Accra. The urban-rural difference in LST recorded 1.4 °C in 2003 and 0.28 °C in 2017. The mean size, mean shape, largest patch, and aggregation of Built up, Green 1, and Green 2 had a strong relationship with the mean LST. It is essential for urban planners to carefully examine the formation and effect of the urban heat island (UHI) for sustainable urban development and landscape policy toward mitigation and adaptation planning in Accra.

Understanding the Links between LULC Changes and SUHI in Cities: Insights from Two-Decadal Studies (2001–2020)

“…The findings of this study indicate that the majority of SUHI research has been concentrated in South Asian nations (Section 3.2), namely China and India, with less attention paid to cities in developing countries in other continents, particularly Africa and South America. Nine studies were interested in cities of six African countries-Cairo [5,106,113,143], Ethekwini [77], Hawassa [79], Akure [153], Osogbo [130], and Accra [170]. Only Brazilian cities, including Rio de Janeiro [8,169], Cuiaba-Varzea Grande [171], and Paço do Lumiar [172], were investigated in South America.…”

Urban Heat Island Formation in Greater Cairo: Spatio-Temporal Analysis of Daytime and Nighttime Land Surface Temperatures along the Urban–Rural Gradient

“…Fu et al [53] studied the variability in annual temperature cycles in the USA, also using MODIS data. Athukorala and Murayama [54] discussed the spatial variation in surface urban heat islands in Accra, Ghana, employing the urban-urban gradient and landscape-metrics-based analysis. Thus, many scholars have demonstrated that satellite data are useful for investigating the relationship between landscape patterns and LST [55][56][57].…”

“…Today, urban-rural gradient analysis and spatial configuration analysis based on spatial metrics [58,59] provide valuable insights into the progress in UHI studies as well as useful information on urban design and urban landscape planning [54,60]. However, there are relatively few studies on surface UHIs, especially in rapidly growing cities in Africa [61][62][63][64], including Cairo [65,66].…”

Impacts of Urbanization on the Muthurajawela Marsh and Negombo Lagoon, Sri Lanka: Implications for Landscape Planning towards a Sustainable Urban Wetland Ecosystem

“…A top-to-bottom approach should be adopted to ensure judicious use of wetland to ensure its protection and sustainability. Generally, wetland areas play an essential role in mitigating the urban heat island effect [79]. The MMNL is situated in the CMR which covers a considerable area.…”