Assessing the impact of COVID-19-induced lockdown on land surface temperature in heterogeneous cities

Abstract

Urbanization has brought about significant changes in the land use/land cover (LULC), and land surface temperature (LST) of cities. The impact of the COVID-19 lockdown on LST in Polokwane and Johannesburg, South Africa, was analysed over the years 2020 to 2022, using Landsat images. The findings revealed that throughout the lockdown period, i.e., from January 2020 to March 2021, there was a decrease in LST values across all LULC categories. The LST values witnessed an increase from 2021 (during lockdown) to 2022 (post-lockdown), demonstrating the most notable increases of 1.9°C and 0.6°C for the bare land class in Polokwane and Johannesburg, respectively. There was a strong negative correlation between LST and the normalized difference vegetation index (NDVI), i.e., -0.62, -0.58, and -0.71 for Polokwane and -0.69, -0.69, and -0.73 for Johannesburg in 2020, 2021, and 2022. A strong positive correlation was recorded between LST and the normalized difference built-up index (NDBI), i.e., 0.81, 0.79, and 0.85 and 0.70, 0.59, and 0.77 in Polokwane and Johannesburg, respectively. The findings offer valuable information that is vital for decision-making procedures that are in line with the goals of SDG 11, which are to improve the sustainability of cities.