地球科学と気候変動ジャーナル

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Mapping and Assessing Impervious Surface Areas and Urban Heat Island in Osogbo, Nigeria

Adewale AO, Adepoju KA and Awotoye OO

This paper assessed the percent impervious surface as indicators of surface urban heat island effects in a tropical rapidly urbanizing environment by investigating the change that occurred over 29 years period starting from 1986-2015. Landsat Thematic Mapper (TM) and Operational Land Imager (OLI) data were used to estimate the land surface temperature (LST) for two different periods in the study area. A map of percent impervious surface was also generated for the same period using linear spectral mixture analysis. The results showed that the change in impervious surface value ranged from -9% to 51% between 1984 and 2006, while, the minimum values of LST increased by 2.6°C whereas the maximum LST values exhibited a decrease by 8.5°C; the mean LST values increased by 4.6°C within the same period. The results indicate that increase in imperviousness results in higher temperature. Over the years, the gradual transition of land use from suburban to urban land in peri-urban districts around the highly urbanized hotspots resulted in an increase of 51% in the imperviousness and 29% in temperature. This result suggests that uncontrolled rapid population increase resulting in expansion of impervious surfaces can lead to significant increase in urban heat island formation in urban and peri-urban districts.