Abstract:
This study used geospatial technology in assessing the spatio-temporal dynamics of Urban Heat
Island in Owerri, South East, Nigeria. Landsat TM, ETM+ and OLI/TIRS imageries acquired
during the dry season were used in the study to cover for the period (1986 – 2016). Change
detection analysis showed that between 1986 and 2000, the built-up areas in the study area gained
20.12 km2 while vegetation lost 3.17 km2. On the other hand, bare soil and water bodies lost
approximately 16.91 km2 and 0.04 km2 respectively. However, it was shown that between 2000
and 2016, the built-up areas gained 50.61 km2 while vegetation lost 50.30 km2. Also, bare soil
witnessed a loss of 0.95 km2 while the water body gained 0.64 km2. Accuracy assessment
performed showed that there were high degrees of conformity between classified maps of 1986,
2000 and 2016 and ground-truth reference points. Regression analysis depicted that there exists
strong positive relationship between LST and Urban Index (UI), with correlation coefficient (R)
values of 0.83, 0.91 and 0.80 for 1986, 2000 and 2016 respectively, except for Normalized
Difference Water Index (NDWI) (with correlation coefficient (R) values of -0.83, -0.91 and -0.80
for 1986, 2000 and 2016 respectively) and Normalized Difference Vegetation Index (NDVI) (with
correlation coefficient (R) values of -0.92, -0.89 and -0.88 for 1986, 2000 and 2016 respectively)
that exhibited strong negative relationships. The temporal LST distribution between 1986 and
2000, showed that the mean LST increased by 7.41 ºC and by 4.51 ºC between 2000 and 2016,
Urban growth had played a dominant role in the temperature profile in the study area causing
Owerri City centre to be relatively warmer than the surrounding suburban areas, indicating the
existence of UHI in the study area. The varying degrees of UHI intensities at the chosen urban and
suburban stations in the study area showed that the mean UHI intensity had increased from 1.53
ºC in 1986, 4.2 ºC in 2000 to 5.27 ºC in 2016.
