ASSESSMENT OF URBAN GROWTH ON TEMPORAL VARIATION OF SURFACE TEMPERATURE IN SOKOTO METROPOLIS, NIGERIA

Abstract

In Sokoto Metropolis, land use and land cover patterns have undergone rapid changes due to accelerated population growth and physical expansion over the years. Urban growth has increased tremendously and this expansion has implications on the local climate of the area. This study investigated the effects of urban growth on the land surface temperature of Sokoto metropolis, Nigeria over a thirty-year study period (1986 – 2016) using remote sensing and Geographic Information System (GIS) approach. The satellite imageries used consist of Landsat images of Sokoto metropolis for 6th January, 1986; 11th November, 1999 and 24th November, 2016. The images were classified into different land use/ land cover classes using the” supervised” classification method namely: farmland, built up, vegetation, bare soil and water body. The change detection of each land use class was carried for each period. The land surface temperature of Sokoto metropolis was estimated From the satellite images and the mean land surface temperature of each land use class was assessed for the thirty-year study period. from the land use and cover analysis, bare soil occupied a larger proportion of the total area coverage (71 % )of Sokoto metropolis while built-up area occupied a relatively small portion ( 1.8 %) of the total area coverage in 1986. From 1986 to 2016, bare surface decreased to( 56.5 % )of the total area coverage while built-up area increased to (7.48 % 0of the total area coverage. It was noted that there was a continual increase in the extent of builtup for the study period and this is likely to be the case in the future with the continual increase in the population of Sokoto metropolis. The land surface temperature was estimated from the satellite images. The temperature of Sokoto was 30.6 oC, 32.8 oC and 34.6 oC for 6th January, 1986; 11th November, 1999 and 24th November, 2016 respectively. It was observed that land surface temperature varied spatially for all the period. This is due to the differences in the land covers of the land from witch the tempretures were measured. In order to assess the land surface temperature, change over the years for each land cover class, the mean land surface temperature of each class or each year was plotted. Thus revealed an increase in the mean land surface temperature of each land cover class. In conclusion, there is need to monitor the changes in land use and cover and also the land surface temperature due to the implication these have on the local climate and also various sectors of the economy. Remote sensing provides a suitable tool for the monitoring these changes and will guide in planning for different sectors such as agriculture and urban planning.