Dynamics of Land Surface Temperature in Response to Land Cover Changes in Lagos Metropolis

Abstract

Land Surface Temperature (LST) is one of the key environmental parameters affected by land cover change. Lagos State has been experiencing an increase in surface temperature due to growing areas of impervious surfaces caused by anthropogenic urban sprawl. While the change in LST has been established, its continuous monitoring and relationship with continuing Land Cover (LC) changes have become imperative for appropriate management and policy actions. This study investigated the effect of land cover change on LST in the rapidly urbanising Lagos metropolis. Using spatio-temporal Landsat imageries with their thermal bands and ancillary data, land cover and LST changes were assessed from 1984 - 2015. The spatial patterns of LST and LC were derived to examine the response of LST to urban growth. Findings confirmed urban sprawl in previously rural areas northward of the metropolis in LGAs such as Ikorodu, Kosofe and those fringing the state’s border with Ogun State. This also confirmed new growth areas as occurring west of the metropolis in Amuwo-Odofin LGA. The results further showed that the rapid urbanisation in Lagos metropolis has altered the surface thermal environment as indicated by increased LST. Built-up area and bare land accounted for the highest increase in LST (as high as 1.5℃ in some areas) while wetlands and other vegetated areas played a vital role in moderating the surface temperature in areas they still occupy. This provides reasonable evidence for the appropriate authorities to institute requisite policies and actions towards moderating urban sprawl while ramping up the development of urban green infrastructure to counter global warming.

Potential Influence of Urban Sprawl and Changing Land Surface Temperature on Outdoor Thermal Comfort in Lagos State, Nigeria

“…Following Oguz (2013), Ferrelli et al (2015 and Obiefuna et al (2018), the LST was derived using a single channel method. The first step involved the conversion of the imagery digital numbers (DNs) to spectral radiance.…”

“…All over the world, the intensity of human activities, coupled with fast-paced urbanisation, is leading to alterations of the land cover and, in effect, the LST. Land cover change, including variations in surface reflectance and topography, are important indicators that influence LST (Hou et al 2010, Obiefuna et al 2018, Alademomi et al 2020. Due to the physical properties of the land surface, surface temperatures are typically higher in urban areas than in vegetated areas and in the countryside; this difference is attributable to their physical properties (Nse et al 2020).…”

“…In a previous study by Nwilo et al (2012), a trend of changing LST within Lagos State, and in particular Lagos Metropolis, between 1984 and 2006 was established. Similarly, Obiefuna et al (2018) followed up this study by tracking the dynamics of LST with land cover changes between 1984 and 2015 in Lagos Metropolis. Despite these studies, Ojeh et al ( 2016) had earlier lamented the dearth of UHI studies both in tropical and Nigerian cities and emphasised particularly on the absence of consideration of UHI effects in the Lagos State Climate Change Policy document of 2012-2014.…”

Assessing the Relationship of LST, NDVI and EVI with Land Cover Changes in the Lagos Lagoon Environment

“…The retrieval of LST followed the single-channel method (Oguz 2013, Ferrelli et al 2015, Obiefuna et al 2018. Landsat TM thermal Band 6, ETM Band 6_1 and TIRS Band 10 were used for the retrieval.…”

“…In recent times, researchers have studied and documented the changes in the coastal environments of Nigeria with remote sensing methods. Such studies include observations of changes in the Lower Ogun River flood plain (Odunuga, Oyebande 2007), evaluation of the degree of mangrove ecosystem changes in the Niger Delta (James et al 2007), application of satellite remote sensing in monitoring land degradation along the coast of Ondo in Nigeria (Abbas 2008, Abbas, Fasona 2012, wetland changes in the Lagos/Lekki lagoon environments (Obiefuna et al 2013a(Obiefuna et al , 2013b and dynamics of land cover and LST changes in Lagos metropolis (Obiefuna et al 2018). However, the link between land cover, LST and VIs has not been well exploited in the monitoring of the Lagos Lagoon environment.…”