A Quantitative Assessment of Surface Urban Heat Islands Using Satellite Multitemporal Data over Abeokuta, Nigeria (original) (raw)
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ISPRS International Journal of Geo-Information
Rapid urbanization in cities and urban centers has recently contributed to notable land use/land cover (LULC) changes, affecting both the climate and environment. Therefore, this study seeks to analyze changes in LULC and its spatiotemporal influence on the surface urban heat islands (UHI) in Abuja metropolis, Nigeria. To achieve this, we employed Multi-temporal Landsat data to monitor the study area’s LULC pattern and land surface temperature (LST) over the last 29 years. The study then analyzed the relationship between LULC, LST, and other vital spectral indices comprising NDVI and NDBI using correlation analysis. The results revealed a significant urban expansion with the transformation of 358.3 sq. km of natural surface into built-up areas. It further showed a considerable increase in the mean LST of Abuja metropolis from 30.65 °C in 1990 to 32.69 °C in 2019, with a notable increase of 2.53 °C between 2009 and 2019. The results also indicated an inverse relationship between LST ...
FUTY Journal of the Environment, 2012
Temperature is an important component of the climate. The temperature of a developing city or state is constantly changing. The trend in temperature change in Nigeria is not consistent. Changes in temperature appear to be closely related to concentrations of atmospheric carbon dioxide. The degree of concentration depends on human interventions and the amount of sunlight reaching the earth's surface. Lagos State particularly in recent time has experienced decrease in vegetation and water pervious surfaces, which reduces surface temperature through evapotranspiration. This is as a result of rapid urbanization arising from inundating rural-urban migration. One of the implications is that anthropogenic heat is released to the environment due to energy consumption and increased impervious surface coverage thereby increasing the surface and atmospheric temperatures. LandSat Satellite imageries have been used to estimate Land Surface Temperature (LST) and urban thermal conditions. The mean LST result shows that, there is a significant increase in the temperature values from 1984 to 2002 (28.40 0 C-28.86 0 C). However, in 2006 the temperature decreases significantly to 28.37 0 C below 2002 temperatures in all LGAs. This variation could be attributed to the economic crisis/power outage in Nigeria which left manufacturing companies out of production/manufacturing between 2002 and 2006. Findings from this study reveals that there is a relationship between the surface temperature and the various Land Cover types. It shows a broad classification of the Land Cover types into Water bodies, Vegetation and Built-up areas respectively. With the spatial resolution and temporal coverage of two Landsat data of the environment, the derivation of the temperature information was achieved.
Urban Heat Island and Land Use/Cover Dynamics Evaluation in Enugu Urban, Nigeria
Journal of Geoscience and Environment Protection, 2022
This study specifically estimated the effect of land use/cover change (LULC) processes on land surface temperature (LST) in Enugu urban and its suburbs. With Landsat images and supervised classification technique, four LULC classes comprising built-up areas, vegetation, rock outcrop, bare ground/farmland areas were delineated. The LST was extracted from the thermal bands of the images. The rate of change in land cover classes between 2009 and 2018 showed that from 2009 to 2013, built-up areas increased from 31.65% to about 47.5%, while vegetation cover decreased from 18.43% to 11.23%. Also, the periods witnessed about 8.69 km 2 of vegetation being converted to other land surfaces. The trend in the LST in Enugu urban showed the highest mean temperatures of 34.5˚C in 2018 and 32.26˚C in 2015. However, in 2013 there was a slight decrease in mean LST to 31.65˚C which further decreased to 31.26˚C in 2009. This change in temperature suggests that urbanisation could have significant effect on the micro-climate of Enugu city. Result also revealed weak relationships between LULC classes and the LST throughout the years. The results of the surface heat intensity for the urban and rural areas showed general increase over the years and this suggests that rural areas are also experiencing high temperature which could be due to the loss of vegetation, increase in artificial surfaces and urban encroachment. Findings from this study could be useful for effective urban land-use planning, policy development and management in Nigeria, and elsewhere.
Analytical Study on The Intensity of Surface Urban Heat Island (1)
CSID Journal of Infrastructure Development, 2024
Urbanization and climate change are significant drivers of rising Land Surface Temperature (LST) and the formation of Surface Urban Heat Islands (UHIs), which have emerged as pressing environmental challenges in recent decades. This study examines the relationship between Land Use/Cover (LU/C) indices and LST in Kaduna, Nigeria, using multi-temporal Landsat imagery spanning five periods from 2001 to 2021. LST values were derived from the Landsat thermal bands, while LU/C dynamics were identified using the Maximum Likelihood Classifier algorithm. LU/C indices—including the Normalized Difference Vegetation Index (NDVI), Normalized Difference Built-up Index (NDBI), Modified Normalized Difference Water Index (MNDWI), and Soil-Adjusted Vegetation Index (SAVI)—were generated to evaluate their correlation with LST. The results highlight a substantial increase in built-up areas over the 20-year period, accompanied by rising LST values, particularly over bare land and built-up regions, while water bodies exhibited the lowest LST values. Among the LU/C indices, NDBI showed the strongest positive correlation with LST, emphasizing the influence of urban expansion on surface thermal dynamics. The study underscores the critical need for sustainable urban planning and holistic design strategies to mitigate rising LST and SUHI effects in rapidly urbanizing regions like Kaduna.
Spatial Analysis of Surface Urban Heat Islands in Four Rapidly Growing African Cities
Remote Sensing
Africa’s unprecedented, uncontrolled and unplanned urbanization has put many African cities under constant ecological and environmental threat. One of the critical ecological impacts of urbanization likely to adversely affect Africa’s urban dwellers is the urban heat island (UHI) effect. However, UHI studies in African cities remain uncommon. Therefore, this study attempts to examine the relationship between land surface temperature (LST) and the spatial patterns, composition and configuration of impervious surfaces/green spaces in four African cities, Lagos (Nigeria), Nairobi (Kenya), Addis Ababa (Ethiopia) and Lusaka (Zambia). Landsat OLI/TIRS data and various geospatial approaches, including urban–rural gradient, urban heat island intensity, statistics and urban landscape metrics-based techniques, were used to facilitate the analysis. The results show significantly strong correlation between mean LST and the density of impervious surface (positive) and green space (negative) alon...
2017
A B S T R A C T The study is aimed at investigating urban heat island over Abuja based on the relationship between land surface temperature estimated from Landsat 8 Thermal Infrared Sensor (TIRS) band and four vegetation indices from Landsat 8 Operational Land Imager (OLI) bands. The four vegetation indices considered are the Red Edge Normalized Difference Vegetation Index 705 (NDVI705), Modified Soil Adjusted Vegetation Index 2 (MSAVI2), Ratio Vegetation Index (RVI) and Normalized Difference Built-up Index (NDBI). A linear regression is generated to evaluate the correlation of Land Surface Temperature (LST) with the four vegetation indices. LST relationships with NDVI705 and MSAVI2 showed negative correlations and low correlation coefficients (R) values while the relationships with NDBI and RVI showed positive correlations with NDBI having R value of 0.84. Negative and near-negative values NDVI705 and MSAVI2 were observed on built up areas, water bodies and bare surfaces while highest values of RVI and NDBI were recorded on built up surfaces. The trend analysis of LST against different Land use Land cover (LULC) indicated that there is a decreasing trend of LST across the sample points from bare surfaces to water bodies with R of 0.83. Significant hot spots of high LST were recorded in built up areas and bare surfaces while significant cold spots were seen on vegetated surfaces. In general, the LST, hot spots and cold spots were shown to have been greatly influenced by the LULC of the area.
Remote Sensing
Urban growth, typified by conversion from natural to built-up impervious surfaces, is known to cause warming and associated adverse impacts. Local climate zones present a standardized technique for evaluating the implications of urban land use and surface changes on temperatures of the overlying atmosphere. In this study, long term changes in local climate zones of the Bulawayo metropolitan city were used to assess the influence of the city’s growth on its thermal characteristics. The zones were mapped using the World Urban Database and Access Portal Tool (WUDAPT) procedure while Landsat data were used to determine temporal changes. Data were divided into 1990 to 2005 and 2005 to 2020 temporal splits and intensity analysis used to characterize transformation patterns at each interval. Results indicated that growth of the built local climate zones (LCZ) in Bulawayo was faster in the 1990 to 2005 interval than the 2005 to 2020. Transition level intensity analysis showed that growth of...
Assessment of the thermal response of variations in land surface around an urban area
The ancient city of Ibadan has experienced major development and this development has led to modifications of the land surface over the years. This study assessed the changes that have occurred in the Land Use Land Cover (LULC) of Ibadan city using satellite image from Landsat covering 1984, 2000 and 2016. Supervised classification scheme was done using the maximum likelihood classifier for classifying the images. The extent of change of the LULC classes was performed on the classified images using Land Change Modeller (LCM). The implication of the change in LULC on Land Surface Temperature (LST) and related indices was assessed. Over a period of 32 years (1984-2016), the area coverage of the built-up region of Ibadan increased from 11.23 to 54.64 hectares in thousands with a net change of 8%. Thick vegetation was identified as the major contributor to the increase in the built-up area thus indicating urban encroachment. The implication of this was observed in thermal hotspots distribution and increase in the average LST over Ibadan as there was a decrease in vegetated surfaces that dampen the LST and an increase in the impervious surface revealed by the impervious and built-up index. In general, this study showed the capability of impervious surface indices in depicting the variations in land use land cover around a region, majorly urban sprawl. Furthermore, the evaluation of the spectral indices showed Urban Index (UI) as the best predictor LST.
Geospatial Dimensions of Land Cover Transitions and Land Surface Temperature in Abuja City, Nigeria
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences
Urbanization is often accompanied by succession of underlying land cover with impervious surfaces. Built intensification significantly alters the surface energy budget making cities warmer than their outlying suburbs, which signifies an ecological deterioration. Landsat imageries with scene covering Abuja city is processed using Google Earth Engine platform to estimate land cover and land surface temperature over the span of 30 years (1990-2020). Dimensions of land cover transitions were examined in-terms losses, gains, swaps, net-change and persistency. Thermal signature of each land cover type was estimated using land surface temperature. Urban thermal field variance index is computed from land surface temperature to evaluate the thermal conditions in the city. Results indicate that netchanges for built-up exhibited gains of 40% while agricultural land, bare-land and vegetation exhibited loss of 27%, 7% and 8% respectively. Built-up also showed the highest proportion of persistence (12%). Results shows that land surface temperature has increased by 2.01°C from 1990 to 2020. Agricultural land, bare-land and built-up were found with the highest temperature. Lowest temperature was found in waterbody and vegetation. The ecological evaluation showed that 47% of the city is experiencing bad to worst thermal condition. These findings provide further information that can contribute towards an informed spatial planning in cities.