Assessment of urban heat island warming in the greater accra region (original) (raw)
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Urban Heat Island (UHI) effect controls internal climates of buildings and affects energy use and comfort of urban dwellers. The objective of this study was to detect UHI from Land Surface Temperature (LST) and to investigate whether land cover has any influence on UHI in Tarkwa, South West Ghana using satellite remote sensing techniques. A Landsat 7 ETM+ image, DEM and meteorological data were used to generate a land cover map with the maximum likelihood classification algorithm whiles LST was modeled with the Landsat Plank's curve. Validation of the LST map was achieved by comparing it with air temperature measured at the UMaT meteorological station. The mean modeled LST of 298.60 Kelvin compared well with the mean observed air temperature of 298.30 Kelvin. Furthermore, LST ranged between 289 and 305 Kelvin while urban areas and bare soils had higher LSTs than vegetated areas implying that higher NDVI areas are associated with lower temperatures. Hence, LST maps produced indic...
World Academy of Science, Engineering and Technology, International Journal of Civil, Environmental, Structural, Construction and Architectural Engineering, 2017
The effects of rapid urbanisation of tropical sub-saharan developing cities on local and global climate is of great concern due to the negative impacts of Urban Heat Island (UHI) effects. The importance of urban parks, vegetative cover and forest reserves in these tropical cities has been undervalued. Rapid degradation and depletion of the vegetation covers, and continuous urban developments, daily mean temperatures have increased with resultant changes to local climatic conditions. Using Landsat data of the same months and period intervals, the spatial variations of land cover changes, temperature, and vegetation were examined to determine how vegetation improves local temperature and the effects of urbanisation on daily mean temperatures over the past 12 years. The remote sensing techniques of maximum likelihood supervised classification, land surface temperature retrieval technique, and normalised differential vegetation index techniques were used to analyse and create the land use land cover (LULC), land surface temperature (LST), and vegetation and non-vegetation cover maps respectively. Results from the study showed an increase in daily mean temperature by 0.80 °C as a result of rapid increase in urban area by 46.13 sq. km and loss of vegetative cover by 46.24 sq. km between 2005 and 2017. The LST map also shows the existence of UHI within the urban areas of Accra, the potential mitigating effects offered by the existence of forest and vegetative cover as demonstrated by the existence of cool islands around the Achimota ecological forest and University of Ghana botanical gardens areas.
International Journal of Environment and Geoinformatics
The effects of urban heat islands (UHI) have received a lot of attention because they have a huge impact on human health and environmental resource sustainability. A key moment in the history of mankind has been urbanization, and there is no doubt that the world is rapidly urbanizing, which is causing temperature changes. The relationship between climate change and rapid urbanization in Nguru Local Government Area, Yobe State, Nigeria, is investigated in this paper. The study used remote sensing data to reveal the extent of urban microclimate change trends over the next two decades (2001–2021). Thus, the microclimate temperature increased by nearly +5.32 °C in 2021 (39.39°C) compared to 34.07°C in 2001. Furthermore, the minimum temperature in 2001 was 22.33 °C, while that of 2021 was 23.36 ℃. The built-up area increased by 556.73%, from 446 hectares in 2001 to 2,483 hectares in 2021. Accelerated urbanization and the city's blue and green facilities, which are not preserved or sa...
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.
Urbanisation Effect on the Occurrence of Urban Heat Island over Kano Metropolis, Nigeria
International Journal for Scientific and Engineering Research, 2017
The Urban Heat Island (UHI) effect is a phenomenon of higher atmospheric and surface temperatures occurring in urban areas than in surrounding rural areas happening majorly as a result of urbanisation and industrialisation. The effect of urbanisation on the occurrence of UHI in Kano metropolis was investigated. Landsat images of the study area for the years of 1986, 1998, 2006 and 2016 sourced from the archives of the United States Geological Survey (USGS) were utilised in this study. Land Surface Temperature (LST) and Land Use/Land Cover (LULC) maps for the years of 1986, 1996, 2006 and 2016 were estimated using Model Maker in Earth Resource Development Assessment System (ERDAS) Imaging 14 software. The urban city centre exhibit higher surface temperatures compared to its suburban counterparts thus, indicating the presence of the Surface UHI over Kano Metropolis. Urbanisation accounted for 80.5% increment in the LST of Kano Metropolis, thus indicating a very strong positive relationship between urbanisation and UHI. Conclusively, urbanisation is identified as the major factor that leads to the occurrence of surface UHI in Kano Metropolis. Recommendations include afforestation programmes, adoption of green and cool roofing technologies, proper spacing between houses, and accommodation of green areas and open spaces and continuous monitoring of weather events.
Assessment of Urban Heat Island in Kaduna Metropolis Between 2000 and 2018
FUDMA JOURNAL OF SCIENCES, 2021
Urbanization is a major event in human history and there is no doubt the world is urbanizing rapidly and this is resulting in changes in temperature. This research aims is to identify changes in land surface temperature (LST) between 2000 and 2018. The technique used is the Landsat TM. The result of the land cover classification revealed a +15.93% increase in built-up areas, -27.21% decrease in vegetative cover, +11.19% increase in bare land and +0.09 increase in water bodies between 2000 and 2018. NDVI analysis showed a +0.02 and +0.17 increase in the maximum and minimum range and a +2.16 and -7.76 increase and decrease in maximum and minimum temperature respectively for LST. The finding revealed that the repelling of vegetative cover by built-up is an evidence of rapid urbanization taking place in Kaduna metropolis and a major driver of UHI in Kaduna metropolis. Conclusively, there is a correlation between the various land covers of study i.e built-up, vegetative cover, bare l...
The fast urban expansion has led to the transformation of the natural landscape into anthropogenic surfaces. The city of Abeokuta, for instance, is located in a region experiencing rapid urbanization, which has produced a remarkable effect on the surface thermal response. This effect significantly influences urban internal microclimatology on a regional scale. In this study, the surface temperatures and land cover types retrieved from Landsat TM and ETM+ images of Abeokuta city for 1984, 2003, and 2014 were analyzed. A quantitative approach was used to assess surface urban heat islands through the relationships among surface temperature and land cover types. Results showed that impervious surface areas were found to be correlated positively with high temperatures. Conversely, vegetated areas and bare surfaces correlated positively with mid temperature zones. This study found that areas with increasing impervious surfaces will accelerate LST rise and consequently lead to increasing effect of surface urban heat islands. These findings pose a major challenge to urban planners. However, the study would help to quantify the impacts of different scenarios (e.g., vegetation loss to accommodate urban growth) on LST and consequently to devise appropriate policy measures.
Remote Sensing and GIS Based Assessment of Urban Heat Island Pattern in Kaduna
descriptionInternational Journal For Research In Applied And Natural S c i e n c e, 2017
This study examines the pattern and distribution of heat island in Kaduna metropolis based on Landsat Imageries of 1995, 2005 and 2015, whose spatial resolution is sufficient for measurement of some important environmental parameters.The study first identified patterns of land cover changes between the periods and investigated their d from the corrected image and a relationship with Land surface temperature (LST) was established based on Environmental Criticality Index (ECI). Land surface temperature (LST) was retrieved using the mono-window algorithm with area of UHI identified in the study area. Results show that Kaduna city’s urban heat island effect is on the increase, substantial and in variance, which could be visually characterized by the spatial pattern of retrieved thermal properties. The study, therefore, concluded that different Land Use Land Cover (LULC) revealed varying temperature, and identified UHI was apparent and more conspicuous in the 2015 as compared to 1995 and 2005 within the metropolis. Particularly, due to the scarcity of vegetation, some hotspots are built-up areas, bare surfaces, central business districts (CBD) areas, and the surface temperature of which is even slightly higher than suburbs. This study suggested a strict adherence to Kaduna master plan, vegetation regeneration and establishment of green areas and parks (go-green initiatives), reflective roofing materials, and lightening of pavements as adaptive/mitigation measures against UHI in the study area.
Modeling Earth Systems and Environment, 2020
In recent times, land surface temperature and its associated effect urban heat island (UHI) has attracted massive research and public attention due to their effects on the environment, climate and public health. Specifically, UHI adversely affects the quality of life of city dwellers in the form of thermal discomfort, resulting in a rise in energy consumption to mitigate the effects of the increase in surface temperature. Therefore, studying the presence, extent, spatial distribution and changes in surface temperature is essential as it could generate meaningful and useful information for sustainable urban planning. This research used four multi-temporal Landsat images covering three decades to examine surface temperature changes and urban heat islands in the Wassa West areas of southwestern Ghana. The research was implemented through the application of several mathematical models, remote sensing and GIS techniques to determine land surface temperature variations over the study period. The results of the study showed a consistent rise in surface temperature over the 30-year period. For instance, in 1990, the minimum and maximum surface temperatures were 14.96 °C and 27.17 °C, respectively. In 2020, the minimum and maximum temperatures had increase to 24.22 °C and 31.23 °C, respectively. A consistent decline in the vegetation of the study was equally observed over the period, and this was attributed to the increase in urban settlements and large-scale mining activities in the study area. The results further indicated that low surface temperatures were observed in rural areas with high vegetation, whereas high surface temperature values were consistently observed in areas with impervious surface covers such as mining and urban areas, suggesting the presence of the UHI phenomenon. The study identifies environmentally critical areas in the study areas warranting the urgent attention of society and specific measures that could contribute to reducing the fast increase in surface temperature and mitigate the risk of heat-related conditions has been discussed.
Spatial and Temporal Changes of Urban Heat Island in Kano Metropolis, Nigeria
Major cities of the world are faced with the problem of overwhelming increase in temperature as compared with their surrounding countryside. Recent researches concluded that, the reason behind this phenomenon is the conversion of natural surfaces such as vegetation, with low thermal inertia to man-made structures like tarred roads and concrete structure with high thermal inertia. This concept is known as " Urban Heat Island " and remote sensing and GIS is found to be a significant technique to study this phenomenon. The present study investigates the spatial and temporal pattern and changes of urban heat island (UHI) in Kano metropolis, Kano state Nigeria. Land surface temperature (LST) values were extracted from Landsat TM image (1986), ETM+ (2000) and OLI (2014). Built-up area and road system were derived from 1:50,000 scale topographic maps. A Normalized Difference Vegetation Index (NDVI) map was extracted from the same image. Multiple correlation analyses were used to examine the relationship between UHI pattern and land use/land cover parameters (NDVI, built-up density and road density). Results show that, multiple heat islands emerged over central part of the city and along the major road that linked the city with other states. These areas coincide with the densely build-up area of the metropolis. Likewise, heat island emerges around the international airport of the state. The statistical analysis indicates that the UHI intensities had a negative relationship with NDVI, but a positive correlation with built-up. Interestingly, the temporal analysis indicate that, areas observe with lower land Surface Temperature In 1986 Have Been Recorded With Higher Temperature In 2000 And 2014.