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Analysis of spatial-temporal pattern of Land Surface Temperature (LST) due to NDVI and elevation in Ilorin, Nigeria

Njoku, Elijah A LU (2019) In Master Thesis in Geographical Information Science GISM01 20191
Dept of Physical Geography and Ecosystem Science
Abstract
The rate of global urbanization in the 21st century has been unprecedented especially in the African and the Asian continents. Urbanization typically causes a removal of natural vegetation and replacement of same with impervious and non-evaporative urban materials with high heat capacity and low solar reflectivity. The alteration of the natural land cover due to urbanization causes a change in the thermal properties of the urban landscape, with the effect that the urban land surface typically has a relatively higher thermal capacity than that of the surrounding rural areas; a phenomenon known as Urban Heat Island (UHI).

Studies have shown that, in the last few decades, Ilorin city has undergone significant changes in landscape,... (More)
The rate of global urbanization in the 21st century has been unprecedented especially in the African and the Asian continents. Urbanization typically causes a removal of natural vegetation and replacement of same with impervious and non-evaporative urban materials with high heat capacity and low solar reflectivity. The alteration of the natural land cover due to urbanization causes a change in the thermal properties of the urban landscape, with the effect that the urban land surface typically has a relatively higher thermal capacity than that of the surrounding rural areas; a phenomenon known as Urban Heat Island (UHI).

Studies have shown that, in the last few decades, Ilorin city has undergone significant changes in landscape, population structure, and urban form and the city has witnessed a rise in urban temperature. Similarly, Nigerian Meteorological Agency (NIMET) and epidemiologists have warned of possible outbreak of some diseases that thrive in hot weather such as meningitis, tuberculosis, malaria, dengue fever, etc. Given this scenario, UHI effects is estimated to affect a large number of persons in the city. This study investigates to what extent the observed Land Surface Temperature (LST) could be accounted for by vegetation cover measured via Normalized Difference Vegetation Index (NDVI) in the study area from 2000 to 2016. The spatial pattern and trend of LST, and the magnitude of UHI within the period was also estimated.

Result shows a statistically significant clustering of LST values in all the investigated epochs with Global Moran’s I index showing values greater than 0.6 and z-scores greater than 220 in all cases at p < 0.001. Analysis of regression reveals that NDVI explained between 50% - 71% of the variation in LST between 2000 and 2002, and NDVI increasingly diminished in importance as an explanatory variable for LST in 2016, where only 29% - 49% explanation was provided by NDVI. For all the seasons and years, the coefficients of the regression analysis results for NDVI in the study area are negative indicating that NDVI is inversely related to LST. Research result shows a presence of UHI with an intensity ranging between 0.2OC to 4.6OC, with peaks in the wet seasons and tending towards a decreasing trend. (Less)
Popular Abstract
The world is currently going through a high rate of urbanization especially in the African and the Asian continents. Urbanization causes a removal of natural vegetation and replacement of same with materials that reflect only a small amount of incoming solar radiation but have high capacity to absorb heat, such as concrete masses, asphalt roads and metal surfaces. The scenario has led to a situation where the urban landscape is typically hotter than the surrounding non-urban areas - a situation known as urban heat island (UHI).

Studies have shown that urbanization in Ilorin has caused notable changes in landscape, population structure, and urban form and the city has also witnessed a rise in urban temperature. Similarly, Nigerian... (More)
The world is currently going through a high rate of urbanization especially in the African and the Asian continents. Urbanization causes a removal of natural vegetation and replacement of same with materials that reflect only a small amount of incoming solar radiation but have high capacity to absorb heat, such as concrete masses, asphalt roads and metal surfaces. The scenario has led to a situation where the urban landscape is typically hotter than the surrounding non-urban areas - a situation known as urban heat island (UHI).

Studies have shown that urbanization in Ilorin has caused notable changes in landscape, population structure, and urban form and the city has also witnessed a rise in urban temperature. Similarly, Nigerian Meteorologists (NIMet) and epidemiologists have warned of possible outbreak of some diseases that thrive in hot weather such as meningitis, tuberculosis, malaria, dengue fever, measles, etc. Because of the typical nature of urban areas in terms of population density and the concentration of human activities in the cities, the impacts of a rising temperature is estimated to affect a large number of persons in the city. This study investigates to what extent the observed land surface temperature used to measure UHI could be accounted for by vegetation cover in the study area from 2000 to 2016. The spatial pattern and trend of LST, and the intensity of UHI within the period was also estimated.

Global Moran’s I index used for measuring the spatial pattern of LST for all the scenarios shows high values and this signifies a statistically significant clustering of LST in all the investigated time periods. Also, conducted regression analysis reveals that vegetation cover explained between 50% - 71% of the variation in LST between 2000 and 2002, and vegetation cover increasingly diminished in importance as an explanatory variable for LST in 2016, where only 29% - 49% explanation was provided by vegetation cover. For all the seasons and years, the coefficients of the regression analysis results for vegetation cover in the study area are negative indicating that, as vegetation cover increases, the LST decreases. UHI intensity ranged between 0.2OC to 4.6 OC and are highest in the wet seasons. (Less)
Please use this url to cite or link to this publication:
author
Njoku, Elijah A LU
supervisor
organization
alternative title
Analysis of spatial pattern of land surface temperature due to vegetation cover and elevation in Ilorin, Nigeria
course
GISM01 20191
year
type
H2 - Master's Degree (Two Years)
subject
keywords
GIS, LST, Vegetation cover, Ilorin, Elevation, Urban Heat Island
publication/series
Master Thesis in Geographical Information Science
report number
106
language
English
id
8990876
date added to LUP
2019-07-18 11:25:13
date last changed
2019-07-18 11:25:13
@misc{8990876,
  abstract     = {{The rate of global urbanization in the 21st century has been unprecedented especially in the African and the Asian continents. Urbanization typically causes a removal of natural vegetation and replacement of same with impervious and non-evaporative urban materials with high heat capacity and low solar reflectivity. The alteration of the natural land cover due to urbanization causes a change in the thermal properties of the urban landscape, with the effect that the urban land surface typically has a relatively higher thermal capacity than that of the surrounding rural areas; a phenomenon known as Urban Heat Island (UHI). 

Studies have shown that, in the last few decades, Ilorin city has undergone significant changes in landscape, population structure, and urban form and the city has witnessed a rise in urban temperature. Similarly, Nigerian Meteorological Agency (NIMET) and epidemiologists have warned of possible outbreak of some diseases that thrive in hot weather such as meningitis, tuberculosis, malaria, dengue fever, etc. Given this scenario, UHI effects is estimated to affect a large number of persons in the city. This study investigates to what extent the observed Land Surface Temperature (LST) could be accounted for by vegetation cover measured via Normalized Difference Vegetation Index (NDVI) in the study area from 2000 to 2016. The spatial pattern and trend of LST, and the magnitude of UHI within the period was also estimated.

Result shows a statistically significant clustering of LST values in all the investigated epochs with Global Moran’s I index showing values greater than 0.6 and z-scores greater than 220 in all cases at p < 0.001. Analysis of regression reveals that NDVI explained between 50% - 71% of the variation in LST between 2000 and 2002, and NDVI increasingly diminished in importance as an explanatory variable for LST in 2016, where only 29% - 49% explanation was provided by NDVI. For all the seasons and years, the coefficients of the regression analysis results for NDVI in the study area are negative indicating that NDVI is inversely related to LST. Research result shows a presence of UHI with an intensity ranging between 0.2OC to 4.6OC, with peaks in the wet seasons and tending towards a decreasing trend.}},
  author       = {{Njoku, Elijah A}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Master Thesis in Geographical Information Science}},
  title        = {{Analysis of spatial-temporal pattern of Land Surface Temperature (LST) due to NDVI and elevation in Ilorin, Nigeria}},
  year         = {{2019}},
}