Urbanization has become one of the most important human activities modifying the Earth’s land surfaces; and its impacts on tropical and subtropical cities (e.g., in South/Southeast Asia) are not fully understood. Colombo; the capital of Sri Lanka; has been urbanized for about 2000 years; due to its strategic position on the east–west sea trade routes. This study aims to investigate the characteristics of urban expansion and its impacts on land surface temperature in Colombo from 1988 to 2016; using a time-series of Landsat images. Urban land cover changes (ULCC) were derived from time-series satellite images with the assistance of machine learning methods. Urban density was selected as a measure of urbanization; derived from both the multi-buffer ring method and a gravity model; which were comparatively adopted to evaluate the impacts of ULCC on the changes in land surface temperature (LST) over the study period. The experimental results indicate that: (1) the urban land cover classification during the study period was conducted with satisfactory accuracy; with more than 80% for the overall accuracy and over 0.73 for the Kappa coefficient; (2) the Colombo Metropolitan Area exhibits a diffusion pattern of urban growth; especially along the west coastal line; from both the multi-buffer ring approach and the gravity model; (3) urban density was identified as having a positive relationship with LST through time; (4) there was a noticeable increase in the mean LST; of 5.24 °C for water surfaces; 5.92 °C for vegetation; 8.62 °C for bare land; and 8.94 °C for urban areas. The results provide a scientific reference for policy makers and urban planners working towards a healthy and sustainable Colombo Metropolitan Area.
Urbanization and Its Impacts on Land Surface Temperature in Colombo Metropolitan Area, Sri Lanka, from 1988 to 2016
H. P. U. Fonseka,Hongsheng Zhang,Ying Sun,Hua Su,Hui Lin,Yinyi Lin
Published 2019 in Remote Sensing
ABSTRACT
PUBLICATION RECORD
- Publication year
2019
- Venue
Remote Sensing
- Publication date
2019-04-22
- Fields of study
Geology, Geography, Computer Science, Environmental Science
- Identifiers
- External record
- Source metadata
Semantic Scholar
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CLAIMS
CONCEPTS
- colombo metropolitan area
The Sri Lankan metropolitan region analyzed as the study area for urban expansion and temperature change.
Aliases: Colombo
- gravity model
A distance-weighted spatial model used to estimate urban density for comparison with the buffer approach.
- landsat images
A time series of Landsat satellite scenes used to derive land-cover and temperature variables.
Aliases: Landsat
- land surface temperature
Satellite-derived surface temperature measured for different land-cover classes in the study area.
Aliases: LST
- machine learning methods
Classification methods applied to the Landsat time series to map urban land cover change.
- multi-buffer ring method
A concentric-buffer spatial approach used to estimate urban density at increasing distances from the city center.
- urban density
A spatial measure of urbanization estimated from the distribution of built-up land around the city center.
- urban land cover change
Temporal changes in urban land cover mapped from the satellite image series for Colombo.
Aliases: ULCC
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