Appraisal of Urban Heat Island Detection of Peshawar Using Land Surface Temperature and Its Impacts on Environment
Abstract
Last couple of decades witnessed a rapid escalation in urban temperature of Peshawar city and its neighboring localities.
This alarming condition gave birth to climatic term urban heat island-created drastic alteration in surface temperatures. In this study, thermal infrared remote sensing data have been employed to map out and monitor such micro-climatic variation in temperatures in land use/land cover exposed surface to the environment. To assess these outcomes resulting from human activities, Landsat TM data band 6 was subjected through ERDAS Imagine 2013. For further processing, ARC GIS helped a lot in making maps to pinpoint the heat island in and around the city. Moreover, a relationship of land surface temperature
with urban sprawl, environmental and industrialization was established. This study has shown a substantial upsurge in temperature about to 1–3. Urban sprawl and industrialization at the edges are accounting for these conditions. Urban and industrial data have also reinforced the fact being drawn from remotely sensed data. Hence, evaluation of land surface temperature data captured through remote satellite has proven to be effective tool not only for monitoring and analyzing temperature but also for assessing its adverse impacts on the environment and climate.
Keywords Land surface temperature Urban heat island Thermal infrared Landsat TM
Introduction
LST is the measure of heat emitted from land surface due to numerous activities connected with the land surface. Upsurge in paved land cover is an indication of intense human activities, which often leads to increased LSTs (Ramachandra and Kumar 2009). Amplified LST in certain urban sacks in comparison with its surroundings subsequent to the increase in cement surfaces is known as urban heat island (UHI) phenomenon (Gallo and Owen 1998). Urban heat island (UHI) formation and heating effect in urban is a property associated with urban and land transformation that is the key interest in scientific disciplines.
This is because UHI signal gives insight about land surface changes occurring due to human activities. It casts drastic impact on human health, ecosystem function, weather and climate in the long run. All the negative impacts happen as a result of reduction in latent heat flux and also increase in sensible heat in a populated area. Hence, changes in albedo occur by all the factors. It brings about temperature a differential phenomenon which was referred as urban heat island (UHI) by Manley (1958) and later on effort on urban area has been started on both air and surface temperature estimation (Rosenzweig et al. 2005). Thermal infrared image is a prime source of information to mark the surface heat islands (Weng 2009). Temperature map can be drawn from time series imageries of the same resolution. It reveals a drastic results depicting 1–3 upsurge in Peshawar city. This situation can be lethal and challenge the efforts being made for provision of quality foods, health facilities, housing, education and adequate infrastructure to common people. Remote sensing and GIS have developed such techniques that to monitor the rise in urban temperature are now possible with thermal imagery captured through the Landsat TM sensor. Land surface temperature (LST) estimation is handy analysis in projecting future trends in terms of temperatures. Spatiotemporal data were used to develop models of land surface atmosphere exchange, and to analyze the relationship between temperature and land
use and land cover (LULC) in urban areas (Voogt and Oke 2003). This goal was achieved through time series imagery used before for urban sprawl mapping and change detection. Remotely sensed data were subjected through Landsat TM spatial temperature graphical model (.gmd format) in ERDAS 2013 software. Output showed the spatial temperature variation in gray scales. For thematic mapping, it
further was processed in ARC GIS which displayed more clear and sharp changes in temperatures (Celsius). Such implication requires the imagery of the same spatial resolution as employed in this analysis.
Conclusion
This study draws a clear difference between two imageries in terms of temperatures in the 19-year gap. Hence urban heat island is created due to urban sprawl and human industrial activities. It has also unveiled the fact that the surface temperature is creeping up as time passes on. Meteorological and climatic figures reveal that over the preceding couple of decades Peshawar and its suburbs have
received extreme temperatures and severe seasons in different months. The average rainfall trend has been varied and turning out to be vegetation-free urban and neighboring area.
Land surface temperature estimation also unveils these facts showing thematic temperature distribution over the land surface. The figures suggest urban temperature increased up to 1–3 last 19 years.
Acknowledgements This is partly sponsored by urban unit, P&D Department, Government of the Punjab. Sir Amer Mehmood associate professor in the Space Science Department assisted me technically
and financially in this study.
