Appraisal of Urban Heat Island and Its Impacts on Environment Using Landsat TM in Peshawar , Pakistan

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 (UHI) created drastic alteration in surface temperatures. In this study, thermal infrared remote sensing data has 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 1 to 3 degrees. Urban sprawl and industrialization at the edges are accounting for these conditions. Urban and industrial data has 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.


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 [1].Amplified LST in certain urban sacks in comparison to its surroundings subsequent to the increase in cement surfaces is known as urban heat island (UHI) phenomenon [2].
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 [3] and later on effort on urban area has been started on both air and surface temperature estimation [4].Thermal infrared image is a prime source of information to mark the surface heat islands [5].
Temperature map can be drawn from time series imageries of the same reso- Such implication requires the imagery of the same spatial resolution as employed in this analysis.

Aims and Objectives
The aim of the current study is to monitor urban heat island (UHI) and temperature variations in Peshawar and its suburbs.Moreover, how much variation has taken place in temperatures during the span of 19 years.
Prime objectives of this research study are: 1. To classify the imagery for urban area identification and quantification 2. To process and calculate the thermal band for LST estimation and summer precipitation respectively.Comparatively, average winter rainfall is on the higher side than summer rainfall.In Peshawar, wind speed swings around 5 knots in December to 24 knots in hot June.In same way, the relative humidity fluctuates from 46% in June to 76% in August respectively [7].While doing all these calculations, a few values like LMIN and LMAX can be drawn from the satellite header file.

Results and Discussions
The results from the above methodology are as follows: Figure 3 shows urban area located in Peshawar and its outskirts.
The satellite image is classified into five major classes, Urban, Soil, Rock, Vegetation and Water.After supervised classification, above spatial distribution of these classes can be seen clearly.From this pattern, temperature variation can be observed through Landsat TM time series imagery by employing Land Surface Temperature.It is evident from the temperature ranges in 2011 LST imagery that the surface temperatures of an urban built up area are shifted towards high as it was in 1992 LST imagery.

Urban Sprawl and Environment Linkage
As the urban area expands it brings about the many activities like sewage, construction, transportation, deforestation, and industrialization.These Transportation is another factor along with the above stated factors.It is necessary for human mobilization to earn and get a livelihood.It also adds toxic elements to the air because it consumes fossil fuels.

Conclusions
This study draws a clear difference between two imageries in terms of tempera- How to cite this paper: Mehmood, R., Butt, M.A., Mahmood, S.A. and Ali, F. (2017) Appraisal of Urban Heat Island and Its Impacts on Environment Using Landsat R. Mehmood et al.DOI: 10.4236/ars.2017.63014193 Advances in Remote Sensing

Figure 1
Figure 1 explains the study area Geo-spatial presence starting from Pakistan

Figure 2 .
Figure 2. Flow chart of research procedure.

Figure 4
Figure 4 exhibits land use area covered in Square kilometers in 2011.

Figure 5
Figure 5 shows highest maximum air temperature during the period of 1931 to 2012.Above statistical facts and figures of climate drawn from various instruments and sources may also be verified through remote sensing data (Satellite Imagery) and evaluation techniques.In following practice, land surface temperature was subjected through spatial analysis and rise or fall in temperature was identified, distributed over the surface exposed to free the air present on every land use/land cover class.As air temperature ranges observed in the months September and October

Figure 4 .
Figure 4. Land use/land cover bar graph of 2011 image.
factors affects directly to the local environment in terms of more exhaust to the air directly or sometimes indirectly.As Peshawar is third fastest growing cities of Pakistan, it encompasses new housing societies, industries and colonies which are made at the cost of vegetated area in the outer part of the city.Resultantly, more greenhouse gases are added to the air, which produces not only warm and degradation in the local environment but also destroy ecosystems.It results climatic variation in local and international environment.

R.
Mehmood et al.DOI: 10.4236/ars.2017.63014200 Advances in Remote Sensing tures in the 19 year gap.Hence urban heat island created due 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 sever 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 risen up to 1 to 3 degree last 19 years.
Peshawar is largest and the capital city of the Khyber Pakhtunkhwa.To the west, The Federally Administered Tribal Areas (FATA) shares the boundary and Mohmand Agency located at its North.Similarly, Kohat district is on its Southern side.Charsadda and Nowshera link towards its North and North-East respectively.Moreover, Afghan boundary is just 40 Km away from west of the city.
3. To map out both land use/land cover classification and surface tempera-R.Mehmood et al.DOI: 10.4236/ars.2017.63014194 Advances in Remote Sensing tures 4. To compare and analyze the results of time series imagery 3. Study Area of February and April.The March and August have witnessed highest winter