Journal of Global Resources
Volume 6 (01)August 2019-January 2020
Page 189-197
UGC–CARE Listed Journal in Group D
ISSN: 2395-3160 (Print), 2455-2445 (Online)

30
ASSESSMENT OF URBAN HEAT ISLAND IN BILASPUR CITY, CHHATTISGARH
Z. T. Khan1 and Dipankar Bera2
Ex-Professor & Dean of Science Faculty, 2Research Scholar,
SOS in Geography, Pt. Ravi Shankar Shukla University, (CG), India
Email: beradipankar79@yahoo.com
1

Abstract: The air temperature is gradually rising in all cities of the world. One of the possible
causes is the drastic reduction in the vegetation cover in cities. In 1971 Indian Census thecity’s population had 98,410 but now it has 3, 35,293 (2011 Indian Census) population. In thecities over the last fifty years has become over populated. Bilaspur city of Chhattisgarh is
experiencing rapid industrialization which has resulted remarkable UHI. The LULC map of thestudy area developed for the year 2002 and 2017 using supervised classification method. Eightland use classes have been identified as Built-upland, mixed Built-up, Water bodies,
Agricultural fields, Tree clad area, Open land, Industry and River Sand. Using bands 1- 4 ofLandsat 7 and 2 – 5 of Landsat 8 the pre-processed images the land use land cover pattern
was mapped by Visual interpretation of Arc GIS 10.3 software. Urban heat island phenomenon
is evident from the LST images. Understanding the distribution of Land Surface Temperature(LST) and its spatial variation will be helpful to urban developer and also to find out present
urban crisis and possible solution. Investigate and identify land used types which have the mostactive role to the increase of ambient temperature in Bilaspur City. Landsat 7 ETM+ images of2002 and Landsat 8 TIRS image of 2017 obtained from USGS and used for the study. Using
bands 1- 4 and 7 of Landsat 7 ETM+ and 2-5 and 10, 11 of Landsat 8 TIRS for processing the
LST and NDVI map. The digital number of thermal infrared band is converted into spectral
radiance using the equation supplied by the Landsat user’s hand book. The effective at-sensor
brightness temperature is obtained from the spectral radiance using Plank’s inverse function.
The study reveals that appropriate urban planning is necessary for the sustainable
development of the urban area.
Key words: Urban Heat, Surface Temperature, Normalized Difference Vegetation Index.
Introduction
Rapid urbanization has significant role on different aspects of the quality of life and research indetermining the patterns of urbanization and quantifying their impacts is the need of the time.
The changes in land use and land cover include loss of agricultural lands, loss of forest lands,
increase of barren area, increase of impermeable surface of the area because of the built up
area, etc. Development of land use land cover is very much useful to the city planner andpolicy makers. For the sustainable urban ecosystems the amount of land required for growing
the vegetation can be estimated from these studies. One of the major implications ofurbanization is increase of surface temperature and development of Urban Heat Island.
Surface temperature is increased by anthropogenic heat discharges due to energy
consumption, increased land surface coverage by artificial materials having high heat
capacities and conductivities, and the associated decrease in vegetation and water pervious
surfaces which reduce the surface temperature through evapotranspiration. Landsat ETM+
images have widely used to observe the biophysical characteristics of the land surface. In
addition to the development of Land use/cover maps band 6 of the Landsat imagery is usefulfor deriving the surface temperature. Urban Heat Island is one of the upcoming urban microclimatological problems developing in the city. Land surface temperature is gradually
increasing in the urban area due to reduced vegetative cover and increased built-up surfaces
with concrete, asphalt, object and material. Because of these phenomena certain parts of theurban area of the city are becoming extremely hot during day time and particularly during
summer seasons, causing lot of discomfort to the citizens.

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Literature Review
There are so many studies done by Geographers, Planners, and Scientists & Researchers in
the concerned filed. Oke, 1973, and Torok et al., 2001 described that even towns withpopulations of 1000 people had urban heating of about 2.2oC compared to the nearby ruralcountryside. The land-use and land-cover maps, four vegetation-impervious surface-soil (V-I-S)
patterns of the city development were identified pertain to Mississauga’s features. Anotherstudy report provided by Seto et al., 2002 described that the land-use changes into the Pearl
River Delta, using Landsat TM. Field assessments confirm a high overall accuracy of the landuse change map (93.5%) and support the use of change vectors and multi date Landsat TM
imagery to monitor land-use change. Field-based accuracy assessment to identify problems ina land-use map and to improve area estimates for each class (Seto et al., 2002). Land surface
temperature is sensitive to vegetation and soil moisture, hence it can be used to detect land
use/land cover change, and e.g. tendencies towards urbanization, and deforestation etc.
various studies have been carried out to investigate LST using the vegetation abundance(Weng et al., 2004). According to Mallik et al., 2008 estimated land surface temperature overDelhi using Landsat-7 ETM+. Argued that Satellite derived emissivity values were in theacceptable range and the NDVI and fractional vegetation cover are effective in deriving surface
emissivity and surface.
Study Area
Bilaspur city has a District Headquarters of Bilaspur District in Chhattisgarh, situated 133 km(83 miles) north of the state capital, Naya Raipur. Bilaspur City Municipal population is 3, 35,
293, (2011census), which is the Third-largest city after Raipur and Bhilai-Durg. Bilaspur city is
located on bank of Arpa River with latitude 22o6’5’’N to 22o6’30’’N and longitude 82o6’45’’E to82o12’5’’E. The climate is tropical, with hot summers and moderate winters. The peaktemperature reaches 45 °C in May- June, while the winter temperature is 23-270C in month
Dec-Jan. The average humidity is 78% and the average annual rainfall is 103 cm. Bilaspur gets
its rainfall from both the south-west monsoon and north-east monsoon. The topography ofBilaspur is flat, with a few small to medium sized hills. It is also a major railway junction
connecting all states in the country. The Bilaspur city is the commercial capital of the state of
Chhattisgarh. The geographical location study area of Bilaspur is shown in Fig. 1.
Figure 01: Location of Study Area

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Objectives
The main objectives of the research paper are as follows:To study attempts to find changes in land use patterns of Bilaspur city in 2002 to2017 and analyze the relation between the land use/cover and land surface temperature.
To suggest planning strategies for future healthy urban development.
Methodology
For the present study the following methodology is adopted which involves satellite data
download , classification of the imagery, development of land use/cover maps, preparation of
NDVI maps, retrieval of Land Surface Temperature maps and correlation studies. Remotesensing has the capability of monitoring such changes, extracting the changes information fromsatellite data. In this work Landsat 7 ETM+ and Landsat 8 TIRS images of Bilaspur city has
downloaded from USGS earth explorer web site. These are briefly outlined here.
Data Download
Cloud Free Landsat satellite data of 2002 and 2017 for the study area has been downloaded
from USGS Earth Explorer website. All the data are pre-processed and projected to the
Universal Transverse Mercator (UTM) projection system. The Landsat satellite image of thestudy area down loaded for the year 2002 and 2017. The study area is obtained by sub setting
the image with a rectangular area of interest (AOI).
Development of Land Use/Cover Map
Using bands 1- 4 of Landsat 7 and 2 – 5 of Landsat 8 the pre-processed images the land use
land cover pattern was mapped by Visual interpretation of Arc GIS 10.3 software. The eightclasses considered for the study area are Built-upland, mixed Built-up, Water bodies,
Agricultural fields, Tree clad area, Open land, Industry and River Sand.
Derivation of NDVI Image
The Normalized Difference Vegetation Index (NDVI) is a measure of the amount and vigor ofvegetation at the surface. The reason NDVI is related to vegetation is that healthy vegetationreflects very well in the near infrared part of the spectrum. Green leaves have a reflectance of
20 % or less in the 0.5 to 0.7 range (green to red) and about 60 % in the 0.7 to 1.3μm ranges(near infrared). The value is then normalized to -1<=NDVI<=1 to partially account fordifferences in illumination and surface slope. The index is defined by equation 1.
NDVI= (NIR-RED)/ (NIR+RED)………………………… (1)RETRIEVAL OF LSTFROM LANDSAT 7 ETM+:
The digital number (DN) of thermal infrared band is converted in to spectral radiance (Lλ)
using the equation supplied by the Landsat user’s hand book.
LMAX−LMIN
Lλ = { QCALMAX−QCALMIN}*DN-1+ LMIN ……………………………… (2)LMAX = the spectral radiance that is scaled to QCALMAX in W/(m2 * sr * μm)
LMIN = the spectral radiance that is scaled to QCALMIN in W/(m2 * sr * μm)
QCALMAX = the maximum quantized calibrated pixel value (corresponding to LMAX) in
DN = 255 QCALMIN = the minimum quantized calibrated pixel value (corresponding
to LMIN) in DN = 1.
LMAX and LMIN are obtained from the Meta data file available with the image and are given in the
Table 1 below.
Table 01: LMAX and LMIN values of Landsat data
Band No
Satellite/ Sensor
LMAX
LMIN
6.1
Landsat7 /ETM+ High gain
12.65
3.2
6.2
Landsat7 /ETM +Low gain
17.04
0.0
The effective at-sensor brightness temperature (TB) also known as black body temperature is
obtained from the spectral radiance .Conversion of spectral radiance to temperature in Kelvin.
Tb=K2/ ln ((K1/L) +1 ……………………………… (3)Where, K1= Calibration constant 1
K2= Calibration constant 2191

Tb=surface temperature
The calibration constants K1 and K2 obtained from Landsat data user’s manual are given in thetable 2.
Table 02: Calibration Constants for Thermal Band
Sensor
K1
K2
Landsat 7/ ETM+
666.091282.71
From Landsat 8 TIRSOLI and TIRS band data can be converted to TOA spectral radiance using the radiancerescaling factors provided in the metadata file:
Lλ = MLQcal + AL
Where:
Lλ = TOA spectral radiance (Watts/ (m2 * srad * μm))
ML = Band-specific multiplicative rescaling factor from theMeta Data (Radiance_mult_band_x, Where x is the band number)
AL= Band-specific additive Rescaling factor from the metadata(Radiance_add_band_x, where x is the band number)
Q Cal = Quantized and calibrated standard product pixel values (DN)

Rescaling Factor
ML
AL

Table 03: Rescaling Factor
Band 100.000342
0.1Band 110.000342
0.1

IRS band data can be converted from spectral radiance to brightness temperature using thethermal constants provided in the metadata file:
T=
ln(

K2
K1
Lλ

+1)

Where:T = At-satellite brightness temperature (K)Lλ = TOA spectral radiance (Watts/ (m2 * srad * μm))
K1 = Band-specific thermal conversion constant from the metadata (K1_constant_band_x,
where x is the thermal band number)
K2 = Band-specific thermal conversion constant from the metadata (K2_constant_band_x,
where x is the thermal band number)

Thermal Constant
K1
K2

Table 04: K1 and K2 Values
Band 101321.08
777.89

Band111201.14480.8922.3 Land Surface Emissivity to find LST it is necessary to calculate the LSE of the region. LSE
was estimated using NDVI threshold method.
LSE = εs (1-FVC) + εv * FVCWhere,
εs and εv - soil and vegetative emissivity values of the corresponding bands.

Emissivityεsεv

Table 05: Emissivity Values
Band 10
0.971
0.987

192

Band 11
0.977
0.989

RESULTS AND DISCUSSION
Land Use/Cover Change Analysis
The land use land cover map of the study area developed for the year 2002 and 2017 using
supervised classification method. Eight land use classes have been identified as Built-upland,
mixed Built-up, Water bodies, Agricultural fields, Tree clad area, Open land, Industry and River
Sand. The LULC map is given in below as Fig.2 a & 2 b. Post classification change analysis ofland use and land covers have been calculated from the land use change detection using
following formula (1-6)
Gain/increase = L t+1 –CP………1
Losses/decrease = L t-1 -CP ……2
Net Change = Gain - Losses ……..3
Gross change = Gain + losses……4
Percent gains =gain*100/CP where, CP >0 else gain *100…….5
Percent Losses =Losses*100/CP where, CP >0 else Losses *100…….6
L= land use /Land cover t = present time.t+1 = Future time. T-1 = Past time
CP= changing Persistence. When CP is ‘0’ means no change, When CP is <0 means
decrease, when CP is >0 means increase.
Fig. 2aFig. 2b

The total area of the rectangular area of interest (AOI) is 22748.4 square kilometers.
The details of the land cover of the area under study are given in the following Table 6 below.
The table 6 explained the amount of land gained, lost and per year change which was occurred
due to transition of one type land cover into another during this period. The buildup land was
gained high amount of land (172.4 hector.) as compared to other urban land due to rapidtransition of the agricultural land, open land, Tree clad area, and waterbodies into thiscategories. In the same way mixed built up land was also gained high amount of land (56.6
hector) due to rapid transition of agriculture land ,vegetation, waterbodies and industries(verynegligible) into this categories. In other hand out of total develop land, agriculture land was
rapidly lost (84.89 hector) due to the transition into other urban land as compared to others.
Similarly, out of total urban land water bodies (23.83 hector), Tree clad area (1.61 hector) andopen land (121.71) were also due to transition into urban land during this period. Therefore,
present gross change has 474 hector (gain + losses), out of the total develop land. Thus, out of
total developed urban land, built up area was very rapid dynamic rate of positive change(+172.4) and similarly, open land area was very rapidly rate of negative change (-121.71) due
to rapid loos rates and slow gain rate as compared to other urban land. Using hand held GPS
field survey nearly 100 points were identified. Field knowledge and Google Earth were served
as basis for estimation of classification accuracy.
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Table 06: Change of Land use and Land Covers in Bilaspur City, 2002-2017#

Land use
Categories

In year 2017

In year 2002

1

Agriculture

Area
78.07

Percent
2.56

Area
172.96Percent
5.67

Gross change
Gain (+)
Losses (-)
Area
Percent
Area
Percent------94.89-3.11

Per year Change

2

Built up1716.656.29

1544.2

50.64

172.4

5.67

---

--

Area
6.326
11.49

3
4

Industry
Mixed Built

7.10
532.790.23
17.47----476.19----15.61---56.6--1.86

-----

-----

--3.77-0.12

5Open land

292.449.59

414.15

13.58

---

---

-3.99

-8.11

-0.26

6

Riverine

191.806.29

185.74

6.09

6.06

0.2

121.71
--

--

0.40

0.01

7

Tree clad Area

137.82

4.52

139.43

4.57

---

----

-1.61

-0.05

-0.11

-0.0038

Water bodies

93.15

3.05

116.98

3.84

----

---

-23.83

-0.79

-1.59

-0.05

Total

3049.71003049.65100

235.06

7.73-242.04-7.94

Percent-0.21
0.38

Sources: Calculated by author using satellite imageries and referenced dataset, 2002-2017

NDVI ImageNDVI is one of the most widely used index of which applicability in satellite analysis and inmonitoring of vegetation cover was sufficiently verified in the last two decades. The NDVI valueof the pixels varies between -1 and +1. Higher values of NDVI indicate the richer and healthiervegetation. Vegetation affects the latent thermos flux of the surface intent to the atmospherethrough the evapotranspiration. Lower LST (except water bodies) is usually measured in areas
with higher NDVI values. The Normalized Difference Vegetation Index (NDVI) image developed
is shown in the Fig.3a & 3b below.
Figure: 3a and 3b NDVI image of the Study Area for the year 2002 & 2017

LST Image
From brightness temperature (TB) and Emissivity images the final Land Surface Temperature
image was obtained by developing a model in ERDAS Imagine 9.1.The Final LST image isshown in the Fig.4a and 4b.
LST and NDVI Relationship
There is an apparent correlation between LST and NDVI from the visual interpretation of LST
and NDVI contrasts. Mean LST and NDVI values associated with different land‐use types are
significantly different. Multiple comparisons of mean LST and NDVI values associated withpairings of each land‐use type are also shown to be significantly different. The result of aregressive analysis shows an inverse correlation relationship between LST and NDVI of 2002
and 2017.

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Figure: 4a and 4b Land Surface Temperature image for the year 2002 & 2017

Figure 05: Correlation between LST and NDVI (2002) Figure 06: Correlation between LST and NDVI (2017)

Relation between LULC and LST
In 2002 Land Surface Temperature (LST) image has highest temperature of about 40 o c exist
in urban built up area of LULC map and other hand impervious area has lowest temperature ofabout 23oc in vegetation area. A surface temperature profile line is drown from South-Westend to North-West end of the study area to show the relationship between LULC map and LST
map shown in the Fig.7a and 7b.

195

Figure 07a and 07b: Land Use / Land Cover Map and Land Surface Temperature line from SouthWest end to the North East end of the study area (2002)

The temperature profiles shown in the Fig.8 below, clearly demonstrates the Urban Heat Islandeffect. More than 100 points are selected randomly form the LST image and corresponding
LULC values are obtained to find the correlation between LULC and LST. In 2017 LST image
has observed that highest temperatures of about 45oC exist at urban built up and Riverine
sandy areas and other impervious areas and lowest temperatures of about 23oC are exist atvegetative areas and water body. A Surface temperature profile line is drown from South-Westend to North-West end of the study area to show the relationship between LULC map and LST
map shown in the Fig.9a and 9b. More than 100 points were selected randomly form the LST
values to find the correlation between LULC and LST.
Figure 08: Land Surface Temperature profile from South West end to the North East end

Figure 9a and 9b: Land Surface Temp. Line from South West end to the North East end (2017)196

Figure 10: Land Surface Temperature profile from North end to the South end

Conclusion and Suggestion
Bilaspur is the third (after Raipur, Bhilai-Durg) largest city of Chhattisgarh and commercial
capital of the state. It is experiencing a rapid urbanization. With urbanization most of the land
surface is covered with concrete, asphalt and other such impervious materials. This leads to avariety of urban environmental issues like increase in runoff, increase in land surface
temperatures, etc. The cities are experiencing more heat than the surrounding rural areas
mainly due lack of vegetative cover. Surface temperature is retrieved to understand thevariation of temperature from low density mixed built up area to core built up areas of the city.
From the LST images it is clearly understood that surface temperature is more in core built up
area compared to fringe areas. Also the correlation study shows that the LST is strongly andnegatively correlated with NDVI, which also land use reflect how much brightness temperature.
This information assists in monitoring the dynamics of land use resulting out of changing
demands of increasing population and associated issues like Urban Heat Island. Average
Land surface temperature has increased near about 5oc in last 15 years (2002-2017).
Its structure shades anthropogenic surfaces, limiting the accumulation of direct solar
radiation and subsequent emission of converted thermal radiation. It increases relative air
humidity and reduces air temperature. Besides microclimatic function, vegetation also has
health, aesthetic, recreational and other functions. In conclusion, vegetation with higher canopy
cover improved environmental conditions in terms of relative humidity. Generally, if increasing
the urban zone canopy cover by 50% would reduce the UHI by 2.05 degrees C. So, this issue
is nonstop but it would be minimize this problem It is possible through, maximum plantation in
urban Environment, Development of ideal towns (where proper flow of winds direction towards
North-South and East-West), Protection of Forests and water bodies ,Installation of green
roofs (Gardens),Painting roofs with cool material and Use of Non-conventional energy.
References
1. Li, J. and Zhao, H. M. (2003) “Detecting Urban Land Use and Land Cover Changes in
Mississauga using Landsat TM images.” Vol 2, No.1, PP.38-47.
2. Mallik, J., Kant, Y. and Bharath, B. D. (2008) “Estimation of land surface temperature overDelhi using landsat-7 ETM+, Journal of Indian Geophysics Union, Vol.12, No.3, P131-140.
3. Oke, T. R. (1973) “City size and the urban heat island.” Atmospheric Environment, Vol.7
PP.769-779.
4. Seto, K. C., Woodcock, C. E., Song, C., Huang, X., Lu, J. and Kaufmann, R. K. (2002)
Monitoring land-use change in the Pearl River Delta using Landsat TM, Int. J. Remote
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5. Torok, S., Morris, C., Skinner, C., Plummer, N. (2001) Urban heat island feature ofsoutheast Australian town. Australian Meteorological Magazine, Vol.50, N0.1, PP.1-13
6. Weng, Q., Lu, D. and Schubring, J., (2004) Estimation of land surface temperaturevegetation abundance relationship for heat island studies, Remote Sensing of Environment,
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