Results and Discussion
In this study, Landsat satellite imageries were used to classify the
LULC change in class transition. The classified LULC maps of Islamabad
for four decades are presented in Fig.2. In addition, the LULC change in
class areas is graphically shown in Fig 3. The achieved overall
classification accuracy of LULC maps for the years 1979, 1989, 1999,
2009 and 2019 were 90.5%, 91.13%, 95.32%, 94.44% and 95.1%,
respectively. The overall Kappa statistics of the agreement were 0.90,
0.92, 0.94, 0.92 and 0.93 respectively. In the image classification
process, the accuracy assessment is an important component. According to
Lea and Curtis (2010), the Kappa statistics above 0.9 and overall
classification accuracy above 90% indicate a successful classification
which succeeded in the present study. The individual LULC class area
statistics and rate of change over the various study periods are
summarized in Table 3.
The image classification results indicated that the total land area of
Islamabad is 906.62 km2. Our results showed that in
1979 approximately 10.7% of the land was covered by build-up land and
14.3% by agriculture and 19.3% by forest and 1.7% by water bodies,
adding up to 53.1% of the land area as barren. Whereas, our result
indicated that in 2019 approximately 52.4% of the land was covered by
build-up land and 19.5% by agriculture and 10.3% by forest and 0.7%
by water bodies whereas 17.1% of the land area was covered by barren
land. The results revealed that a major expansion with respect to area
coverage in Islamabad city was observed in built-up and agriculture land
whereas, the forest and barren areas were declined. The assessment of
individual class of 1979 and 2019 indicated that there has been a
noticeable LULC change during the study period of 4 decades. According
to an earlier study (Hassan et al., 2016) that in Islamabad city rapid
development has been observed in agriculture, commercial, industrial and
urban. This significant trend of LULC use change in urban centers
reinforces that increase economic development, population growth,
traffic infrastructure, administrative services, topographic and
geographic are the major factors of change in land (Mundia and Aniya,
2007; Butt et al., 2015). According to Hassan et al. (2016), the main
driving factors of rapid expansion in LULC of Islamabad city is
increased in economic activity, population growth and climate change.
Rapid development in commercial, industrial, residential and expansion
in agriculture land into forest and barren land has been observed in
surrounded areas of Islamabad. The barren and the forest area near the
population has been cleared for the residential, commercial and
agricultural production in order to fulfill the basic necessities of
life (Hagler Bailly, 2007).
The results presented in Table 4 and Fig. 2 depict that both negative
and positive change followed in the LULC pattern in the Islamabad city
of Pakistan. During the period of 1979-2019, the area and amount of
change in the build-up and agriculture has account +41.7%, +5.2% added
of the total urban sprawl whereas, forest (-9.03%), water bodies
(-1.21%) and barren areas (-36.8%) were subtracted in the study area.
To understand land expansion in various LULC categories, a change
detection matrix (Table 5) was developed which indicate class
conversions during the last four decades (1979-2019). The conversion
between various LULC categories in different years were studied using
cross-tabulation matrix method of Pontius and others (2004).
According to cross tabulation, barren land was converted primarily to
build-up and agriculture land. About 417.45 km2 gained
by build-up class from barren land as well as from other classes while
only 39.87 km2 area converted to other classes. The
LULC with respect to build-up land primarily due to rapid population
growth and economic development. The area of forest lost about 85.78
km2 while only 21.85 km2 gained from
other landscape categories. The rapid expansion of residential,
commercial, industrial and infrastructure as well as political driving
forces contributing to the decline in forest, vegetation and barren
areas (Butt et al., 2015; Hassan et al.,2016). In urban LULC build-up
land obtained by changing areas that were previously barren land,
agriculture, vegetation, water bodies, which indicate that the existence
of high pressure on natural resources to fulfill the growing demand for
urban land (Dewan and Yamguchi, 2009). Worldwide anthropogenic
activities are responsible for such rapid factor of barren and habitat
destruction as well as loss of biodiversity. The rural areas converting
into urban land through rapid population growth and development
occurring at an unprecedented rate in recent human history and severely
degrading functioning of ecosystem services (Lopez, Bocco, Mendoza and
Duhau, 2001; Alphan 2003 and Dewan and Yamguchi, 2009).
Water class loss about 10.37 km2 during the last 40
years period. The results indicate that water resources are at
decreasing rate. Water source are under stress and such uncertain
fluctuations in water bodies may be due to increased urbanization as
well as change in climatic patterns. Water bodies are under high stress
of high demand of water to Islamabad and Rawalpindi and also for
irrigation purposes. Apart from that, water bodies are not only reducing
due unban and agriculture demands but also decline due to seepage,
percolation and evaporation as well as miss management of water
resources (Ashraf et al., 2007; Hagler Bailly, 2007; Keller et al.,
2000; Butt et al., 2016). According to IUCN (2005), due to use of
herbicides and pesticides in the agriculture land as well as urban waste
degrade water quality and quantity (Ahad et al., 2005; Iram et al.,
2009). According to IPCC, due to global warming the Earth temperature is
rising which lead to change in temperature and precipitation patterns.
Consequently, extreme climatic events are occurring such flooding,
drought and heat waves. Such changes in climatic patterns can affect
water resources and biodiversity (Hassan et al., 2016). In 2015 a severe
heat wave struck southern parts of Pakistan and more than 1500 loss
their life due to heat stroke in the Karachi city (Chaudhry, 2015).
Generally land dynamic is a complex process and any one approach is
unable to describe the pattern of LULC change completely (Verburg and
Overmars, 2007).The study indicates that the GIS and remote sensing
technique provide an important information about the spatial
distribution as well as natural of LULC changes. In our study, we
focused only GIS and Remote sensing techniques to examine the LULC
change pattern, but could not consider other factors such as climatic,
geophysical, socioeconomic, housing factor and land use policy related
variables. Therefore future study use policy and other factors along
with current study to achieve sustainable urban LULC management.