183

Comparison of Urban Land Expansion and Population Growth in
the Taipei Metropolitan Region
David KARACSONYI1* and Kang-tsung CHANG2*1

Geographical Institute, Hungarian Academy of Sciences
Budaorsi ut45, 1112 Budapest, Hungary
2
Department of Geography, University of Idaho, Moscow, Idaho, USA*e-mail: karacsonyidavid@gmail.com

Abstract
Recent studies have reported that urban land expansion rates are higher than population growth rates inmany parts of the world, thus raising concerns about a variety of resource and environmental issues. Urban
land expansion is characterized by its intensity as well as the area of its extent. Previous studies of urban
sprawl have focused on the spatial patterns of urban expansion. This study takes a different approach bycombining urban expansion intensity and the urban land ratio into a new index—the area-weighted urban
expansion rate. The index was used for analyzing urban land expansion in the Taipei metropolitan region andfor correlating the two elements of the index with population growth and density. The results showed that theindex was able to distinguish between different stages of urban expansion in areas surrounding the core of themetropolitan region and that the correlations were capable of distinguishing older, more established urban
areas along railways from younger, more dynamic urban areas along highways. The index provides a simple,
yet useful tool for future studies of urban land expansion.
Key words: area-weighted urban expansion rate, population growth, Taipei metropolitan area,
Taiwan, Taoyuan County, urban land expansion

1. Introduction
Two recent studies of urban land expansion havereported that, in many parts of the world, urban land
expansion rates are higher than population growth rates,suggesting that urban growth is becoming more expansive and less compact (Angel et al., 2011; Seto et al.,2011). Urbanization has been linked to a variety of resource and environmental problems worldwide, such as
loss of arable land, habitat loss, species extinction,
land-cover change and alteration of hydrological systems(Seto et al., 2011). It is therefore important to study theprocesses of urban land expansion in different regions.
In a seminal paper on urban sprawl, Harvey and Clark(1965) described three spatial patterns of urban expansion: low-density continuous development, ribbon
sprawl, and leap-frog development. For the past two
decades, researchers have used remote sensing and GIS
to revisit the topic. Hoffhine Wilson et al. (2003) used achange analysis to identify the five classes of urban
growth: infill, expansion, isolated, linear branch, andclustered branch. Using a spatiotemporal landscape metrics analysis (McGarigal et al., 2002), Seto and Fragkias(2005) found that urban growth in four Chinese cities
occurred through the two processes of envelopment andGlobal Environmental Research
18/2014: 183-190
printed in Japan

multiple nuclear development. Many other studies on
urban land expansion have followed, examining urban
land expansion in various countries (e.g., Schneider et al.,2005; Seto et al., 2007; Schneider & Woodcock, 2008;
Huang et al., 2009; Terzi & Bolen, 2009; Sun et al.,2013).
This study takes a different approach to analyzing theprocess of urban land expansion by considering both theintensity and the areal extent of urban expansion. At the
beginning of urban sprawl, the intensity of urban expansion can be high (e.g., the size of urban land doubling in acouple of years) but the areal extent of urban expansion
can be small (e.g., only 1% of the total area converted tourban land). In such a scenario, the degree of urbanization can be exaggerated if we consider only the intensityof urban expansion. Therefore, we propose a method thatcombines the intensity and areal extent in analyzing urban land expansion and apply the method to a case studyof urban expansion in areas surrounding the cores of theTaipei metropolitan region. There are two additional
advantages of using this method. First, the method allows
us to trace the different stages of urban land expansion.
Second, it offers a mechanism by which the relationshipbetween urban land expansion and population growth canbe analyzed.
©2014 AIRIES

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Chinese urban growth is one of the most popular topics in land use and urbanization studies (Seto et al., 2011).
China has been the engine of global urban population
growth, with nearly one third of the global urban population growth realized in China in 2000-2010 (http://data.
worldbank.org/). The Taipei metropolitan area had thesame rapid growth in the past that mainland China is
experiencing now. Due to the cultural similarity, a casestudy from Taiwan can therefore provide a picture ofChinese urban growth over a longer time scale. We cansee the different stages of urban growth in the Taipei
metropolitan region since the 1960s, thanks to detailed
data available in Taiwan.

2. Study Area
The study area includes the Taipei metropolitan area
and Taoyuan County in northern Taiwan (Fig. 1). As

defined by Tsay (2001), the Taipei metropolitan area
encompasses the Taipei, New Taipei and Keelungmunicipalities. The Taipei municipality (Taipei hereafter)
is surrounded by the New Taipei municipality (New
Taipei hereafter), formerly known as Taipei County. To
the northeast of Taipei is Keelung, a port and provincial
city, and to the southwest of Taipei is Taoyuan County,
which has reached a population of 2 million as of 2012
and will be elevated to the status of a municipality in
2014. The study area covers 3,679 sq. km, about one
tenth of the total area of Taiwan. At present, the Taipei
metropolitan area has a population of 7 million andTaoyuan County 2 million; together, the study area
accounts for 40% of Taiwan’s total population. Our
analysis is at the district or township level: Taipei has 12
districts, New Taipei 29 districts, Keelung seven districts,
and Taoyuan County five cities and eight townships.
The Taipei Basin is drained by the Tamsui, Daan,

Fig. 1 Population distribution in the Taipei metropolitan area and Taoyuan County, 2012.

Fig. 2 Population density distribution in the Taipei metropolitan area and Taoyuan County, 2000.

Comparison of Urban Land Expansion and Population Growth

Xindian, and Keelung rivers. Taipei is located on the eastside of the Tamsui River, and the core of New Taipei,
including Sanchong and Baqiao, on the west side of theriver. Taipei and the city core of New Taipei are functionally one large urban center with approximately
5.5 million people. They also have the highest population
densities in the Taipei Basin, with an average ofover 5,000 people/sq. km but in some cases even over
10,000 people/sq. km. (Fig 2).

3. Data and Methods
3.1 Land use data
Taiwan’s Ministry of the Interior published nationwide land use maps for 1971 and 2006. The 1971 land
use map was compiled from aerial photographs. The
2006 map was interpreted from SPOT images using the
maximum likelihood classifier method. The accuracy
assessment of the classification results yielded an overall
accuracy of 86% (Huang et al., 2009). We extracted the“built-up” areas as urban land from land use maps for
New Taipei City and Taoyuan County. Unfortunately, our2006 data source did not include Taipei and Keelung;therefore, they were not included in the analysis of urban
expansion. From the maps of 1971 and 2006, we generated a map showing new built-up areas, i.e., areas thatwere not included in the 1971 map (Fig. 3).
3.2 Demographic data
This study used demographic data from Taiwan’s
Population and Housing Census for 1966, 1980, 1990,
and 2000 (http://eng.stat.gov.tw/). We supplemented the185

census data with other government data and online
resources for the entire study area including Taipei City,
New Taipei City, Keelung City and Taoyuan County.
3.3 Ratio of new urban land to the total area
This study developed the ratio of new urban land to
the total area (AU) to quantify and compare urban
expansion in the study area. The index is obtained bymultiplying two elements, urban expansion intensity (UI)
and urban land ratio (UR):UI =Ub − U a
Ub

(1)

UR =

Ub
A

(2)

Ub − U a U b Ub − U a
×
=
Ub
A
A

(3)

AU =

Fig. 4 An idealized diagram showing different stages of urban
sprawl defined by UR, UI and AU.

Fig. 3 Urban sprawl in the study area, 1971–2006.

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D. KARACSONYI and K. CHANG

where U a is the urban land at the beginning of the time
period, Ub is the urban land at the end, and A is the total
area of the administrative unit. Ranging in value from 0
to 1, AU can also be defined as the area-weighted urban
expansion intensity.
The two elements of the index vary in time. Whereas
UI indicates the intensity or dynamics of urban expansion,
UR indicates the size or areal extent of urban land. This
also means that it is possible to split the ratio of new
urban land into the intensity and extension components.
In the early stage (I in Fig. 4) of urban expansion, UI isstrong but UR is low, resulting in a low AU value. In the
final stage (IV) of urban expansion, UR is high but UI is
weak, resulting also in a low AU value. AU values are
expected to be high in the case of large urban areas andintense urban expansion, i.e., in the middle stage of urban
expansion. The middle stage can be further divided into
the dynamic (II) and late stages (III). In the first part ofthe middle stage the intensity component is still dominant
but waning. In the late stage, the extension component
comes to dominate. These different stages can be separated not only in time but also in space. Thus, from thecore urban area to the periphery, we can see changes fromthe final to early stages. Suburban areas typically havethe dynamic or the late stage. Areas of deurbanization
could exhibit the early stage; however, this early stage
does not lead automatically to the dynamic stage.
3.4 Proportion of population increase to the total
population
The proportion of population increase to the total
population (PR) measures the ratio of population increase
realized from 1966 to 2012 to the total population in 2012at the district level:
PR =Pb − Pa
Pb(4)

where Pb is the district population in 2012 and Pa the
district population in 1966. PR can be negative in thecase of a population decrease.
3.5 Normalized population growth index
The normalized population growth index (PD) is ameasure of absolute population growth at the districtlevel, normalized by the size of the district:PD =Pb − PaA(5)

where A represents the area of the district.

4. Results and Discussion
4.1 Size and dynamics of population growth
In the 1970s, the annual rate of population growth in
the study area (6.3%) was more than double that of thenational average. Rapid population growth was concentrated in the Taipei Basin during the 1970s, except for the
Taipei core area, where it has been below the average
since 1966. The first wave of above-average population
growth districts included Beitou and Shilin in the north,Wenshan in the south, and Sanchong, Banqiao, andZhonghe in New Taipei. The central districts of New
Taipei (Baqiao, Zhonghe, Xinzhuang), in particular, hadmore than 400% population increase in the 1970s. The
second wave of urban sprawl came in the 1980s in thewider neighborhood of New Taipei core districts withabove-average growth lasting until 2000. Tucheng,
Luzhou, and Neihu all doubled their population in the
1980s. During the 1990s, the third wave of urban sprawl
occurred in a wider circle away from the core of themetropolitan area, including the shore of the Taiwan
Strait from Tamsui to Dayuan, areas around Taoyuan
International Airport, Xizhi District (between Taipei and
Keelung), Linkou and Luzhou along Freeway 1, andTucheng and Sanxia along the newly opened Freeway 3.
Since 1990, Taoyuan County had a higher annual growthrate (still over 1% yearly) than either Taipei or New
Taipei. After 2000, a relative high rate of population

Fig. 5 Main periods of population growth.

Comparison of Urban Land Expansion and Population Growthincrease began on the previously sparsely populated
mountainous areas of New Taipei (Wulai and Pinglin),
although the absolute number of population increase was
not large. In the 2000s, the annual rate of population
growth in the study area (yearly 0.47%) was only slightly
above the national average. Xizhi District in Taipei andseveral districts along major transportation corridors in
New Taipei and Taoyuan County had above-average
population growth during the entire period of 1966 –2012.
Two districts, Nangang and Banqiao, reversed their decreasing trends after 2000 due to functional revitalization.
Nangang became a high-tech industry center (Chou,
2005), and Banqiao became the CBD (Central BusinessDistrict) of New Taipei. Figure 5 shows the different time
periods in which each district or township had aboveaverage population growth.
Figures 6 and 7 summarize the dynamics and the sizeof population growth in the study area. Figure 6 showsthat high PR rates in 1966–2012 were mainly concentrated in parts of New Taipei surrounding Taipei and inparts of Taoyuan County along major transportation
corridors. The core districts of New Taipei received more187

than 80% of their total population in the last 40 years.
Since 1980, PD in the Taipei core area has decreased,but other parts of the Taipei Basin have continued toexperience a large increase in PD (Fig. 7). The population density increased by more than 10,000 people/sq. km
in Xinzhuang and by more than 20,000 people/sq. km in
Luzhou between 1980 and 2012. Over 90% of the
population in these districts arrived after 1980, resulting
in rapid land use changes from agricultural to industrial
land in the 1970s and 1980s and then to residential areasin the 1990s and 2000s. The same process also occurredin Tucheng, albeit on a more moderate scale. In general,
population density growth was concentrated along theTaipei Basin–Daan River (northeast-southwest) axis
before 2000, but after 2000, some of these same districts
such as Tucheng, Sanchong, Yonghe, and Luzhou began
to experience decreases in population density.
4.2 Ratio of new urban land to the total area
Using the urban land maps of 1971 and 2006, we
calculated UI (Fig. 8), UR (Fig. 9), and AU (Fig. 10). As
mentioned earlier, Taipei and Keelung were not included

Fig. 6 Population growth, 1966 –2012.

Fig. 7 Population density changes, 1980 –2012.

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D. KARACSONYI and K. CHANG

Fig. 8 Urban expansion intensity (UI), 1971–2006.

Fig. 9 Urban land ratios (UR), 1971–2006.

Fig. 10 Area-weighted urban expansion intensity (AU), 1971–2006.

Comparison of Urban Land Expansion and Population Growthin this part of analysis because of lack of data. The
sparsely populated mountainous areas (Pinglin andFuxing) had a very high UI but a very low UR, meaningthat urban land expansion was limited to certain small
areas of deurbanization. At the opposite end, Banqiao
and Sanchong in New Taipei and Taoyuan City andZhongli in Taoyuan County had a high UR but a low UI;
the dynamic urban sprawl had already ended in theseareas during the study period of 1971–2006.
Luzhou and Xinzhuang had a high AU due to a relatively low UI but a very high UR; thus, these districts
were in the late stage of urban sprawl. This was the samein the case of Tucheng; its high AU was a result of having
a moderate UI and a high UR. Linkou, Guishan, andLuzhu all had a high UI and also a relative low UR,
resulting in a high AU. These districts were the main
dynamic urban sprawl areas during the study period.
Using the values of UI, UR, and AU, we createdthresholds for recognizing the urban sprawl stages in the
Taipei metropolitan area and Taoyuan County (Fig. 11).
Tucheng, Wugu, and Taishan districts were between the
dynamic and late stages. The early stage dominated themountainous areas, mostly pockets of deurbanization.
There is the additional category, “slow constant” inFig. 11. This category applied to districts along therailway line, which had experienced urban sprawl on amoderate level because of their relatively high but notoutstanding UR and UI values.
In this study we used only one time period (1971–
2006), so it was possible to recognize the different stagesof urban sprawl only in space but not in time. We
recognize that the values for these 35 years were only
averages. In reality, these values could vary in different
ways during different decades. An investigation overtime will be the aim of a future study. Similarly, thethreshold values we used to separate urban sprawl stages
apply only to our study area and to the period of
1971–2006. They could be different for other areas ordifferent periods.

189

4.3 Correlation between population and urban land
expansion
Table 1 shows a correlation matrix between population growth data (PR and PD) and urban land expansion
data (UI and UR). The correlations between UI andpopulation growth data are negative, whereas the correlations between UR and population growth data arepositive.
To explain the opposite signs of the correlations, we
can examine maps showing the distributions of PD, PR,
UI, and UR. Areas with high UI values are found on the
Linkou Plateau and along Freeway 1, representing the
dynamic stage of urban expansion. But in these areas, thepopulation is still growing and has not reached its maximum stage. Therefore, the correlations between UI and
PD and between UI and PR are negative. On the other
hand, areas with high PD and PR values are found along
the railway line in the Daan River valley. In these areas,urban expansion has reached its late or final stage, thus
they have high UR values. Therefore, the correlations
between UR and PD and between UR and PR are positiveand significant. In other words, we can expect positive
correlations to be found in older, more established urban
areas and negative correlations in younger, more
dynamic urban areas. In a young, dynamic urban area,
urban land expansion is rather extensive (large industrial
parks, shopping centers); however, in an older urban area,
vertical development (high rise buildings) becomes more
Table 1 Correlation matrix between urban land expansion
and population growth data.
UI
UR(1971–2006)(1971–2006)
PD–0.60*
0.87*(1966–2012)
PR
–0.31
0.58*
(1966–2012)*significant at the 5% level (n=61)

UI
No significant
sprawl
Early

Fig. 11 Stages of urban sprawl in the study area.

UR

AU

<0.40

<0.30

<0.10

>0.40

<0.20

<0.10

Dynamic

>0.40

<0.40

>0.15

Late

<0.40

>0.40

>0.15

Final

<0.20

>0.60

<0.15

Slow constant

>0.30

>0.30

0.10-0.15

190

D. KARACSONYI and K. CHANG

important, resulting in a higher population density in thesame area during the period.

5. Conclusion
This study has proposed a new index, ratio of new
urban land to the total area, for analyzing the process ofurban sprawl. The index combines urban expansion
intensity, a measure of the dynamics of expansion, andurban land ratio, a measure of the extent of urban land.
By having these two elements, the index can trace thedifferent stages of urban sprawl, with a strong intensity
and a low ratio in the early stage and a weak intensity anda high ratio in the late stage. Additionally, the two elements of the index can be correlated with population
growth data to separate older, more established urban
areas from younger, more dynamic urban areas. The
index provides a new tool for studies of urban land
expansion.
Several projects are being planned for improving andtesting the usefulness of the index. First, using the index
with a multi-temporal land use database can offer an
opportunity to check the process of urban land expansion
in more detail. This study was limited to the time periodof 1971–2006 and the results covered a 35-year period,
which might be too long in a dynamic region such as the
Taipei metropolitan area and Taoyuan County. Second,
this study used the total population and the total area of
each district in data analysis. In working with urban
sprawl, it would be better to use urban population andonly areas suitable for urban development for calculations. For example, one can use building laws and regulations set up by the government to select potential urban
areas. Finally, it will be important to test the index inother regions of the world such as the Pearl River Delta,
China, where intense, large-scale urban sprawl has
occurred since China’s open door policy in 1979.
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David KARACSONYIDavid KARACSONYI received his M.A. in geography (2005) and Ph.D. in earth sciences (2009)
from Eötvös Loránd University, Budapest. He has
been working at the Geographical Institute of the
Hungarian Academy of Sciences since 2009. His
specialization is human geography, migration,
rural geography of post-Soviet countries, urbanrural fringes and urban expansion in East Asia. He was a visiting fellow in
Taiwan for 10 month during 2013, supported by the Visegrad-Taiwan
Scholarship Programme, financed by the International Visegrad Fund. His
research project in Taiwan was related to GIS technologies and mapping<http://www.mtafki.hu/kutatok/karacsonyi/index_en.html>

Kang-tsung CHANG
Kang-tsung (Karl) CHANG received his B.S. ingeography from National Taiwan University(NTU) and his M.A. and Ph.D., also in geography,
from Clark University. He had a 34-year teachingcareer in the United States, before returning to
Taiwan to teach at NTU in 2005. Currently, he is achair professor at Kainan University and an
adjunct professor of geography at NTU. His research interests include thegeographic information system (GIS) and its applications, natural hazards,
and spatial analysis. He is the author of numerous journal articles on GIS,
landslide modeling and landslide mapping, as well as Introduction to
Geographic Information Systems (7th edition, 2013) published by
McGraw-Hill.

(Received 13 November 2013, Accepted 28 August 2014)