Land use dynamics, built-up land expansion patterns, and driving forces analysis of the fast-growing Hangzhou metropolitan area, eastern China (1978–2008)

Applied Geography 34 (2012) 137e145

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Land use dynamics, built-up land expansion patterns, and driving forces analysis of the fast-growing Hangzhou metropolitan area, eastern China (1978e2008) Kai-ya Wu a, Hao Zhang b, * a b

National Innovative Institute for Public Management and Public Policy, Fudan University, 220 Handan Road, Shanghai 200433, China Department of Environmental Science and Engineering, Fudan University, 220 Handan Road, Shanghai 200433, China

a b s t r a c t Keywords: Land use Remote sensing (RS) Geographic information system (GIS) Socio-economic factors Hangzhou Metropolitan Area (HMA) China

In this study, Hangzhou, the capital city of Zhejiang Province in eastern China was selected as a case study. Based on time series Landsat MSS/TM/ETM þ imagery and historical census data, analysis of the relationship between land use dynamics, built-up land expansion patterns, and underlying driving forces from 1978 to 2008 was performed, using an integrated approach of remote sensing (RS) and geographic information system (GIS) techniques and statistical methods. The results showed that rapid expansion of built-up land in the Hangzhou Metropolitan Area (HMA) led to accelerated land use conversion. The built-up land increased from 319.3 km2 in 1978 to 862.5 km2 in 2008. Expansion patterns of built-up land in the HMA were essentially characterized by axial expansion centered on the former city proper before 1991. In 1996 and 2001, two significant administrative division adjustments for the former city proper and two neighboring municipalities occurred. This led to the success in implementing strategies of “frogleaping development along the Qiantang River” and “crossing the Qiantang River and developing southward”. Spatially, a closer linkage between the former city proper and two neighboring municipalities was established. Consequently, rapid development of infrastructures, facilities, intensive industrial parks, and urban and rural settlements along the Qiantang River resulted in the eastward and southward expansion of built-up land. Thus, from 1991 to 2008 the model of urban expansion resulted in a multi-nuclei pattern. Furthermore, as shown with detailed analysis, the growth pattern of built-up land of the HMA is highly correlated with socio-economic factors, including the gross domestic product (GDP), per capita disposable income, population growth, and processes of industrialization and urbanization, which represent the dominant driving factors for spatiotemporal patterns of built-up land in the HMA. Ó 2011 Elsevier Ltd. All rights reserved.

Introduction Urbanization is a complex process that not only caused profound changes in cultural, sociological, and economical aspects but also caused significant changes in ecological and environmental aspects (Champion, 2001; Chase, Pielke, Kittel, Nemani, & Running, 1999; Grimm, Grove, Pickett, & Redman, 2000; Lambin et al., 2001). Since the end of World War II, population growth and economic expansion have been the primary drivers of land use/land cover (LULC) change associated with urbanization worldwide, especially in developing countries that have an increasing desire for prosperous economy (Li, Wang, Wang, Ma, & Zhang, 2009). Globally, with ongoing urbanization, a large population is inclined to concentrate in urban areas. It is estimated that more than 50% of

* Corresponding author. Tel.: þ86 21 55664052; fax: þ86 21 65643579. E-mail address: [email protected] (H. Zhang). 0143-6228/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.apgeog.2011.11.006

the world’s population lives in urban areas, and the projected proportion of urban population will reach 69.6% by 2050 (United Nations, 2010). Given the importance of urban growth, LULC, and their long-term adverse effects on ecological functioning, modeling LULC and urban growth has been greatly emphasized (Bhatta, 2009; Geymen & Baz, 2008; Hardin, Jackson, & Otterstrom, 2007; Long, Mao, & Dang, 2009; Maktav & Erbek, 2005; Weber & Puissant, 2003). However, less attention has been given to the development of these models to understanding the relationships between urban growth and related socio-economic processes that underlie land use change and urbanization (Irwin & Geoghegan, 2001). As the largest developing country in the world, China has recently experienced unprecedented economic growth and rapid urbanization since 1978. The country’s total number of cities increased from 193 in 1978 to 660 in 2008, and its urban population rapidly increased from 172.45 million to 606.67 million (China National Bureau of Statistics, 2009). Today, many large cities in

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the coastal economic zone, which are the preferred destination for millions of internal migrants and overseas investors, have been the locomotives in propelling China’s economic growth (Chen, Zeng, & Xie, 2000). However, with rapid development of the economy and urban expansion, the accompanied ecological deterioration and economic loss have been pronounced in these hotspots (Su, Jiang, Zhang, & Zhang, 2011; Wang, Wu, Zhang, & Wang, 2006). Therefore, the sustainability of environmental and economic systems for these large cities has attracted much attention. As documented, in the field of land use and socio-economic development, there have been thousands of significant journal papers related with China’s cities. For example, more than twenty papers on land resources exploits and sustainability of China’s cities have recently been published in Applied Geography. The present study focuses on the Hangzhou Metropolitan Area (HMA), which is the capital city of Zhejiang Province and the second largest metropolis in the Yangtze River Basin (Li & Li, 2005). Similar to the other cities in mainland China, the urbanization rate in the HMA between the 1950s and 1970s was low due to political reasons. During this period, the planned economy system, rigid state policies, and catastrophic political disorder impeded the development of a market-oriented economy and citizens’ freedom of migration nationwide. In addition, similar to the neighboring cities in the Yangtze River Basin, Hangzhou’s economic development and urbanization lagged behind cities in the Pearl River Delta before 1990. Since the national strategy of “opening Shanghai’s Pudong new area to the international investment” initialized in 1990, this city has experienced an unprecedented rate of rapid urbanization. Due to its advantageous location, economic power, and international recognition, this representative area lends itself well for providing a useful example to study LULC changes under pressure of intensive human activities. However, comprehensive studies on the relationship between spatiotemporal patterns of built-up land, planning policies, and socio-economic factors in the HMA are relatively scarce. Therefore, the purpose of this study is to examine the relationship between spatiotemporal patterns of builtup land, planning policies, and socio-economic factors using time

series of information from remotely sensed data and statistical methods. This will lead to a better understanding of land use dynamics, driving forces for expansion patterns of built-up land, and planning policies among researchers, urban planners, and decision makers. Moreover, the results from this case study will have practical implications for the other cities in the Yangtze River Basin and similar cities worldwide. Study area The study area is situated between latitudes 29 500 N and 30 320 N and longitudes 119 410 E and 120 430 E (Fig. 1). This area has a northern subtropical monsoon climate with an annual temperature of approximately 15.7e17.2  C. The rainfall duration varies between 138 and 167 days. Annual precipitation within the study area varies widely from 1352 to 1601.7 mm, of which approximately 80% is received during the April and September flood seasons. Topographically, the Qiantang River is the major river encompassing the eastward portion of the HMA. The hilly and mountainous regions account for 28.8% of the study area, with an elevation ranging from 200 to 1100 m. Most of the area is flat with a surface elevation ranging from 2 to 10 m, and the urban areas are located at elevations ranging from 2 to 3 m. Hangzhou is well known for being an international garden city with a recorded history of 2200 years. It was the capital the Southern Song dynasty (AD 1127e1279), and thus, it is widely regarded as one of China’s top seven ancient capitals due to its special cultural heritage and charming natural landscape (The Municipal Government of Hangzhou, 2007). At present, the HMA consists of six administrative wards (namely the Shangcheng district, Xiacheng district, Jianggan district, Xihu district, Bingjiang district, Gongshu district) and two municipalities, including the Yuhang district (formerly Yuhang County) and the Xiaoshan district (formerly Xiaoshan County). The HMA covers an area of approximately 3320 km2 with a total population of 4.99 million. In the end of 2008 local GDP per capita is approximately 77,230 RMB Yuan (equivalent to $11,192 US dollars) (Hangzhou Municipal Bureau of

Fig. 1. Location of the study area.

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Statistics, 2009) and is well above the national average (approximately $3315 US dollars). Methodology Remotely sensed imagery pre-processing, interpretation, and land use detection In this paper, a flowchart describing the detection procedure of LULC is shown in Fig. 2. Time series of satellite data, including five datasets of multispectral Landsat MSS/TM/ETM þ imagery acquired on July 5, 1978, August 4, 1984, July 23, 1991, October 11, 2000, and April 24, 2008, were selected for this study. Prior to interpretation, atmospheric correction was performed to standardize all the images to common reference spectral characteristics. Then, the images were geometrically rectified to a common UTM coordinate system. All the images were resampled to 30 m using the nearest neighbor algorithm to maintain the unchanged original brightness values of pixels, and the RMSE were both found within 1 pixel. The image processing and data manipulation were conducted using algorithms supplied with the GEOSTAR 3.0Ò image processing software. Furthermore, ESRI ARCGIS 10.0Ò was used for spatial analysis. Land use and land cover patterns between 1978 and 2008 were mapped by the use of Landsat MSS, TM, and ETM þ data, respectively. Herein, the classification scheme of the study area was modified based on the land use classification system developed by the China National Committee of Agricultural Divisions (1984). According to our knowledge of the study area, which is based on historical review of the literature (Hangzhou Municipal Government, 2007; Hangzhou Municipal Institute for Urban Planning, 2004) and field surveys, a predetermined classification scheme of eight categories of land covers present within the study area was established. These land covers included built-up land, cropland, fallow land, forest land, shrub land, water (mainly rivers, channels, ponds, and reservoirs), tidal land, and bare land.

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In this study, ancillary data, including land use survey data derived from historical aerial photos acquired in 2000 and 2007, an SPOT image with 2.5 m resolution acquired in 2007, two 1:10,000 digitalized topographic maps and land use maps acquired in 1988, 1991, 2000, and 2006 were used for accuracy assessment of imagery classification. For each image, 150-200 training sites were chosen to ensure that all spectral classes covering each land use and land cover category were adequately represented in the training statistics. Furthermore, the supervised signature extraction with the maximum likelihood algorithm was employed to perform the classification of the satellite images. For each image, 250 samples were randomly selected to check the accuracy of the classified maps. The overall accuracy of LULC maps between 1978 and 2008 was determined to range from 80.70% to 88.56% with an average of 84.82%, and the Kappa statistic ranged from 0.776 to 0.852 with an average of 0.816, which met the recommended value suggested by Jessen, Frans, and Wel (1994). However, further study is needed to confirm these data. Data acquisition of socio-economic factors Given the availability and comparability of census data over the study period, socio-economic factors, including regional total gross domestic product (GDP), GDP per capita, and per capita disposable income. Moreover, the annual demographic growth rate, proportion of population engaging in agriculture, shares of agricultural, industrial, and service sectors in regional total GDP were extracted from the statistical yearbook of Hangzhou (Hangzhou Municipal Bureau of Statistics, 2009) and China’s urban statistical yearbook (China National Bureau of Statistics, 2009). Statistical analysis To quantitatively examine the relationship between expansion patterns of built-up land and socio-economic factors, and therefore

Fig. 2. Flowchart of detection procedure of LULC used in this study.

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provide further information for this study, statistical analyses were performed using the commercial DPS 12.5 statistical package (Tang, 2010). Results and discussion Land use dynamics Fig. 3 showed spatiotemporal patterns of LULC in the HMA from 1978 to 2008. As observed, the extent of the land cover types varied significantly across the years, partly due to seasonal variation. For example, the image acquired in 1984 during the post-harvest can explain why fallow land was the dominant land cover type. In summary, the general description of LULC of the HMA over the study period is shown in Fig. 4. The built-up land increased by 542.50 km2, from 319.40 km2 in 1978 to 861.90 km2 in 2008, or by nearly 18.08 km2 yr1 on average. Bare land grew by 195.50 km2 or nearly by 6.52 km2 yr1 on average. In contrast, shrub land decreased by 567.60 km2 or nearly by 18.92 km2 yr1 on average, followed by water, cropland, and fallow land, which decreased by 59.00 km2 yr1, 51.70 km2 yr1, and 42.80 km2 yr1, respectively. The forest land decreased by 23.30 km2 or nearly 7.77 km2 yr1 on average. Moreover, considerable former built-up land in remote rural or mountainous areas was converted to cropland, forest land, shrub land, and the other LULC types due to land reclamation associated with rural-urban migration. However, significant increases in built-up land from the other land cover types exceeded more than the conversion from the built-up land to the other land cover types. Therefore, as shown in Fig. 3, rapid expansion of builtup land from the urban fringe to the countryside, especially the urban encroachment into natural and semi-natural ecosystems, was detected. This result showed that approximately 80.37% of the newly emerging built-up land was converted from forest land, shrub land, cropland, water, and fallow land. Another significant change was the continuous incline in bare land, which was caused mainly by emerging quarries, mining pits, and abandoned croplands enclosed for construction under the pressure of rapid urbanization. Spatiotemporal patterns of built-up land As shown in Figs. 3 and 4, and Table 1, the expansion of the builtup land of the HMA was relatively slow before 1991, but this trend accelerated between 1991 and 2000 and became even faster

Fig. 4. Temporal pattern of LULC in the HMA from 1978 to 2008.

between 2000 and 2008. Therefore, along with political and socioeconomic factors, expansion patterns of the built-up land of the HMA during the different periods can be described as follows: (1) Stage one (1978e1984): During this period, built-up land of the study area increased by 46.6 km2, from 319.4 km2 to 366 km2, at an annual growth rate of 7.77 km2. Topographically, together with the West Lake and surrounding hilly areas in the west, the Qiantang River between the city proper and Xiaoshan County played a key role in shaping the boundary of the city proper. The direction of built-up land expansion of the city proper was greatly constrained by topographical factors. Moreover, due to the lower political and economic levels for the two municipalities, development of urban/built-up lands in Xiaoshan County and Yuhang County was constrained. The built-up land was sparsely developed in several major towns. Thus, as shown in Fig. 5, most of the developed and developing built-up land was within a distance of D1 (0e3 km) to the center of city proper. The shares of built-up land in land covers rapidly decreased within distances D2 (3e6 km) and D3 (6e10 km) where the peri-urban area with factories and sparse settlements was located. In contrast, the shares of built-up land in land covers decreased slowly and stably with distances between D3 (6e10 km) and D7 (>30 km), indicating lower land use pressure for rural built-up land. Altogether, during this period a single-core pattern for development of the HMA was apparent. (2) Stage two (1984e1991): During this period, built-up land of the study area increased by 25.9 km2, from 366.0 km2 to 391.9 km2, at an annual average rate of 3.70 km2. Spatially, with the development of the radial highway and railway systems leading to the suburban industrial parks, major towns, and rural areas, expansion of the city proper occurred mainly toward the southwest, northwest, and northeast. The axial growth model of the urban development was apparent, which also caused increasing expansion of built-up land in both

Table 1 Built-up land expansion and annual expansion rate in the HMA.

Fig. 3. LULC in the HMA from 1978 to 2008.

Period

Expansion of built-up land (km2)

Annual growth rate (km2/yr)

1978e1984 1984e1991 1991e2000 2000e2008 1978e2008

46.6 25.9 177.2 292.8 542.5

7.77 3.70 19.69 36.60 18.08

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Fig. 5. Expansion patterns of built-up land in the HMA from 1978 to 2008.

Xiaoshan County and Yuhang County. However, aside from constraints in topographic conditions, administration divisions between the city proper, Xiaoshan County, and Yuhang County limited spatial expansion of the built-up land of the city proper. This division can explain the slowdown of urban growth in the HMA during this period. Therefore, the single-core pattern for development of the HMA remained nearly unchanged. Note: To measure expansion patterns of built-up land, seven radial buffer zones with different distances to the center of the city proper were made as follows: D1 (0e3 km), D2 (3e6 km), D3 (6e10 km), D4 (10e15 km), D5 (15e21 km), D6 (21e30 km), and D7 (>30 km). Accordingly, the Y axis shows shares of built-up land in all of the land covers within the different radial buffers. (3) Stage three (1991e2000): During this period, built-up land of the study area increased by 177.2 km2, from 391.9 km2 to 569.1 km2, at an annual average rate of 19.69 km2. To balance the conflicts between rapid urban sprawl and the limitation of very scarce land resources in the city proper, administrative boundaries between the city and the two municipalities were officially readjusted. In 1996, the boundaries of six towns, which belonged to Yuhang County and Xiaoshan County, were readjusted and merged into the city proper. This readjustment was approved by the Zhejiang provincial government. The extent of the city proper increased rapidly from approximately 430 km2e683 km2, which led to the success in implementing government-oriented strategies of “frog-leaping development along the Qiantang River” and “crossing the Qiantang River and developing southward” (The Municipal Government of Hangzhou, 2007). During this period, the city proper expanded eastward along the south bank of the Qiantang River, where the present Xiasa new city is well-developed. This resulted in rapid expansion of urban/built-up land in Yuhang County in the northeast, which is known today as Liping new city. Meanwhile, the development of the Hangzhou high-tech zone (HHTZ) brought the construction of the Xixing bridge, linking the city proper, HHTZ, and downtown Xiaoshan

County; Xiaoshan economic development zone (XEDZ), Xiaoshang international airport, and urban/built-up land in Xiaoshan County rapidly expanded northwest and northeast to the HHTZ and XEDZ. This is known today as Jiangnan new city at the south bank of the Qiantang River. Spatially and economically, a closer link between the city proper, Yuhang County, and Xiaoshan City was established, although Yuhang County and Xiaoshan County still remained two separate municipalities independent of the city proper. As shown in Fig. 4, the increasing shares of built-up land in land covers within distances D2 (3e6 km) and D3 (6e10 km) accelerated the trend of suburbanization at the peri-urban area. Consequently, during this period, a preliminary multi-nuclei pattern formed for the development of the HMA. (4) Stage four (2000e2008): During this period, built-up lands of the study area increased by 292.8 km2, from 369.1 km2 to 861.9 km2, at an annual average rate of 36.6 km2. With the implemention of strategies of “frog-leaping development along the Qiantang River” and “crossing the Qiantang River and developing in Xiaoshan”, the closer linkage between the former city proper and the two municipalities required a new administrative system for balancing the conflicts among the inter-administrative regions and for promoting regional economic integration. This strong demand was reflected in the most recent master planning of Hangzhou city (2001e2020) (The Municipal Government of Hangzhou, 2007). In 2001, approved by the State Council of China, administrative boundaries between Yuhang County, Xiaoshan County and the former city proper were readjusted and merged to shape the greater Hangzhou region. To a large degree, this merge eliminated the former administration division that constrained urban development for the HMA. During this period, a series of development plans for a multi-nuclei pattern of the HMA were made and put in practice. As a result, rapid development of infrastructures, facilities, industrial parks, and urban and rural settlements emerged along the Qiantang River, resulting in the eastward and southward expansion of built-up land. As shown in Fig. 5, a slight decrease in the shares of built-up land in land

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covers within distances D1 (0e3 km) and D2 (3e6 km) was observed. In contrast, shares of built-up land in land covers between distances D3 and D7 (>30 km) increased remarkably, indicating a high pressure of land development for built-up land in the peri-urban area and rural regions. Therefore, as shown in Fig. 6, rapid expansion of built-up land was observed in all directions. It is noted that the city proper, Xiasa new city, Jiangnan new city, Liping new city, and six newly emerging satellite towns (namely Liangzu town, Tangqi town, Yuhang town, Lingpu town, Guali town, and Yipeng town) shaped the multi-nuclei pattern of the HMA. Relationship between growth pattern of built-up land and socio-economic factors Economic growth and its effect Success in economic development can be evaluated with the total gross domestic product (GDP), GDP per capita, and per capita disposable income. Over this study period, regional total GDP increased 40.32 times, from 2123.01 million RMB Yuan (equivalent to $1415.34 million US dollars) in 1978e378891.51 million RMB Yuan (equivalent to $58,480.08 million US dollars) in 2008, with an annual average growth rate of 11.17%. The GDP per capita increased 22.97 times, from 733.5 RMB Yuan (equivalent to $489 US dollars) in 1978 to 77,230 RMB Yuan (equivalent to $11,720 US dollars) in 2008, with an annual average growth rate of 13.21%. Additionally, during the study period, per capita disposable income for urban residents (PCDI_UR) increased 70.31 times, from 338 RMB Yuan (equivalent to $225.33 US dollars) to 24,104 RMB Yuan (equivalent to $3524.09 US dollars). Per capita disposable income for rural residents (PCDI_RR) increased 65.0 times, from 162 RMB Yuan (equivalent to $108 US dollars) to 10,692 RMB Yuan (equivalent to $1560.88 US dollars). Figs. 7 and 8 show the significant logarithmic regression relationship between total GDP, GDP per capita, and built-up area. Furthermore, a multivariate regression was derived:

Built-up area ¼ 296 þ 0.055PCDI_URþ0.249PCDI_RR (R2 ¼ 0.97, p < 0.01). All these fitted regression models demonstrated that increasing economic activities and economic output led to increasing land use for urban growth. Several factors may help explain the relationships between economic variables and urban growth. With robust economic growth, local governments prepared to expand their public finances for development purposes, including generous investments in urban regeneration, key infrastructures, universities and schools, industrial parks, and so on. On the other hand, local enterprises, especially the booming non-state-owned enterprises that dominated local economy tended to expand reproduction or invest new commercial facilities. Simultaneously, both urban and rural residents tended to increase unproductive expenditure, which stimulated local enterprises’ production and reproduction. Therefore, economic growth stimulated the demand for more land development, resulting in rapid expansion of built-up land from the city proper to surrounding rural areas. Population growth and its effect In the HMA, total population increased by 72.66%, from 2.89 million in 1978 to 4.99 million in 2008. However, it should be noted that due to a rigid national policy for population mobility, before the late 1980s, no one was permitted to leave his or her birthplace, seek employment, receive education, or settle in the other cities without special official certification. To a large extent, this depressed urban population growth and urban expansion during the period of planned economy. As witnessed, the urbanization rate measured by the proportion of the population living in urban areas ranged from 17 to 18% (China National Bureau of Statistics, 2008). Thus, the local registered population (namely, permanent residents) in Hangzhou increased slowly and stably. According to a nationwide flexible policy for population migration, both rural and urban residents were permitted to seek employment, receive education, or settle anywhere without any statutory restriction since the 1990s. Therefore, to a large degree, this resulted in

Fig. 6. Hotspots showing recently rapid expansion of built-up lands in the HMA.

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Fig. 9. Relationship between population growth and built-up land in the HMA from 1978 to 2008. Fig. 7. Relationship between regional total GDP and built-up area in the HMA from 1978 to 2008.

unprecedented intra- and inter-province migration in mainland China. Currently, rural-urban migration from remote rural areas to large cities has been a dominant source for urbanization growth nationwide (Zhang & Song, 2003). In the HMA, domestic immigrants, including the intra- and inter-province population, increased from 0.09 million in 1991 to 0.75 million in 2008. Currently, the domestic immigrants accounts for 15.03% of the total population. Fig. 9 showed a significant power regression relation between the total population and built-up area of the study area, indicating the direct effect of population growth on urban land expansion. With the increase in population, both per capita residential areas for urban and rural residents grew remarkably. Over the study period, per capita residential areas for urban residents increased 1.55 times, from 8.8 m2 to 22.4 m2; per capita residential areas for rural residents increased 1.99 times, from 23.3 m2 to 69.7 m2. To accommodate an increasing population, additional settlements in the urban fringe were rapidly developed. As a result, urban areas have expanded into rural areas. Industrialization, urbanization process, and their effects Industrialization and urbanization in the HMA, especially the newly emerging intensive economic development zones and residential areas along the Qiantang River, have triggered dramatic land use change from cultivated land to market-oriented land used for urban/built-up land. As shown in Fig. 2, only 16.95% of the present built-up land were from the built-up land itself. In other words, it indicated that approximately 83.05% of the net increase in built-up land was from the other land covers. In contrast, newly emerging built-up lands have increased by 169.85% from 1978 to

Fig. 8. Relationship between GDP per capita and built-up area in the HMA from 1978 to 2008.

2008, of which 69.02% were reallocated from what were formerly forest land (9.89%), shrub land (24.4%) and cropland (34.74%). This can be explained by the strong competition between urban expansion and non-urban land use, including agriculture, forestry, and other rural land use (Long, Tang, Li, & Heilig, 2007; Reynolds, 2000). In the conversion of low return lands to high return developmental use, forests and shrubs were cleared for cultivation and more croplands were used to meet increasing demand for urban development. Fig. 10 showed that the shares of agriculture/primary industry (mainly farming, forestry, fishery, husbandry and ranching), secondary industry (mainly mining, refining, manufacturing, energy and water supply, construction) and tertiary industry (mainly service and trade) in total GDP were 27.02%, 59.25%, and 13.73%, respectively, in 1978; however, they were 2.17%, 47.28%, and 50.55%, respectively, in 2008. Simultaneously, in response to significant changes in sector composition among the constituent ratios of total population for major professions, the percentage of the population engaging in agriculture decreased by 33.11%, from 65.91% in 1978 to 32.8% in 2008. This indicated the ongoing trends of agricultural land loss and urban growth, which were witnessed with rapid expansion of industrial parks, urban and rural settlements, and infrastructures. For example, the growth of town and village enterprises (TVEs) and the development of an exportoriented economy have transformed the industrial pattern of the HMA radically since the mid-1980s. The output value of TVEs in the HMA amounted to 14.55 million RMB Yuan (equivalent to $9.7 million US dollars) in 1978, which only accounted for 0.48% of the local total output value of industry. The output value of TVEs sharply increased to 675,330 million RMB Yuan (equivalent to

Fig. 10. Change in shares of industries in regional total GDP from 1978 to 2008.

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$98,588 million US dollars) in 2008, which accounted for 82.64% of the local total output value of industry. Rapid development of TVEs provided employment for the former population engaging in agriculture and for migrate workers (Chen, 2004; Lin, 1993). At present, local TVEs employed 2.63 million workers, which accounted for 62.45% of the total workers in the HMA. To accommodate numerous workers employed by the TVEs, housing, traffic and commercial facilities were rapidly developed by enterprises and townships. This caused a great change both in social and economic aspects, which are often cited as rural urbanization (Cui & Ma, 1999). Thus, to a large extent, witnessed as the miniature of a society from rural to recently urbanized, the TVEs played a key role in changing under-urbanization of China, although restrictions on ruraleurban migration still caused insufficient urbanization (Chang & Brada, 2006). Furthermore, Fig. 11 showed a negative logarithmic regression relation between the proportion of the population engaging in agriculture and built-up land area in the study area. This demonstrated rural-urban migration and labor mobility during recent industrialization and urbanization. As a result, there was strong demand for land development, which, in turn, intensified land use in urban area and stimulated expansion of built-up land. Implications for land use policy and urbanization Urban growth patterns, which were reflected as expansion patterns of built-up land, varied across different regions and countries during different developing periods. On a macro scale, effective political and economic institutions are the major determinants in shaping development patterns. This was largely demonstrated by the difference between developed countries with relatively perfect institutional systems and less developed countries that lacked these systems (Hall & Jones, 1999). Institutionally, according to China’s constitution, private land ownership is absolutely prohibited. The governments assume the role of an actual supervisor in the development of land resources and therefore dominate in the decision making for land use, urban planning, and public investment for infrastructure systems. This is known as the traditional top-down pattern for government-oriented urbanization with Chinese characteristics, aimed at limiting the freedom of rural population migration into cities to avoid uncontrolled population growth and accompanied adverse social and environmental problems. Thus, compared with case studies from other developing countries where uncontrolled population growth resulted in problematic land use and environmental deterioration (Dewan & Yamaguchi, 2009; Geymen & Baz, 2008; Henrıquez, Azocar, & Romero, 2006), the Chinese government’s policies were shown to

be effective in controlling population migration and sprawl of illegal settlements, although they were criticized for impeding urban growth and economic development. Currently, it is widely accepted that the objective of a state political system must serve the economic development during China’s recent transition from a planned economy to a marketoriented economy. This triggered changes in the top-down pattern of government-dominated decision making. Similar to well-developed cities such as Dongguan, Shenzhen, and Foshan in southern China, the traditional top-down institution for economic development in our study area gave way to the so-called dual-track urbanization, which is the mixture of the government-oriented urbanization and the bottom-up urbanization (Shen, Feng, & Wong, 2006). In this context, local governments still monopolize the primary land market and dominate public investments in infrastructure systems (Yan, 2010). However, the rich towns with strong demand for land development began to persuade local governments to reconsider and change their policies and strategies for land use and urban development. Since the late 1980s, nonstate-owned enterprises, especially the TVEs boomed, and the well-developed towns in Yuhang County and Xiaoshan County played a key role in suburbanization of the peri-urban area. Given the importance of non-state-owned enterprises, especially the booming TVEs, in local economic growth, there is an increasing demand for land development in fringe areas. Furthermore, public investments from rich towns for rural development rapidly surpassed that from the governments by benefitting from the industrialization propelled by the TVEs. This remarkably resulted in the accelerated rural-urban migration from remote hilly and mountainous areas to the well-developedtownships located in the alluvial plains and, thus, accelerated expansion of the built-up land. Currently, high speed in development of mega cities is a problematic dream due to overloading population growth, severe environmental deterioration, and scarcity of land resources. By merging neighboring municipalities and pushing rural-urban migration via recent adjustment for administrative boundaries, the HMA experienced unprecedented development. It is typical to develop the metropolitan area in the context of dual-track urbanization. However, as shown in the aforementioned sections, large amount of conversion from natural and semi-natural to built-up land occurred. Given the ongoing trends in population growth and urban expansion, it is predicted that urbanization has inevitably impaired ecosystem functioning and will aggravate environmental sustainability of the HMA. Thus, coordination among the administrative agencies should be strengthened to balance the conflicts between land use competition between urban development and ecological conservation. Conclusions

Fig. 11. Relationship between proportion of population engaging in agriculture and area of built-up land in the HMA from 1978 to 2008.

Using the HMA as an example, this study profiled and highlighted the relationship between land use dynamics, built-up land expansion patterns, and driving forces in fast-growing mega cities in China from 1978 to 2008. Due to topographic constraints and low economic and population growth rates, the expansion of the builtup land of the HMA was relatively slow before 1991, which was very common in the Yangtze River Basin. The model of urban expansion of the HMA is essentially characterized by the axial expansion centered on the former city proper before 1991. However, due to two significant administrative division adjustments for the former city proper and two neighboring municipalities in 1996 and 2001, the government-oriented strategies of “frog-leaping development along the Qiantang River” and “crossing the Qiantang River and developing southward” were successfully implemented. As a result, the rapid development of infrastructures, facilities, intensive

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industrial parks, and urban and rural settlements along the Qiantang River resulted in the eastward and southward expansion of built-up land. Thus, the expansion of the built-up land of the HMA accelerated between 1991 and 2000 and became even faster between 2000 and 2008. Consequently, the model of urban expansion was a multi-nuclei pattern from 1991 to 2008. Furthermore, economic development, population growth, industrialization, and urbanization played key roles in affecting spatiotemporal patterns of urban growth and dramatic changes in land use in the fast-growing HMA. As shown with detailed analysis, the expansion patterns of built-up land in the HMA are highly correlated with socio-economic factors, including the gross domestic product (GDP), per capita disposable income, population growth, industrialization and urbanization processes, which represent the dominant factors driving the expansion of the built-up land and urban growth patterns of the HMA. Acknowledgments This study was partly financed by the Youth Science Foundation of Fudan University (Grant No. EXH591330) and the National Science Foundation of China (Grant No. 41171432 and No.71173047). The authors are grateful to Ms. L. J. Yan, N.N. Zhang, Y. Zhang, and Mr. P. F. Luo at the Hangzhou Municipal Bureau of Planning for their generous help with field surveys and collecting the data. References Bhatta, B. (2009). Analysis of urban growth pattern using remote sensing and GIS: a case study of Kolkata, India. International Journal of Remote Sensing, 30(18), 4733e4746. Champion, T. (2001). Urbanization, suburbanisation, counterurbanisation and reurbanisation. In R. Paddison (Ed.), Handbook of urban studies (pp. 143e161). London: Sage. Chang, G. H., & Brada, J. C. (2006). The paradox of China’s growing under-urbanization. Economic Systems, 30, 24e40. Chase, T. N., Pielke, R. A., Kittel, T. G. F., Nemani, R. R., & Running, S. W. (1999). Simulated impacts of historical land cover changes on global climate in northern winter. Climate Dynamics, 16, 93e105. Chen, D. Y. (2004). Study on policies for development of industrial parks in Hangzhou. Hangzhou Science and Technology, 5, 19e21, (in Chinese). Chen, S., Zeng, S., & Xie, C. (2000). Remote sensing and GIS for urban growth analysis in China. Photogrammetric Engineering & Remote Sensing, 66(5), 593e598. China National Bureau of Statistics. (2008). Series report for China’s 30-year achievements in social and economic development since reform and open to the outside world (Report 7). http://www.stats.gov.cn/tjfx/ztfx/jnggkf30n/t20081104_402514247. htm Latest access on 1.10.11. China National Bureau of Statistics. (2009). China statistical yearbook 2009. Beijing: China Statistical Press. (in Chinese). China National Committee of Agricultural Divisions. (1984). Technical regulation of investigation on land use status. Beijing: Surveying and Mapping Publishing House. (in Chinese)5e20. Cui, G., & Ma, L. J. C. (1999). Urbanization from below in China: its development and mechanisms. Acta Geographica Sinica, 54(2), 106e115, (in Chinese). Dewan, A. M., & Yamaguchi, Y. (2009). Land use and land cover change in Greater Dhaka, Bangladesh: using remote sensing to promote sustainable urbanization. Applied Geography, 29(3), 390e401. Geymen, A., & Baz, I. (2008). Monitoring urban growth and detecting land-cover changes on the Istanbul metropolitan area. Environmental Monitoring and Assessment, 136, 449e459.

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