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Urbanization, land use, and water quality in Shanghai
Environment International 29 (2003) 649 – 659 www.elsevier.com/locate/envint
Urbanization, land use, and water quality in Shanghai 1947–1996 Wenwei Ren a, Yang Zhong a, John Meligrana b,*, Bruce Anderson c, W. Edgar Watt c, Jiakuan Chen a, Hok-Lin Leung b a
Key Laboratory of Biodiversity Science and Ecological Engineering, Ministry of Education of China, School of Life Sciences, Fudan University, Shanghai, People’s Republic of China b School of Urban and Regional Planning, Queen’s University, Kingston, Ontario, Canada K7L 3N6 c Department of Civil Engineering, Queen’s University, Kingston, Ontario, Canada Received 3 August 2002; accepted 10 February 2003
Abstract The paper undertakes a preliminary investigation into the relationship between water quality and urbanization as well as the changing patterns of land use within Shanghai. Longitudinal changes to water quality at various points along the course of the Huangpu River are analysed and compared to changes in the rates of urbanization and changes in land uses. The results reveal that rapid urbanization corresponds with rapid degradation of water quality. It also shows that urban land uses are positively correlated with the decline in water quality. A regression model shows that close to 94% of the variability in water quality classifications is explained by industrial land area. The paper concludes with the need for comprehensive land use planning as a way of protecting valuable water resources. D 2003 Elsevier Science Ltd. All rights reserved. Keywords: Urbanization; Land use; Water quality; Shanghai; Huangpu River
1. Introduction Shanghai’s significant economic expansion and corresponding high rates of urbanization have brought rapid changes to this megacity’s urban spatial structure and greatly increased the amount of stress, in the form of waste and pollutants, on the ecosystem. These changes have significantly and adversely affected Shanghai’s water quality. Yet, Shanghai is not alone among the other megacities in the developing world, such as Calcutta, Istanbul, Mexico City, and Sao Paulo, which are grappling with the complex challenge of balancing rapid urbanization with the preservation and maintenance of water supply and quality (Arreguin, 1996; Baykal et al., 2000; Goldenstein, 1998; Robles et al., 1999). In Shanghai’s case, the municipal government has recently identified the provision of clean water, to both enhance the standard of living of its residents and protect the natural environment, as a key government objective (Chen and Bao, 1994; Cheng et al., 2000; Yuan and Tu, 1996; Ge,
1998; Ward and Liang, 1995; Yuan, 2000; Yuan and James, 2002). This paper therefore undertakes a preliminary investigation into the relationship between water quality and urbanization as well as the changing land uses within Shanghai. It does so by focussing on the longitudinal changes to water quality at various points along the course of the Huangpu River. The Huangpu River, which drains an area of approximately 24,000 km2 and has a volume exceeding 10 billion cubic metres annually, is the main watercourse through Shanghai. The paper begins with an examination of the rate of urbanization as well as the changing patterns of land use within Shanghai between 1947 and 1996. It then provides an analysis of the relationship between changes in water quality and changes in the rate of urbanization and land uses. The paper concludes with directions for future research.
2. Research context and background * Corresponding author. Tel.: +1-613-533-2188; fax: +1-613-5336905. E-mail address: [email protected] (J. Meligrana).
The study of the relationship between water quality and urbanization is not new. Specific emphasis has been placed
0160-4120/03/$ - see front matter D 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0160-4120(03)00051-5
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Table 1 Chinese Government water quality classifications No.
Parameter
1
Water temperature (jC)
2 3* 4* 5* 6* 7* 8* 9 10 11 12 13 14 15 16
pH Sulfate (as SO4) V Chloride (as Cl ) V Iron (as Fe2 +) Total manganese (as Mn2 +) Total copper (as Cu2 +) Total zinc V (as Zn2 +) Nitrate nitrogen (as N) V Nitrite nitrogen (as N) V Non-ionic ammonia Kjeldahl nitrogen V Total phosphorus (as P) V Permanganate value V Dissolved oxygen z Chemical oxygen demand (COD) V Biochemical oxygen demand (BOD5) V Fluoride (as F ) V Selenium (IV) V Total arsenic V Total mercury V Total cadmium V Total chromium (VI) V Total lead V Total cyanide V Volatile phenol V Oils (ether extractable) V Anionic surface-active agents V Total coliform group bacteria (#/l) V Benzo(a)pyrene (Ag/l) V
Water quality classifications I
17 18 19 20 21 22 23 24 25 26 27 28 29 30
II
III
IV
V
Human activities induced temperature changes of the water environment should be within: summer weekly average maximum temperature rise V 1; winter weekly average maximum temperature down V 2 6.5 – 8.5 below 250 250 250 250 below 250 250 250 250 below 0.3 0.3 0.5 0.5 below 0.1 0.1 0.1 0.5 below 0.1 1.0 1.0 1.0 0.05 1.0 1.0 2.0 below 10 10 20 20 0.06 0.1 0.15 1.0 0.02 0.02 0.02 0.2 0.5 0.5 1.0 2.0 0.02 0.1 0.1 0.2 2.0 4.0 6.0 8.0 90% of saturation value 6.0 5.0 3.0 below 15 below 15 15 20
6–9 250 250 1.0 1.0 1.0 2.0 25 1.0 0.2 2.0 0.2 10.0 2.0 25
below 3.0
3.0
6.0
10
below 1.0 below 0.01 0.05 0.05 0.001 0.01 0.01 0.005 0.002 0.05 below 0.2
1.0 0.01 0.05 0.05 0.005 0.05 0.05 0.05 0.002 0.05 0.2
1.5 0.02 0.1 0.1 0.005 0.05 0.05 0.2 0.01 0.5 0.3
1.5 0.02 0.1 0.1 0.01 0.1 0.1 0.2 0.1 1.0 0.3
0.0025
0.0025
4.0 1.0 0.01 0.05 0.05 0.005 0.05 0.05 0.2 0.005 0.05 0.2 10,000 0.0025
Units are mg/l, except for pH and Class I of soluble oxygen and unless otherwise stated. For a complete list of standards, see GB 3838-88; available at: http://www.muep.net/gb3838-8.htm. * Adjustments of standard values are allowed in accordance with the characteristics for the background values of local water.
on how urbanization influenced the chemistry of spring water (Al-Kharabsheh, 1999), the temperature of urban streams (LeBlanc et al., 1997), and the reduction of urban groundwater supplies (Gupta, 2002). Other research has examined how the form and rate of urbanization influence water quality. For example, Goda (1991) examined the effects of density and industrial activities on a range of water quality classifications. Wang (2001) provides a comprehensive examination of the spatial variation to water quality across an entire watershed. His findings reveal a strong relationship between the degradation of water quality and urban land use. Previous research, however, is deficient with respect to examining the variation of water quality across an entire city-region and over time. For example, how different environments (e.g., urban, suburban, rural) and different land uses (e.g., industrial, residential, etc.) within a cityregion influence water quality remains to be fully examined. Also, the literature offers only a ‘‘snap-shot’’ of urban water
quality for one or a limited number of periods. Links between the changing urban spatial structure and water quality over an extended period is an important dimension Table 2 Urban area and rates of urbanization in Shanghai City Proper, 1947 – 1996 Urbanized area (km2) 1947 1958 1964 1979 1984 1988 1993 1996 1947 – 1996
111.8 146.9 165.5 184.8 207.7 229.2 250.4 269.9
Increase in urban area* (km2)
Annual rate of urbanization* (km2)
35.1 18.6 19.3 22.9 21.5 21.2 19.5 158.1
3.19 3.10 1.29 4.58 5.38 4.24 6.50 3.23
Percent urban** 40 52.4 59 65.9 72.3 81.7 89.3 96.2
* Over the previous report year. ** The city proper boundaries are held constant giving a total area of 280 km2.
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Table 3 Urban land uses within Shanghai’s City Proper, 1947 – 1996 Residential Row Industrial – Row Roads Row Public land Row Agricultural Row Greenbelt Row Other % commercial % use (km2) % (km2) % (km2) % (km2) (km2) (km2) % (km2) 1947 32.71 1958 46.38 1964 49.08 1979 49.45 1984 57.19 1988 65.91 1993 79.73 1996 85.67 1947 – 1996 53.00 Change in area (km2) 1947 – 1996 (%) 161.9
11.7 16.5 17.5 17.6 20.4 23.5 28.4 30.5
16.2 19.16 33.19 45.73 52.11 60.86 63.44 60.13 43.90
271.2
5.8 6.8 11.8 16.3 18.6 21.7 22.6 21.4
28.78 40.46 40.56 41.02 41.13 42.89 43.92 41.99 13.20
10.3 14.4 14.5 14.6 14.7 15.3 15.7 15.0
45.9
9.52 14.74 16.16 20.32 23.87 28.25 28.98 29.57 20.10
210.6
3.4 5.3 5.8 7.2 8.5 10.1 10.3 10.5
188.87 153.08 130.4 110.9 91.98 64.75 39.76 29.82 159.10
84.2
67.3 54.6 46.5 39.5 32.8 23.1 14.2 10.6
1.42 4.66 4.55 6 6.18 6.93 6.86 7.85 6.40
452.8
0.5 1.7 1.6 2.1 2.2 2.5 2.4 2.8
2.95 1.97 6.51 7.52 7.59 10.86 17.94 26.42 23.50
Row Total % (km2) 1.1 0.7 2.3 2.7 2.7 3.9 6.4 9.4
280 280 280 281 280 280 281 281
795.6
Source: Shanghai Statistical Yearbook.
to monitoring and planning for improvements to urban water resources. This paper’s examination of 50 years of water and urban data for the entire Shanghai urban region helps to fill this gap within the literature. Previous research has identified a number of water quality challenges confronting Shanghai. The following is a brief overview of these challenges. First, the development of modern and intensive agricultural practices has introduced chemical fertilizers and insecticides into the urban environment. The residues of these chemicals flow into the river during rainfall events, causing river eutrophication
among other impacts (Kung Hsiang and Ying Long, 1991). Second, the low capacity of sewage treatment has resulted in industrial and residential waste being discharged directly into the City’s watershed (Ward and Liang, 1995). Third, the pollution sources have gradually changed from point sources to non-point sources. These non-point sources include fertilizer, insecticides, domestic animal waste from agricultural activities, and wastewater from village and town-owned factories. The amount of pollutants coming from non-point sources account for more than 60% of the total pollutants (Huang and Chen, 1998).
Fig. 1. Shanghai city-region illustrating the city proper and the water quality sampling sites.
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To set the spatial context to this paper’s analysis of Shanghai’s water quality, a brief overview of the geography of this city-region is provided. This overview also serves to define key spatial terms and concepts critical to an understanding of the methodology used by this paper to link changes in water quality to changes in urbanization and land uses (Tables 1– 3). Shanghai is located within a vast inland plain of the Changjiang (Yangtze) River basin (Fig. 1). This flat and fertile land plain is a highly productive agricultural area as well as an area upon which urban growth has rapidly taken place. The total area of the Municipality of Shanghai is 6340 km2 of which 6219 km2 is land and 121 km2 is water (Editorial Committee, 1998). A small portion of this area is identified as the City Proper. This is largely an administrative term which defines the City’s central business district, the new Pudong financial area and surrounding suburban districts. The land uses within the City Proper contain a range of urban and rural land uses (Tables 2 and 3). The urban land uses include industrial, commercial, residential, and supporting land uses, such as roads, which define the urbanized area of the City Proper (Table 2). The City Proper also includes rural land uses, mainly agricultural. A portion of this agricultural land is protected from development, while the rest is held as urban reserve land. This urban reserve is defined as rural lands that are available for urban development. If more urban land is required than is procurable within the City Proper, it is annexed from surrounding counties. Therefore, the size of Shanghai’s City Proper has increased over the years to accommodate the need for more urban land. Currently, the size of the City Proper is 280 km2. Areas beyond Shanghai’s City Proper are divided into administrative regions known as counties. In theory, the counties contain and maintain the agricultural land uses, while the urban area, as discussed above, is contained within the City Proper. In practice, however, pockets of industrial and other suburban land uses, e.g., low density residential and commercial developments, are occurring in the counties.
3. Methodology This section is divided into three parts. The first describes and justifies the water quality sampling sites. Next, the water quality classification system is described (Table 1). Then the databases from which information was collected on historical changes to Shanghai’s urban spatial structure and water quality is discussed. 3.1. Sampling sites Water quality data were collected for five sites along Shanghai’s Huangpu River for eight census years:1947, 1958, 1964, 1979, 1984, 1988, 1993, and 1996. Historical records as well as samples collected by the authors were
used to determine the water quality classifications at each site for each period. The selection of water sampling sites along the Huangpu River is important for two main reasons. First, it is Shanghai’s primary source of drinking water, providing over 80% of the city’s water supply. It is therefore postulated that the water quality of the Huangpu River represents, to a degree, the general water quality situation in the whole of Shanghai. The river’s water quality has also been the subject of extensive research and government efforts at rehabilitation. Second, the Huangpu River traverses the vast spectrum of land use change within Shanghai’s urban region (Fig. 1). For example, the Huangpu’s 113-km journey begins at Dianshan Lake and enters Shanghai from the west, a mainly rural –agricultural area, and then flows through the city’s suburban areas and continues through numerous industrial areas and the city’s urban core before emptying into the Yangtze River. In fact, the Huangpu River divides Shanghai’s urban core into two main areas: Puxi (Western Shanghai), which has an over one hundred year history of urban development, and Pudong (Eastern Shanghai), which has developed in only 10 years from mainly farmland to a burgeoning international financial centre. Furthermore, most of Shanghai’s water bodies are tributaries of the Huangpu River, for example, Suzhou Creek, which is the second main river flowing through Shanghai. These two reasons form the basis for this paper’s analysis of the relationship between water quality and urbanization in Shanghai. The sampling sites are discussed in more detail below and in Section 3.3. The location of the five water quality sampling sites provides information on water quality across the entire land use spectrum of the Shanghai city-region (Fig. 1). Sites 1 and 2 are located in the upper reaches of the Huangpu River: Site 1 is located in the headwaters and serves as a reference or control site; and Site 2 is located in a mainly rural – agricultural area. Sites 3, 4, and 5 are located in the lower reaches of the river: Site 3 is located on the edge of the city proper; Site 4 is located within the central business district; and Site 5 is located at the river’s mouth. 3.2. Water classification and monitoring The water quality at each sampling site was classified according to the Chinese Government standard for water quality issued in 1988 (GB 3838-88). This standard includes the following five water classifications: Category I. It is mainly applicable to the source of the water bodies and the national nature preserves. This is the highest water quality classification and includes water that requires only simple disinfection. Such water can be used for drinking, recreation, fish production, agricultural irrigation, industrial uses, etc.
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Category II. It is mainly applicable to water source protection area for centralized drinking water supply, sanctuaries for rare species of fish, spawning grounds of fishes and shrimps, etc. This water quality classification identifies slightly polluted water. This water can only become part of the water supply after pertinent treatment, i.e., treatment specific to the particular pollutant. Category III. It is mainly applicable to water source protection area for centralized drinking water supply, sanctuaries for common species of fish, and swimming zones. Water in this classification can only enter the water supply after a series of physical, chemical, and biological treatments. Category IV. It is mainly applicable to water bodies for general industrial water supply and recreational waters in which there is no direct contact of the human body with the water. Water in this category represents polluted water and requires complex treatment before being used for agricultural irrigation and industrial uses except for those like food and textile industries, which need a higher quality of water. Category V. It is mainly applicable to water bodies for agricultural water supply and for the general landscape requirements. It is seriously polluted water. In addition to the above five water quality classifications, a sixth classification, V+, is commonly used by government reporting agencies to indicate water quality worse than the national standard. In other words, it is used where water quality results far exceed the criteria set for classifying water within Category V. The above qualitative descriptions of water quality classifications are based on a series of quantitative indices and formulas developed by the Chinese Government (Table 1). China’s National Environmental Protection Agency provides a guideline for the monitoring of surface water. This guideline includes the Huangpu River, which is sampled from three vertical lines located 0.5 m below surface. Two samples are taken during each of the rainy, regular, and dry seasons. For each of the six sampling events, four water samples are collected at different tidal levels (United Nations Economic and Social Commision for Asia and the Pacific (UNESCAP), 2002). The number of variables used to place water in one of the five water quality classifications, as noted above, varied with each period given the available historical record. For example, in 1947, only four variables were used to classify water quality which increased to 30 indices used in 1988 as a result of the adoption of national water quality standards. Although the number of indices varies by period, the classification of water quality remained constant. In other words, the authors applied the 1988 national water quality classifications (Table 1) to the available historical water sampling records even though such national standards did not exist.
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Using water classifications that span over 50 years is an appropriate vehicle for discussing long-term changes to water quality. Another comparative procedure, using raw water quality information, suggests that the same testing methods, variables/indices, and technologies were available during each sampling year. This is not the case. In other words, the analysis of actual water sampling results during each sampling period over the entire study period would, in the opinion of the authors, mistakenly portray historical water data as representing uniform standards of measurement. However, a common classification method was applied to all the raw water quality variables throughout the study period. Thus, the discussion is limited to the water quality classifications alone and not to test results for each variable used to measure water quality at each site during each period. This may seem subjective, yet, the purpose of this paper is to illustrate general trends in water quality and urbanization over a 50-year period. The authors assert that this is an initial exploration into a longitudinal study of water quality changes over an extensive period. Given the varying quality of the historical records, the authors made some modifications to the water quality classifications by awarding half scores, such as a classification of 2.5 rather than 2 or 3. This was done when the historical record indicated that the water quality classification could be in either category. This could occur when a proportion of the indices fall into one classification and a similar proportion fall into a different water quality classification. In fact, the Chinese Government routinely classifies water quality using half scores (Yuan, 2000). 3.3. Data collection, analysis, and limitations The data were obtained from published government reports, for example, the Shanghai Municipal Statistical Year Book, the Atlas of Shanghai, and various environmental and water quality reports, as well as unpublished water data provided by the Shanghai Environmental Protection Agency, and related research undertaken by the authors (Shanghai Statistic Bureau, 1950 – 1998). Fortunately, the five water sampling sites represent a constant and uninterrupted record of water quality spanning over six decades. This corresponds to a period of significant change to the urban-economic development of Shanghai. Unfortunately, there are no regularly published data regarding urbanization and land use trends for the Shanghai city-region. The Shanghai Statistical Yearbook records the most comprehensive and consistent urban data, but only for the years 1947, 1958, 1964, 1979, 1984, 1988, 1993, and 1996. Although representing uneven temporal periods, collectively, the yearbook records over 50 years of urban development. Therefore, these eight years are used as the basis to document the trend and relationship between urbanization and changes in water quality in Shanghai.
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A further limitation of the above database is that changes in urbanization and land uses are only recorded for Shanghai’s City Proper. Thus, the land uses and urban trends in the catchment area of each water sampling site are unknown. To overcome this limitation, changes in water quality classifications for the sample sites located within and adjacent to the City Proper were compared to the changes in land uses and rates of urbanization for the entire City Proper. This enabled a general comparison of changes in water quality and urbanization. Specifically, sampling site nos. 4 and 5 are located within Shanghai’s City Proper, while sampling site no. 3 is located adjacent to it. Although Site 3 is located just outside the City Proper, the backwash of the Haungpu River, a result of the tidal influence of the East China Sea on the Yangtze River, provides a strong potential for land use influence on water quality samples taken at this site. Previous research has discovered that the transfer and the accumulation of water pollutants in Shanghai are sensitive to tides. With the change in tides, the pollutants often flow up and down the river channel, thus, they do not easily flow out of the city proper and into the sea (Cheng et al., 2000). The variations in water quality classifications for the five sampling sites were compared to the change in the rate of urban growth. The water quality classifications for the sampling sites within and adjacent to the City Proper over the study period were plotted against the proportion of various land uses, e.g., agricultural, residential, and industrial, as well as the percent of the urban land within the City Proper. The sampling sites located outside the City Proper are not included as the land uses adjacent to these sites over the study period are unknown as mentioned above. A stepwise multiple regression model using SPSS was produced to determine the relative importance of various land uses on water quality classifications. Stepwise regression models have been applied by a number of researchers studying water quality and its relationship to urbanization (Wang, 2001). The stepwise regression builds a model by examining each land use variable at each step for entry or removal. The significance values in the output are based on fitting a single model. All land use variables must pass the tolerance criterion to be entered in the equation. Also, a land use variable is not entered if it would cause the tolerance of another land use variable already in the model to drop below the tolerance criterion. The default tolerance level used was 0.0001. The focus of this paper on the potential influence of land use change and urbanization on water quality has a number of limitations in addition to those addressed above. First, approximately 40% of Shanghai’s wastewater currently receives at least primary treatment. This low capacity of sewage treatment is an important variable in water quality analysis. However, the authors’ longitudinal study of changes in water quality can best be correlated to changes in land uses and urbanization given the limitations of the
historical database, with the understanding that wastewater discharges will probably have a significant influence on any observed decline in water quality. Second, the water quality classifications for each site represent a cumulative effect of water quality degradation throughout the entire river system. In particular, Sites 3, 4, and 5 are influenced by factors degrading the water quality in the upper reaches of the Huangpu River. This indicates that factors beyond urbanization and land use change within the City Proper are likely influencing the water quality sampled at Sites 3, 4, and 5. Nevertheless, the correlation of water quality classifications with changing land uses isolates a single variable, land use/urbanization, as a first step toward a comprehensive analysis of water quality change over time and across a large cityregion.
4. Results 4.1. Urbanization rates and land-use types in Shanghai Table 2 shows the urban area and the rate of its expansion in Shanghai’s City Proper for the eight periods between 1947 and 1996. In 1947, Shanghai’s built-up area was approximately 112 km2, which expanded to over 269 km2 by 1996, an increase of over 158 km2. The urban expansion of Shanghai’s City Proper can be divided into three distinct growth periods: (i) a period of sustained urban growth (1947 – 1964), (ii) a period of slow urban growth (1964 – 1979), and (iii) a period of rapid urban growth (1979 –1996). During the period of sustained urban growth of the 1950s and early 1960s, Shanghai’s built-up area expanded by approximately 35.1 and 18.6 km2, 1947 –1958 and 1959– 1964, respectively. During this time, Shanghai City Proper grew at a steady rate of just over 3 km2 per year, slightly lower than the average of 3.25 km2 per year for the entire study period, 1947– 1996. The proportion of urban land use in the city proper increased from 40% in 1947 to almost 60% in 1964. The period of slow urban growth occurred between the mid-to-late 1960s and the 1970s. During this time, the annual rate of urbanization was only 1.29 km2, the lowest of all the periods. The proportion of total land area classified as urban increased from approximately 60 – 72% between 1964 and 1979. This slow rate of urbanization corresponds to the period of China’s Cultural Revolution (1966 – 1976). In contrast, the annual rate of urbanization was at its highest with over 6.5 km2 of land per year converted to urban uses during the 1980s and 1990s. Furthermore, of the total 158 km2 increase in urban area over half of that occurred between 1979 and 1996. The proportion of
W. Ren et al. / Environment International 29 (2003) 649–659 Table 4 Water quality classifications for each sampling site, 1947 – 1996 Census year
Site 1
Site 2
Site 3
Site 4
Site 5
1947 1958 1964 1979 1984 1988 1993 1996
1 1 2 2 2 2 2.5 2.5
1 2 2 2 3 3 3.5 3.5
2 2 3 3 4 4 4 4
3 3 3 3.5 4 4.5 5 5.5
2 2 2 3 4 4 4 4
urban land increased from 72% at the start of the 1980s to over 96% by the mid-1990s. This period of rapid urban growth corresponds to the swift market reforms to China’s economy. The areal distribution of land uses within Shanghai’s City Proper recorded during each of the 8 years between 1947 and 1996 was also investigated (Table 3). Both residential and industrial land uses recorded the largest absolute increase in area between 1947 and 1996, increases of 53 and 44 km2, respectively. Within a total built-up area of 280 km2, residential land uses increased by over 160% from 32.7 km2 in 1947 to 85.67 km2 in 1996. Industrial land uses increased from 16.2 km2 in 1947 to 63.44 km2 in 1993. After 1993, the amount of industrial land began to decrease due to the closure and relocation of large factories beyond the City Proper. By 1996, industrial land decreased to 60.13 km2, but it still accounts for approximately 20% of the entire City Proper area. In general, Shanghai has a proportionately higher percentage of land use devoted to industry than many other large cities (Ta, 1994). Roads recorded the smallest percentage increase of all land uses, an increase of only 45.9% representing a change in area from approximately 29 km2 in 1947 to 42 km2 in 1996, an enlargement of only 13.2 km2. In contrast, greenbelt land use expanded the fastest among all land uses, recording a 450% increase in area from 1947 to 1996. However, the greenbelt area accounts for less than 10% of the City Proper in 1996, up from 0.5% in 1947. Public land uses (e.g., schools, engineering works, etc.), increased in area by over 20 km2, from 9.5 km2 in 1947 to over 29.5 in 1996. Agricultural land was the only land use category to decline in total area. Specifically, agricultural land use accounted for over twothirds of all land uses in 1947, however, this dropped to under 11% in 1996, a decline of 84% representing a total loss of over 159 km2 within the City Proper between 1947 and 1996. The changing trends to the proportion of different land uses may explain some of the reasons for Shanghai’s water quality problems. In particular, the rapid decline in agriculture land, the high proportion of industrial land, and the lack of green space may be contributing factors to Shanghai’s rapidly deteriorating water quality. For example, as agricultural land declined, it was replaced by industrial or resi-
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dential land, which, in general, has a much greater potential for degrading water quality. Furthermore, the agricultural land use during the early part of the study period, i.e., 1940s/1950s, was not very advanced in terms of using technology, such as chemicals and motorized equipment, and therefore would not likely have as negative an effect on water quality as urban and residential land uses. 4.2. Correlation between urbanization, land use, and water quality of Shanghai The water quality classifications for the five sampling sites from 1947 to 1996 are shown in Tables 4 and 5. (It should be noted that the classification is an inverse index, therefore, the higher the score, the worse the water quality). The change in water quality classification for all sites along the Huangpu River reveals a rapid deterioration of water quality between 1947 and 1996. The sampling sites located in the City Proper (e.g., Sites 3, 4, and 5) consistently scored higher, i.e., poorer, water classifications than the sites located outside, indicating the strong influence of intense urban activity on the water quality within the lower reaches of the Huangpu River. Specifically, Site 4 has the worst water quality classification among all sites throughout the study period. Its rapid increase in water quality classification is illustrated by the sharp rise, from 3.5 to 5.5, between the 1980s and 1990s (Table 4). In 1993, Site 4 is the only sample site to achieve the worst water quality classification, i.e., Category V. This can be attributed to the fact that this site is located in one of the most densely populated and most intensively industrialized parts of Shanghai. The two other sites in the City Proper achieved one classification better than Site 4, i.e., Category IV. Site 5’s improved classification in comparison to Site 4 can be attributed, to a degree, to the dilution effect from the Changjiang River. Site 3’s location on the edge of the urban area suggests that its classification is better than Site 4 due, in part, to the following factors: (i) the relatively cleaner water from the upper reacher of the Huangpu River and (ii) adjacent developments, particularly industrial, are newer than the relatively older and poorer designed factories located adjacent to Site 4 and are therefore expected to have better environmental controls and practices.
Table 5 Changes in water quality classifications* and urban growth periods, 1947 – 1996 Period
Site 1
Site 2
Site 3
Site 4
Site 5
Sustained urban growth, 1947 – 1964 Slow urban growth, 1964 – 1979 Rapid urban growth, 1979 – 1996 Overall, 1947 – 1996
+1
+1
+1
no change + 0.5
no change + 1.5
no change +1
no change + 0.5
no change +1
+2
+1
+ 1.5
+ 2.5
+ 2.0
+ 2.5
+ 2.0
* Increment in index scores.
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The sites located outside the City Proper (e.g., Sites 1 and 2) consistently recorded lower (i.e., better) water quality classifications than the other sampling sites (Table 4). These sites are the only ones to start with the best water quality classification at the beginning of the study period, i.e., Category I. However, Site 2 (as with Site 4) registered the largest increase in water quality classification from 1 to 3.5, an increase of 2.5 classifications between 1947 and 1996. While Site 1’s increased classification increased by 1.5 units, from 1 to 2.5, over the entire study period. This might be attributed to the changing farming practices in the suburban areas of Shanghai particularly the increasing use of chemicals. It may also be related to suburbanization of industry. This is also a location of ad hoc development with few controls or regulations. In particular, the operation of village/town industrial enterprises in the suburban areas of Shanghai are commonly believed to be heavy polluters as
they lack the knowledge, resources, and technology to deal with industrial waste. Most are run by villagers (i.e., farmers) with little or no education regarding environmental protection. The variations in water quality classifications for the five sampling sites correspond to the different growth periods (Table 5). During the period of sustained urban growth (1947 – 1964), Sites 4 and 5’s water quality classification remained unchanged, likely the result of the fact that these sites started with very high classifications. Sites 1, 2, and 3 each recorded an increase of one water quality classification unit during this period. The largest increase in water quality classifications, i.e., over one classification unit, occurred during Shanghai’s period of rapid urban growth (1979 – 1996). During this period, all sites recorded an increase in water quality classification. This is in contrast to the period of slow urban growth (1964 –1979) when the change in
Fig. 2. (a) Proportion of urban land and water quality classifications. (b) Proportion of residential land and water quality classifications. (c) Proportion of industrial land and water quality classifications. (d) Proportion of agricultural land and water quality classifications.
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Fig. 2 (continued).
water quality classification increased by half a classification for Site 4, one classification for Site 5, and the three other sites remaining unchanged. Sites 1, 2, and 3 record no change in water quality classifications. Fig. 2a and Table 6 reveal a strong positive correlation between the water quality classification and urbanization. As the percent of land area within the City Proper becomes increasingly urban, the water quality classifications become progressively worse. This is observed for all three sampling sites. The strength of the correlation is indicated by the high R2 values that range from 0.80 for Site 5 to 0.83 for Site 3 and 0.91 for Site 4. Site 4’s higher R value may be an indication of its geographic location within the heart of Shanghai’s built-up area. In contrast to Fig. 2a, Fig. 2d illustrates a strong negative correlation between the percent of agricultural land and the water quality classifications for the three sampling sites. As the percent of agricultural land increases a corresponding
decline in water quality classifications is observed. The R2 value reveals a strong relationship with values ranging from a high of 0.89 for Site 4 to a low of 0.81 for Site 5 (Table 6). The proportion of residential and industrial lands have positive correlations with the water quality classifications for each sampling site within the City Proper (Table 6). For percent residential land, the strongest R2 of 0.92 is recorded by Site 4, while Sites 3 and 5 have somewhat weaker values, 0.70 and 0.68, respectively. The R2 values for the scatterplot Table 6 Correlation of land uses and water quality classifications
Urban land use* Residential land use Industrial land use Agricultural land use
Site 3 R2
Site 4 R2
Site 5 R2
0.83 0.70 0.93 0.85
0.91 0.92 0.78 0.89
0.80 0.68 0.89 0.81
* Urban land use includes residential, industrial, and other land uses.
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Table 7 Stepwise regression model of urban land uses and water quality classifications, Shanghai City Proper Sample site
Independent variables included in regression model*
R2
Independent variables excluded from regression model
Site 3
Industrial land use (km2)
0.94
Site 4
Industrial land use (km2)
0.92
Site 5
Industrial land use (km2)
0.89
Public land use (km2), residential land use (km2), agricultural land use (km2), road area (km2), greenbelt (km2), other land use (km2) Public land use (km2), residential land use (km2), agricultural land use (km2), road area (km2), greenbelt (km2), other land use (km2) Public land use (km2), residential land use (km2), agricultural land use (km2), road area (km2), greenbelt (km2), other land use (km2)
* The dependent variable is the water quality classification.
of industrial land use versus water quality classifications also indicates a strong relationship (Fig. 2b; Table 6). In particular, the highest R2 of 0.93 was registered by Site 3, followed by 0.89 for Site 5 and 0.78 for Site 4 (Fig. 2b and c; Table 6). The stepwise regression model for the Sites 3, 4, and 5 shows that a strong variability in water quality classifications is explained by industrial land area (Table 7). In fact, industrial land use is the only land use to predict water quality classifications for all three sites. Residential, agricultural, roads, public, greenbelt, and other land uses were excluded variables from the stepwise regression model. In particular, the R2 value was highest for Site 3, 0.94, and slightly lower for Sites 4 and 5, values of 0.92 and 0.89, respectively. This indicates the strong influence of industrial land use on the changing water quality classifications over the study period. However, the type and nature of industrial activities, changing technologies, and other factors need to be more fully explored. Overall, the regression analysis points to the need to develop land use planning policies and regulations that are sensitive to the preservation of water quality.
5. Conclusion This paper examined the water quality at five sampling sites along the course of Shanghai’s Huangpu River between 1947 and 1996. The analysis revealed that rapid urbanization corresponds to the rapid degradation of water quality. There is also a strong positive correlation between proportion of urban land use (e.g., residential and industrial) and worsening water quality classifications. However, there is a strong negative correlation between the proportion of agricultural land and water quality classifications. It appears that land use is an important contributor and
explaining factor regarding the quality of water in Shanghai. Thus, the management of land with respect to its development and use needs to be addressed in any attempt to mitigate against the further erosion of water quality classifications along the Huangpu River. Therefore, the findings of this paper suggest that land use planning policies need to work in tandem with technological solutions to improve Shanghai’s water quality. Controlling the rate, form, and type of urbanization can play an important role in protecting valuable urban water resources. This points to the fact that no single approach can be effectively used for water quality control in a megacity such as Shanghai. Rather, an integrated management strategy, which includes a number of disciplines, such as environmental engineering and urban-regional planning, is required. It also suggests that longitudinal studies that attempt to link changes to the urban spatial structure of a city-region to changes in water quality needs to be further studied. Ongoing and consistent monitoring of changes to water quality will assist in identifying how land use planning can help to ensure the preservation of water resources. It is important to provide benchmarks on which to measure the environmental performance of future attempts to improve Shanghai’s water quality.
Acknowledgements The authors wish to acknowledge the support received from Dr. John Dixon, Associate Vice-Principal, Queen’s University. This paper is the result of funds obtained from the Memorandum of Understanding between Queen’s University (Kingston) and Fudan University (Shanghai) and the Principal’s Development Fund Grant Number 379 035.
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Urbanization, land use, and water quality in Shanghai 1947–1996 Wenwei Ren a, Yang Zhong a, John Meligrana b,*, Bruce Anderson c, W. Edgar Watt c, Jiakuan Chen a, Hok-Lin Leung b a
Key Laboratory of Biodiversity Science and Ecological Engineering, Ministry of Education of China, School of Life Sciences, Fudan University, Shanghai, People’s Republic of China b School of Urban and Regional Planning, Queen’s University, Kingston, Ontario, Canada K7L 3N6 c Department of Civil Engineering, Queen’s University, Kingston, Ontario, Canada Received 3 August 2002; accepted 10 February 2003
Abstract The paper undertakes a preliminary investigation into the relationship between water quality and urbanization as well as the changing patterns of land use within Shanghai. Longitudinal changes to water quality at various points along the course of the Huangpu River are analysed and compared to changes in the rates of urbanization and changes in land uses. The results reveal that rapid urbanization corresponds with rapid degradation of water quality. It also shows that urban land uses are positively correlated with the decline in water quality. A regression model shows that close to 94% of the variability in water quality classifications is explained by industrial land area. The paper concludes with the need for comprehensive land use planning as a way of protecting valuable water resources. D 2003 Elsevier Science Ltd. All rights reserved. Keywords: Urbanization; Land use; Water quality; Shanghai; Huangpu River
1. Introduction Shanghai’s significant economic expansion and corresponding high rates of urbanization have brought rapid changes to this megacity’s urban spatial structure and greatly increased the amount of stress, in the form of waste and pollutants, on the ecosystem. These changes have significantly and adversely affected Shanghai’s water quality. Yet, Shanghai is not alone among the other megacities in the developing world, such as Calcutta, Istanbul, Mexico City, and Sao Paulo, which are grappling with the complex challenge of balancing rapid urbanization with the preservation and maintenance of water supply and quality (Arreguin, 1996; Baykal et al., 2000; Goldenstein, 1998; Robles et al., 1999). In Shanghai’s case, the municipal government has recently identified the provision of clean water, to both enhance the standard of living of its residents and protect the natural environment, as a key government objective (Chen and Bao, 1994; Cheng et al., 2000; Yuan and Tu, 1996; Ge,
1998; Ward and Liang, 1995; Yuan, 2000; Yuan and James, 2002). This paper therefore undertakes a preliminary investigation into the relationship between water quality and urbanization as well as the changing land uses within Shanghai. It does so by focussing on the longitudinal changes to water quality at various points along the course of the Huangpu River. The Huangpu River, which drains an area of approximately 24,000 km2 and has a volume exceeding 10 billion cubic metres annually, is the main watercourse through Shanghai. The paper begins with an examination of the rate of urbanization as well as the changing patterns of land use within Shanghai between 1947 and 1996. It then provides an analysis of the relationship between changes in water quality and changes in the rate of urbanization and land uses. The paper concludes with directions for future research.
2. Research context and background * Corresponding author. Tel.: +1-613-533-2188; fax: +1-613-5336905. E-mail address: [email protected] (J. Meligrana).
The study of the relationship between water quality and urbanization is not new. Specific emphasis has been placed
0160-4120/03/$ - see front matter D 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0160-4120(03)00051-5
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Table 1 Chinese Government water quality classifications No.
Parameter
1
Water temperature (jC)
2 3* 4* 5* 6* 7* 8* 9 10 11 12 13 14 15 16
pH Sulfate (as SO4) V Chloride (as Cl ) V Iron (as Fe2 +) Total manganese (as Mn2 +) Total copper (as Cu2 +) Total zinc V (as Zn2 +) Nitrate nitrogen (as N) V Nitrite nitrogen (as N) V Non-ionic ammonia Kjeldahl nitrogen V Total phosphorus (as P) V Permanganate value V Dissolved oxygen z Chemical oxygen demand (COD) V Biochemical oxygen demand (BOD5) V Fluoride (as F ) V Selenium (IV) V Total arsenic V Total mercury V Total cadmium V Total chromium (VI) V Total lead V Total cyanide V Volatile phenol V Oils (ether extractable) V Anionic surface-active agents V Total coliform group bacteria (#/l) V Benzo(a)pyrene (Ag/l) V
Water quality classifications I
17 18 19 20 21 22 23 24 25 26 27 28 29 30
II
III
IV
V
Human activities induced temperature changes of the water environment should be within: summer weekly average maximum temperature rise V 1; winter weekly average maximum temperature down V 2 6.5 – 8.5 below 250 250 250 250 below 250 250 250 250 below 0.3 0.3 0.5 0.5 below 0.1 0.1 0.1 0.5 below 0.1 1.0 1.0 1.0 0.05 1.0 1.0 2.0 below 10 10 20 20 0.06 0.1 0.15 1.0 0.02 0.02 0.02 0.2 0.5 0.5 1.0 2.0 0.02 0.1 0.1 0.2 2.0 4.0 6.0 8.0 90% of saturation value 6.0 5.0 3.0 below 15 below 15 15 20
6–9 250 250 1.0 1.0 1.0 2.0 25 1.0 0.2 2.0 0.2 10.0 2.0 25
below 3.0
3.0
6.0
10
below 1.0 below 0.01 0.05 0.05 0.001 0.01 0.01 0.005 0.002 0.05 below 0.2
1.0 0.01 0.05 0.05 0.005 0.05 0.05 0.05 0.002 0.05 0.2
1.5 0.02 0.1 0.1 0.005 0.05 0.05 0.2 0.01 0.5 0.3
1.5 0.02 0.1 0.1 0.01 0.1 0.1 0.2 0.1 1.0 0.3
0.0025
0.0025
4.0 1.0 0.01 0.05 0.05 0.005 0.05 0.05 0.2 0.005 0.05 0.2 10,000 0.0025
Units are mg/l, except for pH and Class I of soluble oxygen and unless otherwise stated. For a complete list of standards, see GB 3838-88; available at: http://www.muep.net/gb3838-8.htm. * Adjustments of standard values are allowed in accordance with the characteristics for the background values of local water.
on how urbanization influenced the chemistry of spring water (Al-Kharabsheh, 1999), the temperature of urban streams (LeBlanc et al., 1997), and the reduction of urban groundwater supplies (Gupta, 2002). Other research has examined how the form and rate of urbanization influence water quality. For example, Goda (1991) examined the effects of density and industrial activities on a range of water quality classifications. Wang (2001) provides a comprehensive examination of the spatial variation to water quality across an entire watershed. His findings reveal a strong relationship between the degradation of water quality and urban land use. Previous research, however, is deficient with respect to examining the variation of water quality across an entire city-region and over time. For example, how different environments (e.g., urban, suburban, rural) and different land uses (e.g., industrial, residential, etc.) within a cityregion influence water quality remains to be fully examined. Also, the literature offers only a ‘‘snap-shot’’ of urban water
quality for one or a limited number of periods. Links between the changing urban spatial structure and water quality over an extended period is an important dimension Table 2 Urban area and rates of urbanization in Shanghai City Proper, 1947 – 1996 Urbanized area (km2) 1947 1958 1964 1979 1984 1988 1993 1996 1947 – 1996
111.8 146.9 165.5 184.8 207.7 229.2 250.4 269.9
Increase in urban area* (km2)
Annual rate of urbanization* (km2)
35.1 18.6 19.3 22.9 21.5 21.2 19.5 158.1
3.19 3.10 1.29 4.58 5.38 4.24 6.50 3.23
Percent urban** 40 52.4 59 65.9 72.3 81.7 89.3 96.2
* Over the previous report year. ** The city proper boundaries are held constant giving a total area of 280 km2.
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Table 3 Urban land uses within Shanghai’s City Proper, 1947 – 1996 Residential Row Industrial – Row Roads Row Public land Row Agricultural Row Greenbelt Row Other % commercial % use (km2) % (km2) % (km2) % (km2) (km2) (km2) % (km2) 1947 32.71 1958 46.38 1964 49.08 1979 49.45 1984 57.19 1988 65.91 1993 79.73 1996 85.67 1947 – 1996 53.00 Change in area (km2) 1947 – 1996 (%) 161.9
11.7 16.5 17.5 17.6 20.4 23.5 28.4 30.5
16.2 19.16 33.19 45.73 52.11 60.86 63.44 60.13 43.90
271.2
5.8 6.8 11.8 16.3 18.6 21.7 22.6 21.4
28.78 40.46 40.56 41.02 41.13 42.89 43.92 41.99 13.20
10.3 14.4 14.5 14.6 14.7 15.3 15.7 15.0
45.9
9.52 14.74 16.16 20.32 23.87 28.25 28.98 29.57 20.10
210.6
3.4 5.3 5.8 7.2 8.5 10.1 10.3 10.5
188.87 153.08 130.4 110.9 91.98 64.75 39.76 29.82 159.10
84.2
67.3 54.6 46.5 39.5 32.8 23.1 14.2 10.6
1.42 4.66 4.55 6 6.18 6.93 6.86 7.85 6.40
452.8
0.5 1.7 1.6 2.1 2.2 2.5 2.4 2.8
2.95 1.97 6.51 7.52 7.59 10.86 17.94 26.42 23.50
Row Total % (km2) 1.1 0.7 2.3 2.7 2.7 3.9 6.4 9.4
280 280 280 281 280 280 281 281
795.6
Source: Shanghai Statistical Yearbook.
to monitoring and planning for improvements to urban water resources. This paper’s examination of 50 years of water and urban data for the entire Shanghai urban region helps to fill this gap within the literature. Previous research has identified a number of water quality challenges confronting Shanghai. The following is a brief overview of these challenges. First, the development of modern and intensive agricultural practices has introduced chemical fertilizers and insecticides into the urban environment. The residues of these chemicals flow into the river during rainfall events, causing river eutrophication
among other impacts (Kung Hsiang and Ying Long, 1991). Second, the low capacity of sewage treatment has resulted in industrial and residential waste being discharged directly into the City’s watershed (Ward and Liang, 1995). Third, the pollution sources have gradually changed from point sources to non-point sources. These non-point sources include fertilizer, insecticides, domestic animal waste from agricultural activities, and wastewater from village and town-owned factories. The amount of pollutants coming from non-point sources account for more than 60% of the total pollutants (Huang and Chen, 1998).
Fig. 1. Shanghai city-region illustrating the city proper and the water quality sampling sites.
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To set the spatial context to this paper’s analysis of Shanghai’s water quality, a brief overview of the geography of this city-region is provided. This overview also serves to define key spatial terms and concepts critical to an understanding of the methodology used by this paper to link changes in water quality to changes in urbanization and land uses (Tables 1– 3). Shanghai is located within a vast inland plain of the Changjiang (Yangtze) River basin (Fig. 1). This flat and fertile land plain is a highly productive agricultural area as well as an area upon which urban growth has rapidly taken place. The total area of the Municipality of Shanghai is 6340 km2 of which 6219 km2 is land and 121 km2 is water (Editorial Committee, 1998). A small portion of this area is identified as the City Proper. This is largely an administrative term which defines the City’s central business district, the new Pudong financial area and surrounding suburban districts. The land uses within the City Proper contain a range of urban and rural land uses (Tables 2 and 3). The urban land uses include industrial, commercial, residential, and supporting land uses, such as roads, which define the urbanized area of the City Proper (Table 2). The City Proper also includes rural land uses, mainly agricultural. A portion of this agricultural land is protected from development, while the rest is held as urban reserve land. This urban reserve is defined as rural lands that are available for urban development. If more urban land is required than is procurable within the City Proper, it is annexed from surrounding counties. Therefore, the size of Shanghai’s City Proper has increased over the years to accommodate the need for more urban land. Currently, the size of the City Proper is 280 km2. Areas beyond Shanghai’s City Proper are divided into administrative regions known as counties. In theory, the counties contain and maintain the agricultural land uses, while the urban area, as discussed above, is contained within the City Proper. In practice, however, pockets of industrial and other suburban land uses, e.g., low density residential and commercial developments, are occurring in the counties.
3. Methodology This section is divided into three parts. The first describes and justifies the water quality sampling sites. Next, the water quality classification system is described (Table 1). Then the databases from which information was collected on historical changes to Shanghai’s urban spatial structure and water quality is discussed. 3.1. Sampling sites Water quality data were collected for five sites along Shanghai’s Huangpu River for eight census years:1947, 1958, 1964, 1979, 1984, 1988, 1993, and 1996. Historical records as well as samples collected by the authors were
used to determine the water quality classifications at each site for each period. The selection of water sampling sites along the Huangpu River is important for two main reasons. First, it is Shanghai’s primary source of drinking water, providing over 80% of the city’s water supply. It is therefore postulated that the water quality of the Huangpu River represents, to a degree, the general water quality situation in the whole of Shanghai. The river’s water quality has also been the subject of extensive research and government efforts at rehabilitation. Second, the Huangpu River traverses the vast spectrum of land use change within Shanghai’s urban region (Fig. 1). For example, the Huangpu’s 113-km journey begins at Dianshan Lake and enters Shanghai from the west, a mainly rural –agricultural area, and then flows through the city’s suburban areas and continues through numerous industrial areas and the city’s urban core before emptying into the Yangtze River. In fact, the Huangpu River divides Shanghai’s urban core into two main areas: Puxi (Western Shanghai), which has an over one hundred year history of urban development, and Pudong (Eastern Shanghai), which has developed in only 10 years from mainly farmland to a burgeoning international financial centre. Furthermore, most of Shanghai’s water bodies are tributaries of the Huangpu River, for example, Suzhou Creek, which is the second main river flowing through Shanghai. These two reasons form the basis for this paper’s analysis of the relationship between water quality and urbanization in Shanghai. The sampling sites are discussed in more detail below and in Section 3.3. The location of the five water quality sampling sites provides information on water quality across the entire land use spectrum of the Shanghai city-region (Fig. 1). Sites 1 and 2 are located in the upper reaches of the Huangpu River: Site 1 is located in the headwaters and serves as a reference or control site; and Site 2 is located in a mainly rural – agricultural area. Sites 3, 4, and 5 are located in the lower reaches of the river: Site 3 is located on the edge of the city proper; Site 4 is located within the central business district; and Site 5 is located at the river’s mouth. 3.2. Water classification and monitoring The water quality at each sampling site was classified according to the Chinese Government standard for water quality issued in 1988 (GB 3838-88). This standard includes the following five water classifications: Category I. It is mainly applicable to the source of the water bodies and the national nature preserves. This is the highest water quality classification and includes water that requires only simple disinfection. Such water can be used for drinking, recreation, fish production, agricultural irrigation, industrial uses, etc.
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Category II. It is mainly applicable to water source protection area for centralized drinking water supply, sanctuaries for rare species of fish, spawning grounds of fishes and shrimps, etc. This water quality classification identifies slightly polluted water. This water can only become part of the water supply after pertinent treatment, i.e., treatment specific to the particular pollutant. Category III. It is mainly applicable to water source protection area for centralized drinking water supply, sanctuaries for common species of fish, and swimming zones. Water in this classification can only enter the water supply after a series of physical, chemical, and biological treatments. Category IV. It is mainly applicable to water bodies for general industrial water supply and recreational waters in which there is no direct contact of the human body with the water. Water in this category represents polluted water and requires complex treatment before being used for agricultural irrigation and industrial uses except for those like food and textile industries, which need a higher quality of water. Category V. It is mainly applicable to water bodies for agricultural water supply and for the general landscape requirements. It is seriously polluted water. In addition to the above five water quality classifications, a sixth classification, V+, is commonly used by government reporting agencies to indicate water quality worse than the national standard. In other words, it is used where water quality results far exceed the criteria set for classifying water within Category V. The above qualitative descriptions of water quality classifications are based on a series of quantitative indices and formulas developed by the Chinese Government (Table 1). China’s National Environmental Protection Agency provides a guideline for the monitoring of surface water. This guideline includes the Huangpu River, which is sampled from three vertical lines located 0.5 m below surface. Two samples are taken during each of the rainy, regular, and dry seasons. For each of the six sampling events, four water samples are collected at different tidal levels (United Nations Economic and Social Commision for Asia and the Pacific (UNESCAP), 2002). The number of variables used to place water in one of the five water quality classifications, as noted above, varied with each period given the available historical record. For example, in 1947, only four variables were used to classify water quality which increased to 30 indices used in 1988 as a result of the adoption of national water quality standards. Although the number of indices varies by period, the classification of water quality remained constant. In other words, the authors applied the 1988 national water quality classifications (Table 1) to the available historical water sampling records even though such national standards did not exist.
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Using water classifications that span over 50 years is an appropriate vehicle for discussing long-term changes to water quality. Another comparative procedure, using raw water quality information, suggests that the same testing methods, variables/indices, and technologies were available during each sampling year. This is not the case. In other words, the analysis of actual water sampling results during each sampling period over the entire study period would, in the opinion of the authors, mistakenly portray historical water data as representing uniform standards of measurement. However, a common classification method was applied to all the raw water quality variables throughout the study period. Thus, the discussion is limited to the water quality classifications alone and not to test results for each variable used to measure water quality at each site during each period. This may seem subjective, yet, the purpose of this paper is to illustrate general trends in water quality and urbanization over a 50-year period. The authors assert that this is an initial exploration into a longitudinal study of water quality changes over an extensive period. Given the varying quality of the historical records, the authors made some modifications to the water quality classifications by awarding half scores, such as a classification of 2.5 rather than 2 or 3. This was done when the historical record indicated that the water quality classification could be in either category. This could occur when a proportion of the indices fall into one classification and a similar proportion fall into a different water quality classification. In fact, the Chinese Government routinely classifies water quality using half scores (Yuan, 2000). 3.3. Data collection, analysis, and limitations The data were obtained from published government reports, for example, the Shanghai Municipal Statistical Year Book, the Atlas of Shanghai, and various environmental and water quality reports, as well as unpublished water data provided by the Shanghai Environmental Protection Agency, and related research undertaken by the authors (Shanghai Statistic Bureau, 1950 – 1998). Fortunately, the five water sampling sites represent a constant and uninterrupted record of water quality spanning over six decades. This corresponds to a period of significant change to the urban-economic development of Shanghai. Unfortunately, there are no regularly published data regarding urbanization and land use trends for the Shanghai city-region. The Shanghai Statistical Yearbook records the most comprehensive and consistent urban data, but only for the years 1947, 1958, 1964, 1979, 1984, 1988, 1993, and 1996. Although representing uneven temporal periods, collectively, the yearbook records over 50 years of urban development. Therefore, these eight years are used as the basis to document the trend and relationship between urbanization and changes in water quality in Shanghai.
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A further limitation of the above database is that changes in urbanization and land uses are only recorded for Shanghai’s City Proper. Thus, the land uses and urban trends in the catchment area of each water sampling site are unknown. To overcome this limitation, changes in water quality classifications for the sample sites located within and adjacent to the City Proper were compared to the changes in land uses and rates of urbanization for the entire City Proper. This enabled a general comparison of changes in water quality and urbanization. Specifically, sampling site nos. 4 and 5 are located within Shanghai’s City Proper, while sampling site no. 3 is located adjacent to it. Although Site 3 is located just outside the City Proper, the backwash of the Haungpu River, a result of the tidal influence of the East China Sea on the Yangtze River, provides a strong potential for land use influence on water quality samples taken at this site. Previous research has discovered that the transfer and the accumulation of water pollutants in Shanghai are sensitive to tides. With the change in tides, the pollutants often flow up and down the river channel, thus, they do not easily flow out of the city proper and into the sea (Cheng et al., 2000). The variations in water quality classifications for the five sampling sites were compared to the change in the rate of urban growth. The water quality classifications for the sampling sites within and adjacent to the City Proper over the study period were plotted against the proportion of various land uses, e.g., agricultural, residential, and industrial, as well as the percent of the urban land within the City Proper. The sampling sites located outside the City Proper are not included as the land uses adjacent to these sites over the study period are unknown as mentioned above. A stepwise multiple regression model using SPSS was produced to determine the relative importance of various land uses on water quality classifications. Stepwise regression models have been applied by a number of researchers studying water quality and its relationship to urbanization (Wang, 2001). The stepwise regression builds a model by examining each land use variable at each step for entry or removal. The significance values in the output are based on fitting a single model. All land use variables must pass the tolerance criterion to be entered in the equation. Also, a land use variable is not entered if it would cause the tolerance of another land use variable already in the model to drop below the tolerance criterion. The default tolerance level used was 0.0001. The focus of this paper on the potential influence of land use change and urbanization on water quality has a number of limitations in addition to those addressed above. First, approximately 40% of Shanghai’s wastewater currently receives at least primary treatment. This low capacity of sewage treatment is an important variable in water quality analysis. However, the authors’ longitudinal study of changes in water quality can best be correlated to changes in land uses and urbanization given the limitations of the
historical database, with the understanding that wastewater discharges will probably have a significant influence on any observed decline in water quality. Second, the water quality classifications for each site represent a cumulative effect of water quality degradation throughout the entire river system. In particular, Sites 3, 4, and 5 are influenced by factors degrading the water quality in the upper reaches of the Huangpu River. This indicates that factors beyond urbanization and land use change within the City Proper are likely influencing the water quality sampled at Sites 3, 4, and 5. Nevertheless, the correlation of water quality classifications with changing land uses isolates a single variable, land use/urbanization, as a first step toward a comprehensive analysis of water quality change over time and across a large cityregion.
4. Results 4.1. Urbanization rates and land-use types in Shanghai Table 2 shows the urban area and the rate of its expansion in Shanghai’s City Proper for the eight periods between 1947 and 1996. In 1947, Shanghai’s built-up area was approximately 112 km2, which expanded to over 269 km2 by 1996, an increase of over 158 km2. The urban expansion of Shanghai’s City Proper can be divided into three distinct growth periods: (i) a period of sustained urban growth (1947 – 1964), (ii) a period of slow urban growth (1964 – 1979), and (iii) a period of rapid urban growth (1979 –1996). During the period of sustained urban growth of the 1950s and early 1960s, Shanghai’s built-up area expanded by approximately 35.1 and 18.6 km2, 1947 –1958 and 1959– 1964, respectively. During this time, Shanghai City Proper grew at a steady rate of just over 3 km2 per year, slightly lower than the average of 3.25 km2 per year for the entire study period, 1947– 1996. The proportion of urban land use in the city proper increased from 40% in 1947 to almost 60% in 1964. The period of slow urban growth occurred between the mid-to-late 1960s and the 1970s. During this time, the annual rate of urbanization was only 1.29 km2, the lowest of all the periods. The proportion of total land area classified as urban increased from approximately 60 – 72% between 1964 and 1979. This slow rate of urbanization corresponds to the period of China’s Cultural Revolution (1966 – 1976). In contrast, the annual rate of urbanization was at its highest with over 6.5 km2 of land per year converted to urban uses during the 1980s and 1990s. Furthermore, of the total 158 km2 increase in urban area over half of that occurred between 1979 and 1996. The proportion of
W. Ren et al. / Environment International 29 (2003) 649–659 Table 4 Water quality classifications for each sampling site, 1947 – 1996 Census year
Site 1
Site 2
Site 3
Site 4
Site 5
1947 1958 1964 1979 1984 1988 1993 1996
1 1 2 2 2 2 2.5 2.5
1 2 2 2 3 3 3.5 3.5
2 2 3 3 4 4 4 4
3 3 3 3.5 4 4.5 5 5.5
2 2 2 3 4 4 4 4
urban land increased from 72% at the start of the 1980s to over 96% by the mid-1990s. This period of rapid urban growth corresponds to the swift market reforms to China’s economy. The areal distribution of land uses within Shanghai’s City Proper recorded during each of the 8 years between 1947 and 1996 was also investigated (Table 3). Both residential and industrial land uses recorded the largest absolute increase in area between 1947 and 1996, increases of 53 and 44 km2, respectively. Within a total built-up area of 280 km2, residential land uses increased by over 160% from 32.7 km2 in 1947 to 85.67 km2 in 1996. Industrial land uses increased from 16.2 km2 in 1947 to 63.44 km2 in 1993. After 1993, the amount of industrial land began to decrease due to the closure and relocation of large factories beyond the City Proper. By 1996, industrial land decreased to 60.13 km2, but it still accounts for approximately 20% of the entire City Proper area. In general, Shanghai has a proportionately higher percentage of land use devoted to industry than many other large cities (Ta, 1994). Roads recorded the smallest percentage increase of all land uses, an increase of only 45.9% representing a change in area from approximately 29 km2 in 1947 to 42 km2 in 1996, an enlargement of only 13.2 km2. In contrast, greenbelt land use expanded the fastest among all land uses, recording a 450% increase in area from 1947 to 1996. However, the greenbelt area accounts for less than 10% of the City Proper in 1996, up from 0.5% in 1947. Public land uses (e.g., schools, engineering works, etc.), increased in area by over 20 km2, from 9.5 km2 in 1947 to over 29.5 in 1996. Agricultural land was the only land use category to decline in total area. Specifically, agricultural land use accounted for over twothirds of all land uses in 1947, however, this dropped to under 11% in 1996, a decline of 84% representing a total loss of over 159 km2 within the City Proper between 1947 and 1996. The changing trends to the proportion of different land uses may explain some of the reasons for Shanghai’s water quality problems. In particular, the rapid decline in agriculture land, the high proportion of industrial land, and the lack of green space may be contributing factors to Shanghai’s rapidly deteriorating water quality. For example, as agricultural land declined, it was replaced by industrial or resi-
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dential land, which, in general, has a much greater potential for degrading water quality. Furthermore, the agricultural land use during the early part of the study period, i.e., 1940s/1950s, was not very advanced in terms of using technology, such as chemicals and motorized equipment, and therefore would not likely have as negative an effect on water quality as urban and residential land uses. 4.2. Correlation between urbanization, land use, and water quality of Shanghai The water quality classifications for the five sampling sites from 1947 to 1996 are shown in Tables 4 and 5. (It should be noted that the classification is an inverse index, therefore, the higher the score, the worse the water quality). The change in water quality classification for all sites along the Huangpu River reveals a rapid deterioration of water quality between 1947 and 1996. The sampling sites located in the City Proper (e.g., Sites 3, 4, and 5) consistently scored higher, i.e., poorer, water classifications than the sites located outside, indicating the strong influence of intense urban activity on the water quality within the lower reaches of the Huangpu River. Specifically, Site 4 has the worst water quality classification among all sites throughout the study period. Its rapid increase in water quality classification is illustrated by the sharp rise, from 3.5 to 5.5, between the 1980s and 1990s (Table 4). In 1993, Site 4 is the only sample site to achieve the worst water quality classification, i.e., Category V. This can be attributed to the fact that this site is located in one of the most densely populated and most intensively industrialized parts of Shanghai. The two other sites in the City Proper achieved one classification better than Site 4, i.e., Category IV. Site 5’s improved classification in comparison to Site 4 can be attributed, to a degree, to the dilution effect from the Changjiang River. Site 3’s location on the edge of the urban area suggests that its classification is better than Site 4 due, in part, to the following factors: (i) the relatively cleaner water from the upper reacher of the Huangpu River and (ii) adjacent developments, particularly industrial, are newer than the relatively older and poorer designed factories located adjacent to Site 4 and are therefore expected to have better environmental controls and practices.
Table 5 Changes in water quality classifications* and urban growth periods, 1947 – 1996 Period
Site 1
Site 2
Site 3
Site 4
Site 5
Sustained urban growth, 1947 – 1964 Slow urban growth, 1964 – 1979 Rapid urban growth, 1979 – 1996 Overall, 1947 – 1996
+1
+1
+1
no change + 0.5
no change + 1.5
no change +1
no change + 0.5
no change +1
+2
+1
+ 1.5
+ 2.5
+ 2.0
+ 2.5
+ 2.0
* Increment in index scores.
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The sites located outside the City Proper (e.g., Sites 1 and 2) consistently recorded lower (i.e., better) water quality classifications than the other sampling sites (Table 4). These sites are the only ones to start with the best water quality classification at the beginning of the study period, i.e., Category I. However, Site 2 (as with Site 4) registered the largest increase in water quality classification from 1 to 3.5, an increase of 2.5 classifications between 1947 and 1996. While Site 1’s increased classification increased by 1.5 units, from 1 to 2.5, over the entire study period. This might be attributed to the changing farming practices in the suburban areas of Shanghai particularly the increasing use of chemicals. It may also be related to suburbanization of industry. This is also a location of ad hoc development with few controls or regulations. In particular, the operation of village/town industrial enterprises in the suburban areas of Shanghai are commonly believed to be heavy polluters as
they lack the knowledge, resources, and technology to deal with industrial waste. Most are run by villagers (i.e., farmers) with little or no education regarding environmental protection. The variations in water quality classifications for the five sampling sites correspond to the different growth periods (Table 5). During the period of sustained urban growth (1947 – 1964), Sites 4 and 5’s water quality classification remained unchanged, likely the result of the fact that these sites started with very high classifications. Sites 1, 2, and 3 each recorded an increase of one water quality classification unit during this period. The largest increase in water quality classifications, i.e., over one classification unit, occurred during Shanghai’s period of rapid urban growth (1979 – 1996). During this period, all sites recorded an increase in water quality classification. This is in contrast to the period of slow urban growth (1964 –1979) when the change in
Fig. 2. (a) Proportion of urban land and water quality classifications. (b) Proportion of residential land and water quality classifications. (c) Proportion of industrial land and water quality classifications. (d) Proportion of agricultural land and water quality classifications.
W. Ren et al. / Environment International 29 (2003) 649–659
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Fig. 2 (continued).
water quality classification increased by half a classification for Site 4, one classification for Site 5, and the three other sites remaining unchanged. Sites 1, 2, and 3 record no change in water quality classifications. Fig. 2a and Table 6 reveal a strong positive correlation between the water quality classification and urbanization. As the percent of land area within the City Proper becomes increasingly urban, the water quality classifications become progressively worse. This is observed for all three sampling sites. The strength of the correlation is indicated by the high R2 values that range from 0.80 for Site 5 to 0.83 for Site 3 and 0.91 for Site 4. Site 4’s higher R value may be an indication of its geographic location within the heart of Shanghai’s built-up area. In contrast to Fig. 2a, Fig. 2d illustrates a strong negative correlation between the percent of agricultural land and the water quality classifications for the three sampling sites. As the percent of agricultural land increases a corresponding
decline in water quality classifications is observed. The R2 value reveals a strong relationship with values ranging from a high of 0.89 for Site 4 to a low of 0.81 for Site 5 (Table 6). The proportion of residential and industrial lands have positive correlations with the water quality classifications for each sampling site within the City Proper (Table 6). For percent residential land, the strongest R2 of 0.92 is recorded by Site 4, while Sites 3 and 5 have somewhat weaker values, 0.70 and 0.68, respectively. The R2 values for the scatterplot Table 6 Correlation of land uses and water quality classifications
Urban land use* Residential land use Industrial land use Agricultural land use
Site 3 R2
Site 4 R2
Site 5 R2
0.83 0.70 0.93 0.85
0.91 0.92 0.78 0.89
0.80 0.68 0.89 0.81
* Urban land use includes residential, industrial, and other land uses.
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Table 7 Stepwise regression model of urban land uses and water quality classifications, Shanghai City Proper Sample site
Independent variables included in regression model*
R2
Independent variables excluded from regression model
Site 3
Industrial land use (km2)
0.94
Site 4
Industrial land use (km2)
0.92
Site 5
Industrial land use (km2)
0.89
Public land use (km2), residential land use (km2), agricultural land use (km2), road area (km2), greenbelt (km2), other land use (km2) Public land use (km2), residential land use (km2), agricultural land use (km2), road area (km2), greenbelt (km2), other land use (km2) Public land use (km2), residential land use (km2), agricultural land use (km2), road area (km2), greenbelt (km2), other land use (km2)
* The dependent variable is the water quality classification.
of industrial land use versus water quality classifications also indicates a strong relationship (Fig. 2b; Table 6). In particular, the highest R2 of 0.93 was registered by Site 3, followed by 0.89 for Site 5 and 0.78 for Site 4 (Fig. 2b and c; Table 6). The stepwise regression model for the Sites 3, 4, and 5 shows that a strong variability in water quality classifications is explained by industrial land area (Table 7). In fact, industrial land use is the only land use to predict water quality classifications for all three sites. Residential, agricultural, roads, public, greenbelt, and other land uses were excluded variables from the stepwise regression model. In particular, the R2 value was highest for Site 3, 0.94, and slightly lower for Sites 4 and 5, values of 0.92 and 0.89, respectively. This indicates the strong influence of industrial land use on the changing water quality classifications over the study period. However, the type and nature of industrial activities, changing technologies, and other factors need to be more fully explored. Overall, the regression analysis points to the need to develop land use planning policies and regulations that are sensitive to the preservation of water quality.
5. Conclusion This paper examined the water quality at five sampling sites along the course of Shanghai’s Huangpu River between 1947 and 1996. The analysis revealed that rapid urbanization corresponds to the rapid degradation of water quality. There is also a strong positive correlation between proportion of urban land use (e.g., residential and industrial) and worsening water quality classifications. However, there is a strong negative correlation between the proportion of agricultural land and water quality classifications. It appears that land use is an important contributor and
explaining factor regarding the quality of water in Shanghai. Thus, the management of land with respect to its development and use needs to be addressed in any attempt to mitigate against the further erosion of water quality classifications along the Huangpu River. Therefore, the findings of this paper suggest that land use planning policies need to work in tandem with technological solutions to improve Shanghai’s water quality. Controlling the rate, form, and type of urbanization can play an important role in protecting valuable urban water resources. This points to the fact that no single approach can be effectively used for water quality control in a megacity such as Shanghai. Rather, an integrated management strategy, which includes a number of disciplines, such as environmental engineering and urban-regional planning, is required. It also suggests that longitudinal studies that attempt to link changes to the urban spatial structure of a city-region to changes in water quality needs to be further studied. Ongoing and consistent monitoring of changes to water quality will assist in identifying how land use planning can help to ensure the preservation of water resources. It is important to provide benchmarks on which to measure the environmental performance of future attempts to improve Shanghai’s water quality.
Acknowledgements The authors wish to acknowledge the support received from Dr. John Dixon, Associate Vice-Principal, Queen’s University. This paper is the result of funds obtained from the Memorandum of Understanding between Queen’s University (Kingston) and Fudan University (Shanghai) and the Principal’s Development Fund Grant Number 379 035.
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