Changes of Canal Networks and Canal Spaces of Suzhou






The old city of Suzhou is a famous water oriented city in the Yangtze Basin of China. Suzhou is called ecanal cityf in the world because there are a lot of canals in the city and it has a special water-oriented landscape. With development of the old city, canals were occupied and filled up gradually recently, the distinctive water oriented landscape is also being damaged with the reduction of canals. In this paper, in order to retain and preserve the historic water oriented characteristics and to create new water-oriented landscape of modern life, we analyze and show the historic changes of canal networks in the old city from Song Dynasty to modern times, and classify the spaces of canal into three patterns and 10 types to show the character of canal spaces. Based on the results of these researches, some useful and constructive suggestions are presented for the old cityfs redevelopment.



1.          INTRODUCTION


The old city of Suzhou, which is called eThe Venice of the Orientf, is a typical of traditional water oriented city in the south of the Yangtze Basin of China. Canals run north-south and east-west over the city and form the canal grid which is called e3-Horizontal and 3-Verticalf in the old city, restrict the street pattern and the residencesf location. It formed a special and abundant landscape of canals that other cities have not. Canals become important spaces in the construction of Suzhou city. But in the last two hundred years, with change of times and cityfs redevelopment, canals were occupied and filled up gradually. Canals, the most important element of the main landscape feature of Suzhou water-oriented city that is called gsmall bridge, running water and housesh, are disappearing. And the feature of water oriented also disappeared gradually without canals. New canals are also rebuilt and maintained, are more regular, beautiful but also more monotonous and stiffer than old canals, losing its natural property.

       There are some papers concerned with the researches of Chinafs water-oriented city. Yu[1] and Suzuki[2]fs paper analyzed the characteristic of city space from the viewpoint of city history and the formative process of residence area. Bao[3]fs paper was about space construction of old residence by morphology. Wang[4][5]fs paper summarized the development system of city after 1949, and discussed the possibility of development and management plan by the viewpoint of space design theory. Jinnai[6]es book argued the cultures of water-oriented city, analyzed the city space from water-oriented city facilities based on surveys, and presented a method about how to preserve and restore the traditional streets. But these papers are all mainly for dwellings and construction of city space in Suzhou. However, as we know that there are no any papers on canal spaces of water-oriented city.

       In this paper, we want to look for some formations and evaluation of canal spaces of the old city of Suzhou through the analyses of the canal networksf changes with the standpoint of historical development. We analyze the changes of canal networks from Song Dynasty up to now and obtain some important results. Also we divide the canal spaces into three patterns and 10 types and show the characteristics of canal spaces of the old city. The purpose of this study is to present some useful and constructive suggestions for the old cityfs redevelopment criteria and design guidelines, to help to retain the historic feature and to recreate new characteristic of water oriented landscape.




Here, we will show the changes of canal networks from Song Dynasty up to now based on the Suzhou traditional maps in various periods.

       Suzhou as a city was built in 514BC, dates back 2,500 years and is one of the oldest cities in the Yangtze Basin. It is said that there are no any maps or pictures described about Suzhou before Song Dynasty.


       2.1 Song Dynasty (960-1276)

       Fig. 1 called ePing-Jiang Mapf (1229) is the earliest map about Suzhou, carved in a stone monument, whose scale is out of proportion. By the scale map [7], we got a figure of canal systems of Song dynasty shown as Fig. 2. It can be seen that the canal networks of Song dynasty were very complete at that time. The city is large as 14.2 m2 as like a rectangular. There is an outer moat that is 17.48 km in length and about 50-130 m in width, and there are three inner moats in the northern, eastern and southern.

       Hundreds irregular canals composed canal networks and led everywhere in the city. Canals and their associate streets formed a checkerboard etartanf grid. There are five major canals of north-south direction shown by N1-S1, N2-S2, N3-S3, N4-S4 and N5-S5, and three major canals of east-west direction shown by E1-W1, E2-W2, and E3-W3 in Fig.2. Other canals connected with these major canals. The small canals dividing the city into different rectangles gathered at the center of the city.

       In that time, the length of all the canals was about 82 km.



2.2 Ming Dynasty (1368-1644)

       Based on eSuzhoufs General Irrigation Mapf (1600), we drafted a canal system of Ming Dynasty shown as Fig. 3. Compared Fig.3 with Fig. 2, we can see that there were nearly no changes, but the canal density of Ming increased. The amount of length of Ming canals was the longest in its history. On Fig. 3, we use the broken lines to indicate newly created canals and dotted lines to express disappeared canals.


       2.3 Qing Dynasty (1644-1911)

       Fig. 4 is a canal system of Qing Dynasty that we made corresponding to eThe Complete Map of Suzhouf (1769). Fig. 4 shows that small canals dividing areas in the west and the center of the city disappeared mostly, but some one in the east remained. And one of major north-south canals which was indicated by heavy dotted lines N3-S3 disappeared. One of the reasons why the canals vanished was that canals had not been dredged for nearly 50 years since 1746 to 1797 so that lots of canals blocked up, moreover, residential buildings occupied canals [2]. The remained major canals formed the old cityfs dimension of e3-Horizontal and 4-Verticalf grid at that time.

       The total length of Qing canals was about 57 km.

       2.4 Modern Times (1949-  )

       From the eProject of 1989-2000 Suzhou Gardens and Trees Plantingf (1989), we extracted the canal system shown as Fig. 5. We can find that one north-south major canal (N4-S4), half of the east-west major canal (E3-W3) and some inner canals were filled up, the northern outer inner moat and middle part of eastern inner moat also disappeared which is indicated by dotted lines. The main aim of filling these canals was in order to renovate the environment of the old city and to satisfy the needs of city development from 1949 [2]. The city style becomes e3- Horizontal and 3-Verticalf grid (The E3-W3 was replaced by E3f-W3 to see Fig. 5). Compare Fig. 2 with Fig. 5, it is evident that the canal systems formed from Song Dynasty disappeared at that time.

       The total length of canals is about 35 km at that time. The main canals forming the city style mentioned above account for 51% of the total length and the other small canals account for 49%[8].

       Fig. 6 is the newest figure of canal systems that is made by the 1997fs eSuzhou Mapf. Compare it with Fig. 5, we can see that some canals are reconstructed or revamped indicated by the broken lines.


       From above analyses of the changes of canal system in every period, the following statements can be obtained.

       1) The old city of Suzhou is different from other all cities, which are set by the road networks. Over the centuries it has been seen that the canal systems are the main urban structure in Suzhou. Canals restrict the location and direction of roads and buildings, influence the layout of the whole city and build the physical fabric of the old city. This is a real implication of water-oriented city.

       2) The development of Suzhoufs canal networks can be divided into four periods. The first is a forming period from 514 BC to Tang Dynasty. The second is a prosperous period including Song Dynasty and Ming Dynasty. The third is a declining period from Qing Dynasty to 1970fs; The forth is a redeveloping period from 1970fs to now.

       3) There are two great changes in the history of the old city canal systems. One was in Qing Dynasty, a lot of small canals disappeared. Other was after 1949, one and a half of the major canals and some inner moats were filled up. This is the reason why Songfs canal system can not be seen now.

       4) The present e3-Horizontal and 3-Verticalf city grid formed since 1970, after the two great changes of the canal networks.

       5) The canalsf location of present situation has not changed practically since Song Dynasty.

       6) Canals that were left over by history were nearly the major canals of Song canal systems, though other small canals disappeared mostly.

       7) The canal systems of Song Dynasty are not existing now, but the canal fabric of Song Dynasty is still existing. After two great changes the canalsf total length decreases rapidly, from 82km (Song) to 36km(Now). It is equal to say that the more than half of canals disappeared. But for the most major canals remained and the locations of most canals changed not, the canals of today still control the whole city, limit the shape of road networks and building blocks of the old city. The cityfs physical fabric did not change.


The reasons why the canals reduced from 82 km to 35 km for near 700 years can be summarized as the following 3 points.

1) Lack maintains and dredge. The history of China was full of wars. It was impossible to maintain and dredge canals for wars. Some canals were filled up by mud and vanished gradually.

        2) Invaded and occupied. With the development of old city and increase in population, more space was needed for dwellings and city facilities. Some canals were filled up for getting more land.

        3) Pollution and Loss of main functions. The main functions of canals were transportation and living water, but now the former is instead by other traffic and the latter is replaced by waterworks. So people didnft mind the quality of water again that has been very important in their life before. The pollution of canal water become more seriously and more seriously. And the increase of population aggravated the pollution too. Some canals had to be filled up for getting a clean environment.



By above analyses, we can get a result that the canal systems are integral part to the historic character of the old city of Suzhou as they shape the city by control the road networks and street blocks inwardly. It is imperative to preserve the canals and the canal networks. And it can be seen that government control and administration are very important preserve the canals from above reasons.



3.          SPACES OF CANAL


We showed the change and the distribution of canal systems in different periods above. Here, we consider the formation of canal spaces, which is defined as the region within 30m from the edge of canal on both sides.

       According to the relation of canal, street and building, we can divide of the canal spaces into three patterns as I, II and III shown as Fig.7 [9]. Pattern I is eCanal without Streetf, the canal is existing with building walls aligned with the canal bulkhead on two sides. Pattern II is eCanal with One Streetf, one side of canal is building and the other side is street. Pattern III is eCanal with Two Streetsf, there are two streets on both sides of the canal.

       In this paper, we analyze the canal spaces of Ping-jiang Canal, Sheng-jiadai Canal, Dao-qian Canal, Shi-quan Canal and Gan-jiang Canal respectively as followings. Fig. 8 is the configuration images of those canals.


       3.1 Ping-jiang canal

     Ping-jiang Canal is the north-south canal that is indicated by N1-S1 in Fig.6, one of major horizontal canals in the e3-Horizontal and 3-Verticalf grid. By the analyses of canal networks above, it can been seen that the most canals around Ping-jiang Canal were remained from song Dynasty. We could find some Ming or Qing Dynastyfs canal bulkheads in Ping-jiang Canal when we investigated in Suzhou. There are many distinct historical buildings such as one or two stories along the canal. The historical character of water-oriented city of Suzhou could be find here. The space of this canal belongs to Pattern II.


       3.2 Sheng-jiadai Canal

     Sheng-jiadai Canal was linked with Ping-jian Canal formerly, located in the south of Ping-jian Canal and whose space is similar to Ping-jian Canal. But there are some new condominiums of three or four stories beside the western street of the canal, built in 1996. The streets along the canal are wider than Ping-jian Canalfs. The scale of space is also different between Sheng-jiadai Canal and Ping-jiang Canal. The space of this canal is Pattern III.


       3.3 Dao-qian Canal

       Dao-qian Canal is the east-west canal shown by E3-W3 (the half part in west) in Fig.6, one of major vertical canal in the e3-Horizontal and 3-Verticalf grid. Traditional houses are in the south of the canal, in the north of the canal there is a modern city road whose width is 12m. There is green-space between the road and canal, but in the past there have been residences in there. There is a path in the green-space. Northern side of the path is row of trees, southern side of the path is lawn with trees, shrubs and also has benchs in it. The road and the green-space are constructed in 1985. The space of the canal belongs to Pattern II.


       3.4 Shi-quan Canal

     Shi-quan Canal is the east part of E3f-W3 in Fig. 6. The southern street of the canal is a shopping street formed by two or three stories buildings built in 1995, and the southern canal bulkhead also was revamped at the same time. In the north of the canal there are old buildings of one or two stories. It forms a strong contrast between new and old on both sides of the canal. The space of the canal is Pattern I.


       3.5 Gan-jiang Canal

       Gan-jiang Canal is the east-west canal shown by E2-W2 in Fig.6, which has been filled up and re-created in 1993, so it is a completely new canal in the old city. On the two sides of the canal, there are modern city roads of 12m width and there are no any buildings. Between the canal and roads, there is green-space of lawn but where people are forbidden to enter. The lawn green-space was a place of buildings before. The space of the canal is Pattern III.

Only using above three patterns to analyze the space of canal is not enough to represent them. The canal spaces encompass many plentiful variations. In addition to the elements of canal, street and building, there is also other element such as open space like green-space, which is gstatich space but different from the street or road that is eactivef space. The static and the active spaces play different roles in the sensation given to one and the landscape. Therefore, we furthermore divide the three patterns of canal spaces into 10 types by considering the static space. Fig. 9 shows the 3 patterns and 10 types. For example, IC is one of Pattern I but it has the type C of  estreet-house-canal-house-streetf, IIBf is one of Pattern II and has the type Bf of estreet-greenspace-canal-house-streetf and IIIAh is one of Pattern III and has the type Ah of estreet-greenspace-canal-greenspace-streetf.

     According to above classification, based on the plane map of canals, we show the spaces of each canal longitudinally in Fig. 10 where the lengthwise variations of each canal can be found clearly.

       From Fig.10, some characteristics about the spaces of canal can be summarized as the followings:

       1) There is surely a street paralleled with canal on one or two sides of every canal. It can be seen clearly that the structure of the water-oriented city is the ecanal-streetf pattern. This is the main historic feature of the cityfs physical fabric.

       2) By the frequency of change of canal spaces, we arrange the canals as the order as followings. Ping-jiang Canal (14 major changes), Shi-quan Canal (9 major changes), Sheng-jiadai Canal (6 major changes), Dao-qian Canal (2 major changes) and Gan-jiang Canal (only one type). Except Dao-qian Canal and Gan-jiang Canal, the average distance between two major change of canal space is about 143m. In other words, there will be a big change once on the canal spaces every 143m.

       There are also many tiny changes in every major change of these canals.

       3) Buildings beside a canal have great influence on the changes of canal spaces. The more the buildings beside canal change frequently along a canal, the more the space of the canal changes variously such as Ping-jiang Canal. If the buildings have no change and keep one state along the canal, there will be no change on the space of the canal as Gan-jiang Canal.

       4) About Dao-qian Canal, there are only two main changes whose pattern-type are IIBf and IIAf. But as Fig.10 Shown, the green-space is not pure space of lawn, also including path and trees. The changes of canal space ought to be evaluated by the path rather than the road in the north of the canal. The green-space on the right of the path also has changes, like the tiny changes in every main change.

       5) Gan-jiang Canal, which only has one type as IIIAh, is really a canal without any changes. And to enter the green-space is forbidden. The canal becomes a space unrelated to people, only cars running on its two sides.               

       6) Tree is an important element on changes of green-space.

       Dao-qian Canal and Gan-jiang Canal have modern green-space in common, which are not belong to old canal spaces and were constructed recently. But Dao-qian Canalfs green-space has various changes, Gan-jiang Canalfs has not. The difference between Dao-qian Canal and Gan-jiang Canal on the green-space is that Dao-qian Canalfs green-space has trees in the lawn and Gan-jiang Canalfs green-space has lawn only. That is, tree is the different point for the two green-space. Tree can covers onefs eyes, can be felt as block like building. So the existence and density of trees are influential in the canal space as the effect of building.





Urban regeneration is taking place around the world. The old city of Suzhou is the historical water oriented city and is redeveloping. To retain and preserve historic feature is very important for creating local characteristics of the old city of Suzhou. In this paper, we analyzed the changes of canal networks in different periods, and defined and evaluated the spaces of existing major canals. We pointed out that the spaces of canal are integral part of water oriented cityfs structure and it is imperative to preserve the character of canals.

       As further research, we will analyze the elements of canal spaces to find out the composition of water-oriented landscape. We hope the results of the study are helpful in seeking a rational and feasible recommendation between preservation and new redevelopment.



(This research won support from the Foundation of River Environment of Japan, the authors would like to thank their both financial and spiritual encouragement.)







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