IJERD – International Journal of Environmental and Rural Development (2022) 13-2

Research article
erd

The Legacy of the Waternetwork from the Past:
Characteristics and Types of the Covered Waterways in
Tokyo
IVANA ANGELOVA*
Meiji University, Tokyo, Japan
Email: ivanaangelova@meiji.ac.jp

DAVISI BOONTHARM
Chulalongkorn University, Bangkok, Thailand

MASAMI KOBAYASHI
Meiji University, Tokyo, Japan
Email: mkob@gol.com
Received 31 January 2022

Accepted 18 July 2022(*Corresponding Author)

Abstract Edo was once a city of water and everyday life was intertwined with its rich water
network. Unfortunately, the connection with water was lost due to the rapid urban growthof the city and now most of the local scale water streams in Tokyo are culverted. They haveturned into green streets and their tributaries into narrow pathways. The objective of thisstudy is to trace the covered waterways in the broader network of the blue and green
infrastructure of the city and to catalogue them in accordance with their different
features like design and usage. In the first part, analysis is done on the legacy of the urban
streams from Edo to Tokyo. Furthermore, the methodology and the results of the research
are presented, showing a map of the covered waterways and their classification. For thisreason, two different scales of the linear elements are assessed. The findings show that,based on a short section, considering the width and landscape design, there are four groupsof types of which three are covered kind of types. Based on assessing a few hundred
meters long segment, there and five groups of types based on their primary usage eachhaving two sub-types except for the last that has only one. According to the results a
conclusion is drawn that today most of the covered streams in the city have somecommonalities in their design and how people use the space. Typically, the route of most of
those ancient streams is accompanied by endless kilometers of pedestrian and cycling paths
regarded as ''green ways''. Together they form a rich network spreading throughout the city.
They represent inclusive public spaces that plays a vital part in strengthening communities
and need further research.
Keywords Tokyo, covered waterways, legacy, scales, typology

INTRODUCTION
Since its formation up until the end of Edo (old name of Tokyo) the city has been compared to
Venice and Amsterdam in Europe. Unfortunately, the connection with water was lost due to therapid urban growth of the city, especially after the Olympics in 1964 when many of the rivers andstreams were covered by roads and now remain as hidden waterways. In his book Tokyo: A Spatial
Anthropology, the renowned architectural historian Hidenobu Jinnai, 1995 states that water was theelement that brought people together and the first public spaces in the city of Tokyo emerged on
the riverbanks and around bridges. He argues that the waterways today, even though overlooked in
the planning practices, are an asset so valuable as to make Tokyo stand up as a unique nature-based
metropolis of the future. But even though “Edo- a beautiful city integrated into the great naturalⒸ ISERD

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world’’ today "the city itself faces a crisis because we, the citizens of present-day Tokyo arediscarding this legacy in the name of functionality and efficiency (Jinnai, 1995)”.
In the past decade a growing number of literatures appeared with the aims to evoke the water
network of Tokyo. Moreover, in the midst of scrap and build culture, the attention is growing
stronger for permanent elements in the city such as topography and terrain (Jinnai, 2017). Whilethe existing works are focused in exploring the appearance and geographical features of the open
and hidden waterways, a more comprehensive study is lacking in the field of their identificationand cataloguing based on different features.
Therefore, this study is trying to fill the knowledge gap by adding more valuable information
for studying the urban open and covered water network. Emphasis is given in exploring the smallerscale streams which have a local character and are mostly culverted and transformed intogreenways. Both primary and secondary data are used to meet the objective of this study.
Quantitative data comes in form of a map showing the covered streams and empirical data ispresented by their classification by two different factors.
URBAN WATERWAYS TROUGH HISTORY
The city’s connection to water through history is giving a background to the phenomena of thehidden waterways today. Using literature review and historical maps, three points in history arerecognized as major water related transformations. Fig. 1 shows the timeline and the consequencesof urban transformation to water in each period.

Fig. 1 Waterway transformation timeline for Tokyo
Edo Period (1603-1867): Tokyo AquaticTokyo is a legacy of the original urban planning of Edo, the old name of the city. By definition theword ‘Edo’ equals an ‘estuary’. This period was the most fruitful for the city expansion and theestablishment of its wider structure that grew along with the spiraling moat system. The rich water
network enabled a close connection to water for the people in the marsh lands. All sorts ofcommercial, cultural and even spiritual activities happened along the riverbanks in the low land
Edo. Water is depicted in more than 80% of the paintings in “One Hundred Famous View of Edo”,
showing how entrenched it was in the livelihood of the people. Many of the shrines and temples
were faced towards the water edge. In the peripheral areas of the city, numerous townships
produced food and transported it by boats to central Edo making use of the rivers and aqueducts.
According to the land use of Edo, over 40% of the land was used for farming (Fujii et al., 2002),
Edo was a garden city making use of the abundance of water. As the city was growing over time, it
took an organic shape respectful of the natural topography and conditions. "The city has been builtwith knowledge of its vulnerability to natural forces (Shelton, 2012) “. In this period not only did
the city blueprint was established but also the cultural and social life reached its peak. Water
brought value to people’s life and there was a very sophisticated and sustainable water treatment
unbeknownst to any western civilization at the time.
Meiji Restoration (1868-1912) and Taisho Period (1912-1926): Channelizing Urban Waterways
Meiji Era came as the time of industrialization and implementation of Western ideologies. To keep
up with the trend of technological advancements, the process of industrialization took on a high
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speed in Japan. Neoclassical approach in the urban planning and architecture practices of the time
was applied on top of the old layers of the city (Hein, 2008). Major transportation networks for cars
and trains were planned but were not fully constructed due to the scarcity in resources after WorldWar 1. As land transportation took over, local streams were left neglected, and the lively riverbanks
slowly lost their cultural value and were left to serve as mere industrial complexes. Moreover, thecity's water-based structure experienced a second huge disruption when the devastating Great
Kanto earthquake of 1923 caused a myriad of uncontrolled fires that left devastating consequenceson people’s lives and their environments. This natural disaster has led to revaluation of thewaterside spaces and their safety. The event marked the beginning of channelizing the city’swaterways. The disaster response was a clear sense that "Japan had been granted an unprecedented
chance to upgrade the city. (Charles, 2008) ".
Showa Era (1926-1989) to Modern Tokyo: Local Culverts
Showa period is represented by two contrasting periods, before and after World War 2. After thedevastating raid that took over the city during the war, it took 6 years to completely recover. This
period is when most of the waterways were covered due to safety, aesthetic and land reclamation
reasons. In the upheaval period after the 50s big urban plans for the city were executed and local
urban planners adopted the ideas that could easily implement the concept of machi-small town
"comprised of many small towns with different purposes (Hein, 2008)". In line with thoseideologies, planning principles from the 20s and 30s were adopted that emphasized polycentricity
and green areas in between neighborhoods. In Tokyo Olympic Games land-based infrastructure
grew immensely in order to give the city a new international look. There was a boom in theconstruction of expressways and many of the rivers and canals were left covered by the elevatedroad structures. This period of intense construction led to huge environmental crisis. The smallerscale waterways were contaminated, and people complained from the bad smell. Taking inconsideration the natural disaster prevention management and the decay of the local streams,
decisions were made to culvert most of them. In the 80s Tokyo was re-discovered as a city on water.
Old societal ideologies that celebrated the connection to the natural environment and culture werereconsidered and gained popularity. Appreciation for the local qualities emerged again. Urban
policies for the protection of water and greenery, and conservation of historical sites were
established. Many waterside regeneration projects took part like converting the river coast into
public leisure areas (Jinnai, 2017). Smaller and more local initiatives took interest in revival of thecovered waterways that continued through the 90s.
Present Day Tokyo: Reconsidering the Role of the Local Culverts
Today Tokyo represents the largest city in the world, an agglomeration of many machi, apolycentric city (Shelton, 2012). The township culture is still kept until the present day, providing a
sense of authenticity and belonging, a vital factor for strengthening communities (Kuma et al.,2021). Even though due to strong globalization forces the city has drastically lost its rurallandscape and connection to water, the legacy of the abundant water network is kept in the form of
myriad of greenways curving their way in the city landscape. They are very much used andtreasured by the citizens.
Future brings challenges, and for Japan the main one is the demographic change, natural
disasters and public debt (Ohno, 2018). When the challenges mentioned above translates onto thecity landscape, it is expectable to see some urban patterns completely change. One of therepercussions will be the decaying infrastructure in suburban areas caused by the drop in residential
density. According to Hidetoshi Ohno, in this scenario the city will be reduced to smaller centerswith inclination towards urban greenery, supported with the creation of new open spaces.
Reconsidering the role of the linear public spaces created on top of the culverted waterways is
crucial for addressing the forthcoming challenges. It is important to examine what kind of asset
those elements represent for the quality of life of the city dwellers.
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OBJECTIVE
Public spaces can solve a number of the above-mentioned challenges at once. They contribute forthe increasement of biodiversity, humans’ health and pollution. In the Japanese setting public
spaces such as plazas do not exist but instead, multiple sites for social interchanges have been
constructed to the scale and form that are appropriate to the Japanese physical and cultural context.
Many of the small-scale common spaces are overlooked in the urban research practices but are
frequently used and often exclusively known by locals. The linear public space, the path on top of
the culverted rivers is such a place. Thus, this research is trying to address the importance of thisurban phenomena in the context of Tokyo.
The objective of this study is to, initially, identify the location of the covered waterways in the
broader network of the blue and green infrastructure in the city and, subsequently, to identify andgroup them in accordance with their design features and the way people use them. The study
location is within Tokyo 23 Special wards. According to the classification given by Bureau ofConstruction (2015) there are Class A, Class B and Secondary rivers or streams. This research is
focusing on the secondary rivers that can be either covered or open and are administrated by thewards.
METHODOLOGY
A research design was developed in an integrated manner to guide each phase of the research.
Table 1 (Yin, 2014) defines a research design as a coherent and logical plan to collect data,measure and analyze the data collected, connecting empirical information to the research question
and its conclusion. The research design created for this study is comprised of five consecutive
parts: Research question; Source of data; Methods of data analysis; Data processing & tools andResult. In the first phase of the research, three questions were modelled in relation to the objectiveof the study. Secondary, the source of data needed to answer each of the question is identified.
Primary data is being collected through extended systemized fieldwork of one year, from April
2020 to April 2021, using the map of covered waterways developed in the first phase of the study.
Secondary data is collected from official digital maps, namely the online database from National
Land Numerical Information in conjunction with Google Satellite View and the authors own
fieldwork mapping based on observation. Methods of data analysis show how the data was studied.
20 samples were used to classify the waterways in question 2 and 3. To process the data, tools suchas QGIS software, LiDAR 3D camera and Google Street View were used to process the data. The
expected results from each research question are presented at the end of the research design.
Table 1 Research design
Research question

Source of data

Methods of data
analysis
Spatial distribution
analysis

Data processing &tools
Overlaying both
sources of data in GIS(Geographic
Information System)
software

2. What kind of
Primary data (fieldwaterways are there research)according to design? + Secondary data
(Open street Map)

Comparative analysis
of 20 samples ofwaterways shortsections.

LiDAR camera andOpen Street Map
measurement tool tomeasure the width ofshort sections

Classification based on
types of design

3. What kind of
Primary data (fieldwaterways are there observation)according to primary + Secondary data
usage?
(Google Street View)

Comparative analysis
of 20 samples ofwaterways line
segments.

Field observed data
and Google Street
View recordings ofline- segments

Classification based on
types of use (including
design)1. What part ofSecondary data
Tokyo’s waterway (National Land
network is covered? Numerical Information&Google Satellite
View) +Primary data
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ResultMap of Tokyo
metropolitan area
showing open andcovered waterways

IJERD – International Journal of Environmental and Rural Development (2022) 13-2

RESULTS AND DISCUSSION
A digital map of Tokyo metropolitan area is showing what part of the water network of the city iscovered and is serving as green corridor and what part of it are open rivers and streams is shown in
Fig. 2. For data on the overall water network in the city the GIS Data on waterways from National
Land Numerical Information (in blue) is used. To make a clear distinction between covered andopen streams, data from Google Satellite view, municipality maps of greenways and fieldobservation maps were combined to trace the covered streams (in red). Findings show that while
there are a total of 712 kilometers of urban waterways, 490 kilometers or 68% are covered. In
terms of distribution by districts, Edogawa ward has the largest number of waterways in total while
Setagaya ward has the largest number of covered waterways landscaped like greenways.

Fig. 2 Map of open and covered waterways in Tokyo
Given the linear shape of the waterway, varieties in use and design can be different in different
segments. The same waterway can have a portion with an open stream and a portion of it that isculverted. However, in most cases the treatment is the same for the whole waterway. It is either
open or covered. To respond to the second research question, a method was established that focusedon the design on a waterway in a micro scale of a few meters long. The width of the waterway andits landscape design, the use of the adjacent streets like vehicle or pedestrian and the land use ofadjacent plots were taken in consideration. After an extensive field observation, 20 samples of shortsections of different waterways around the city were chosen to test the method. The types and theircategorization into groups are presented in Fig. 3. According to the overall design there are four
sub-typologies in the large size group, 5-12 meters wide. All of them are open. The other threegroups represent the covered streams: medium size, 3-6 meters wide, typically landscaped like agreenway that can have surface water; small size, 2-4 meters wide, narrower greenways; extra
small size, 1-3 meters wide, narrow pathways. The medium and the small size have four sub- typesof covered streams while the extra small size only two.

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Fig. 3 Types of waterway segments based on landscaping
In terms of the primary usage of the waterway, it depends on the context of where they arelocated. For example, a stream can run through a commercial area or a residential area which interms results in different characteristics of use. To respond to the third research question, a method
was established that focused on usage of a waterway in a meso scale, of a few hundred meters long.
This method tested 20 samples of line segments based on the frequency of users and type ofactivities they were doing there.

Fig. 4 Types of waterways in line-segments based on their usage
Fig. 4 shows the classification according to the types of use. They are categorized into fivemain groups: prominent-high intensity in use and popularity; shinsui-landscaped for water play andⒸ ISERD

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enjoyment; vital-long greenways that connect neighborhoods; operational-used for irrigation anddrainage on the outskirts of the city; inner-active-narrow lanes. Each main type has several subtypes. The Prominent type: preserved landscape-protected nature with an open stream andcommercial street-culverted stream in the middle of a commercial zone. The Shinsui type: waterparks-landscaped as a water park playground and open stream-not landscaped as a water park but
used as such. The Vital type: linear park-landscaped as a greenway and sport/play area attachedplayground or a sport field is attached on the greenway. The operational: irrigation canalsupplying water for urban farming and drainage canals-small scale open type runoff water. The
inner-active: sewage water canal- small scale pedestrian street.
CONCLUSION
The study examined two different scales of the urban waterways. Looking in the micro scale, it canbe observed that different design principles were used to landscape the covered streams. Most ofthem are landscaped like linear parks with greenery and some have surface water or even waterparks for play. In general, they are inclusively designed for pedestrian activity while most often
than not, cycling is prohibited. The adjacent streets mainly have a controlled vehicle activity withspeed and use limits. The land use of the area where the covered waterways flow is primarily
residential and often times there are schools or sport fields attached to the waterway. In the meso
scale different types of activities were observed. People used the space in accordance with its
landscaping and the location of the waterway. For example, in the commercial zone people usedthose elements as pedestrian streets and rarely for recreational activities, while the water park andthe greenway type saw a huge amount of people doing leisure activities. In conclusion the covered
streams have a specific social, spiritual and environmental dimension. Today a new culture of life
related to water, different from that of the past emerged after culverting the streams. A culture
specific to the Japanese context of public space use and the challenges of the contemporary way oflife. A further exploration of their quality as single linear entities and that of the network quality
should be done to understand the broader implications of this urban phenomena in the whole city ofTokyo. For this matter the proposed methodology should be broadened to include an inductive
approach for analyzing qualitative data.
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