I thought it would be interesting in this post to take a look at some of these water courses and consider the policies that have brought us to the current situation. Also, I'd like to think about ways in which planning and urban design might be used to re-connect the population with its river network and begin to restore the historic importance of the water courses to the city of Tokyo.
Historical background:
Historically, Edo, which became known as Tokyo, was a city built on the back of its waterways. The original settlement upon which the city of Edo was built was a fishing village on the Sumida River. The name Edo literally means "gateway to the bay." As the great city of Edo grew, it was through the increase in trade that thrived along its network of rivers and canals that stretched inland from the bay. These water courses became the focus of daily life during the Edo period as they formed the transportation corridors that sustained the city and also, provided areas along their banks for recreation and pleasure.
Originally, much of the land close to Tokyo Bay was a poorly drained marsh and development of the settlement that became the great city of Edo involved a series of drainage projects that gradually expanded the urban area. Throughout the Edo period, canals were built and formed a fundamental part of the city's infrastructure. The water courses became a fundamental element in the expansion of trade and growth of the city and residents took pride in their rivers and canals.
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| Nihonbashi - Edo period |
Planning Policy:
1933 - Tokyo's Reconstruction Plan:
The amenity value of Tokyo's rivers and canals at this time was not highly valued and many water courses that were not required for either transportation or drainage were filled in to provide for new roads or open spaces. The remaining network became progressively polluted and disregarded as development turned its back on its rivers.
1964 - Tokyo Olympics:
In the build up to the Olympics in Tokyo, there was a boom in infrastructure construction and highways became the major priority. Elevated roadways were built directly above rivers, completely changing their character and environment. It's difficult to comprehend such drastic policy actions from today's perspective, but at the time, the enablement of rapid economic growth was at the core of planning policy.
1987 - Tokyo's 2nd Long-term Plan:
By the 1980's there was a change in attitude towards the city's rivers which began to respect their amenity value. Amongst the key policies within the plan were:-
- Promotion of flood control measures
- Respect for waterside recreation in flood control projects
- Development of a harmonious cityscape, making the most of rivers, lakes, etc.
- Renovation of famous bridges in Tokyo
Out of necessity, in the face of the devastation wrought by earthquake and war, Japan has focussed policy towards economic regeneration for much of the 20th century. As the country emerged as a powerful and prosperous country in the latter part of the century, policy was able to be re-directed to address environmental and public health issues. The Japanese however, seem to have consistently viewed this as a technological problem, requiring a technological solution, rather than considering the social and aesthetic implications. As a result, contamination and safety issues seem to have been addressed in isolation of other neglected urban design considerations, such as ecology, amenity and access.
Flood Prevention Policy:
As Tokyo has developed, it has grown into a very high density urban area with vast areas of buildings and hardstanding. The areas of soft landscaping that would normally allow rainwater to filter down to the water table and naturally drain into the rivers over time are far smaller than in equivalent other big cities. As a result, the run-off during periods of high rainfall quickly enters the river system and the huge volumes involved create a significant flood risk downstream.
Tokyo's response to this problem has been to create a heavily engineered network of rivers with a built-in capacity to deal with flash storms or periods of prolonged heavy rainfall. In addition, some innovative new approaches have been developed, including the creation of some vast underground reservoirs that provide storage areas for run-off during peak flooding. The Metropolitan Area Outer Underground Discharge Channel in Saitama is an incredible structure and is the world's largest underground flood water diversion system. Huge volumes of water can be stored and gradually pumped back into the river system as water levels begin to fall. Similarly, a new underground reservoir has been built in Minato, including the area around Roppongi Hills.
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| Tokyo Metropolitan Area Outer Underground Discharge Channel 首都圏外郭放水路 shutoken gaikaku hōsuiro |
These are impressive engineering feats that go a long way to addressing current flooding risks, but are also representative of an approach that treats the symptoms rather than addressing the causes of the problem. In many other developed countries, there is an emphasis on slowing the run-off into the river system to avoid the peak flooding problems that occur downstream. This may be through the creation of flood plains upstream or the adoption of sustainable urban drainage systems (SUDS) in urban areas, which reduce run-off through specially designed porous paved areas. A more naturalised treatment of river corridors also reduces run-off and avoids some of the peak flooding problems that can occur from flash storms.
Although some SUDS solutions have been introduced in limited areas of Tokyo, the general approach has been to create an efficient storm drainage system from the urban river network. This has led to a number of issues that have seriously impacted the environmental quality of Tokyo's rivers.
Main Issues affecting Tokyo's Rivers:
Tokyo's rivers have certainly been impacted by the various pressures of urban development, natural and man-made disaster and the practical problems of dealing with flooding. So, let's look at the main issues which affect landscape and urban quality.
Access:
Limited planning control has led to development hard up against the river corridors, limiting or preventing public access to the river.
Where access to the river corridor is available, accessibility to the waterside is strictly controlled and footpaths are often narrow and inadequate for dual footpath and cycle use.
Visibility:
Dense urban form often limits visual connectivity between the river and the surrounding urban area.
Dense linear tree planting along river corridor sometimes limits visibility.
Bridges over rivers in some suburban areas often lack openness to allow them to define these key nodal points.
Landscape:
Heavily engineered river banks have created what are no more than concrete channels in many cases with artificial bank profiles devoid of vegetation.
Water levels are often very low in relation to concrete bank heights, adding to the dominant impact of hard surface.
The limited space along the river corridor often allows for no more than a narrow footpath with no space for soft landscaping.
Major cities in the 21st Century are beginning to understand that the city is an ecosystem and that its health relies on the health of that ecosystem. Natural habitats rely on connectivity and a city's river system is often vital to sustain animal and bird populations in urban areas. Over-engineered river corridors in Tokyo have seriously undermined this.
Activity:
Historically, rivers were a place of activity in Edo times, but to a large extent they have lost this role and the city has turned its back on them. If they are once again to become a vital part of Tokyo's urban landscape, they need to become "destinations." They need to be places that people want to visit and have the facilities or environment that will once again attract the city's population.
Some Examples of Tokyo's Water courses
I thought I'd take a look at 3 examples of water courses in different parts of Tokyo that illustrate some of the issues that I've outline above.
- Zenpukuji River, Asagaya / Ogikubu - a river close to where I live that passes through dense urban areas before opening out into a linear park.
- Meguro River, Ohashi Junction - a river in a heavily built up area and adjacent to a major new highway infrastructure project. I regularly play futsal on the all-weather pitch inside the oval-shaped enclosed highway structure.
- Nihonbashi River - The river runs through a heavily built up urban area and is characterised by concrete walls and enclosed by a major highway overpass directly over the river.
1. Zenpukuji River
The Zenpukuji River passes to the south of Ogikubo and Asagaya in Suginami Ward and over a distance of several kilometres it runs through a linear park called Zenpukuji Gawa Ryokuchi. I've lived close to this park for a number of years and it provides a great facility for local people to jog, cycle or just use the open space for play and picnics. The park has a number of play areas and cherry trees line the river, making it a popular destination for "hanami" (cherry blossom watching) in Springtime.
Whilst the park itself is an excellent facility with plenty of access points, I remember when I first visited the park, being struck by the sterile stone and concrete channel that forms the river and how the river itself seemed at odds with the green surroundings of the park. The water level generally lies 4 or 5 meters below the adjacent footpath and I can honestly say I've never seen the river level rise beyond about a metre or so, even after very heavy rainfall.
Upstream from the linear park towards Ogikubo, the surrounding urban area squeezes the river into a narrow area that provides only room for a small footpath either side of the river with adjacent housing hard up against the footpath edge. Here, there is little vegetation to soften the impact of the vertical concrete edges of the river channel.
The key issues that need to be addressed are:-
- Allow access to the actual waterside, where space permits.
- Introduce vegetation into the river channel to soften the hard engineered edges.
- Provide an ecological corridor for wildlife.
- Create markers to identify bridge crossings, eg. surface changes, signage, bridge design
View 1:
Vertical concrete walls line the edge of the river corridor at this point. The river is relatively wide but the encroachment of housing on either side allows for only a narrow footpath. Remediation works could include:-
- Gabion baskets to create a low retaining wall within the river channel.
- Waterside planting to break up the expanse of concrete wall and attract wildlife.
The river passes through the linear park at this point and generous footpaths follow the top of the river banks on either side. The river corridor has an engineered v-section stone clad profile and narrow walkways alongside the water's edge. No access to these walkways exists.
Improvement works could include:-
- Create access to water's edge footway.
- Provide informal and robust seating along the river's edge.
- Allow ground cover planting to spill over v-shaped channel to soften hard surfaces and visually integrate with surroundings.
2. Meguro River
This stretch of the Meguro River passes next to a large and recently completed infrastructure project at O-hashi junction. A huge concrete oval has been created with traffic entering a tunnel built within the structure and connecting with the overpass that runs through Ikejiriohashi. Inside the oval there's an all-weather futsal pitch that I'm a regular visitor to and on the top of the oval is an elevated park, known as "Meguro Sky Garden, rising from 15 to 35m above the surrounding street level."
Clearly, a lot of money has been spent in creating the landscape and sports facilities that have resulted from the highway infrastructure project and the "Sky Garden" is an innovative and well-delivered new urban space. Innevitably though, there is a physical disconnect between the park and the surrounding urban environment and unless you already know of its existence, you be hard pushed to find it. Given the scale of the overall project and the opportunity this provided, I can't help feeling that an opportunity was missed to make a real impact at street level and to integrate the river into the scheme.
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| View 1 |
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| View 2 |
By creating an active frontage along the perimeter of the Oval, a real destination can evolve, providing day time and night time activities.
A pedestrian-priority zone up to the river's edge would help to integrate the river into the surrounding urban space. Informal seating along the riverside under the cherry trees would draw activity towards the river and access could be provided to the water's edge below.
Introducing heavy loose stones along base of the river channel would create a more natural setting for the water course and reduce the overbearing scale of the concrete channel.
3. Nihonbashi River:
The Nihonbashi bridge lies at the historical commercial centre of the city and its significance dates back well into the Edo period, often being represented in the ukiyoe pictures of Edo life. With this in mind, it seems even more incredible that the scene is now totally dominated by a huge series of highway overpasses, stretching over the bridge and following the course of the river. If ever there was a symbol of the impact of unplanned urban development in Tokyo, then this is probably it.The massive steel members of the overpass, arching over the river has a hugely negative impact on the setting of the bridge. The adjacent commercial buildings lie hard against the river edge along this stretch of the waterway so there is no opportunity for riverside walks. A river ferry does however, leave from a floating wharf below Nihonbashi bridge and is accessible from the street above.
Having acknowledged all of the above, there is something uniquely dramatic about the space under the overpass. Great pillars support the curves of the highway structure creating a powerful sense of enclosure. We can safely assume that the overpasses are here to stay for the foreseeable future, so what can be achieved from this situation?Opportunities:
Floating Market -
The central location of Nihonbashi makes it feasible to establish some kind of market alongside the river. Access to the river ferry terminal already exists and the wharf could be extended to enable a regular market or entertainment destination to be created. This would introduce something unique to the city centre and would transform the relationship between the river and the surrounding urban area.
Art Installation -
The unusual setting of the river and the visual impact of the overpasses calls for some imaginative new interpretation of the space. A bold art installation has the potential to create a new sense of place in what has become an urban back water. The highway structure provides the means to suspend or attach an installation that could make a major impact. The use of movement, light, wind or sound could create a new and animated landmark.
Lighting -
The dramatic forms of the highway overpass and columns have the potential to come alive at night through lighting. This is probably the most practical and cost effective opportunity to change perceptions of the urban environment in this part of the city and may become the catalyst for a closer relationship between the city's inhabitants and the river.
The above examples of Tokyo's river network represent just a fraction of the waterways that pass through the city. Whilst, it seems that there is now a common recognition of the importance of this resource to the city, decades of neglect will not be overturned easily. There are huge practical issues that stand in the way of meaningful change, but perhaps, with the approaching 2020 Olympics, there will now be a political will to make a difference. Let us hope that this will be the catalyst for real change.
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