The city of Toronto is a massive never-ending blur of concrete. The immense redevelopment of the waterfront consists of apartment towers as far as one can see. Looking at the city from the Sky-tower the outskirts have a green look, but don’t let the image fool you: down at the ground asphalt and cars are the main occupants of space. In this context, resilience is necessary and difficult at the same time. Nevertheless reconsidering the ecological qualities as a contributor to the quality of life is an important issue, especially in a city that is confined, busy and traffic-jammed. Climate change adds up to this need to create bigger green spaces and give water a more prominent role in landscape forming. This subject raised interest at the City government and the Dutch Consulate and has led to a Resilient City Summit in May 2015, where future resilient planning was discussed amongst academics and practitioners from Canada and the Netherlands.

Don River Watershed

One of eight watersheds in Toronto, the Don River watershed covers an area of approximately 36,000 hectares and stretches almost 38 km in length, flowing south from its headwaters on the Oak Ridges Moraine to the Keating Channel, where it empties into Lake Ontario. The Don River watershed is almost entirely urbanised, leaving very little undeveloped land. Almost half of the watershed is dedicated to housing its 1.2 million residents. On average, 35% of the urbanised areas along the Don are paved with impervious surfaces. One of two North-South highways, the Don River Parkway runs along the mid to lower section of the Don River. A system of bike and walking trails makes the Don a heavily used recreational corridor. Due to the intense urbanisation in the Don watershed, hard paved surfaces increasingly prevent storm-water from slowly seeping into the soil, or from being taken up by vegetation. Therefore, much of the storm-water run off the surface into the Don River, resulting in stream-bank erosion and increased flooding during large storm events, particularly from combined sewers. The challenge is to protect and restore the natural heritage features of the watershed while trying to accommodate the competing recreational demands.

The design task for this area lies on two scales. The entire watershed should be enhanced in its ecological quality, the amount of water storage and the connectivity, both for recreation as ecological purposes. At a lower scale, three design sites have been used to elaborate the design solution at the watershed level on the urban design scale. An upstream (Hoggs Hollow), middle stream (Thorncliff Park) and mouth (Port Lands) site were chosen wherein the near future developments and changes are expected.

Design Charrette

For these design tasks, students and staff participated in a design charrette Roggema, 2013) of three days. A total of 16 students participated, originating from the University of Toronto, John H. Daniels Faculty of Architecture, Landscape & Design and from the Delft University of Technology, Faculty of Architecture, Landscape Architecture and Urbanism departments. The first day consisted of site visits to the three project sites. The second day started with introductions on general design theories and the resilience concept and concrete expectations for the design projects. After this the students worked on identifying the crucial interventions that changed the area 30 years ago and which ones they expect to do the same 30 years ahead. This exercise delivered for the themes of climate change, urban development, economy and society the ingredients for the first design sketches. Based on this, by the end of the day four groups presented their concepts for a resilient watershed. The design of the water flow should be designed to minimise the negative impact on the entire urban region while increasing its resilience by looking for space and means in the public realm for water storage, re-use and treatment, and slow-release, and link other green uses with water propositions (such as park, leisure, food). The third day the groups detailed their concepts and designed at the lower scale site detailed proposals. These designs should address integral sustainability issues (such as energy, mobility, ecology) and their implications on the urban patterns and structures of each pilot site. In the afternoon these designs were enriched using a 3D-modelling technique. The day was concluded with a final presentation for an audience of experienced scholars, high-level government officials and urban sustainability entrepreneurs. All four presentations were very well received.


The design charrette is an intensive and creative way of tackling complex problems in a design-led way. The four groups of design students each came up with a strategic plan for the entire watershed and a detailed proposition for one of the pilot sites.

The project for Hogg’s Hollow proposes to stage the water discharge at the level of the watershed, introducing so-called hydro-corridors, in which the upstream water is collected and redistributed. One of the locations the water is distributed to is Hogg’s Hollow, where leisure, ecology and energy supply are integrated in the design for water capture and storage.

The ‘Cars are the cigarettes of the future’ project emphasise emergent urbanism. It proposes to create separate autonomous sewer-sheds, which take control over the water quality and quantity of their own area. The design proposal for Thorncliff Park estimates the car use in the future will be semi-automatic hence doesn’t require much space, which can be used for other purposes such as food production, water storage and public green.

The ‘Flood Fingers’ project increases the capacity of the water system in the fingers of the system, which feed the main river. The natural topography of the steep river edges is used to generate energy, filtrate water and store water for future use in the city. In Thorncliff park several of these filtrating energy-generating hillsides are proposed.

The fourth proposition, Eroding to a new future, embraces the natural process of erosion in the riverbeds. Due to climate change the number and intensity of extreme storm events increases. This begs the question of whether it is prudent to continue resisting change or to utilise the change in propelling us forward in a new direction. Following this idea erosion is no longer the culprit but rather the catalyst of progress. The process of erosion that occurs throughout the Don watershed would then be allowed to occur naturally and is further intensified by removing channelisation and slope stabilisation techniques, resulting in widening the riverbanks. This natural process carves a new central conveyance system within the city and allows the creation of socio-economic nodes at places of the intersection with major infrastructure (figure 1). These nodes are adaptable to changing water conditions, with floating markets and buildings, creating a dynamic riverine landscape that becomes an integral part of the urban network.

Water filtration sites along the river corridors allow filtration of runoff and household water, which is fed back into the system assisting with sediment release and conveyance. The eroded sediment extracted from the river beds is deposited downstream, feeding the growth and development of island communities (figure 2), which will add additional prime real-estate to the city and provide an opportunity for productive islands from where food and produce can be transported up the riverine network back into the city. This dynamic system ultimately both adopts and adapts to ever-changing conditions.

A resilient watershed

The designs developed during the design charrette provide solutions and spatial directions to increase the resilience of the watershed of the Don River, and also increase the resilience of the city and its inhabitants. The results achieved in one day of site visits and one and a half-day of intensive design studio work are innovative, relevant and realistic. The short time available to develop the proposals shows that the approach to limit the time available increases the originality of the designs and the accuracy in responding to the fundamental research question. It is clear that each of the models and designs requires further detailed elaboration.

The groups each presented strategic designs for the entire watershed, which determines the possibilities and challenges at a lower scale of the urban design. This phenomenon, to rise above the individual project site or plot was relatively new for the Canadian designers and was received with great interest. The students presented the results at the Resilient Cities Summit and had the opportunity to explain their propositions to the Dutch Royal Couple (figure 3), who attended the summit and were very interested in the innovative character of the design proposals and plasticine models.


Roggema, R. (Ed.) (2013) The Design Charrette: Ways to Envision

Sustainable Futures. Dordrecht, Heidelberg, London: Springer, 335 pp.

Roggema, R., Margolis, L., Van Loon, F. and Kossowsky, D. (2015)

Design Brief Canada-Netherlands Resilient Cities Summit Design

Charrette: Don River Watershed, Hogg’s Hollow, Thorncliffe Park,

Port Lands. Velp: VHL University of Applied Sciences.

Rob Roggema with Liat Margolis (University of Toronto) and Frits van Loon (TU Delft), and Master students

Landscape Architecture, Urbanism and Architecture of University of Toronto and Delft University of Technology.


Dr Rob Roggema

Professor of Design for Urban Agriculture & Slow Urbanism

VHL University of Applied Sciences

Tel: +31 6 19267143


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