Glendon River Bank Restoration Project

Picture This: An absolutely perfect fall day….. The leaves on the trees are just changing colours, and Glendon looks absolutely picturesque. As Liron and I took in our surroundings, we realized this was going to be a great afternoon. With our stomachs full of coffee and bagels, we set out to find our stretch of the river bank.

glendon-map

Our Section of the Riverbank

Our journey began with us becoming very lost, very quickly. We somehow had to figure out how we could access the Bayview segment of the river. We decided to walk along Bayview Avenue, and managed to get some wonderful bird’s eye view photos of the riverbank. The first thing that caught our attention were the stabilization structures implemented. At the first part of the river segment there were sheet piling walls, and an eroding mattress gabion. However these structures did not extend very far past the bridge, so they did not contain or help revitalize the majority of our river segment. When we travelled closer to the river, we could see that other parts of our segment had signs of slumping and erosion, with debris all along the bank. Also, right across from the bridge was a sewer pipe, and its waste was being directed straight into the river. Moreover, the majority of the bank that was photographed did not have any other stabilization structures in place as well.  All of these descriptions can be seen in the slide show below.

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Riverbank Structure (adapted from Li et al. 2002)

The majority of slumping and erosion that were seen along the riverbank were the sides of the Toe and Splash zone as illustrated above. Moreover, the first segment of the river facing Bayview Avenue had a lot of sedimentation along the toe zone as well.

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Now the first question Liron and I thought to ourselves, was why the riverbank was eroding in those places observed to begin with?

According to a study by Nichols (2009), when the city of Toronto underwent urbanization changes were made to the river. This included altering the river to be straighter in order to reduce spring flooding, however by doing so this created a lot of ecological problems (Nichols 2009). By channeling the river, this causes increased velocity of the water which can increase erosion and loss of biodiversity (Li & Eddleman, 2002). This occurs because soil erosion and sedimentation damages soil quality, and thus promotes loss of biodiversity of plant species along the river bank (Li & Eddleman, 2002).

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Stream Channelization Effects on Bank Stabilization and Biodiversity (Li et al. 2002)

Other factors that contribute to the erosion observed, include drainage into the river via a sewer pipe, which retains waste water and salt run off, that also contributes to further erosion of the soil from the riverbank (Cardini et al. 1978).

What can Glendon Do?

In terms of stabilizing the riverbank, there are many stabilization techniques that can be implemented. The first step that can be taken to reduce waste and pollution into the river would be to re-direct sewage and run off drainage into the river. This would help stabilize the river, as well as keeping it cleaner for the species that live and depend on the water.

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Shrubs used in Bioengineering to stabilize Riverbank 

Glendon can also implement Bioengineering methods such as live fascines, or planting shrubs and vegetation along the river bed, in order to stabilize and strengthen the quality of the soil, and to prevent and combat further slumping and erosion of the riverbank edges (Montgomery 1997 and Petry 2003). This is also beneficial because it helps promote more greenery and vegetation into the environment and can help increase the overall aesthetic and biodiversity of the riverbank (Montgomery 1997).

Therefore there are many ways Glendon can help stabilize and improve the riverbank, so that students and the community can continue to enjoy a historic part of Toronto’s nature!

References:

Image: https://www.bluestem.ca/willows-stabilization.htm

Cardini, D. B. and L. (1978). Toronto Field Naturalists Ravine Survey: Study Number Eight.

Li, M.-H., & Eddleman, K. E. (2002). Biotechnical engineering as an alternative to traditional engineering methods: A biotechnical streambank stabilization design approach. Landscape and Urban Planning, 60(4), 225–242. JOUR. http://doi.org/http://dx.doi.org/10.1016/S0169-2046(02)00057-9

Montgomery, D. R. (1997). River management:  What’s best on the banks? Nature, 388(6640), 328–329. JOUR.

Paul L. Nichols, « Constructing connections: urban forestry and toronto’s west don lands revitalization », Environnement Urbain / Urban Environment [En ligne], Volume 3 | 2009, mis en ligne le 09 septembre 2009, consulté le 15 décembre 2016. URL : http://eue.revues.org/981

Petry, S. (2003). Alternatives for Bank Stabilization- Literature Review.

 

 

 

 

 

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