Glendon College Don River & Walking Trails: a photo essay

Located in the midtown Toronto Lawrence Park neighborhood, Glendon College is surrounded by gorgeous grounds occupying up to 85 acres which was once used by the botany and forestry departments at the University of Toronto.  Naduni, Claire and I were assigned to document a segment of the Don River bank stretch as well as the state of the walking trails found on Glendon Campus. We photographed segment 4 of the river in addition to the walking trails on November 23, 2016 on a chilly afternoon (2:30pm) with a temperature of about 3°C.

Although we took the photos during the cold winter season in which all the leaves had fallen from their trees, segment 4 was seen to be surrounded by heavy vegetation which would potentially create  a high canopy cover over the riverbank during the spring and summer seasons. One side of the riverbank appeared to be somewhat slumping and had a lack of vegetation closer to the edge of the river. This may have been due to erosion caused by the flow of water through the river which removed soil/ rock from the edge of the river and therefore caused it to slump. The use of live vegetation and woody material closer to the riverbank for bank stabilization may have proved useful.

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Selected image of segment 4 of the Don River showing the slumping of the riverbank and the lack of vegetation near the river edge (above).

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Stabilization methods in wet habitats to strengthen riverbanks can be used to prevent problems such as riverbank erosion. This includes riverbank ripraps or revetments which create barricades and permanent ground cover structures that absorb energy released by water waves therefore preventing erosion from occurring (Sotir & Nunnally, 1995).

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An example of a riverbank stabilization method using ripraps. The ground cover structure made up of loose stones prevents the river from eroding/ slumping.

Examples of revetments include gabions, concrete mattresses and sacks which are used for emergency stream bank protection and would be essential for preventing erosion in the future.  Other approaches to river bank stabilization include bioengineering which prohibits inner erosion and vegetation by re-introducing native species. This also helps increase the biodiversity of species within the rivers habitat (Fischenich, 1989). No previous bank stabilization methods were observed during our visit to this particular segment of the river bank however there are projects set into place for restoration of the Don watershed (info found here). Various photographs shown below illustrate the ways in which ecologists can help prevent erosion using vegetation through tree and bush revetments in areas with smaller rivers and streams.

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An example of pole planting bioengineering which is used as an inexpensive approach for bank stabilization

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Example of riverbank using vegetative ripraps at high flow in June

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Example of riverbank using vegetative ripraps at lower flow in August

The walking trails along the Don River are surrounded by thick forests which follow a gravel and dirt path as shown below from the images that we took. Now these trails are beautiful in the fall time but by the time we had gone, all the leaves had fallen and the trees were bare. The state of the trails were somewhat decent however the wildlife near the gravel path had been deteriorated. This could have been prevented if fences were put up on either sides of the trail to avoid damaging the plants. Wildlife closer to the trail appeared less maintained most likely due to the impact and urbanization of humans.

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The above slideshow illustrates various photographs taken along the Glendon walking trail following an evening of snowfall which is noticeable from the small patches of snow leftover. The trees lining the path and parallel to the river can be seen to be slightly on a tilt possibly as a result of riverbank erosion.

References:

Sotir, R.B., and N.R. Nunnally. 1995. Use of rip-rap in soil bioengineering streambank protection. Pages 577-589

Fischenich, J.C. (1989). Channel Erosion Analysis and Control. In Woessmer, W. and D.F. Potts, eds. Proceedings Headwaters Hydrology. American Water Resources Association. Bethesda, Md.

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