Partner: Awais Nasir
In our assigned Glendon riverbank area, there was no evidence of reinforcements made to combat riverbank failure. Riverbank failure is very much dependent on the degree and extent of erosion and on the location of the riverbank. Habitat fragmentation and buildings built too close to the bank of the river weights the bank and cause slumping (such as parking lots and driveways in our case). This happens as the weight of the building or structure surpasses the weight of the riverbank. Water saturation also increases failure of the riverbank as it reduces soils strength thus causing soil erosion. The presence of driveways in the region further weakens the bank by targeting runoff water directly into the riverbank.
While deep-rooted vegetation can increase the strength of river banks. The increased constant exposure to water has led to a specific type of erosion in this case called toe erosion. This can be seen in the pictures where roots of deep-rooted plants are left exposed and hanging.
Riverbank overhang can be observed in the following pictures which has resulted in slumping.
Overall, the pictures show evidence of erosion and slumping and it can be seen that no past reinforcements were noticed in the assigned riverbank area and the possible restoration goals should include installation of riprap blankets and windrow revetments. These two restoration methods will help in controlling slumping and overhang bank and help reduce riverbank erosion in long-term.
Riprap blankets: They are made up of rocks and are arranged by the riverbank to inhibit soil erosion.
Windrow revetments: Stones put strategically either partially buried or on the ground level alongside an eroding bank.
The following picture is an example of a riverbank with the riprap and windrow revetment.