What is River Restoration:
River restoration is the active task of taking a damaged riparian or river ecosystem and restoring it to a stable condition. More so, the act of restoration generally refers to a combined use of physical, spatial and ecological management and maintenance techniques and procedures. While the science behind restoration is important for a project to succeed there needs to be a great deal of planning involved for a successful project. Planning includes the actual detailed design, funding, constructing and even more important future monitoring to determine if restoration is working (NOAA).
Image 1: A riverbank being restored.
What Variables Should We Consider:
Restoration of streams and rivers considers the aquatic environment and the surrounding land as one unit. The riparian zone is a transitional area between the land and water and is integral as an ecosystem. Within riparian zones, vegetation plays a key role and has several different functions (Donat, 1995).
(a) Regulation of microclimates
Riparian vegetation can shade aquatic areas reducing the surface temperature of water. They also increase dew formation, precipitation and soil moisture in the surrounding areas, while reducing evapotranspiration and wind speed as seen in Figure 1 (Wildermuth, 1978).
(b) Securing banks
The riparian vegetation decreases flow velocity on banks which helps with channel erosion, it also assists in promoting sedimentation. The vegetation also aids in bank stabilization by reducing soil erosion through reinforcement with roots (Waldron et al, 1981).
(c) Creating suitable habitat
Vegetation provides shelter for both aquatic and terrestrial species as seen in Figure 2, which is especially important in areas with intensive land use where these riparian areas act as refugia (Donat, 1995).
Policies On River Bank Restoration + Case Study:
One of the main reasons for river and stream degradation is due to inadequate land stewardship. Anthropogenic activities including the alteration of riverbanks, and surrounding land have adverse effects on the health of riverbanks and streams. Attempts at minimizing long-term damage are mitigated through riverbank policies. For instance, the “East Don River- South of Finch Bank Restoration Project” is an example of an TRCA project addressing the ongoing erosion along the East Don Parkland riverbank which must follow the Canadian terms and conditions found in the “Protection Policy for Lakeshores, Riverbanks, Littoral Zones and Floodplains Environment Quality Act” (“Légis Québec”, 2016).Image 2: The East Don River project planning, an effort by the TRCA which must follow the “Protection Policy for Lakeshores, Riverbanks, Littoral Zones and Floodplains Environment Quality Act”
Image 3: The East Don River being restored.
- Encouraging the natural state of the observed riverbank/ stream in order to prevent further degradation, erosion and loss of riverbanks, floodplains and littoral zones.
- Strict limits to human access to areas considered “high risk” in order to preserve biodiversity and quality of riverbank zone. This includes human actives such as swimming, water sports, hiking, biking etc.
- In the event of a floodplain, property and people must be protected to ensure minimal loss of funding and expensive equipment.
- Protection of flora and fauna through the use of biological characteristics pertaining to the environment, this includes natural fauna behaviour and flora locations.
The following video will give you a visual aid in understanding riverbank restoration
Riverbank Restoration Delaware & Lehigh NHC
Specifications for shore and riverbank protection:
Measured horizontally, a list of policies for the strip of land that bordering the edge of a lake and extends inland (“Légis Québec”, 2016). Adapted from the Canadian Government website on Riverbank policies (“Légis Québec”, 2016).
(1) The lakeshore or riverbank is at least 10m wide where:
-Slope is less than or greater than 30% with a bank less than 5 meters high.
(2) The lakeshore or riverbank is at least 15m wide where:
-Slope is continuous and greater than 30%.
Wildermuth, H. 1978. Natur als Aufgabe. Schweizerischer Bund für Naturschutz (Eigenverlag). Basel.
Waldron, L. J., and Suren Dakessian. “Soil reinforcement by roots: calculation of increased soil shear resistance from root properties.” Soil science 132, no. 6 (1981): 427-435.
Donat, Martin. “Bioengineering techniques for streambank restoration.” A Review of Central European Practices. Vancouver, BC, Canada: Watershed Restoration Program. Ministry of Environment, Lands and Parks, and Ministry f Forests (1995).
“Légis Québec”. Legisquebec.gouv.qc.ca. N.p., 2016. Web. 8 Dec. 2016.
“Streams and Rivers Restoration.habitat.noaa.gov/restoration/techniques/srrestoration.html.2016.web. 8 Dec, 2016.