Rivers are constantly migrating across their floodplains in rates varying from centimeters to hundreds of meters per year as river banks erode and new gravel bars form. This natural river movement is the basis of the entire ripariarian ecosystem on many Canadian rivers as it is how riparian forests establish and how a diversity of fish habitat is created.
The area a river migrates through, is called its “Meander Belt” and is usually easily observable using Lidar imagery. However the geologic history of the river valley needs to be understood to ensure the LiDAR observed meander belt is part of the current climactic condition.
Meander belts are often highly sought after developable lands which creates conflicts between allowing natural river migration and protecting developed land from erosion. Some work has been done to identify these areas as erosion risk zones or to provide recommendations to avoid their development under concepts such as “room for the river”.
This work attempts to find a balance between allowing development and minimizing morphologic impacts to the river. It provides a methodology for determining natural meander belt widths, but also meander belt widths over various times scales (i.e. the 200 year meander belt). It further provides guidance on developing appropriate development setbacks to ensure natural river movement and morphologic functions can continue in the future while minimizing erosion risk to developable lands. Lastly, it provides a case study along the Bow River in Calgary using the methodologies that could be applied to other rivers in Canada.
