River banks are vitally important to the life of the river. The bank provides breeding grounds for birds and mammals that feed in or near the water and acts as a habitat for insects such as dragonflies that emerge from the river. River bank erosion can threaten these lifeforms and pose a number of other important problems. It helps to understand why river bank erosion occurs and the methods we currently have that can stop bank erosion from occurring.
What is River Bank Erosion and Why is it Harmful?
River bank erosion is the wearing away of slopes and banks along dynamic waterways like rivers and streams. Bank erosion causes these high current channels to constantly change course and can affect the land that borders them. While river erosion is a process that occurs naturally, human impacts can increase the destructive rate.
There are several contributing factors to river and stream bank erosion. Potential causes include intense rainfall and flooding, the characteristics of river bank soil, river redirection around debris in the channel, and clearing vegetation away from the river bank. Other causes could include stream and land management use, river straightening, and river bank saturation from non-river water.
What are the Impacts of River Bank Erosion?
All dynamic waterways, such as rivers, have some amount of healthy bank erosion. The problem arises when unstable rivers experience substantial amounts of erosion. When this occurs, issues can include loss of farmland and businesses, which can then result in economic hardship in the general area.
Soil erosion can also increase pollution and sedimentation in streams and rivers, which can lead to clogging. Fish and other species can be affected, causing their populations to decline.
Erosion can eventually lead to homelessness and migration if masses of people become displaced and are forced to move. The worst-case scenario would see mass failure, which is when the entire section of the river bank collapses into the river.
River bank erosion is bad enough for the area where the erosion occurs. The bank erosion can also affect life down the river. The erosive forces send extra sediment downstream, which can alter the river’s course and disrupt shipping channels.
What are the Best Methods for Stopping River Bank Erosion?
River bank erosion is an ever-present problem along dynamic waterways, but we do have methods for slowing or stopping the process entirely. Since bank erosion is a naturally occurring process, most engineers and workers prefer to use natural materials when seeking an erosion control solution. There are biodegradable materials, temporary, and permanent solutions available, depending on the scope of the project.
Natural Vegetation
Vegetation, and in particular the roots, offer natural erosion control along river banks. Banks that have vegetation tend to erode at a slower pace than those without. Strong roots fortify soil strength along the river bank, which makes the river bank less susceptible to mass failure. Plants along dynamic waterways also function as shock absorbers during heavy rains and floods, which further slows the rate and degree of erosion.
Tree Revetment
This river bank erosion control system uses small-scale fallen trees. The trees are anchored horizontally in place along the bank to control the rate of erosion. The trees work by slowing the flow of water, which drastically reduces erosion and catches sediment to prevent it from flowing downriver. The sediment caught by the tree branches creates an effective soil bed that allows natural vegetation to root.
Vegetated Concrete Block Mats
These concrete block mats stabilizes stream and riverbanks while incorporating natural vegetation or even tree revetment methods. Often, willow stakes and riparian plugs are incorporated within Flexamat concrete mats. Riparian vegetation thrives within the armor. The low profile of Flexamat prevents debris or logs from catching the mat and helps keep the waterway open to positive flow.
Wildlife can safely cross Flexamat armor. The matting also helps provide a stable walking surface if using the shoreline as an entry point for canoes or kayaks.
Ask About Temporary, Biodegradable, and Permanent River bank Erosion Control
River bank erosion can have dire consequences. You now know of several options for slowing or controlling erosion along dynamic water banks. To learn more about natural and synthetic methods for preventing erosive forces for any project big or small, call the Flexamat team.