How to Control Streambank Erosion

Methods of erosion control include runoff traps and hydromulching techniques.

Erosion is the process by which wind, water or weather wears away soil and stone, such as the flow of a stream gradually eroding its own banks. Streambank erosion can make for unstable soil and increase the likelihood of flooding, so it's imperative that you monitor and control it, especially if the stream is near any structures. An assortment of materials and techniques are available that inhibit bank erosion.

Things You'll Need

• Coir logs
• Shovels
• Wooden stakes
• Willow cuttings
• Erosion control blankets
• Jute twine

Instructions

1. Measure and record the widths and circumferences of your coir logs. Coir logs are tightly wound coils of coconut fiber, which are biodegradable and often encased in coconut fiber or jute netting. They are dense enough to provide environmentally friendly solutions to aid in the re-vegetation and stabilization of steep banks and other soil erosion sites.

   Find the base of the bank you wish to protect from erosion, and begin digging a trench where it meets the riverbed. Your trench should be roughly two-thirds the depth of your coir logs, so that one-third of the log will rest above the riverbed once placed in the trench.

2. Line the bottom of the trench with erosion control blankets, unrolling them so that they stretch up the side of the stream bank rather than horizontally following the trench. Natural erosion control blankets are available -- such as those made from coir, jute, straw or aspen fiber -- which will fully biodegrade over time. Using wooden stakes, peg the blankets into place.

3. Place your coir logs in the trench, securing the bottom flaps of the erosion control blankets. Hold them in place with more wooden stakes, which can be driven into the ground through the netting on either side of the logs. Continue placing coir logs until the trench can transition to a firmly established and stabilized bank, and until water can no longer directly impact the bank. The soil of the bank should not noticeably shift or slide towards the water as you walk towards its crest. Using your jute twine, tie adjoining logs together.

4. Place the live willow cuttings and bundles into the substrate on the bank side of the coir logs at a 45 degree angle, so that they are somewhat supported by the logs. You may need to cut tears in sections of the erosion control blanket to accomplish this, depending on the type you have purchased. These willow cuttings will develop strong roots to deter erosion throughout the bank.

Tips & Warnings

• If your bank is particularly steep, in dire danger of eroding or receives the force of a high-velocity stream, you may benefit from digging more than one trench for your coir logs. Place each consecutive trench at a 3 or 4 foot interval, moving up the bank so the vegetation has pockets of softer soil where it can establish itself.

• Coir logs should be installed in dry seasons or with the use of water determents such as silt fences to isolate the area from the stream's water flow.

References

• University of Wisconsin; The Physical Environment: An Introduction to Physical Geography; Michael E. Ritter; 2006
• University of Washington: Erosion Control