The latest Marine Extension Bulletin, a joint effort of Woods Hole Sea Grant and Cape Cod Cooperative Extension, is an overview of biodegradable erosion control methods. It provides the theory behind such methods and describes design components such as fiber rolls, sand envelopes and erosion control mats made from coir, jute and hemp.
This guidebook is a great resource for helping stakeholders understand biodegradable erosion control projects such as Woods Hole Group’s ongoing work at Bayswater Seaside in New Seabury.
Author Greg Berman concisely relates the key tenet of biodegradable erosion control (BEC) methods:
A boulder in a revetment would persist in the placed location for longer than the life of any home it might be protecting, (while) a BEC biodegrades and is intended to be replaced by root systems from native plants that are effective at stabilizing shorelines, but would still allow erosion under some conditions.
The document also contains an informative diagram that speaks to the use of coir logs and geotextile membranes, and their influence on root penetration and bank stabilization. Our bioengineered bank stabilization project in New Seabury utilizes geotextiles only to reinforce the sand envelopes that compose the lower bank, where periodic beach nourishment will occur. At the top of the bank, the design calls for beach grass plantings in the fiber rolls in such a manner as to allow sufficient root penetration to the existing bank to stabilize the project.
For more information on biodegradable erosion control, see the Marine Extension Bulletin.