Only concrete blocks remain atop this ocean side coastal bank
Coastal banks, composed of consolidated sediments created by Glacial Process, can never be restored, once they have been exposed to wind, wave and tide erosion. Nourishment strategy may provide an alternative to the permanent loss of the coastal bank itself. By placing limited amounts of sand along the toe of the bank, erosion activity will remove the sand and not the bank.
Beach sand absorbs wave energy. Eroding beaches may be resupplied by sand from the toe of a coastal bank. When the toe is used up, a new section of bank will collapse to create a new toe. This "Coastal Process" inexorably whittles away at the Outer Cape's bay side and gobbles away the ocean.side. On the slower eroding bay side, the placement of gabions and revetments provide short term, hard solutions but cause other problems by interfering with the Coastal Process . The ocean side's "average" erosion rate is several feet per year, often plays out at several low years followed by a very high year.
The two classic responses to coastal erosion have been to build stone revetments and re-nourish beaches. These responses impact beaches in several ways: Heavy equipment necessary for construction of revetments and beach re-nourishment directly impacts the beach; Revetments redirect wave and current energy, "end scouring" sand from both ends of the revetment; the revetment itself blocks off the sand supply from the coastal bank that would normally erode to compensate for beach erosion; When property owners built revetments, they made an agreement to provide a sand supply (re-nourishment) for the beach; The delivery of this re-nourishment sand creates unnatural conditions by placing large amounts of sand into play on the beach; Shell fishing interests have expressed concerns regarding re-nourishment.
Suppose we considered a solution that could be found within the problem itself. Using sand to renourish the toe of the bank instead of the beach. That way the beach could draw on the sand supply from the toe as needed. The toe would protect the beach as well as the bank and could be renourished as necessary. Where practical, sand could be supplied with a lot less effort from the top of the bank, naturally creating a toe at the bottom.
We believe this system merits investigtion. Techniques have been suggested for supplying sand by crane, bulldozer, dump truck and even helicopter. Coastal bank vegetation could be impacted but in the long term would be protected. This system could offer a low impact degree of protection on the ocean side coastal banks as well.The coastal process would continue and property owners would be buying time...with sand.Current state of the art for engineered "soft solutions". These fiber roles are destined for the top of a rock revetment, for a project by Wellfleet excavator "E-Z Doze It" in Chatham, Coconut fiber rolls are used for beach stabilization in high loss areas. Rolls absorb storm wave impact to reduce erosion.Safe Harbor has been experimenting with modified sand fencing on Cape Cod Bay. The majority of wind blown sand moves in the first 24 inches above the beach. This fence can be used in restricted areas and installed without posts by using a rubber mallet to drive in each slat. Fencing not only prevents erosion by slowing down wind but can also contribute to deposition when placed perpendicular to onshore winter winds. We use multiple lines of fence.
At a recent erosion control conference, we were sharing our experience with 24 inch sand fencing. The most common question was "where can we get 24 " fence?".
Here is the answer