Soft Solutions
The alternative to hard engineered solutions are soft solutions, which refer to a toolkit of protection practices that work with the preexisting elements of a shoreline. In examining how erosion happens as part of the longshore sediment transport system, preserving the toe is the most critical element to mitigating the affect of erosion, since the toe is the targeted area that is carried away. This can be simplified to an equation: the beach protects the cliffs and the cliffs protect the properties on them. There are three elements that can be used as building blocks to design a soft solution: sand, wind and vegetation. By reducing the problems of a particular site down to these factors, an innovative, low-impact solution can be crafted. Once the basic strategy has been designed for a site working with these three factors, subtler design principles are used, which will not be explored here.
Beach Nourishment
One soft solution technique is beach nourishment, also known as beach replenishment or enrichment, whereby complimentary sand of a similar grain size and composition is deposited onto the toe thus adding potentially up to ten years to its life and subsequently to the asset(s) behind the toe. Once this sand is imported it can be vegetated to stabilize the new sand from eroding. Compatible native vegetation should be used to revegetate like American Dunegrass, Bayberry and Rosa Rugosa (Saltspray Rose).
While the rate of erosion is not affected, the impact of the erosion for the remediated area is lessened by the presence of additional sand. This type of soft solution is much more economical than the alternative of allowing the coastal bluff or dune to erode, considering the cost of having to move a vulnerable structure or pay for a clean-up of fallen or eroded debris. It can cost around $10,000 to bring in enough sand to build the toe of a small section of beach, which is considerable less than the thousands that it can cost to even have a new location sighted for a relocated building. This strategy is one of the most effective options for preserving the toe since strategies like erecting sand fencing or planting dune grass cannot offset the impact of large scale erosion.
Dune Grass and Sand Fencing
Dune grass planted at 116 N Pamet to help reinforce the bluff after the house was moved. Reinforcing the plantings with burlap screen was used to ensure that the grass would take hold in this highly volatile area.
Another sustainable soft solution that compliments the natural environment is planting dune grass because sand that is vegetated benefits from much greater stability than sand that is barren of vegetation. Dune grass and vegetation in general work as screens to blowing by sand, catching it where it will hopefully settle and accumulate. Planting dune grass is the most commonly implemented technique to stabilize sand across the Cape, but it is also labor intensive and the plant itself is very fragile. Stepping on the root of a piece of dune grass more than twice can kill it, so it cannot tolerate an excessive amount of traffic. For this reason it is essential that beach goers follow marked trails and paths.
Safe Harbor volunteers drive rods into the sand to create holes to plant each piece of grass.
Sand fencing, otherwise known as snow fencing is another low-tech and non-invasive erosion control method, which works similar to dune grass by catching drifting sand. The best way to preventatively manage erosion is to use the two in conjunction by strategically placing dune grass and sand fencing in fragile areas to help build up the dune by trapping the sand as it is blown into these two types of barriers. By working as sieves, they have the ability to influence the shape of the dunes in how they erode and accrete.
Gordon Peabody of Safe Harbor cuts standard 48" sand fencing into two 24" sections.
[1] Considering the true drift of sand, using standard four foot sand fencing is an unnecessary measure, since sand does not typically blow that high. Safe Harbor modifies their sand fencing to be half that dimension, rendering it equally effective and more economical since twice the fencing can be utilized from one roll.
