Types of Breakers:
The slope of the beach directly correlates to the type of wave.
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Spilling Breaker: Gentle beach slope, waves break far from shore and surf gently rolls over the front of the wave.
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Plunging Breaker: Moderately steep beach slope, less steep wave, slightly longer period, wave curls over forming a tunnel until the wave breaks.
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Surging Breaker: Steep beach slope, a low wave of long period, doesn’t actually break, wave rolls onto the beach.
Beach Erosion to Sand Dunes:
What is Sand Fencing?
Sand fencing, also called snow fencing, is designed to help capture sand to build dunes. It is typically made of thin, wooden slats that are connected with twisted wire to wooden or metal stakes. While other fence materials such as plastic, polyethylene, and metal are sometimes used to trap sand, they are not recommended for coastal use because of the impacts they can cause.
Benefits of Sand Fencing:
Sand fencing provides a low-cost, easy-to-install, and effective way to help build up dunes and protect inland areas from storm damage. Unlike seawalls, rock revetments, or other “hard” shoreline stabilization structures, properly designed sand fencing projects do not reflect or redirect waves onto beaches or neighboring properties. The design of a hard structure affects how much wave energy is reflected, for example, vertical walls reflect more wave energy than sloping rock revetments. These reflected waves erode beaches in front of and next to a hard structure, eventually undermining and reducing the effectiveness of the structure and leading to costly repairs. This erosion also results in a loss of dry beach at high tide, reducing the beach’s value for storm damage protection, recreation, and wildlife habitat. Hard structures also impede the natural flow of sand, which can cause erosion in down-current areas of the beach system. Sand fencing projects, however, increase protection to landward areas while allowing the system’s natural process of erosion and accretion to continue.
Impacts of Sand Fencing:
The impacts of sand fencing projects are relatively minor compared to other options. The most significant factor is the proximity of the fencing to sensitive habitats, particularly nesting habitat for protected shorebird and turtle species (i.e., species that are considered endangered, threatened, or of special concern in Massachusetts). Sand fencing traps lighter, fine-grained sand, creates steeper slopes, and otherwise physically alters the area in a way that impedes shorebird nesting. These birds prefer relatively flat dune areas with coarser sand. The fencing also is a physical barrier that can block unfledged chicks from getting from their nests to their food source, and the posts or stakes can serve as perches for hawks and other predators that feed on the chicks. Another negative impact occurs when fencing destroyed during a storm becomes marine debris. Slats, posts, and wire littered on the beach or floating in the water are not only unsightly, they can harm people and wildlife. For example, wire can entangle wildlife and broken slats can puncture the bare feet of recreational beach users. Certain sand fencing designs and materials, such as sturdy drift fencing and plastic fencing, have additional impacts.
Logging Requirements:
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Do you think that this sand fence is effective in building up the sand dunes? Describe what you see at the GZ.
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What material is the sand fence made out of?
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Estimate the size of the sand dunes behind the sand fence.
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Identify the type of beach slope and corresponding breaker that is found at Monmouth Beach.
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As of June 2019, earthcaches are now allowed to have a required photo logging task. Please provide a photo of yourself, your GPSr, or a personal item that proves that you have visited this site. Please post this in your log.
Congrats to MatthewCat for the FTF!
Sources:
https://en.wikipedia.org/wiki/Sand_fence
https://cleanisland.org/sand-fences-help-beach-restoration/
https://www.mass.gov/files/documents/2018/05/29/ssp-factsheet-6-sandfencing-new.pdf
https://teara.govt.nz/en/diagram/4825/fore-dune-formation-and-erosion
https://manoa.hawaii.edu/exploringourfluidearth/media_colorbox/2173/media_original/en
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