The Importance of a Healthy Beach

The four most important reasons to maintain a healthy beach are: their environmental impact, protection from storms, their effect on the economy, and leisure.

Environmental Impact: Beaches and their associated plant growth are a vital part of the ocean ecosystem, playing a key role in both the water and carbon cycles needed to create rainwater and absorb atmospheric carbon dioxide. Also, without healthy beaches, a wide variety of sea creatures are unable to nest or feed.

CarbonWaterCyclesStorm Protection: The sand contained in offshore shoals and on beaches is nature’s way to dissipate the energy of incoming waves. Vegetation on sand dunes and seagrass in the oceans help keep the sand in place. Together, they protect our coastal communities from intense storm damage. With little or no sand on beaches, waves crash onto coastlines, rip away the land and accompanying structures, and flood the local community. Below is a healthy beach ecosystem (source: Sea Grant California)

beach-ecosystems1Economic Impact: More than 50% of the US population lives within 50 miles of the coast. Healthy sandy beaches are major tourist attractions that generate hundreds of thousands of jobs and billions of dollars in revenue.

Recreation: Beaches are by far our nation’s top destination, attracting more visitors than all the national parks combined. Beaches are often easy to reach, accessible, and free, while providing various forms of exercise in addition to relaxation. Below left shows a “typical beach day” at Coney Island, NY in the mid ’30s, while below right shows how much the Coney Island shoreline has eroded since 1850.

ConeyIslandPostcards

Why Beaches Erode

Wave energy naturally breaks up sediment in the oceans and carries it shoreward with the tide. The heavier granules drop out first, while the finer ones get deposited on land, creating our beaches and sandbars. Just as deep sand can very quickly de-energize and stop a speeding car, it can also do the same to large waves from storm activity, thereby protecting our coastlines.

The “problem” is that shallow sandy waterways near the shore also impede large boats from getting close to land and into and out of protected harbors. Over the last century, in the name of commerce, we have continually dredged these areas to remove huge quantities of protective sand. Any child playing at the beach knows that when you dig a hole in the ocean, nature immediately tries to fill it in– with the surrounding beach. Further, by removing so much sand, waves are no longer de-energized and crash onto the shore, ripping away even more beach.

WhyBeachesErode

Most infuriating are those people who look at the resulting massive erosion and say “erosion is simply mother nature doing her thing, you can’t fight nature, nor should you even try”. Wrong. Rather, this is the earth desperately trying to heal itself from being horribly ripped open in a totally unnatural way by man.

The good news is that there are solutions. We can build off-shore ports where the water is naturally deep. We have accretion engineering solutions that allow our shore bottoms and beaches to heal in months, not years.

How can I tell if “my” beach is eroding?

Simply take a walk on your favorite beach and answer these questions:

1. Have you seen a noticeable loss of sand, a narrowing of the beach, or, does the water appear to be “higher” at high tides?  [This indicates a loss of beach elevation.]

2. Do you have a marina, a river mouth, or man-made structures such as seawalls, revetments, rock piles, jetties or groins within a mile of your beach- either upstream or downstream from your beach? [These structures would disrupt the littoral drift.]

3. Do you have areas of the beach that “drop off”, or look like small “broken cliffs”, known as scarping? [This would be the result of excessive wave energy.]

4. Do you have buildings, parking lots, homes within 1000 feet (330m) of the water? [These might be causing excessive rainwater runoff.]

5. Do you have periodic beach closings during the summer months, if so approximately how many times per year? [This would signify excessive rainwater runoff carrying toxins.]

6. Is there a current ban on shell-fishing in your area, or in recent memory?  [This would signify excessive rainwater runoff carrying toxins.]

7. Is there a noticeable downward slope from the beach area to the water? [This would be the result of excessive wave energy.]

8. If you have jetties or rock groins that extend into the water, is there a noticeable difference in the height of the sand on one side to the other? [This would indicate sand is being trapped in an unbalanced way.]

9. Has there been sand renourishment (sand dumping) needed to stave off beach loss? [Obviously the beach was declared as eroded.]

10. Was the sand renourishment effort “washed away” after a large storm or in less than a 2-5 year period? [This indicates the erosion “fix” was merely cosmetic.]

If you answered yes to one or more of these questions, it is likely that your beach is at risk or is already experiencing excessive erosion. Contact the Beach Recovery Foundation today to talk about possible solutions.

Dredging

Dredging is the act of underwater excavation. The two most common uses for dredging are to 1) keep waterways navigable by digging a channel deep enough for large boats to pass through, and 2) suck up sand to be deposited elsewhere, such as on an eroded beach. Regardless of the purpose for a dredge, the effect on the area being excavated is profound in two ways: 1) the affected ecosystem is greatly disturbed, both biologically and chemically, and 2) nature will attempt to fill the hole back in that was dug by dredging, often using the sand ripped away from nearby beaches, causing further erosion.

DredgerThis is what a common form of dredging boat looks like:

Below is what happens to an excavated area. The sea bottom is torn and sucked up, the sand filtered out, and the once buried “debris” (shells, rocks, etc.) are then tossed back overboard. The debris then litters the sea bottom, smothering the organisms underneath. Meanwhile, a plume of silt settles over the bottom and near the surface, polluting the area and promoting plankton blooms from the released nutrients. The disturbance from the dredge often churn up buried poisonous heavy metals and hydrogen sulphide for re-release back into the water.

dredgingeffects

The deeper the cut, the more water volume that passes over the area, hence the higher the energy of the resulting waves. This increased wave energy then causes the waves to crash harder and further up their coastlines, ripping away large chunks of it in the process.

During storm events, there is now nothing to prevent the waves from overrunning the coastline, picking up debris, and depositing it on roads and in people’s yards. Had the sand source been left intact, much of the sand carried by the waves would have been deposited on the coastline instead.

See also: How Beach Nourishment Projects Work

Traditional Methods of Fighting Beach Erosion

Erosion control structures fall into two basic categories: 1) “Shoreline Hardening”, for the purpose of protecting coastal property (e.g. seawalls, bulkheads and revetments), and 2) “Sand Retention”, for the purpose of trapping and retaining sand (e.g. groins and breakwaters). Note that, unlike accretion engineering whose purpose is to reverse the erosion process and accrete sand, these structures attempt to merely limit further erosion.

Shoreline Hardening Structures

Shoreline hardening structures are intended to protect coastal property immediately behind them, and are therefore built parallel to the shore. Unfortunately, the energy reflected from these structures usually exacerbates erosion both in front and on adjacent areas, where sand is often washed away leaving only rocks. Nevertheless, where roads and buildings need to be protected from the sea, shoreline hardening devices might be necessary. But with no way to dissipate wave energy, one big storm can often do severe damage to such structures.

Seawalls 

Seawalls are designed to be the most resilient of shoreline hardening structures. As such, they are built using pilings sunk deep into the earth for stability to better withstand the pounding of the surf. Though they are for the most part vertical in nature, their faces may also be curved, stepped, or both.

seawall

Revetments 

A revetment is typically constructed to protect a scarp (deep slope), embankment, or other shoreline feature from eroding. Unlike a seawall, a revetment is not designed to maintain the integrity of all the land behind it, and is therefore not constructed to withstand the same forces. As such, the materials used to construct it are laid on top of the earth, not deep within it.

revetment

Bulkheads 

When backfill is added to shore up an eroding bluff, a retaining wall called a bulkhead is typically built to protect the backfill from eroding into the water. Bulkheads are often constructed at marinas and places where deep water is needed close to shore for docking boats. As boats are mostly docked in relatively protected areas, bulkheads are designed to withstand only light to moderate wave action.

See also: http://www.climatetechwiki.org/content/seawalls
See also: http://www.coastalwiki.org/wiki/Seawalls_and_revetments
See also: http://nersp.nerdc.ufl.edu/~millerw/Revements,%20Seawalls%20and%20Bulkheads,%20Part%201.doc

bulkhead

Sand Retention Structures

Sand retention structures are intended to alter the course of the waves and affect the current. As waves transport sand, these structures attempt to trap the sand flowing by. Unfortunately, trapping sand in one area deprives it from accumulating in the adjacent area, forcing those living in the adjacent area to install similar devices, and so on. The end result is often a shoreline littered with sand retention structures, all effectively canceling each other out. This is why many communities and even entire states have outlawed such structures entirely.

Groins (aka Groynes)

Groins are by far the most common sand retention structures. They are simply a pile of material that extends, most often perpendicularly, from the shore into the sea. For coastlines that are normally devoid of sand, groins can be effective in keeping sand artificially pumped onto the beaches there longer. However, where there is sand either on the beaches or offshore, groins disrupt natural sand migration, enriching some areas while robbing it from others, causing severe erosion.

See also: http://www.coastalwiki.org/wiki/Groins
See also: http://oceanica.cofc.edu/an%20educator’sl%20guide%20to%20folly%20beach/guide/process3.htm

groin

Terminal Groins

Tidal inlets produce their own energy as they carry their water out to sea. If strong enough, such as after an inlet has been dredged (cut), this current can deflect the incoming sand-carrying waves, preventing sand from accumulating on the nearby shores. Not only is sand diverted elsewhere, but what sand is left on the updrift beaches gets sucked into the inlet as nature’s way to heal itself by filling in the cut. In an attempt to prevent such massive sand loss, a groin is constructed on the updrift side for the purpose of trapping this sand.

Unfortunately, terminal groins, like regular groins, exacerbate erosion upstream by blocking the flow of sand that would normally be deposited on those beaches. They also obstruct the normal ebb and flow of tidal inlets, have a negative impact on wildlife habitats, and are of limited value in preventing the inlet from trying to heal itself by refilling with sediment. Note: Jetties differ from terminal groins in that their purpose is not for erosion control, but rather to keep inlets from filling with sediment.

See also: http://dukespace.lib.duke.edu/dspace/bitstream/handle/10161/5182/Knapp_Whitney_MP.pdf?sequence=1
See also: http://core.ecu.edu/geology/riggs/IMPACTS%20OREGON%20INLET%20TERMINAL%20GROIN%2011-30-09%20(2).pdf

terminalgroin

Breakwaters

Breakwaters are hard structures intended to reflect and dissipate incoming wave energy with the principal purpose of reducing beach erosion. There are two types of breakwaters: detached and submerged. Both are small, relatively short off-shore structures– the former extend above the water line while the latter do not.

Unfortunately, breakwaters are quite unsightly and have been shown to intensify beach erosion, not prevent it, by trapping sand offshore. During storm events, detached breakwaters normally become submerged, rendering them useless. In some popular tourist locales, however, breakwaters are effective in making the area between them and the shore calmer and safer for swimming, though often to the detriment of adjacent beaches.

breakwaters

See also: http://etd.lsu.edu/docs/available/etd-11152012-174353/unrestricted/20121126_Woodroof_Thesis.pdf

T-Head Groins (aka Attached Breakwaters)

T-head groins are a combination of groins (in that they are attached perpendicular to the shore) and breakwaters (the top part of the “T”). Unfortunately, they also share all the negative impacts of groins and breakwaters.

See also: http://www.asbpa.org/publications/white_papers/ReintroducingStructuresforErosionControlFINAL.pdf

Accretion Engineering

Accretion Engineering is the science of de-energizing waves such that they drop the sand they are carrying onto the near shore. Accretion engineering is designed to work with nature, not against it, by absorbing wave energy, not reflecting it. Though accretion technology may be “hard” to the touch, it is the exact opposite of so-called “hard structure” engineering such as groins, breakwaters, and seawalls.

Below is a typical accretion engineering solution. Note that the system is a collection of very long concrete filled geotextile tubes. The “back system” of tubes sits along the shoreline, holding securely in place a series of prongs that stick way out into the ocean, slightly below the surface of the water. Using computer modeling, each gap between the prongs is designed to initiate a vortice within it, thereby de-energizing the wave, causing it to drop its sand. Gravity dictates that the heavier sand falls out first, followed by the lighter sand. The end result is that the tubes are quickly (i.e. over months, not years) completely buried under tons of sand, creating a naturally stratified beach that supports healthy dune growth (as opposed to jumbled dredged sand that often completely washes away).

AEModels

The first accretion engineering technology was developed in the early 1970s by a natural earth scientist named Dick Holmberg. Holmberg has been exceedingly generous over the last decade in helping the Beach Recovery Foundation understand, explain, and advocate for more widespread adoption of accretion engineering solutions. Please watch these three amazing videos, and then ask yourself why our state, local, and federal government quickly green light expensive and highly temporary and environmentally damaging dredging projects, yet bury accretion engineering technology not under sand, but rather under a mountain of red tape.

A healthy beach continues to accrete sand, not erode. Here are a few before and after pictures of sites that used Holmberg’s accretion engineering technology. The tubes have long since been buried, covered over not just by sand but also lush dune growth.

AEBeforeAfter

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