Plum Island Erosion

Sustainable Solutions

Insert Page Header Pic: Sustainable Solutions July 20 2008

In our efforts to stabilize a river entrance and occupy a migrating & fragile dune system, we have fought natures processes, with little understanding and respect of them. Consequently we’ve disrupted sand migration & are the cause of the very erosion we are fighting. We now have an understanding of Nature’s processes, that we didn’t have 100 years ago. It’s not an inexpensive or easy problem to solve, but the dynamics can be made to work in our favor. If we finally accept the opportunity to work with nature’s processes, then maybe we can end our 100 year fight against them.

Erosion Control Measures

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Plum Island has employed short term erosion control measures that include beach nourishment, beach scraping & the use of sea walls in the form of geo-tubes or coir sandbags. Let’s look at these practices, their caveats & how well they performed.

Insert Power Point Presentation  & Narrative  Here: The results of the 2010 River Dredging & Beach Nourishment Project

 

Insert Power point & Narrative Here: Beach Scraping

 

Insert Power Point Presentation Here: Hard Structures Sea Walls & geotubes 

Super Storm Sandy – A Meteorological Near Miss

(Caption) Super Storm Sandy, October 29, 2012

The earth is engaged in a never ending struggle to balance its temperature extremes - that is the extreme cold at the poles with the extreme heat of the tropics. The job of tropical weather systems is to vacuum heat from the tropical oceans & deliver it to the poles. Conversely cold fronts & cold core low pressure systems take the cold from the poles & cast it south over the warm oceans, cooling  the warm sea which concurrently warms the cold air mass. This dance of cold & warm air oftentimes results in intense storms. Some storms are purely tropical, like Hurricanes, while others are purely cold core, such as Nor’easters that tap their heat energy from the warm Gulf Stream. Others however are a combination of the two – a Hybrid storm. These hybrid systems typically occur in the fall when ocean temperatures are the warmest, tropical systems are common, and the northern jet tracks cold core low pressure systems further south where they feed off this tropical heat energy. These intense storms form because of the relative extreme contrast of the two clashing air masses & the immense amount of heat energy infused by a tropical system. With the temperature of the oceans rising, it is logical to conclude that there is more heat energy available & hence a greater clash to be had when the air masses collide.

Insert clickable Image:  Atlantic 2012 Hurricane Track Summary Here 

(Caption: 2012 Atlantic Hurricane Track Summary – Most Tropical Systems Don’t Impact us.)

Envision the Atlantic as an immense bowling alley & the east coast population centers are its pins. Each year the tropics roll a series of systems in our direction. While the majority of tropical disturbances don’t have much punch, and many end up as “gutter balls” curving back out to sea, some do manage to develop into “strikes”, impacting the U.S. east coast, but that isn’t so common. More common are cold core low pressure systems that ride up the east coast, feeding off the Gulf Stream, sometimes “striking” as intense Nor’easters.  As we transition from summer into fall & winter, tropical systems often combine with advancing cold core systems to produce some very intense “Hybrid Storms” – part Hurricane, part Extra Tropical Low. Hybrid storms happen quite often. Virtually every tropical system that is drawn northward transitions or becomes absorbed into a cold core area of low pressure. We just don’t hear much about them as this frequently occurs NE of us, in the North Atlantic. However, sometimes variables align such that this clash happens closer to home. Three noteworthy storms that most adults of today will remember are the Perfect Storm or Halloween Gale of 1991, the Halloween Northeaster of 2011 that dropped a foot of snow and was also accompanied by huge seas, and of course Super Storm Sandy in October of 2012. Interestingly, all three of these systems unleashed their fury during the last week of October. 

Insert 3 Clickable Images Here: Perfect Storm Satellite Oct 30, 1991 NOAA 

(Caption: The Perfect Storm October 1991, CREDIT NOAA)

Halloween 2011 Northeaster

(Caption: The Halloween Northeaster October 30, 2011 CREDIT Washington.edu)

Sandy Satellite October 29

(Caption: Super Storm Sandy October 29, 2012, CREDIT NASA)

 

On the grand scale of things, Plum Island dodged a bullet with Sandy. A meteorological wobble in the storm which spanned 1000 miles of ocean, altered its storm track by 150 miles, sparing New England, while devastating Long Island & New Jersey. Let’s examine how close we came.

As Sandy tracked N/NE off the mid- Atlantic coast, she was blocked by an area of low pressure to her east & high pressure to her N/NW. This funneled the storm into the Northeast U.S. It became a challenge of predicting how far north she’d travel, before she was forced west, after which she would stall.  Had the storm continued north for just 6-12 additional hours before turning west, she would have made land fall on Long Island, instead of southern New Jersey. This 150 mile alteration in storm track would have placed her northern wind-field & storm surge across Massachusetts, where she may have stalled for 3 days as she spun herself down. Imagine 6 storm tide cycles; it would have changed the landscape.

Insert Clickable Image: Worst-Case-E-LI-Landfall-Oct-28 

(Caption: Our Worst Case Scenario Wind & Sea State- a Long Island Landfall for Sandy)

New Jersey & Long Island’s Devastation would have been ours…

Insert Clickable Image:  Seaside Heights Overwash CREDIT AP Images

Insert Clickable Image: Seaside Heights Sandy Aftermath CREDIT AP IMAGES

Insert Clickable Image: Sandy forms a New Inlet CREDIT Reuters

(Caption: Sandy Forms a New Inlet)

 

Insert Clickable Image: The Next Inlet (CREDIT: Mike Morris)

(Caption: Where Would Our New Inlet Form?)

Climate Change, Sea Level Rise & Barrier Island Retreat

Long ago, the Plum Island & Salisbury Beach Barrier Islands formed transgressively in response to a slowly warming planet that prompted a gradual rise in sea level. Wave action plowed glacial deposits landward, shallowing the sea. Once sands were washed above sea level by varying wave energies, winds took over & built dunes. Since the process was gradual, plants were able to take root, building the Islands vertically, as they captured the wind driven sands driven ashore by ocean waves. Overtime the sea continued to rise, storms helped to erode the foreshore & dunes, sometimes even creating new inlets. Waves would eventually top the dunes in low spots, pushing sands to the island’s rear. As the foreshore was encroached upon by the sea, plant growth would retreat & eventually establish itself in these over wash sands. As a result, the island would in effect slowly “transgress” or retreat toward the mainland, migrating over the salt water marsh in the process.

Because all of this happened slowly over thousands of years, the marsh located behind the barriers, had the opportunity to also retreat as waters rose & the islands encroached upon them. Offshore of Salisbury beach for example, it is possible to see the peat & clay of an ancient marsh rising from the sea floor, as the barrier’s sands continue to migrate westward. If you walk the beach following large wave events, you might find parts of this peat broken up & washed ashore there.

Today, due to Human Induced Climate Change, storms are more frequent & intense, and sea level is rising faster than it ever has in the world’s Geologic past. Scientists are uncertain about how fast sea level will rise, & how quickly barrier Islands & their backwater marshes will, or can respond. If barrier island retreat happens too quickly, the marshes may not be able to keep pace with the rising waters & the advancing sand mass.  This will have far reaching ecological impacts, one of which will severely impact local fisheries. For developed Barrier Islands, recent history reveals that the combination of climate induced sea level rise coupled with climate enhanced storm activity, will have devastating results when barrier over wash & new inlet formation occurs. In fact, long before the water gets uncomfortably high in the calm bays & estuaries, or begins to seep up the streets along the backside of Plum Island, climate enhanced storm activity & frequency will begin to dramatically alter the shore. A hotter ocean contains more heat energy & a warmer climate will allow the atmosphere to absorb more moisture. When the meteorological variables align (as they did with Super Storm Sandy & the February 2013 Blizzard) the ingredients will combine to produce incredibly intense storms. Climate change & Sea Level Rise will have far reaching implications for Humanity & our Planet. Implications, we are just beginning to understand. As the climate warms & sea levels rise, we are literally entering uncharted waters.

For more on this topic and its implications read John Englander’s:

High Tide on Main Street: Rising Sea Level and the Coming Coastal Crisis

By John Englander; Foreword by Jean-Michel Cousteau                            

(Publisher: The Science Bookshelf; ISBN 978-0615637952

 

Insert Power Point: Climate Change, Sea Level Rise & Barrier Island Retreat