The Barrier Dune System

The barrier dune system represents a second line of defense for our shore & Barrier Island. Our first line of defense is the Beach Berm – the sandy area between the dunes & the water where you place your towel or chair to spend a day at the beach. But the Beach Berm is really a no man’s land for sand. With nothing to cling to wind moves sand along the beach, into the dunes or even back into the water. The Beach Berm is like your check book. The sand or money that’s there today isn’t the same sand or money that will be there tomorrow, or in a week. With constant withdrawals & deposits, we strive to maintain an average, albeit transient “Daily Balance”. Like unexpected expenses, storms can make large withdrawals from a Beach Berm, but a healthy barrier dune acts like a savings account, keeping the checkbook in balance when necessary. Erosion occurs when withdrawals exceed deposits & the sand reserves of the Barrier Dune have been depleted. 

On developed shores, the Barrier Dune system is at best neglected & most often severely compromised. There the dunes can’t store sand as the dunes themselves are filled with houses. On Plum Island, the Barrier Dune system that we rely on has dwindled to a slim sliver of sand. With climate change & sea level rise a reality, a robust barrier dune system is essential to preventing storm induced wash over & Barrier Island Retreat. We should learn to treat it well.

(To Illustrate Certain Points, Some of the Power Point Slides contain Images from Salisbury Beach & are so noted)

“The Barrier Dune System”

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 “How to Grow a Sand Dune”

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Mike Morris

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