Published on March 29, 2009
Slide 1: Left Click your computer’s mouse to advance the presentation & to activate animations w/in a slide. One can also advance or go back within the presentation by using the controls in the lower left corner of any slide. Move your mouse there & the forward/back arrows will appear. Jump to any given slide within the presentation or exit the presentation by clicking on the square button located to the left of the forward arrow. Select “Go to Slide” or “End Show” Viewing Instructions: The Barrier Dune System : The Barrier Dune System Slide 3: What is the status of our Barrier Dune? The Parker River Wildlife Refuge has a very healthy dune system… Stable Back Dune system that stores vast amounts of sand Densely vegetated dunes Contain complex root Structures that retain sand Vegetation grows To base of dune because… Organic ocean debris traps sand providing incentive for new growth to dune base. In this way dunes can regenerate growth after wave attack The Refuge is the Federal Reserve of Plum island Sand. Slide 4: To the North, Large homes Dominate the Landscape… all the way to Plum Island Point Some dunes have been replaced entirely, : Some dunes have been replaced entirely, and therefore aren’t capable of storing sand… Slide 6: Some dunes don’t even exist… This area is susceptible to a breach, as there is no barrier dune within 3 house lots of Plum Island Basin Slide 7: This dune is inviting a storm driven wash over… Slide 8: Some dunes can’t grow vegetation… Dense gravel nit pack layer, remnants of an old parking lot, limits vegetative growth. No root Penetration Below dense layer Thus sand is not retained & is subject to wind & water erosion. Slide 9: Dunes that host the foundations of older Homes, contain no roots & therefore can’t hold, let alone store, sand. Dune grass grows on either side of a structure But won’t grow under a foundation Once a dune erodes back to a foundation, self regeneration is difficult & slow. Slide 10: Large homes… Built tightly together, in series, to the edge of the barrier dune Rely on a thin noncontiguous strip of vegetation to contain the very foundation upon which they sit. What would happen if the beach berm were to erode here? More Plum Island home owners need to actively maintain their dunes. : More Plum Island home owners need to actively maintain their dunes. In too many instances the barrier dune is neglected & compromised. As a result, sand isn’t being stored for that stormy day. Some residents understand the situation they are in and are actively promoting the growth of their dunes… : Some residents understand the situation they are in and are actively promoting the growth of their dunes… …they’re saving sand for a stormy day Slide 13: Plants will eventually grow to the dune’s base. Here, a snow fence & driftwood protect plantings… Organic debris is placed at the dune’s base to trap sand & fertilize the dune. Creating a sand “bank” takes some effort, but pays dividends when a storm is calling. : Creating a sand “bank” takes some effort, but pays dividends when a storm is calling. … It is part of the responsibility of “owning “ a barrier dune. Slide 15: While it is legal, are we acting responsibly by building a 3900 Sq ft house in this tiny dune? Dunes hosting homes whose footprints are based on virtual lot size Further compromising the dune & neighboring structures. Have their vegetative cover disproportionately reduced Slide 16: The foot print of this house, while legally 20% of the lot size, occupies almost 70% of the dune upon which it sits… Slide 17: Are we treating our barrier dune as if it were truly valuable? Slide 18: 39ft 32.5 26 ft 19.5ft 13ft. 6.5ft. Are we really doing the right thing? 43 ft? 33.5 ft? “Each time history repeats itself, the price goes up.” : “Each time history repeats itself, the price goes up.” ~ Author Unknown Building homes at the expense of the barrier dune has happened before… Slide 20: These dunes can’t offer sand to an eroding beach berm, nor can they accept & store sand when the berm offers it… Here the sand is sealed & locked down by buildings & pavement. Slide 21: With 75% of the back dunes covered by roads & structures How can a westerly wind deliver sand to a stressed barrier dune? Slide 22: Clark, John, 1971, Coastal Ecosystems Ecological Considerations for Management of the Coastal Zone. The Conservation Foundation, Washington, DC in Cooperation w/ NOAA Office of Coastal Environment & US Dept of Commerce “When dunes are destroyed by man, there is nothing left to stabilize the remaining sea of drifting sand but man himself.” Actually, we do thisnow… Slide 23: The barrier dune system we rely upon is a thin sliver of sand… We should learn to treat it well.