Cause and Elimination of the Deflation Zones Along the Atlantic City (New Jersey) Shorelineby Erich R. Gundlach, E-Tech Inc, Narragansett, RI, USA,
S. Jonathan Siah, E-Tech Inc, Narragansett, RI, USA,
Abstract: After recent construction of several large hotels and apartment buildings directly fronting the Atlantic City boardwalk, large blowouts were observed to occur during the winter season along the beach seaward of the boardwalk. A field survey and sedimentary analyses determined that the mean grain size of the site was 0. 19 mm (fine sand) with 95% being finer than 0. 11 mm. The position of the deflation zone indicated that strong winds from the northerly/westerly directions were the cause of the blowout. Calculations indicate that a wind over 15 knots is sufficient to transport 50% of the sand present. The vortex effect created by the position of the structure in relation to the beach greatly increases the airport-measured wind velocities and causes the deflation zone. A solution for these areas is to place a layer of coarse sand, greater than 1 mm, into the zone to prevent movement by winds. During the summer season, finer and more typical beach sand could be placed over the coarser material. For the future, it is important that large structures be set back from the beach or that the structure be designed such that a vortex of increased wind velocities does not develop.
Subject Headings: Urban areas | Beaches | Shoreline | Wind engineering | Wind forces | Vortices | Sandy soils | Sand (hydraulic) | Seasonal variations | New Jersey | North America | United States
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