RECENT NATURAL AND ENGINEERED CHANGES ON A NEW YORK CITY BEACH, ARVERNE, ROCKAWAY, NEW YORK

The morphology of Rockaway's shoreline which has been shaped by natural forces changed greatly after the early 1930s due to coastal engineering which modifies the character of these natural forces. Rockaway barrier beach experiences a positive sediment budget on the western portion and a negative sediment budget on the eastern portion. Arverne is located on the eastern eroding portion. The U.S. Army Corps of Engineers began an extensive beach replenishment program for the eastern part of the Rockaway barrier beach in 1970 and the program has continued up through the present.

Three survey maps are compared: 2002 Quennell Rothschild & Partners Arverne-By-The-Sea Beachfront Preserve Schematic Design (Queens Borough datum) by Vollmer Associates, 1999 U.S. Army Corps of Engineers Rockaway Beach (NGVD29) by Rogers Surveying, and 1969 U.S. Geologic Survey Far Rockaway Quadrangle (NGVD29). Datum is adjusted by adding 2.725 feet to each of the elevations and contour lines on the 2002 map and moving the 2002 shoreline off shore from the 2002 zero contour line. Erosional and depositional changes from 1969 through 2002 is analyzed by mapping the spatial distribution of volumetric changes depicted on 2002-1969 and 2002-1999 departure maps.

A starved beach is depicted on the 1969 survey showing a narrow berm with from 100 feet to 200 feet of beach between the boardwalk and mean sea level. The 2002 shoreline is approximately 200 feet south of the 1969 shoreline, the distal off-shore area has a net replenishment of ~6 feet of sand, and the near off shore area has a net replenishment of ~12 feet of sand resulting from the 1975 beach nourishment program. The berm is shown to have ~2.7 feet of deposition along a narrow strip adjacent to the boardwalk. Beach nourishment in 1996 broadened the berm in this area.

The 1999 survey shows the shoreline midway along the length of the groins and the 2002 survey indicates the shoreline eroded an average of 200 feet. Most of the area north of the boardwalk experienced 0.1 feet to 1.3 feet of erosion between the years 1999 and 2002. The area with the greatest erosion is on the eastern side of the Arverne beach. Between 1999 and 2002, the area adjacent to the boardwalk eroded up to 3.3 feet of the replenished sand that was emplaced in both 1975 and 1996. As of 2002, the elevation of this area is only 2.7 feet above the 1969 elevation.