HURRICANE IMPACTS ON A RECENTLY NOURISHED CHRONICALLY-ERODING BEACH
To quantify the effects of the hurricanes, beach profiles, spaced every 100 m, and GPS shoreline and dune line surveys were conducted weekly during September 2004. In addition, offshore bathymetry was surveyed at the beginning and end of the month, and an offshore directional wave gauge was deployed, allowing for differentiation between waves from the different hurricanes. Less than one month after project completion, the shoreline of Upham Beach eroded 60 m, a loss of over 60,000 m3 (or 20% of the total amount of beach fill), which is nearly equivalent to a year's worth of erosion based on previous nourishment performance.
The surveys captured pre- and post-storm beach profile and nourishment planform morphologies. Relatively high-energy conditions during the storms resulted in increased cross-shore and longshore transport of the nourished material. Profile equilibration, typically thought to occur on the order of years, occurred within one month. Accelerated planform adjustment also occurred. Overall, the post-nourishment response of a typically rapidly eroding beach was accelerated by nearly an order of magnitude due to the passage of three hurricanes in less than one month.