Temporal and Spatial Scales of Profile and Planform Adjustment on a Nourished Beach

Weekly beach profiles, shoreline surveys, and nearshore wave measurements were collected before, during, and immediately after construction of the 1100-m Upham Beach nourishment project on the low-energy, west coast of Florida. Substantial planform diffusion occurred prior to construction completion via formation of a spit extending from the widest portion of the fill. Longshore spreading occurred abruptly, as opposed to gradual adjustment predicted by long-term models. Profile equilibration also occurred rapidly due to the passage of three hurricanes. Nine days after nourishment, Hurricane Frances generated high wave conditions ( H _sig = 1.7 m) for this region, reducing the steep post-nourishment beach slope from 0.078 to 0.036, nearly the equilibrium slope (0.034). Hurricanes Ivan and Jeanne, which were nearly as energetic, resulted in much less slope change. This study indicated that profile equilibration was an event-driven process, contradicting the concept of long-term equilibration.