FACTORS CONTROLLING THE FIRST YEAR PERFORMANCE OF EIGHT ADJACENT BEACH NOURISHMENT PROJECTS, WEST-CENTRAL FLORIDA, USA

Eight beach nourishment projects were constructed in 2006 on three barrier islands along the west-central Florida coast. A total of 2.0x10(6)m(3) of sand borrowed from Egmont Shoal near the entrance of Tampa Bay, were placed on beaches with varying lengths and orientations. An intensive monitoring study including monthly surveys of 125 profiles was conducted to quantify the performance of the beach fills. The first year performance of the beach nourishment projects is controlled by the following factors, including 1) high energy events, particularly the first storm after nourishment, 2) sediment grain size, 3) project length, and 4) longshore transport gradient. Profile equilibration is dominated by the first storm. For most of the profiles, equilibration occurred in the form of a nearshore bar development. The dynamic bar responds to the subsequent storm impacts and protects the dry beach. The longshore spreading pattern is controlled by sediment grain size. For the 2006 projects, longshore spreading occurred through transport and deposition of the fine sediment along the nearshore bar. Project length and transport gradient also strongly influence performance. The longer Sand Key project performed better with much less volume loss than the shorter projects with greater background erosion rates.