Evaluation of Sand Fence and Vegetation for Dune Building Following Overwash by Hurricane Opal on Santa Rosa Island, Florida

Abstract

Santa Rosa Island, a barrier island located in the panhandle of Florida, was severely impacted by hurricane Opal's 3-4 m tidal surge in October 1995. Rapid reestablishment of the fragmented dune system through sand accumulation and stabilization is essential for many wildlife and plant species and protection of coastal structures against storm surge. Comparisons of sand accumulation rates for two biodegradable materials, three-fence orientations and non-fenced controls were assessed in a secondary dune position. Effect of winter and spring planting without supplemental water on survival and growth of nursery-grown sea oats and bitter panicum was also evaluated. Wood and Geojute material sand fences in three orientations were installed at six sites. Sand accumulation associated with these fence material/orientation combinations and non-fenced controls was measured twice a year (1996-99). There were no significant differences in sand accumulation between Geojute and wood fences at most positions for the first eight months. Following this, Geojute degraded and its accumulated sand was no more than that of the controls 18 months after installation. Sand accumulation did not differ significantly among wood fence configurations at most distances from the fence. Through time the straight-conventional wood and perpendicular-wood fence treatments had consistently higher sand accumulation values compared to unfenced controls. While survival of transplanted sea oats and bitter panicum was not effected by season of planting, growth varied with planting season.