Lagging Behind: Impact of Non-native Gravel Within a Coastal Dune System

Keywords: Aeolian, Sediment Transport, Lag
Session Type: Virtual Paper Abstract
Day: Monday
Session Start / End Time: 2/28/2022 03:40 PM (Eastern Time (US & Canada)) - 2/28/2022 05:00 PM (Eastern Time (US & Canada))
Room: Virtual 39

Abstract

Scattered throughout Santa Rosa Island, Florida there are extensive concentrations of gravel within the back barrier system. This human introduced gravel is an intrusive sediment and holds potentially negative implications for aeolian sedimentary transport and coastal dune development. The primary goal of this research is to evaluate the influence this intrusive gravel lag has on aeolian sediment transport activity. The study site consists of two ten-meter by ten-meter survey plots. One of the plots contained a moderate concentration of the gravel lag (~60% coverage) while the second plot was cleared of all lag deposits, representing the natural sand of the barrier island system. Wind speed and sediment transport were measured via a vertical array of anemometers and Wenglor sediment particle counters. To assess the difference in transport activity between the two sediment plots, wind velocities were categorized across wind ranges of 0.5 ms-1 intervals and evaluated via a dual spline knot analysis and a Bayesian Information Criterion (BIC). The models determined significantly different interactions in sediment transport activity between the two plots for wind speeds less than 9 ms-1 (p<0.001) and wind speeds between 9 ms-1 and 11 ms-1 (p=0.001), yet for wind speeds greater than 11 ms-1 no significant difference was observed (p=0.841). This signifies that at lower wind speeds the gravel lag diminishes aeolian transport. However, as wind speeds increase, there is a threshold at 11 ms-1 upon which the gravel lag has little to no impact on transport activity.