| A two-year span (1991-92) aeolian sand budget was calculated for Shackleford Banks, NC through use of a statistical model developed based on real time short-term field measurements using manned traps. This is the first complete aeolian sand budget on a barrier island that includes the aeolian sand flux on both ocean and sound shoreline. The island's shoreline was divided into 21 reaches based on orientation, sediment size, vegetation, and topography. Sand flux was calculated separately for each reach. With two exceptions all shoreline reaches had net sand transport in an onshore direction; rates varied from 0.11 to 12.97 m{dollar}sp3{dollar}/m/yr and averaged 6.09 m{dollar}sp3{dollar}/m/yr for the entire island. Net sand gain for the entire island was 188,000 m{dollar}sp3{dollar}/yr with 78,000 m{dollar}sp3{dollar}/yr from the ocean shoreline and 110,000 m{dollar}sp3{dollar}/yr from the sound shoreline.; Multiple regression analyses were employed to develop the equations for sand transport rate. The 0.05 significance level was selected for the tests of significance. Sand transport rate is the dependent variable. Onshore and offshore aeolian transport rates are considered separately. Other than two common independent variables for both onshore and offshore transports, wind speed and median sand size, two beach-related independent variables for onshore transport and six dune- and vegetation-related variables for offshore transport were measured. The regression analysis shows that all four selected parameters are statistically significant in quantifying onshore transport rate. Only three parameters for offshore transport are statistically significant. Based on the equations, wind speed is the major sand transport contributor, and wider beaches and steeper beach slopes increase onshore sand transport while higher vegetation and greater vegetation density on fore slopes of foredunes inhibit offshore sand transport. The F-statistics of both equations indicate the validity of their use for predicting aeolian sand transport rate. |
