David Johnson

Honors in Geography

Major: Geography Minor: Environmental Studies

Supervisors: Joanne Halls, Geography and Geology

An Investigation of Barrier Island Topography using LIDAR and GPS Mapping Techniques

Barrier islands are dominated by several dynamic processes that determine their size, shape and structure. These include sea level rise, storm activity, sediment supply and the mainland’s topography. When sea level rises due to abnormally high high-tide events or as a result of storm activity, the waves can breach the foredune of the island and carry sediment to its backside, creating an overwash fan. This research was conducted to verify if a high resolution GPS survey and LIDAR data can be used to determine the relationship between topography and the location and size of overwash fans. Compared to GPS data, LIDAR is more spatially comprehensive, though it can be very expensive to collect. While, a GPS survey is more economically feasible, it entails in situ data collection, which can be very time intensive. It was found that LIDAR airborne elevation data and GPS elevation data are both viable techniques and result in comparable findings. At the study area on Masonboro Island, North Carolina, there was an inverse relationship between dune height and length of overwash fan. Therefore, during storm events, more sand is transferred from the foredune to the back barrier when there is a lower dune.